Project Proposal and Feasibility Study

Transcription

1 Project Proposal and Feasibility Study Team 16: The Nuclear Family Meredy Brichford, Christina Headley, Joel Smith, Thane Symens Engineering 339/340 Senior Design Project Calvin College 8 December 2014

2 2014, Meredy Brichford, Christina Headley, Joel Smith, Thane Symens

3 Executive Summary The purpose of this report is to explore the feasibility of designing a thorium-fueled nuclear reactor and an accompanying small (200 MW) modular power plant. It details the research phase of this senior design project; the design phase will be completed during the spring semester. After learning the basics of nuclear physics and reactor design, the team developed proposal for a design including the consideration of reactor type, associated safety features, geographic location, cooling technologies, excess heat usage, and spent fuel disposal. System fluids, components, and materials of construction will also be chosen. Alternatives will be evaluated with respect to safety, thermal energy output, environmental impact, and economic analysis. Design variables will be optimized with data from reactors currently in operation and computer models. In addition to technical analysis, the team will combat nuclear power s stigma by emphasizing its safety and environmental benefits. This will promote caring, stewardship, and trust in the team s design and the nuclear industry as a whole.

4 Contents 1. Introduction Project Description Problem Definition Solution Customer Objective Scope Proposal Personnel Team Members... 8 Meredy Brichford... 8 Christina Headley... 8 Joel Smith... 8 Thane Symens Advisors... 9 Jeremy VanAntwerp... 9 Sigval Berg Calvin College Engineering Department Project Management Team and Document Organization Schedule Project Budget Approach Background Nuclear Physics i

5 Notation Radioactive Decay Types of Decay Half life Hazards Neutron Reactions Types of Reactions Fission Scattering Absorption Nuclear Cross Sections Critical Mass Fast vs. Thermal Spectrum Neutrons Six Factor Formula Nuclear Fuel Cycles Nuclear Power Plant Considerations Reactor Loop Moderator Fuel Reactor Core Shield Control Rods Power Loop Brayton Cycle Rankine Cycle Reactor Safety Cooling Technology ii

6 3.3. Nuclear Waste Disposal Fission Products Current Containment Technology Transportation High-Level Waste Disposal Low-Level Waste Disposal Decommissioning System Engineering Requirements Interface Requirements Functional Requirements Performance Requirements Environmental Requirements Design Criteria Alternatives Thermal Reactors Light Water Reactors Boiling Water Reactors Pressurized Water Reactors Heavy Water Reactors Supercritical Water-Cooled Reactors Very High Temperature Gas-Cooled Reactors Pebble Bed Prismatic Molten Salt Reactors Fast Reactors iii

7 Gas-Cooled Fast Reactors Liquid Metal-Cooled Reactors Lead Cooled Fast Reactors Sodium-Cooled Fast Reactors Accelerator Driven Subcritical Reactors Decisions Testing Implementation Business Plan Mission and Vision Entrepreneur's vision for the company Values and principles on which the business stands Fissionary Energy s mission Industry Profile and Overview Industry background and overview Company Objectives Strengths Weaknesses Opportunities Threats (SWOT) Analysis Competitive Strategy Market Size and Trends Advertising and Promotion Existing competitors Potential competitors Company structure Conclusion Acknowledgements References iv

8 Table of Figures Figure 1. Of the U.S. s energy consumption, 9% comes from nuclear plants Figure 2. Hubbert s peak oil prediction for the U.S. matches historical data Figure 3. The cost of electricity production varies with time and energy source. Nuclear is consistently the lowest-costing power producer Figure 4: The fission of U-233 in a Liquid Fluoride Thorium Reactor (LFTR) produces many desirable products Figure 5. A preliminary WBS was developed for the first semester Figure 6. The periodic table of elements organizes the elements by size and properties Figure 7. The electromagnetic spectrum Figure 8. The stability of a nucleus is correlated to its nucleon composition Figure 9. The minimum critical mass depends on the material properties of the fuel Figure 10: Thermal neutron flux varies with neutron energy in thermal and fast reactors Figure 11. The Th-232 fuel cycle traces an atom s path from raw material to waste [] Figure 12. Most reactor cores conform to a general basic design with the same components [] Figure 13: This method of desalination uses a distillation process combined with excess reactor heat Figure 14: Schematic diagram for desalination using reverse osmosis powered by excess heat from a nuclear reactor Figure 15: The various options for hydrogen generation that use heat from a nuclear reactor Figure 16. These are options for reactor types given certain hydrogen generation processes Figure 17. There are many uses for the extra heat that comes out of the turbine Figure 18. Uranium-235 fission products caused by thermal-spectrum neutrons Figure 19. The speed of the neutron also changes the probabilities of the fission products from Th Figure 20. The BWR has the least number of components of the different reactors Figure 21. The PWR is a simple system compared to other designs Figure 22. This block flow diagram of the HWR shows the movement of fluid throughout the system Figure 23. This detailed view inside the AHWR shows the complex piping necessary throughout the core Figure 24. The SCWR uses super critical water to cool the reactor and spin the turbine Figure 25. A general style for the very high temperature reactor that can be either pebble-bed or prismatic in configuration [] v

9 Figure 26. Inside the pebble-bed VHTGR is shown Figure 27. The fuel cell for a VHTGCR can be arranged like a prism Figure 28. Pictured is the block flow diagram of a GCFR Figure 29. Pictured is the block flow diagram of an MSR Figure 30. Pictured is the block flow diagram of an LCFR Figure 31. How the neutron spallation process happens Figure 32. Above is the component layout of SNS system at ORNL [] Figure 33. Mission and SWOT analysis diagram shown Figure 34. The annual energy produced in the U.S. [] Figure 35. Shown is hypothetical management structure of Fissionary Energy vi

10 Table of Tables Table 1. Most nuclear reactors in operation use water as a coolant and moderator and uranium as fuel Table 2. Alpha and beta decay reactions are typical of plutonium and protactinium nuclei Table 3. Penetration abilities of radioactive decay products are measured qualitatively and quantitatively Table 4. Specifications were calculated for each working fluid power cycle Table 5. As the generations progress, there is also an increased focus on safety Table 6. First-round qualitative decision matrix to eliminate certain designs Table 7. The decision matrix to decide final reactor design vii

11 Table of Symbols and Abbreviations MSR SCWR BWR PWR ORNL VHTGR GCFR SWOT HLW LLW NRC SMR EPA Molten Salt Reactor Super-Critical Water Reactor Boiling Water Reactor Pressurized Water Reactor Oak Ridge National Lab Very High Temperature Gas Cooled Reactor Gas Cooled Fast Reactor Strengths Weaknesses Opportunities Threats Analysis High-Level Waste Low-Level Waste Nuclear Regulatory Commission Small Modular Reactor Environmental Protection Agency viii

12 1. Introduction This section highlights the overall purpose and scope of the project. It includes project description, team personnel, and a description the engineering senior design project courses at Calvin College Project Description The team began by researching the problems with the current methods of power production via fossil fuels, current nuclear technologies, and renewable resources. Once identified, a project objective was developed to solve these issues and answer the needs of the intended customers. The objective was narrowed to meet the scope of the engineering senior design project class. From this analysis, a feasible project was proposed. This project will be completed and presented by the end of the spring semester Problem Definition As the world s population grows and technological advancements necessitate more electricity, electrical power generation has become a worldwide issue. Currently, the world is highly dependent on fossil fuels (Figure 1). Nuclear Electric Power 9% Renewable Energy 9% Coal 21% Petroleum 37% Natural Gas 24% Figure 1. Of the U.S. s energy consumption, 9% comes from nuclear plants [1]. However, fossil fuel reserves are dwindling. In 1956, Marion King Hubbert developed his peak theory, predicting that the production of power from any source fits a Gaussian curve. While his 1

13 prediction that U.S. oil production would peak in 1971 was accurate (see Figure 2), his world oil predictions proved pessimistic. Still, more recent and accurate studies by The Association for the Study of Peak Oil and Gas predict a peak for both between 2010 and 2040 [2]. Peak coal predictions range from 1 to 200 years in the future [3]. Figure 2. Hubbert s peak oil prediction for the U.S. matches historical data[4]. Although these predictions are imprecise and controversial, the eventual need for an alternative form of energy is undeniable. The burning of fossil fuels results in carbon emissions, which are destructive to the ozone layer. In 2004, 26% of carbon emissions came from the supplying of energy, more than any other greenhouse gas source [5].These emissions can be mitigated by the adoption of cleaner forms of energy. In fact, the Environmental Protection Agency s (EPA) Clean Power Plan proposes a thirty percent decrease in carbon pollution from 2005 by While much emphasis is placed on the development of renewable energies, nuclear energy must also be considered. Current fossil fuel plants provide dependable base load power. Nuclear power plants can also consistently produce enough power to meet demand. Renewables such as solar, wind, and wave energy are dependent on weather conditions and are, therefore, less reliable. In combination with geothermal energy and hydropower, and clean-burning materials, renewables may be capable of supplying eighty percent of the U.S. s power by 2050 [6]. However, in the transition to cleaner energy, 2

14 the diversification of fuel sources is desired, as depending on only a few sources is risky. The replacement of fossil fuel power generation should be an energy mix including both renewable and nuclear power. The stigma of nuclear technologies also prevents its implementation. Associations with nuclear weapons, radioactive waste, and power plant disasters at Chernobyl, Three Mile Island, and Fukushima contribute to the vociferous anti-nuclear movement. As of 2012, forty percent of the American population believed nuclear power plants to be unsafe [7]. In addition to technical analysis, the team must combat nuclear power s negative perception by emphasizing its safety and environmental benefits in the design. This will promote caring, stewardship, and trust in the team s design and the nuclear industry as a whole. Through the transparency of the design, it is hoped that the public will understand the benefits of including nuclear in the energy mix, as well as recognizing that nuclear reactors are a safe and feasible option for clean energy production. Besides the stigma of nuclear power, capital cost of plant construction is another drawback. It is much higher for nuclear than for other types of power plants, as nuclear requires more elaborate safety features and systems [8]. Although the cost of electricity generation by nuclear power has consistently been the lowest of the primary power sources (Figure 3), the high initial cost are a deterrent. Figure 3. The cost of electricity production varies with time and energy source. Nuclear is consistently the lowest-costing power producer [9]. 3

