Chemical Engineering 412

Transcription

1 Chemical Engineering 412 Introductory Nuclear Engineering Lecture 21 Nuclear Power Plants III Nuclear Power Plants: Advanced Reactors

2 Spiritual Thought 2

3 Fast Reactors - Advantages Most transuranics act as fuel Reduces waste toxicity Reduces waste lifetime (dramatically) Expand potential fuel Thermal is primarily odd-numbered actinides ( 235 U) Fast is all actinides, including 238 U, Th, etc. In waste Depleted uranium Actinides generated in the fuel When operated in breeder (as opposed to burner) mode, creates more fissionable fuel than it consumes, extending total available fuel.

4 Fast Reactors Disadvantages Low response time complicates control! control rods less effective, other means must be used: Fuel thermal expansion Doppler broadening Absorbers Reflectors Small cross sections large critical mass Leads to either large cores or high enrichment. Sodium and sodium/potassium highly reactive! Lead, salts and gases avoid this problem, but more absorption Liquid metals and salts can become radioactive (n, γγ) reactions 4 He avoids this problem (absorption cross section near zero). Potential positive void coefficient of liquids not He.

5 Waste 1000 Traditional Fuel Cycle Approaches Relative Radiological Toxicity Natural Uranium Ore Westinghouse Approach Transuranic Elements (TRUs) MOX Single Pass TRUs TRUs with No Pu Fission Products (same for all cases) ,000 10, ,000 1,000, years Years 2013 Westinghouse Electric Company LLC. All Rights Reserved.

6 Conversion Ratio 6 Ratio of Created fuel to burned fuel Breeder reactors 1.01 up to ~1.21 Burner reactors ~ Example: In a critical reactor fueled with natural uranium, it is observed that, for every neutron absorbed in 235U, neutrons are absorbed in resonances of 238U and neutrons are absorbed by 238U at thermal energies. There is essentially no leakage of neutrons from the reactor. What is the conversion ratio? How much 239Pu in kg is produced when 1 kg of 235U is consumed?

7 Small Modular Reactors Small < 300 MW e (IAEA definition) Right size for remote grids Insurance cutoff Modular systems can be almost entirely fabricated in shops 7, 3, 1 factory, site, hole Advantages Large reduction in capital cost! Reduction of financial risk construction at a single location ability to add incremental power. Disadvantages Loss of economies of scale. Lower Power density. Include III, III+, and IV or other designs

8 B&W ipwr SMR Design 6,8 upper and lower pressure vessels 30 reactor core 40,42 control rod insertion and guide 24 steam generator 26 pressurizer optional reactor coolants pumps and associated drive, impeller, etc. Source: Integral Pressurized Water Reactor, Patent US A1 Nov 14, 2013

9 B&W/Bechtel mpower Reactor 530 MW th developed by joint venture of Babcock & Wilcox and Bechtel, 155 to 180 MW e output on air or water cooling, respectively 13 ft diameter, 83 ft tall $226 M in DOE cost-shared funding TVA Clinch River potential host site 5% enriched fuel for 4-yr core life Construction permit target date psi (56 bar) steam w/ 50 F (28 C) superheat

10 Toshiba 4S Super-safe, small and simple (4S) design. Na-cooled fast reactor using U-Zr or U-Pu-Zr fuel, allowing operation for up to 30 years without refueling Uses a movable neutron reflector to adjust neutron population. Electro-magnetic (EM) pumps, with natural circulation used in emergencies

11 Small Modular Reactors Strengths: Grid Stability Compact and modular Economics Smaller up-front investment Safety No-large bore piping Improved passive safety (no operator action) Weaknesses: Economics Unproven, new licensing process ($1B needed) Small technology improvement for $1B Safety Still only 7 days of passive cooling in some scenarios Waste No improvement on current methods 2013 Westinghouse Electric Company LLC. All Rights Reserved.

12 Small Modular Reactors Name Power Technology Producer VK MWe BWR Atomstroyexport, Russia S-PRISM 311 MWe FBR GE Hitachi Nuclear Energy 4S MWe FNR Toshiba - Japan GT-MHR 285 MWe HTGR General Atomics (USA), Minatom (Russia) et al. PBMR 165 MWe HTGR Eskom, South Africa, et al. BREST[2] 300 MWe LFR RDIPE (Russia) Hyperion Power Module[1] 25 MWe LFR Hyperion Pwr Gen - Santa Fe, NM USA SVBR[3] MWe LFR OKB Gidropress (Russia) MASLWR 45 MWe LWR NuScale Power LLC, USA Fuji MSR MWe MSR ITHMSO, Japan-Russia-USA WAMSR 200 MW MSR Transatomic Power, USA CAREM 27 MWe PWR CNEA & INVAP, Argentina Flexblue MWe PWR Areva TA / DCNS group, France IRIS MWe PWR Westinghouse-led, international KLT MWe PWR OKBM, Russia mpower 180 MWE PWR Babcock & Wilcox, USA MRX MWe PWR JAERI, Japan NP MWe PWR Areva TA, France SMART 100 MWe PWR KAERI, S. Korea SMR MWE PWR Holtec International, USA Westinghouse SMR 225 MWe PWR Westinghouse Electric Company, USA TerraPower 10 MWe TWR Intellectual Ventures - Bellevue, WA USA BWR - boiling water reactor FBR - fast breeder reactor FNR - fast neutron reactor HTGR - high-temperature gas reactor LFR - lead-cooled fast reactor MSR - molten salt reactor PWR - pressurized water reactor TWR - traveling wave reactor

13 Traveling Wave Reactor Fast reactor core with fission igniter buried for entire 60 year or so lifetime. Reaction front propagates through core in wave fashion. Core also is long-term containment, simplifying decommissioning and waste storage. Designed at both modular and utility scales

14 Pebble Bed Reactor Inherently safe (strong Doppler effect decreases fuel reactivity with increasing temperature) VHTGR cannot have steam explosion.

15 Hybrid Designs Hybrid of HTGR and MSR Developed by both Chinese and US MIT, UW, UCB + Westinghouse and INL US DOE NEUP IRP 2011 Strengths: Safety High thermal inertia Atmospheric pressure No air-ingress Melt down-proof fuel Grid Modular, small, low investment Weaknesses: Economics Licensing, e.g. pebble locations No data, high development costs Safety Fuel handling challenges Waste How to reprocess pebbles??

16 Integral, Inherently Safe Light Water Reactor (I 2 S-LWR) 4 Loop PWR, rated at ~1000 MW e Designed to capture benefits of SMR concepts Integral PWR; primary components in RPV Elimination of large bore piping Modular construction Economically competitive Enhanced passive safety systems