15 Solution The team evaluated the scarcity and environmental issues associated with fossil fuel power generation as well as the base load power requirements. This analysis pointed to nuclear power as a necessary component of the solution to the world energy crisis. Its stigma is the greatest obstacle. However, many of the issues highlighted by those of antinuclear sentiment are mitigated by the use of thorium-232 (Th-232) instead of uranium-235 (U-235) in nuclear fuel cells. U-235 is currently the most widely used nuclear fuel. This is attributed to the Cold War. When the first nuclear power plants were constructed, fissile products were desired for the manufacture of nuclear weapons. Unreacted U-235 was easier to extract from spent uranium fuel than U-233 from spent thorium fuel, making U-235 the preferable fuel. Now, however, nonproliferation concerns dominate and Th-232 s popularity is resurging. Thorium also mitigates availability and waste issues. Thorium is three times as abundant as uranium in the earth s crust. Furthermore, the only naturally occurring isotope of thorium is Th-232. Uranium reserves are less than 0.007% U-235; the balance is U-238. The enrichment process results increases the U-235 concentration to 3%. However, the 97% of U-238 is unreacted and emitted from the reactor as spent fuel. All the U-233 produced from thorium, however, is fissile; fuel from thorium does not contain high concentrations of inert material. Therefore, the radioactive waste produced by thorium reactors is roughly half of that produced by uranium reactors. Nuclear power s negative connotation can be combatted by replacing U-235 reactor fuel with U-233 from Th-232. In addition to ameliorating proliferation issues, Th-232 s recyclability reduces the production of nuclear waste. Furthermore, its abundance in the earth s crust is over three times that of natural U-235. With the current reactor fleet, peak uranium is projected to occur in 100 years [10]. Between advancements in reactor technology and the transition to Th-232, this date can be extended. To make the start-up of nuclear reactors cost competitive, a small modular reactor (SMR) will be designed. Small refers to the electrical power output, less than 200 MWe, and modular means that the reactors can be connected in series to increase power output. Most current reactors operate near 1,000 net GWe (Table 1). Compared to large industrial reactors, SMRs are simple and inexpensive; they are also compatible with lower grid capacities, not producing more power than can be consumed. The team will use 200 MW as a design basis. 4

16 Table 1. Most nuclear reactors in operation use water as a coolant and moderator and uranium as fuel [11]. Reactor type Main Countries Number GWe Fuel Coolant Moderator Pressurized Water US, France, enriched water water Reactor (PWR) Japan, Russia, China UO 2 Boiling Water Reactor US, Japan, enriched water water (BWR) Pressurized Heavy Water Reactor 'CANDU' (PHWR) Gas-cooled Reactor (AGR & Magnox) Light Water Graphite Reactor (RBMK & EGP) Fast Neutron Reactor (FBR) Sweden UO 2 Canada natural UO 2 heavy water UK 15 8 natural U (metal), enriched UO 2 Russia enriched UO 2 Russia PuO 2 and UO 2 TOTAL CO 2 water liquid sodium heavy water graphite graphite none Customer This project will target a direct and indirect customer base. The direct customers will be electrical power companies. As the nuclear plant will not be implemented for this project, the team will focus on developing a system design which could be sold to a company interested in building one. The company operating the team s reactor design would then sell electrical power to energy consumers, making them indirect customers of the team. The team will also evaluate the possibility of extracting fission products from spent fuel. The most valuable products from Th-232 reactions are Pu-238 and molybdenum-99 (Mo-99). Pu-238 is used for deep space exploration and Mo-99 is a parent isotope of technetium-99 (Tc-99), which is used in nuclear medicine [12]. Consumers of these products are indirect customers of the reactor design. See Figure 4 for a breakdown of fission products. 5

17 Figure 4: The fission of U-233 in a Liquid Fluoride Thorium Reactor (LFTR) produces many desirable products [13]. The applications of excess system heat are also sources for potential customers. The team will investigate the possibility of using excess heat in desalination and hydrogen generation processes. In the cases of both fission and waste heat products, the cost of their production will be weighed against their market value. The economic benefits will dictate the team s recommendations to the primary customer Objective The team s goal for this report is to develop the technical knowledge of nuclear engineering required to design a thorium-fueled nuclear power plant. In the subsequent semester, the team will design and perform an economic analysis on the reactor and plant. Thermal efficiency, cost, and human and environmental safety will be evaluated for each alternative. Alternative considerations include reactor type, associated safety features, geographic location, cooling technologies, excess heat usage, and spent fuel disposal. System fluids, components, and materials of construction will also be chosen Scope There are many different types of nuclear reactors currently in use worldwide such as thermal reactors, breeder reactors, and fast-neutron reactors, many of which are compatible with thorium as a fuel. 6

18 When choosing the appropriate reactor, production capacity and plant space must be considered. In addition, economic and safety issues inherent to a specific reactor design must be considered when determining the reactor to design. Research on the economic prospects of designing and building a general nuclear power plant shows that a startup cost, on average, would be approximately $1900/kWe [14]. This number may change considering the use of thorium as a fuel. It was estimated that the total capital startup cost for a plant would be around $15 - $25 billion [15]. While this is a significant cost, the lifetime of a nuclear reactor may give it an advantage over a coal-powered plant. Nuclear reactors were designed to have an expected lifetime of 30 to 40 years; however, most reactors have been shown to run on an average of 40 to 60 years before needing to be decommissioned [16]. Transportation of spent fuel isn t a huge consideration for nuclear facilities because most are designed with storage ponds that can hold the spent fuel generated over the lifetime of the reactor. Thus, location need not be a consideration when considering transportation. However, more land is necessary to build the ponds Proposal For the upcoming semester, the team proposes to finalize the reactor type decision and design its core, containment, and safety systems. The heat transfer fluid for the power loop will be chosen and the components and stream specifications decided. The thorium fuel cycle will be studied with the intent of determining the required fuel amount to produce 200 MWe of power. A plant location will be determined. Waste containment and disposal will also be considered. The methods of excess heat use will be evaluated. A cost analysis of all aspects of the plant will be performed to determine the ultimate feasibility of the implementation, although Team 16 will not physically implement the project. This design will be written in a final report and presented to the Calvin engineering faculty, public, and Thorium Energy Alliance Conference attendees Personnel The Nuclear Family consists of four Calvin College engineering students, two in the chemical concentration and two in the mechanical concentrations. They are guided by a faculty advisor and industrial consultant. Other contributors are acknowledged at the end of this report. 7

19 Team Members Meredy Brichford Meredy Brichford, a Farmington Hills native, is a senior at Calvin College studying chemical engineering and flute performance. She has held engineering internships at MacDermid (New Hudson, MI) and Vertellus Specialties (Zeeland, MI). At Calvin, she plays principal flute in the Wind Ensemble and Orchestra and is a member of the Renewable Energy Organization. She plans to pursue nuclear engineering in graduate school and is currently applying to Ph.D. programs. When she is not doing homework or practicing, Meredy enjoys reading, watching Jeopardy!, and riding her unicycle. Christina Headley Christina Headley grew up in Chesterland, Ohio where she graduated from Cornerstone Christian Academy. She is a senior at Calvin College studying chemical engineering. While at Calvin, she participated in the student martial arts club. During the summers of 2013 and 2014, she interned at Sherwin-Williams (Cleveland, OH) and Lubrizol (Wickliffe, OH) respectively. After graduating from Calvin, Christina would like to work in the food processing industry. Joel Smith Joel Smith is from Port Huron, MI and will graduate with a degree in engineering in the mechanical concentration as well as with a degree in French and a minor in Physics. He enjoys playing the trumpet with the Salvation Army as well as with the Calvin College Wind Ensemble and Orchestra, time permitting. He held an internship position at Dunn Paper (Port Huron, MI) during the summers of 2012 and After finishing his engineering degree, he plans on participating in a study abroad program through Calvin College in Grenoble, France, where he will finish his bachelor s degree for French. Then after, Joel intends to pursue a master s degree in the renewable energy field. Thane Symens Thane Symens hails from Maple Grove, MN and will be graduating from Calvin College in May of 2015 with Bachelor of Science in Engineering with a mechanical concentration and a minor in mathematics. Thane enjoys camping and being outdoors in general. He has a passion for anything that flies and is especially excited by space. After graduation, Thane will be seeking full-time employment and ultimately hopes to enter the aerospace industry. 8

20 Advisors Jeremy VanAntwerp Jeremy VanAntwerp is a chemical engineering professor at Calvin College and is Team 16 s faculty advisor. He received his undergraduate degree in Chemical Engineering from Michigan State University and his doctorate in Chemical Engineering from the University of Illinois Urbana-Champaign. Currently, he is an assistant editor for IEEE Control Systems Magazine. Sigval Berg Sigval Berg is the industrial consultant for Team 16. He attended the United States Naval Academy. He has experience in the U.S. Navy Nuclear Program, World Association of Nuclear Operators, Institute of Nuclear Power Operators, and Severn Leadership Group. In addition, he has taught informational and certification classes on the basics and operation of boiling water reactors Calvin College Engineering Department The Calvin College Engineering Program is accredited by the Engineering Accreditation Commission of the Accreditation Board for Engineering and Technology (ABET). Students who complete the program graduate with a Bachelor of Science in Engineering with concentrations in chemical, civil and environmental, electrical and computer, or mechanical engineering. Beyond achieving mastery of technical curriculum, the engineering program equips students to glorify God by meeting the needs of the world with responsible and caring engineering [17]. The engineering senior design project course sequence, Engineering 339/340, spans a two semesters. It encompasses many aspects of Christian engineering education: extensive research on a technical subject, application of design procedure, collaboration with a team of student engineers and professional leaders, presentation of a final project to the public, and Christian service through designs and interactions. 9

21 2. Project Management Project management is the underlying structure that determines the success of a project. To ensure the completion of timely and quality deliverables, organization is necessary. This process includes the organization of team interactions and documents, adherence to a proposed schedule, and evaluation of budgetary requirements. From the analysis of these aspects, an approach to the project was developed Team and Document Organization Team 16 is comprised of four senior engineering students: Meredy Brichford, Christina Headley, Joel Smith, and Thane Symens. These members are responsible for the research, design, analysis, writing, and presentation aspects of this project. They are guided by a Calvin College faculty advisor, Jeremy VanAntwerp, and an industrial consultant, Sigval Berg. The team members meet thrice weekly for senior design class time and at least one additional time. The additional meetings were predicated on the work load of a given week. At these team meetings, each member presented his or her accomplishments for the week and new tasks were assigned to be complete by the following meeting. Team 16 also regularly consults with their advisors. Meetings with Jeremy VanAntwerp occur on a roughly weekly basis. In these meetings, the previous week s accomplishments, problems, and the next week s goals were reviewed. Meetings with Sigval Berg were sparser, as he resides in Maryland. However, the group was able to meet with him once for a preliminary evaluation of the project scope and necessary research. Further communications were conducted telephonically. All project documents are kept in a senior design shared folder in Microsoft OneDrive. Each team member has editing capabilities to these documents. The project s subcategories are organized in folders within the parent folder. These categories include meeting minutes, research notes, presentations, and reports Schedule At the beginning of the semester, a work breakdown schedule (WBS) was created to organize the sequence of required tasks and deadlines (Figure 5). 10

22 Figure 5. A preliminary WBS was developed for the first semester. The duration of each task was estimated by the required finish date and the difficulty of the task. From the duration and the finish date, the start date was determined Project Budget Team 16 s deliverables will include reports, posters, and presentations. A physical model will not be built, thus construction material is unnecessary. Therefore, the use of the project budget is limited to Thorium Energy Alliance Conference (TEAC) expenses, purchase of modeling software, and printing. The team has been invited to present at the seventh annual Thorium Energy Alliance Conference. The use of the project budget to cover registration and travel expenses is currently awaiting approval. The team is researching specialized nuclear reactor modeling and simulation programs. If required, the team will select a reasonably priced program. The printing of the reports and presentation materials is not expected to exceed Calvin s allotted student printing budget. In the event of an excessive overdraft, the team s printing history will be consulted and compensation will come from the project budget. 11

23 2.4. Approach The team recognized that significant background research was needed in the realm of nuclear science and engineering. Each member is tasked to research three thorium compatible nuclear reactors in detail. Reactor research will focus on environmental impact, safety, and efficiency. From the research, a reactor will be chosen. Using the chosen reactor and thorium as a fuel a plant will be designed. 12

24 3. Background This section introduces the basics of nuclear physics, reactor design, and waste treatment Nuclear Physics Notation The composition of an atom s nucleus is notated A Z S, where A is the mass number, Z is the atomic number, and S is the chemical symbol. Each of these identifiers can be found on the periodic table of elements; Figure 6. A is the total number of nucleons (protons and neutrons) in the nucleus. Z is the total number of protons in the nucleus. S corresponds to the Z, as each Z is unique to a single element. Each element, however, can have multiple As. These species are called isotopes. Isotopes of an element are identical except for having a different number of neutrons, N. From the above nomenclature, N can be calculated (Equation 1): N = A Z (1) As Z and S are synonymous, a shorthand notation is often used to avoid redundancy: the chemical symbol followed by its mass number alone. For example, equivalent to Th is equivalent to U-235 and Th U is 13

25 Figure 6. The periodic table of elements organizes the elements by size and properties [18] Radioactive Decay Types of Decay Radioactive decay is the process by which unstable nuclei transform into stable ones. It occurs when the balance between strong nuclear and electromagnetic forces in the nucleus is upset. To fix this balance, energy must be released in the form of radiation. There are three mechanisms of radioactive decay: emission of alpha particles, beta particles, or gamma rays. Alpha particles, α 2 4, are identical to helium nuclei. Beta particles, 1 0 β or+1 0 β, are electrons or positrons, respectively. Gamma rays, 0 0 γ, are highenergy radiation with wavelengths below m; see Figure 7. 14

26 Figure 7. The electromagnetic spectrum shows the categorization of types of radiation by wavelength [19]. Decay by alpha and beta emission changes the atom from one chemical element to another. Chemical equations can be written for the decay reactions. To balance the equations, the number of protons and neutrons must be conserved. For example, Table 2. Alpha and beta decay reactions are typical of plutonium and protactinium nuclei. Particle Emitted Alpha Beta or Balanced Equation Pu 92U + 2 α (2) Pa 92U + β Pa 92U + β 1 0 (3) +1 0 (4) Positrons do not exist independently for long. They pair almost immediately with electrons. Each combination produces two gamma rays. Decay by gamma emission involves the release of energy in the form of excited photons. The result is not a different element but a lower-energy element. Gamma emission often accompanies alpha and beta decay but can occur independently as well. Decay continues until the nucleus reaches a stable state. The trend of nuclear stability is shown in Figure 8. 15

27 Figure 8. The stability of a nucleus is correlated to its nucleon composition [20]. Half life The stability of a nucleus is measured by its half-life, or the amount of time it takes for half of the initial mass of the nuclei in a sample to decay. Radioactive decay is a first-order chemical reaction, meaning that for a given element at a given temperature, the half-life is constant. Half-life data can be found. From this information, the ratio of current to initial nuclei present can be determined at any given time (Equation 5): N = ( 1 t th N 0 2 ), (5) where N 0 is the initial number of nuclei present, N is the current number of nuclei present, t is the time elapsed between initial and current conditions, and t H is the half-life of the nucleus. The longer an element s half-life, the closer it is to being stable. A half-life of 14 billion years is considered stable [21]. 16

28 Hazards Nuclear reactors have a negative connotation because of the radioactive waste they produce. There are indeed hazards associated with radioactive decay. However, the different decay mechanisms present different issues (Table 3). Table 3. Penetration abilities of radioactive decay products are measured qualitatively and quantitatively [22]. Mechanism Distance Traveled in Air (m) Shield Alpha paper or clothing Beta 2-3 heavy clothing Gamma 500 lead or concrete Alpha particles present the highest health hazard. In human bones, nuclei emit alpha particles, which exit the bones and leave a network of porous tunnels behind. Because alpha particles have a low penetration capacity, they must be inhaled, ingested, or taken in through an open wound to cause damage. This was an issue in World War II with women working in watch factories, painting glowing numbers on soldiers watches with radium, sharpening the tip of the paintbrush with their teeth, and thus ingesting the radium. Beta particles, or electrons, can cause skin damage on prolonged contact [23]. Protection from gamma rays is similar to that from the slightly less energetic x-rays. Exposure to gamma rays does not produce any lasting effects in non-fictional humans Neutron Reactions Types of Reactions In a nuclear reactor, neutrons interact with the fuel in three possible ways: fission, scattering, and capture [24]. Fission Fission is the reaction that takes place in typical nuclear reactors and provides the heat for power generation. In the fission process, a neutron is fired at a nucleus, splitting the nucleus into two fragments known as fission products. The general form of a fission reaction is U n F 1 A 1 A Z Z F ν n energy, (6)

29 where F 1 and F 2 represent fission products, ν is the number of neutrons produced in the reaction, and energy is another required product to satisfy the mass-energy balance. At this level of detail, mass and energy balances must be combined by the mass-energy equivalency (Equation 7): E = mc 2, (7) where E is energy, m is mass, and c is the speed of light. Nuclear reactors require the maintenance of chain reactions. The nuclear fission chain reaction occurs because the rate of neutron production is greater than that of neutron consumption. However, fission reactions are not the only consumers of neutrons. Scattering Neutron scattering is a phenomenon in which a change of direction or energy results from a neutron s collision with other particles. These collisions can be elastic or inelastic, but they do not result in a production of more neutrons. Absorption Neutrons can also be absorbed by the nucleus. This process is also called neutron capture. This changes the isotopic identity of the nucleus. It is the first step in the mechanism by which Th-232 is transmuted into the fissile U-233. The subsequent steps are beta decay. While this process can result in the production of reactor fuels, it also inhibits the production of new neutrons. Nuclear Cross Sections Nuclear cross sections are used to calculate the probability that a certain neutron reaction will occur. The value essentially represents the effective surface area available for collision. It adjusts for the number of nucleons and energy of the neutron. In its most general form, the cross section can be calculated (Equation 8): σ = R I, (8) where σ is the cross section, I is the neutron flux, and R is the rate of reaction occurrence per nucleus. Cross sections are typically measured in barns, which are equivalent to m 2, and are dependent on the material properties of the fuel. 18

30 Critical Mass Critical mass is the amount of fuel required to sustain a nuclear fission chain reaction in the reactor. Nuclear cross sections must be considered, as neutrons and energy lost to scattering and absorption detract from the fissibility of the fuel. Depending on the fuel, different critical masses may be required. Figure 9 shows a comparison of the critical masses for fissile materials. Figure 9. The minimum critical mass depends on the material properties of the fuel [25]. Some reactors produce enough neutrons not only to sustain a fission chain reaction, but to produce more fuel as well. These reactors are called breeders. This is only possible for fertile, not fissile, materials such as Th-232. Th-232 cannot sustain a nuclear chain reaction; it requires neutron capture to be transmuted into U-233. U-233 is fissile, which means that it can sustain nuclear chain reactions. In a breeder reactor, enough neutrons are emitted as fission products to supply both fission and absorption requirements. Fast vs. Thermal Spectrum Neutrons The core of a reactor produces energy through fission in two possible ways: thermal and fast. Thermal reactors, also known as slow neutron reactors, use a moderator, typically made of graphite, which serves as a mechanism to decrease the energy of the neutrons which in turn slows down the speed of the neutron hitting the nucleus of the fuel. A fast reactor, also known as a fast neutron reactor, works without a moderator, allowing the neutrons to hit the nucleus of the fuel at extremely high speeds [26]. 19

31 There are advantages to both fast and thermal processes. Due to its moderated speed, slow neutrons are several thousand times more likely to cause fission than fast neutrons, making it much more likely for a reaction to occur. However, only the U-235 isotope will undergo fission with a thermal reactor. Fast neutron reactors can fission U-235 as well as U-238 [27]. To better understand fast and thermal reactors pertaining to the use of Th-232, further research will be conducted. Neutron flux, or the power generation rate at any given point in time in a reactor, also varies between thermal and fast reactors [28]. Neutron flux is defined by I = nv, (9) where n is the number of neutrons per cm 3 and v is the speed of the neutrons. [29] As can be seen by the graph in Figure 10, the energy produced from fission between fast and thermal is relatively the same, but the timing of the energy output varies. This is to be expected because, while slow neutron fission produces lower levels of energy, that energy is distributed out over more time than fast neutron fission [30]. Figure 10: Thermal neutron flux varies with neutron energy in thermal and fast reactors [31]. Six Factor Formula [32] The six factor formula predicts the sustainability of nuclear reaction within the reactor core. The six factor formula is k = ηfpϵp fnl P tnl, (10) 20

32 where k is the multiplication factor. If k > 1, then the reaction is supercritical; if k < 1 then the reaction is subcritical; if k = 1 then the reaction is critical. The six factors are the thermal fission factor (η), thermal utilization factor (f), resonance escape probability (p), fast fission factor (ε), fast non-leakage probability (P FNL ), and thermal non-leakage probability (P TNL ). The thermal fission factor is η = νσ f F σ a F, (11) where ν is the average number neutrons produced per fission, σ f F is the microscopic fission cross-section for the fuel, and σ a F is the microscopic absorption cross-section of the fuel. This gives the number of fission neutrons produced per neutron absorbed by something else. The thermal utilization factor is f = Σ a F Σ a, (12) where Σ a F is the macroscopic absorption cross-section of the fuel and Σ a is the macroscopic absorption cross-section of the whole thing. This gives the probability of a neutron getting absorbed by the fuel. The resonance escape probability is N p = exp [ i=1 N ii r,a,i ], (ξ Σ p ) mod (13) where N i is the concentration of atoms per unit volume of a given nuclide [33], ξ is the average energy lost per scattering event, I r,a,i is the resonance integral for absorption, I r,a,i = E 0 Σ p mod σ i a (E ) Σ t (E de ) E E th, (14) This gives the probability that a neutron will be brought to the thermal spectrum without being absorbed. The fast fission factor is ϵ = p p u f ν f P FAF, fν t P TAF P TNL (15) 21

33 where u f is the probability that a fast neutron will be absorbed by the fuel, P FAF is the probability that a fast neutron absorption causes fission, ν f is the average number of neutrons produced per fission from fast neutrons, ν t is the average number of neutrons produced per fission from thermal neutrons. The thermal non-leakage probability is 1 P TNL = 1 + L 2 2 th B, (16) g 2 where B g is the geometric buckling and L 2 th is the diffusion length of thermal neutrons, L 2 th = D. Σ a,th (17) The fast non-leakage probability is P FNL = exp( B g 2 τ th ), (18) and τ th is E τ = 1 D(E ) E E th ξ [D(E )B 2 g + Σ t (E )] de, (19) evaluated at E, the birth energy of a neutron. Management of k is very important because if it stays above one for too long, then the reactor core can quickly run away. However, k fluctuates with time due to changes in material properties at elevated temperatures. As k increases this causes the moderator to increase in size increasing the cross-section slowing the reaction down, bringing k back to one or below one. k is affected by everything in the reactor, from geometry to working fluid. Every element matters in the core Nuclear Fuel Cycles A nuclear fuel cycle is defined as the processes undergone by a nuclear fuel from its mining to its retirement in a waste containment facility. After mining the ore, the fuel cycle typically begins with fuel preparation: 1. enrichment for U-235 (centrifugation), none required for Th oxidation 22

34 3. packing of fuel cells It is loaded into reactor, where some is fissioned. Depending on the type of fuel, more or less may remain unreacted. After remaining the core for too long, the fuel becomes poisoned with fission products. At this point, the fuel cell is removed from the reactor and placed in storage for a given amount of time. It is then retired to an approved disposal site. Figure 11 shows the nuclear fuel cycle for Th-232. Figure 11. The Th-232 fuel cycle traces an atom s path from raw material to waste [34] Nuclear Power Plant Considerations The power plant will use a two-loop system. The two loops are the reactor loop and the power loop. The reactor loop consists of the components that generate the heat necessary to run the power loop. The power loop is where the electricity is ultimately generated and consists of the components associated with that. Using two loops keep the power side from being contaminated by radiation which keeps costs for radiation shielding and employee training down. 23

35 Figure 12. Most reactor cores conform to a general basic design with the same components [35] Reactor Loop The biggest decisions in regards to the reactor loop are the fuel and the reactor core type. The fuel limits what reactor you can build and the reactor core type determines the rest of the specifications on the reactor loop side. Moderator The moderator is only present in thermal spectrum reactors. The job of the moderator is to slow down the neutrons that are present in the reactor core. U-235 is nearly 1000 times more likely to have a collision that results in fission while the neutrons are in the thermal spectrum[36]. Having the neutrons in the thermal spectrum greatly increases the likelihood of fission occurring, at least for U-235. The most common moderator material is graphite due to its high density, low likelihood of absorbing neutrons, and low cost [37]. Heavy water, D 2O, is used as a moderator in the heavy-water reactors. 24

36 Fuel The typical fuel inside of a nuclear reactor is uranium. Uranium is kept inside the reactor as solid rods reacting with itself and heating up the working fluid. Thorium would be dissolved in solution to eliminate concerns of the solid fuel rods becoming structurally unsafe, thus breaking. This also allows for evenly distributed heat generation throughout reactor core. Having thorium in solution only works for liquid metal and molten salt reactors; however, thorium is compatible with other reactors with builds similar to uranium reactors. Reactor Core The reactor core is the component where all the fission happens and needs to be the least-susceptible to failure because it will cause long-lasting radiation damage. Because it needs to be so robust, this is where most of the engineering challenges are. This is also where the fuel and moderator, if present, are kept. Each reactor/fuel combination will have different core designs to meet the specific challenges presented for each arrangement. If sodium is the working fluid, the fluid that transfers the heat from the reactor to the fluid operating the power cycle, then that means the core must be designed for corrosion mitigation, while using helium means designing for higher pressures. The high temperatures, pressures, and radioactivity present in all nuclear reactors cause the materials to undergo creep deformations faster than non-nuclear reactors. Reactor cores can be designed to be either in the fast or thermal spectrum. Shield The shield surrounds the reactor and eliminates any radiation from escaping to the environment. Research will be done in the future once the reactor type is finalized. Control Rods Control rods determine how fast the reactions are happening inside the reactor core. The moderator keeps the reaction happening in the right energy spectrum but the controls rods determine how much thermal power is actually being produced by the reactor core. Research will be conducted in the future to determine further specifications regarding control rods Power Loop The power loop side is where the electricity is actually generated. The two types of power cycles that will be analyzed are the Brayton and Rankine cycle. The Brayton cycle uses gas as the working fluid and the Rankine cycle uses a liquid of some sort. 25

37 Brayton Cycle The Brayton cycle is a thermodynamic power cycle that uses gas as the working fluid. The cycle starts compressing the fluid. Next the fluid is heated, then the high-pressure, heated fluid goes through a turbine to produce power. If the Brayton cycle is closed, then the heated gas is cooled and sent back to the beginning of the cycle. If the Brayton cycle is open, then the gas is simply expelled to the surroundings. This is the cycle that would be used in a very high temperature gas-cooled reactor with the possibility of attaching a Rankine power cycle powered by the exit gas from the Brayton cycle. Three different working fluids were tested with a mathematical model using Engineering Equation Software (EES), those being Air, Helium, and Argon. It was found that of the three, Helium had a much lower mass flow rate through the system, making it a more desirable working fluid. The calculations for these simulations can be found in Appendix B and the values for mass flow rate and required reactor heat transfer can be found in Table 5. Rankine Cycle The Rankine cycle accurately describes steam-powered heat engines. The cycle starts with saturated water then increases the pressure. The pressurized water is then super-heated, typically in a combustion chamber, then the super-heated steam is sent through a turbine to produce power. Then heat is removed from the working fluid. As with the Brayton Cycle, a mathematical model was developed for this cycle using water and steam as the working fluid. It was found that the mass flow rate needed was comparable to that of Helium. Further testing will be conducted to establish a final working fluid choice and system design for the reactor plant. Work for this system can be found in Appendix B. The values for the mass flow rate and required reactor heat transfer can be found in Table 5. 26

38 Table 4. Specifications were calculated for each working fluid power cycle. Power Cycle Brayton Rankine Working Fluid Air Helium Argon Water Mass flow rate (kg/s) Required reactor heat transfer (MW) Reactor Safety Three main characteristics of a safe reactor system can be classified as inherent based on intrinsic physics principles. Passive safety means that it is engineered in such a way to shut down the fission reactions without the need of human action [38]. Several considerations must be made when designing thermal and fast reactors. A thermal reactor design must take into careful consideration the fuel to moderator volume ratio. A concern would be the compaction of the core, which would lead to subcriticality due to lack of moderation, given an inappropriate ratio [39]. The geometry of the reactor is important for both fast and thermal reactors. Arranging the reactor fuel into a more compact shape could possibly increase the reactivity of a fast reactor, but not for a thermal reactor [40]. There are two major concerns that must be addressed when looking at fast reactor safety, those being a possible increase of fission power caused by a reactivity insertion into the reactor and any situation in which the fission chain reaction is stopped but there is not an adequate coolant flow to transfer heat from radioactive decay out of the core [41]. The coolant itself has safety consideration. One issue is the maintenance of the coolant density. A decrease of the density could cause competing reactivity effects including spectral hardening caused by a reduction of moderation by the coolant; reduced absorption by the coolant, reduction of scattering by the coolant which would lead to a higher leakage of neutrons; and higher temperatures due to the absence of coolant which could lead to larger absorption through the Doppler effect [42]. Finally, radiation from the radioactive materials must also be considered when looking at the safety aspects of a reactor design. While there is slight risk in damage from radioactivity of the fuel elements, all current reactor designs are made in such a way that several barriers and fuel cladding are put in place so to not cause a breach of harmful radiation. The possibility of the release of this material has been made in such a way that the likeliness of release of some radioactive material from the containment building would not occur more than once in a thousand years for most all reactor power plants [43]. In addition, may regulatory bodies, such as the American National Standards Institute (ANSI), American Nuclear Society (ANS), the Health Physics Society (HPS), the Institute of Electrical and 27

39 Electronics Engineers (IEEE), and the American Society for Testing and Materials (ASTM) have set regulations to maintain the safety and operation of all current and future nuclear reactor sites [44] Cooling Technology It is important, when looking at the overall reactor design, to account for the proper removal of excess heat from the system to prevent overheating of the system. Several possibilities will be considered when taking into account the need for removal of excess heat. Desalination will be a major consideration as it provides a desirable service to those without access to clean water. What is more, a possible collaboration may be considered with another design team working on a desalination system design. This would require each group to work together when deciding a location for implementation as well as power and heat output. To effectively incorporate a desalination process with a nuclear system, the process must be specified and accounted for in the transfer of heat. This process can be done with distillation process, such as a multistage flash process or multi-effect distillation process shown in Figure 13, or using reverse osmosis such as in Figure 14 [45]. Figure 13: This method of desalination uses a distillation process combined with excess reactor heat [46]. 28

40 Figure 14: Schematic diagram for desalination using reverse osmosis powered by excess heat from a nuclear reactor[47]. Hydrogen generation is another feasible alternative to useful applications of excess heat. The heat from the reactor is used in a thermochemical or electrochemical process which produces the hydrogen, the processes for which can be seen in Figure 15. A main advantage to hydrogen generation using reactor heat is that it provides heat for the thermochemical processes which require less heat to produce hydrogen in the same way that a process like electrolysis alone does, which requires a much higher minimum temperature of 2500 C for operation [48]. Figure 15: The various options for hydrogen generation that use heat from a nuclear reactor [49]. 29

41 Depending on the process chosen for hydrogen generation, different reactors must be considered, the options for which can be seen in Figure 16. If hydrogen generation is chose for use of the excess heat from the reactor, further constraint will be placed on the decision of the reactor type [50]. Figure 16. These are options for reactor types given certain hydrogen generation processes [51]. Further application for using excess heat from the reactor would be to burn garbage or provide heating for reactor facilities. If no useful application is feasible for removal of excess heat, heat removal through use of a cold body, such as a cooling tower, lake, or canal is a viable option. Several possible applications and necessary operating temperatures for said applications can be seen in Figure

42 Figure 17. There are many uses for the extra heat that comes out of the turbine[52] Nuclear Waste Disposal Fission Products Several products result from fission reactions. Since it is not known exactly how the fuel will split once reacted, there are several different stable byproducts that result. When U-235 is used as a fuel, the main byproducts are xenon, cesium-137, barium, lanthanum, cerium, strontium- 90, yttrium, iodine-131, plutonium, and zirconium [53]. Figure 18. Uranium-235 fission products caused by thermal-spectrum neutrons [54]. 31

43 When thorium-232 is used as a fuel, the possible byproducts are molybdenum-99, thorium-229, radio strontium, xenon [55]. Figure 19. The speed of the neutron also changes the probabilities of the fission products from Th-232. [56]. Proliferation is a main concern when nuclear reactors are built in foreign countries. The fear is that hostile countries will gain access to nuclear weapons fueled from the byproducts of the nuclear reactors. With uranium-235 as the fuel to the reactor, the possibility of proliferation becomes a major concern plutonium is a byproduct of uranium-235 fission. However, with thorium-232 as the fuel to the reactor, proliferation is not a concern because plutonium is not a byproduct of thorium-253 fission Current Containment Technology Transportation Transportation of nuclear waste is unavoidable and must be approached with safety being most important. There are three fundamental principles that guide nuclear waste transportation: packaging is to provide protection; the greater the hazard is, the greater the package must be; and design must assure safety.57 The federal Department of Transportation and the Nuclear Regulatory Commission (NRC) regulate how radioactive material is transported.58 The transportation vessels are designed to protect the contents from dangers both within and without the package, including excessive internal heating, criticality, free fall from 30-ft onto solid ground, and fire exposure at 1475 F for 30 min.59 Efforts have also been made to keep local emergency response teams familiar with how to handle an accident 32

44 involving the transportation of radioactive waste.60 All of this is to say that transportation of the nuclear waste is a well-established technology with safety always at the forefront of design. High-Level Waste Disposal High-level waste (HLW) is defined as waste from reactors that still has high levels of radioactivity. Often times, spent fuel is disposed of the same way as HLW despite having recoverable fuel in it.61 Before HLW is stored permanently somewhere, it has the possibility of going through reprocessing which removes some components of the waste to be used in reactors in the future (e.g. unspent U-235). However, this does not always occur as it is not always financially feasible. A popular way of storing nuclear waste is to melt glass and the waste together then pour the mixture into a canister to be stored away somewhere. The only place to legally store HLW in the U.S. is in Yucca Mountain, NV.62 Low-Level Waste Disposal Low-level waste (LLW) is waste that isn t classified as HLW and doesn t contain plutonium or other heavier artificial isotopes. It has large amounts inert material with smaller amounts of radioactive material within it. LLW includes isotopes not associated with the nuclear reaction (e.g. C-14, Ni-63) or contaminated dry materials due to maintenance or leakage of coolant (e.g. paper, metal, wood). However, the level of radioactivity can be comparable to that of HLW. Given the generally lower radioactivity LLW, it can sometimes be disposed of in near-surface containment facilities rather than deep-storage like Yucca Mountain. The material can also be burned with the ashes then being collected or the waste is shredded then stored in concrete blocks.63 Decommissioning After the useful life of a plant is reached, the plant must be shut down and taken care of accordingly. The four options provided by the NRC are SAFSTOR, ENTOMB, DECON, and delayed dismantlement. SAFSTOR is when the plant becomes an abandoned building that is subsequently monitored until a future date. ENTOMB is when all the contaminated materials are encased in concrete or are surrounded by protective barriers. The facility is still under surveillance. DECON is when the plant is immediately dismantled and all contaminated material is sent to an LLW disposal site. Delayed dismantlement is the same as DECON but with a waiting period before the plant is taken apart. 33

45 4. System Engineering 4.1. Requirements Interface Requirements Interface should be taken into consideration when taking into account workplace simplicity. However, due to the scope of this project, that being meeting consumer energy needs rather than designing a tangible product for a consumer base, the interface requirements should meet the operating standards of a typical reactor power plant. The design should be in such a way that employees can be trained in an appropriate amount of time and that outside sources and companies can be integrated into the design and working processes Functional Requirements The functionality of the reactor design will be fairly complex. The design should be such that the power output of the reactor vary depending on the needs of the local grid system dependent on it. A modular design will be the focus of the reactor design as it allows for such a variance as it produces smaller amounts of energy than a standard size reactor, but can also be linked in series with additionally added modular reactor systems for additional power if need be. The functionality of the reactor should be such that the working conditions are safe for employees and simplistic while meeting standards of reactor safety regulations Performance Requirements Due to the modular focus of the reactor, the reactor power plant will be designed in such a way that the amount of power output is approximately 200MW. A typical reactor power plant outputs significantly more energy, around several thousand megawatts of power, which is impractical for certain grid systems, such as in rural or geographically isolated areas with small populations. Using a modular design can meet the needs of any grid system without overpowering the grid system and lowering the economic impact. Furthermore, modular designs can be built to operate underground, making the design significantly less impactful on aesthetics of the area of implementation. Being respectful of the area that the reactor is implemented is one of the goal design norms of this project, that being stewardship. Additionally, the reactor is expected to use thorium as a fuel. For this reason, it is expected that the reactor will produce the desired amount of energy meanwhile producing useful waste, as mentioned in the environmental requirements section, which can be sold for economic gain. 34

46 Environmental Requirements The main concerns of reactor safety pertain to the handling and storage of useful and useless waste. With Uranium, approximately 90% of waste is useless and must be stored for a lengthy amount of time, on the order of magnitude of 10,000 years. In contrast, thorium produces several different types of useful waste, such as Pu-240 and Bis-215, as well as several others. Overall, thorium waste production is 95% useful and 5% useless. This is not only beneficial for production of useful byproducts, but also for the significant decrease in waste. Moreover, thorium waste does not need to be stored as long waste from uranium Design As this project will be completed for the engineering senior design course, design is paramount. When developing a design, alternatives were researched, decision criteria were chosen and ranked, and a decision will ultimately be made. The design process will be discussed throughout the sections, not separately at the end Criteria Being a group focused on Christian values, the design norms will be an integral part of the overall design and implementation of this project. Stewardship will be an important aspect of our project as we hope to serve the community that the reactor will be theoretically providing for. Transparency will also be an integral aspect of this project. The community should be aware of all aspects of the design that should be of concern to them. They should be able to know that the design is safe and effective. A main focus for the design of this system will be to use a modular design. A modular reactor is much smaller than a typical reactor and produces less power. There are several advantages to using a modular design, those being a low initial capital investment, flexibility in adjustable power output, ability to combine with other energy sources both renewable and fossil, and nonproliferation [64]. Additional criteria that this project is dependent on will be the overall safety of the design, thermal efficiency, safety and up-keep as well as reduction of corrosion, overall cost of the system, compatibility with a modular design, and most importantly compatibility with thorium Alternatives Several reactor types were investigated. All of the selected reactors were compatible with Th-232 and were considered either Generation III or IV reactors by the World Nuclear Association. The nuclear reactor generation system classifies the following generations seen in Table 5: 35

47 Table 5. As the generations progress, there is also an increased focus on safety. [65]. Generation Time Frame Design Characteristics I 1950s-60s natural uranium fuel graphite moderator II present enriched uranium fuel light water moderator and coolant III present (Japan) or under construction Advanced Reactors no one general design o some modifications of Gen-II reactors o some new designs IV operational by 2020 at the earliest closed fuel cycles burn actinides; produce only fission products as waste operate at high temperature (gas-cooled), low pressure (liquid metal- or salt-cooled) Both thermal and fast reactors were considered. The following section includes a brief description of the researched reactor types. Thermal Reactors As described in section 3.1, thermal fission reactions take place when the neutrons are in thermal equilibrium with the fuel. Four primary types of thermal reactors were considered for this project: light water reactors (LWRs), heavy water reactors (HWRs), supercritical water-cooled reactors (SCWRs), very high temperature gas reactors (VHTGRs), and molten salt reactors (MSRs). Light Water Reactors LWRs use light water as both the reactor moderator and coolant. Two types are in existence today: boiling and pressurized water reactors. 36

48 Boiling Water Reactors Boiling water reactors (BWRs) are the second common reactor currently in use. BWRs operate at a pressure of 75 atm and a temperature of 285 C [66]. They are classified as Generation II reactors, which means they are in the category of reactors that are currently being used. They are used currently in commercial plants and in large naval vessels. BWRs have a very simple design compared to Generation III and IV reactor designs. A BWR has only one coolant loop. Water is used as both the moderator and the cooling fuel. Water enters the reactor and flows around the reactor core. The water then boils and leaves the reactor as steam. This steam is used to turn the blades of a turbine which in turn creates electricity. Figure 20. The BWR has the least number of components of the different reactors [67]. Since the same water flows through the reactor core and passes through the turbine, the turbine has to be shielded from radionuclides contaminating the water [68]. In addition, the workers must wear protective clothing when performing maintenance on the turbine or any part of the reactor water cycle. 37

49 However, BWRs have a much simpler design that most reactors, thus there is an inherent cost savings due to the simple design which offsets some of the cost which the additional shielding [69]. Pressurized Water Reactors A pressurized water reactor (PWR) is very similar to a BWR. Like a BWR, a PWR is very common and there are 230 currently in use[70]. Like BWRs, PWRs are used in naval vessels and electricity production plants. Figure 21. The PWR is a simple system compared to other designs [71]. The design of a PWR is more intricate than a BWR. It involves two cooling circuits. In the first cooling circuit, the water flows in the vessel containing the control rods, around the cooling rods, out the vessel containing the cooling rods, through a heat exchanger, and then back into the vessel containing the control rods. This water is kept at a temperature of 325 C and a pressure of 150 atm [72]. In the second 38

50 circuit, water flows through a heat exchanger where it is vaporized. The water vapor then flows through a turbine which creates electricity and finally is condensed back to liquid water. Heavy Water Reactors Heavy water (D 2O) is a substance in which the hydrogen atoms ( 1 H) of normal (light) water are replaced with deuterium atoms ( 2 D). 2 D is an isotope of hydrogen containing two protons instead of the typical one proton. A sample of water contains ppm D 2O [73]. D 2O can simply be from H 2O, but this distillation is difficult and demands a high energy input. To remedy this, light water is subjected to single replacement reactions with other deuterated compounds such as hydrogen sulfide (HDS), ammonia (NDH 2), or aminomethane (CH3NDH) [74] (Equation 20). HX + DY DX + HY [20] The resulting compounds are easier to separate from D 2O. Because the kinetics of the latter two options are slow and require catalysis, the Girdler-Sulfide (G-S) method is preferred. Using this process, a concentration of 99.75% D 2O can be achieved [75]. Before their shutdown in 1997, four Canadian G-S plants produced over 2000 tonnes of D 2O per year [76]. The most basic heavy water reactors (HWRs) use D 2O as both the moderator and coolant. Using D 2O as a moderator presents costs and benefits. Neutrons produced by fission are moderated most efficiently when collided with particles of identical size; a larger volume of 2 D is required to slow the neutrons. However, 1 H atoms also have a higher absorption cross-section than 2 D atoms, reducing the total number of working neutrons. By preserving more of the neutrons from the fission reaction, fewer fissions must occur in the first place. Less U-235 is required, and natural (unenriched) uranium can be used. As D 2O is cheaper to obtain than enriched uranium, HWRs are more feasible on a lower budget. For this reason, HWRs are attractive to countries interested in obtaining fissionable plutonium for nuclear weapons. Therefore, the trade of heavy water is strictly regulated [ref]. The systems involved in heavy water reactors (HWRs) are similar to those in pressurized light water reactors. They each contain two loops: a reactor loop and a steam loop. The most common HWR is the Canadian Deuterium Uranium (CANDU) design (Figure 22). 39

51 Figure 22. This block flow diagram of the HWR shows the movement of fluid throughout the system [77]. The CANDU HWRs operates at a low moderator pressure, reducing leakage potential. Coolant temperatures can reach 290 C, requiring high pressures to maintain liquid phase [78]. The moderator resides in the calandria, a large tank where fast neutrons produced by fission reactions are returned to thermal equilibrium with the moderator. Fuel elements are encased in pressure tubes, which are inserted horizontally. These tubes are all independent; they can be refueled one-at-a-time without taking the reactor off line. The control rods are vertical. The Advanced CANDU Reactor (ACR) improved on the original CANDU reactor. It featured a compact, more efficient core. Light water replaced heavy water in the coolant cycle and uranium fuel was slightly enriched. The reactor was run at higher temperature and pressure, yielding higher thermal efficiency and burn-up [79]. Unfortunately, all projects were aborted before they were licensed. ref for background: 40

52 The Indians also proposed improvements to the CANDU design (Figure 18). The Advanced Heavy Water Reactor (AHWR) uses Th-232 fuel and the pressure tubes are rotated to a vertical orientation, eliminating sagging at elevated temperatures. Several passive safety features were also included[80]. negative void coefficient gravity driven water pool (heat sink) natural circulation used to remove head from core increased fuel poisoning at higher temperatures Additional safety control systems such as emergency core cooling and backup shutdown were also implemented. Figure 23. This detailed view inside the AHWR shows the complex piping necessary throughout the core [81]. Supercritical Water-Cooled Reactors SCWRs use water as the working fluid with the pressure above the critical point (22.1 MPa, 647 K). SCWRs are already a proven technology and have been used in coal-fired plants with good success. However, the addition of radiation adds engineering challenges. One of the advantages of SCWRs is that there is only one loop of working fluid. The simplicity of the design decreases overall cost and maintenance of the plant. Because the water is super-critical, the heat 41

53 transfer properties throughout the process remain relatively constant, which allows for more efficient heat transfer. This, together with higher temperatures, greatly increases the overall efficiency. Typical PWR efficiencies are around 33% while it is predicted that SCWRs would be closer to 44%. Increased efficiency means more energy for a given amount of fuel and thus higher profit related to fuel costs during the life of the plant. The overall plant can be smaller because the high enthalpies of the water means that less water is needed to supply the same power output. A smaller plant means a lower initial capital investment. Since boiling does not occur, there is no possibility for voiding to occur. The simplicity of the system is also a drawback. Because there is only one loop, all of the equipment is irradiated and requires special training for the workers and special shielding for everything at the plant. The high pressures inside the reactor mean increased material strength requirements and thus higher costs. In the event of power loss, there have not been any passive safety features that have been developed. The core has the possibility of dealing with the actinides depending on its design. Figure 24. The SCWR uses super critical water to cool the reactor and spin the turbine [82]. 42

54 Very High Temperature Gas-Cooled Reactors When considering the need for higher power energy density, the need for higher operating temperatures to increase thermal efficiency becomes increasingly important. For this reason, gas coolant becomes increasingly desirable as it can operate at very high temperatures with reduced risk of boiling effects because there is no phase change of the gas in the reactor core. When considering types of gases to use, CO 2 was first; however, CO 2 at high temperatures corrodes graphite moderators in thermal reactors. This gave cause to using helium instead, which is chemically inert, has a high specific heat, and is neutronically transparent [83]. Gas-cooled reactors (GCRs) were first developed in the United Kingdom and France; they were designed with natural uranium fuel cladded in a type of magnesium alloy. This design was known as the Magnox reactor. Soon after, advanced GCRs were developed which used 2% to 4% enriched uranium oxide fuel. This type of reactor had a higher power density and burn-up rate and are 10% more efficient than the Magnox reactor [84]. Next in development was the high temperature gas-cooled reactor (HTGR), which used graphite as a moderator and introduced helium as a coolant. During the 1960s several experimental prismatic reactors were built in places like the U.S. and France. However, in 1961, Germany began development of the HTGR using the pebble bed reactor design. Soon after, Germany built a second HTGR called the Thorium High-Temperature Reactor (THTR-300). This reactor went critical in Most recently, two other HTGRs, one in Japan and one in China, have been built which have designed outlet temperatures of up to 950 C, much higher than most other designs [85]. VHTGRs are Generation IV thermal reactors. The main characteristics of these reactors are the use of helium as a coolant and graphite as a moderator. What is more, it is expected that a VHTGR have a coolant exit temperature of above 1000 C from the reactor [86]. There are two types of reactor designs for the VHTGR: pebble bed and prismatic. This difference is discussed in the following sections. 43

55 Figure 25. A general style for the very high temperature reactor that can be either pebble-bed or prismatic in configuration [87]. Pebble Bed Pebble Bed reactors were developed in Germany approximately 20 years ago at the Juelich Research Center. The technology developed for this research reactor ran for 22 years, thus proving the feasibility of the technology. Since this first reactor, work on its advancement in design has been done at the Institute of Nuclear Energy of the Tsinghua University in Beijing, China and at the Petten Research Institute in the Netherlands [88]. Reactors using a pebble bed system use pebbles about 6 cm in diameter. These pebbles have within them microspheres approximately 0.9 mm in diameter, which are made of layers of a porous buffer, silicon carbide, and a pryocarbon outer shell. At the center of the microsphere is the fuel kernel which is typically UO 2. The pebble itself is made of graphite, serving as a moderator for the heat of the reactions [89]. For energy generation, approximately 360,000 pebbles are placed inside of the reactor core where they produce heat upon contact with each other [90]. Helium as the working fluid is then passed through the reactor core where heat is transferred out at high temperatures which can then be used to power a Brayton cycle. Further research in the design of this system have produced a new reactor concepts of this 44

56 type, such as using direct or indirect cycle helium gas turbines as opposed to steam cycles [91]. When considering safety, the pebbles only produce enough heat to reach critical mass when in contact with each other, so when they are emptied out of the core or separated, there is no risk of overheating [92]. Figure 26. Inside the pebble-bed VHTGR is shown [93]. Prismatic Prismatic gas-cooled reactors use a prismatic design for the fuel rods which house the fuel. As is with the pebble bed design, a fuel kernel, typically uranium, is covered in layers of carbon and silicon carbide. These small particles are then pressed into compacts, which being the prismatic fuel rod, analogous to the one seen in the figure. The geometry of the prismatic block which houses the fuel is important for moderating and slowing down the energy level of the neutrons created by the fission process. This allows for them to be absorbed by other fuel molecules in the core, which in turn allows for even more fission to occur. 45

57 Figure 27. The fuel cell for a VHTGCR can be arranged like a prism [94]. Molten Salt Reactors MSRs can be run in either the thermal (advanced high temperature reactors) or fast realm. For this project, only fast MSRs were investigated and will be discussed in the following Fast Reactor section. Fast Reactors Unlike thermal reactors, fast reactors do not require moderators. The neutrons are at a higher energy level than the fuel with which they interact. More information on fast reactors can be found in Section 3.1. Gas-cooled fast reactors (GCFRs), MSRs, liquid metal-cooled reactors (LMCRs), and acceleratordriven subcritical reactors (ADSRs) were researched and considered for this project. 46

58 Gas-Cooled Fast Reactors During the 1950s, much work was done with thermal gas cooled reactors. This led to the advancement of gas cooled fast reactors starting in These reactors were all based on liquid metal fast breeder reactor (LMFBR) designs, at the same time making changes for gas coolant requirements. The difference between LMFBR and GCFR fuel is that the fuel pins are roughened with small ridges perpendicular to the direction of coolant flow. This induces turbulence of the coolant and increases heat exchange between the fuel and coolant [95]. Just like VHTGRs, GCFRs are generation 4 reactors. The main design aspects of the GCFR is for having a fast reactor core without fertile blankets, meaning all new fissile fuel is bred in the core, having the breeding gain equal to zero, and creating a low fuel specific power allowing for the addition of a Brayton cycle powered by the exhaust heat of the core. These reactors operate under a closed loop system and can have one or two loop systems. Improved technology for the core of the reactor comes in the form of matrix or particle fuel designs instead of pin fuel designs to reduce release of radioactive materials into the environment [96]. After construction of the first fast reactors, gas-cooling for fast reactor systems was considered due to several advantages, one being the reduced risk of reactivity induced transients due to coolant voiding or a decrease in coolant density. Additionally, gas coolants in fast reactors reduce parasitic absorption by the coolant which causes better neutron economy and improved breeding gain [97]. A possible concern for fast gas cooled reactors is excess decay heat after shutdown. With metal cooled fast reactors, its high thermal conductivity and use of natural convection prove useful with Decay Heat Removal (DHR). With gas-cooled fast reactors, the removal of decay heat needs to be very efficient and stable without depressurization of the system[98]. 47

59 Figure 28. Pictured is the block flow diagram of a GCFR [99]. Molten Salt Reactors MSRs are reactors that use molten salt as working fluid. They allow the fuel to be dissolved in solution. In solid-fuel reactors, the fuel rods inside the reactor eventually need to be replaced because they are not structurally safe anymore due to the high-heat, radioactive environment. Having the fuel dissolved in solution also allows the actinides and fission products to be removed while the process is still running, allowing the reaction to be more efficient and less likely for the reaction to slow down. Some of these actinides decay into fuel that can be put back into the reactor, while other parts of the waste can be sold. Since the working fluid is always in the liquid state, this stops the need for high pressures inside of the reactor and piping. Decreased pressure means that the system does not need to be as strong, decreasing costs and increasing safety in the event of a system failure. On a cost basis, MSRs look very promising. 48

60 The median of five separate cost estimates put the cost of an MSR at $1.98/watt for initial capital investment, compared to $2.30/watt for coal-fired plants or $4/watt for an LWR.100 Safety is paramount with everything nuclear. An advantage of MSRs is that in the event of a power failure or a runaway reaction, the system can drain into an underground container that is designed to dissipate all the latent heat and stop the reaction. At the base of the reactor there would be a salt plug that would be cooled from the outside to keep the reaction in the reactor. But in the event of a power outage, the cooling system would turn off and the salt plug would break and release the contents of the reactor to the underground container. There are no components that need to be kept powered to keep the facility safe. Corrosion within the piping has not been completely solved. However, when Oak Ridge National Lab (ORNL) tested their MSR using FLiBe salt, corrosion was within acceptable limits to still perform safely after over 3000 hours of successful operation.101 FLiBe salt is a controlled substance because of the beryllium in it. So either the MSR will use FLiBe, which is difficult to obtain, or it will use a more common salt which will be more corrosive. When the salt becomes radiated, the resulting salt reacts much more violently with air than their non-radiated isotope. As a result, there needs to be an additional fuel loop to further remove the radiated salt from the possibility of reacting with air. This added loop increases costs and complexity of the overall system. 49

61 Figure 29. Pictured is the block flow diagram of an MSR [102]. Liquid Metal-Cooled Reactors LMCRs use liquid metal as the coolant and moderator for the reactor system. Lead and nadium are the metals most commonly used in LMCRs. Lead Cooled Fast Reactors While lead-cooled fast reactors (LCFRs) are still in the development phase, there are plans to construct several by Belgium plans to build an LCFR which they call MYRRHA [103]. 50

62 Figure 30. Pictured is the block flow diagram of an LCFR [104]. The working fluid for LCFRs is lead. Lead has a boiling point of 1,740 C [105]. Thus, unlike PWRs, LCFRs do not have to operate under high pressures, which eliminates the safety risk of flashing if pressure is suddenly reduced. In addition, unlike sodium, lead does not readily react with water vapor in the air. LCFRs can be used as a burner to consume actinides from spent LWR fuel [106]. In addition, LCFRs produce electricity and hydrogen. On the down side, lead becomes increasingly corrosive with higher operating temperatures. Sodium-Cooled Fast Reactors Sodium-cooled fast reactors (SCFRs) are almost identical to LCFRs. They use liquid sodium as the working fluid instead of lead. These reactors were not originally researched by the team but were suggested by Dr. Alan Waltar of the Pacific Northwest National Laboratory (PNNL). More information will be gleaned in the near future to make an informed decision. SCFRs currently seem like a feasible option, although concerns must be raised about possible leaks and contact with water. 51

63 Accelerator Driven Subcritical Reactors ADSRs, also known as energy amplifiers, are attractive due to their inherent safety features and ability to incinerate hazardous radioactive waste. By design, they are supplied with less than the critical mass of fuel. Therefore, it is impossible for a meltdown to occur. For instance, in the event of a power outage, the particle accelerator would lose power and stop supplying the neutrons necessary to sustain fission in the reactor. Particle accelerators can be used with many reactor designs. They act as the neutron source alone; the rest of the system can be modified separately. Most often, ADSRs are paired with LCFRs, as in Belgium, but HWRs are also being developed in India [107]. Neutrons are produced in a process called spallation. High-energy protons bombard a heavy metal target and emit a stream of fast neutrons, which is sent to the reactor core (Figure 27). The heavy metals are often of the actinide family, the long-lived waste products of nuclear fission reactions. These radioactive materials are incinerated in the spallation process, reducing waste reserves and producing fast neutrons simultaneously. Figure 31. How the neutron spallation process happens [108]. Oak Ridge National Laboratory (ORNL) has been at the forefront of the development of spallation neutron source (SNS) technology (Figure 32). They use a 1.4-MW linear accelerator to produce neutrons. However, most current ADSR designs require 3- to 4-MW accelerators; the current holdback is not the 52

64 ADSR itself but accelerator technology. Earlier in 2014, the Swedish Nuclear Regulator (SSM) presented a proposal for the European Spallation Source (ESS), which would provide neutron beams thirty times brighter than SNS. This program is to be launched in 2025[109]. Figure 32. Above is the component layout of SNS system at ORNL [110]. Additionally, the large size of particle accelerators may break containment barrier requirements. Reactor down time may also increase due to both accelerator and reactor system maintenance. While ADSRs present safety and environmental benefits, their logistical drawbacks make them reactors of the future, not the present Decisions The decision-making process began with choosing a fuel. The team exhibited a shared interest in the budding technologies associated with Th-232. Additionally, upon discovery of the Thorium Energy 53

65 Alliance (TEA), the prospect of presenting at their conference in May was a deciding factor. Originally, the plan was to research reactor-fuel pairs together to find the absolute optimum reactor design in terms of safety, environmental impact, thermal efficiency, and economics. However, this broadened the scope of the project significantly. To maintain feasibility, a fuel was selected first. Th-232 presented many benefits over U-235, yet was not as futuristic as Pu-240 or U-238. For these reasons, Th-232 was chosen as a basis for reactor design. This decision narrowed the spectrum of reactor possibilities. World Nuclear Association resources were consulted to determine which reactor types were compatible with Th-232, resulting in the reactor alternatives listed in Section Several reactors were eliminated qualitatively due to overarching deficiencies see Table 6. Table 6. First-round qualitative decision matrix to eliminate certain designs. Reactor Type Eliminated Reason GCFR X too futuristic for scope of feasible project VHTGR, prismatic VHTGR, pebble bed HWR ADSR X too complex for scope of feasible project SCWR X radionuclide contamination of water (one loop only) MSR LWR, BWR X radionuclide contamination of water (one loop only) LWR, PWR X Lack of innovative technology LMCR, Pb LMCR, Na The remaining reactors, all Generation IV reactors, are compared in Table 7. The MSR is the best option and that is what the team will pursue moving forward. 54

66 Table 7. The decision matrix to decide final reactor design. Reactor Type Safety (40) Corrosion (10) Environmental Impact (15) Thermal Efficiency (25) Availability of coolant (10) Total VHTGR MSR LMCR (lead) LMCR (sodium) LWR HWR The team weighted safety the heaviest because nuclear radiation and potential dangers need to be avoided at all costs. Safety included passive safety features, safety to works, and considered how much damage would be dealt to workers and the surrounding area. Corrosion considers how the inside of the structure will corrode with time. It is only a large consideration when dealing with the MSR and sodium LMCR. Environment impact deals with environment considerations in the design and manufacturing of the fuel and coolant. Thermal efficiency was second most important because that is closely tied with the economics of the plant. The MSR and LMCRs ranked best because of the coolants can be pushed to very high temperatures without worrying about increased pressure in the system. The coolant in the MSR and VHTGR are hard to come by due to their low production, as with the MSR, or because there isn t much of the coolant available, as with the VHTGR. Ultimately, the MSR was the found to be the best choice Testing Physical construction and testing of a nuclear reactor is not in the realm of possibility for this project. However, simulations can be run. In the spring semester, the team plans to investigate the use of UNISIM, a chemical engineering modeling program. If nothing else, the steam-side cycle can be modeled, analyzed, and tested given a heat input from the nuclear reactor. The team hopes to simulate nuclear reactions in a reactor model as well. The team also plans to visit the D.C. Cook Nuclear Plant in Bridgeman, MI before May. This trip will offer a first-hand view of the operations, requirements, and scope of a nuclear plant. The Cook Nuclear Plant runs two 1500 MWe PWRs while The Nuclear Family plans to design an SMR using a different moderator and coolant. Still the team hopes to develop experiential knowledge of the nuclear industry as a whole and apply it to a more advanced yet smaller-scale project. Finally, the team hopes to attend and present at the TEA Conference in Chicago in May of Some contact has been made with the executive director, so the outlooks are promising. This will provide 55

67 an opportunity to share what we have learned, receive critique on our research and design, and learn from experts on thorium nuclear fuel Implementation Careful consideration will be taken when looking at the implementation of this reactor design. It is the intention of this project that the reactor power plant meet the needs of a real world energy need. The actual customer base and location of implementation will be decided once the reactor design specifications, such as power output and required land area, have been determined. 56

68 5. Business Plan Team 16 completed a business plan for a hypothetical company called Fissionary Energy. For the business project, it was assumed that the company s design was successful and repeatable. A summary of the report is included in the following section Mission and Vision A vision and mission statement outlines the founding principles of Fissionary Energy and the goals which Fissionary Energy strives to achieve Entrepreneur's vision for the company Fissionary Energy s vision is to sell the design of small modular thorium power plants. The company envisions a source of power that mitigates the energy crisis, operates safely, and is environmentally friendly Values and principles on which the business stands The three design principles on which Fissionary Energy was founded are caring, stewardship, and trust. The first design principle is caring. The company demonstrates caring by addressing the world energy crisis. We hope to lessen this issue by providing a source clean, long-lasting energy. The second design principle is stewardship. Unlike burning coal, nuclear power does not contribute to the carbon footprint. Radioactive waste is a popular source of dissent with nuclear power. By employing thorium, nuclear fuel can be recycled, all but eliminating radioactive waste. Most importantly, the aforementioned design norms are meaningless without trust. A lot of negative stigma surrounds nuclear power because of its association with nuclear plant disasters and nuclear weapons. To combat this view, Fissionary Energy must design safe, efficient, and environmentally-friendly reactors and convey this reality to the skeptical public Fissionary Energy s mission Our mission is to: contribute to the advancement of nuclear technology while maintaining safety, efficiency, and environmental health. promote trust, caring, and stewardship through our designs. 57

69 5.2. Industry Profile and Overview Industry background and overview Nuclear power has been around since the 1960s as a result of the Manhattan Project. Despite its 50- year history, only 19% of the United States power is supplied by nuclear energy. This is true mostly because of the public s perception of nuclear power and the government s refusal to fund research and development. Until the last month, France was pushing for 100% electricity generation from nuclear sources. There are currently 62 nuclear power plants located in the U.S. producing just over 100,000 MWe. In France, there are 20 operational nuclear power plants, supplying 75% of the country s needs Company Objectives The objectives of Fissionary Energy include operational, financial, and anastigmatic goals. This section addresses the company s desire to create a consulting firm with enough income to support further research and development. We also hope to address public concerns regarding nuclear energy. The operational goal of Fissionary Energy is to consult with electric power companies on the design and implementation of small modular molten salt reactors (SMMSR). The financial goal is to turn enough profit from design sales and consulting fees to fund continual improvements on our design. The anastigmatic goal is to combat the stigma of nuclear energy through transparency. The management team will promote communication between the public and nuclear engineers and will dedicate time to creating a positive online and physical presence in the community Strengths Weaknesses Opportunities Threats (SWOT) Analysis SWOT is a form of analysis which aids the development of a business plan. It stems from the mission, vision, and goals of the company. By performing this analysis, Fissionary Energy acknowledged the challenges the company will face and highlighted the strengths on which Fissionary Energy should capitalize to combat these challenges. These features include considerations both internal and external to the company. Figure 33 shows a graphical outline of the SWOT analysis. Figure 33 shows a graphical outline of the SWOT analysis. A more detailed description of each facet follows in its respective section. 58

70 Internal Strengths: cutting edge thorium reactor technology small modular design Internal Weaknesses: inexperience of design team Mission: to contribute to the advancement of nuclear technology while maintaining safety, efficiency, and environmental health to promote trust, caring, and stewardship through our designs Analysis External Opportunities: growing interest in safe, clean, inexpensive power advancements in fuel and reactor technology fission byproducts and waste heat use External Threats: stigma of nuclear energy alternative power sources o fossil fuels o uranium o renewables Strategy Figure 33. Mission and SWOT analysis diagram shown Competitive Strategy The primary modes of competition are cost, differentiation, and response. Cost refers to the pricevalue relationship of the product, differentiation to its uniqueness, and response to the company s ability to adjust to the demands of the market in a timely fashion. The team evaluated Fissionary Energy s ability to compete on each of these principles and the company will be competing primarily on differentiation due to the unique, cutting-edge design Market Size and Trends For the United States, the market size of energy production is on the order of 4,000 billion kilowatt hours per year. As seen in Figure 34, the energy production has been increasing until the past ten years where it has leveled off likely due to the economic recession. 59

71 Figure 34. The annual energy produced in the U.S. [111]. This 4,000 billion kilowatt hours per year of generation is worth over 430 billion dollars. Over the past couple of year the production of energy has hit a standstill due to the energy crisis, yet the demand continues to increase to the point where large energy companies suggest to their customers ways to reduce their energy use. With the increase of power production, there will be an increase in demand and thus an increase in the size and number of large energy companies looking for new ways to produce additional energy Advertising and Promotion Fissionary Energy's message is show that nuclear energy is safe and cost effective. The current lull in energy production can be overcome safely through the implementation of nuclear power plants. Thus, an increase in business will likely result. In the media, Fissionary Energy will emphasize the nuclear plants passive and active safety precautions to counteract the sigma surrounding nuclear power. For example, in the event that the reactor core reaches a critical temperature, an automatic shutoff will commence without the initiation of a technician. Specifically, safety features will be shown through an online lecture series hosted by the engineering management team. 60

72 Fissionary Energy will outsource marketing tasks to an independent specialized company. However, we will rely heavily on the communication of large energy companies to overcome the public s stigma of nuclear power plants. Much of the selling of the nuclear power plant design will be done by Fissionary Energy reaching out to large energy companies, which will not require a large allocation of money Existing competitors Current direct competitors with our product are other power plants. The primary good that the reactors will produce is electricity which is readily acquired from existing technologies. Westinghouse Nuclear is the world s current leading provider for nuclear power plants Potential competitors FLiBe Energy is a company that is dedicated to making thorium reactors a reality. They are in the development phase of their own small modular molten salt reactor (SMMSR) that makes 50 MW of power. The company is headed by Kirk Sorensen, a thorium activist, who already has many years of experience in the nuclear industry. While renewable energies are not a direct competitor with Fissionary Energy, with advances in renewables technologies they could reduce the need for nuclear energy by supplying more power to the grid Company structure Fissionary Energy is a limited liabilities company (LLC). It is owned and operated by its current employes, due to the fact that only its six employees (named in Figure 35) have invested time and money into the company. The company management outline is modeled as a consulting firm. 61

73 Figure 35. Shown is hypothetical management structure of Fissionary Energy. 62

74 6. Conclusion The team has begun the design of a nuclear power plant. The plant will run on thorium fuel, which mitigates availability and waste issues associated with uranium. The reactor will be a small (200 MW) modular design. The team has decided on an MSR, which operates in the thermal spectrum. This design decision will be finalized by the first week of the spring semester. The team has also analyzed working fluid and system designs of the power loop. Further research is needed before making a decision on this system. Moving forward, the team will design the safety systems, waste disposal plan, and perform an economic analysis. The background research accomplished this semester gave the team a basic knowledge of nuclear and reactor physics, which can be applied to the reactor design next semester. Additionally, classes in thermal design and control systems will provide the team with enough technical information to complete the design of the entire plant. Guidance from nuclear experts will be sought, especially the team s industrial consultant, Sigval Berg, and members of the Thorium Energy Alliance. In conclusion, the team has decided that the proposed project plan is feasible to complete by May of

75 Acknowledgements The Nuclear Family would like to acknowledge Alan Waltar for providing valuable information on modular reactors. Furthermore, The Nuclear Family would like to acknowledge Sigval Berg for his invaluable insight into nuclear reactors, his continual support of The Nuclear Family, and for the informative documents he provided to the team. Lastly, The Nuclear Family would like to acknowledge Professors Jeremy Van Antwerp, Aubrey Sykes, and Matthew Heun for their advice and suggestions regarding the project. 64

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82 Appendices Appendix A: Generation IV Reactor Properties Appendix B: Thermal Analysis of Working Fluids for Power Loop

83 Appendix A: Generation IV Reactor Properties Reactors/ A-1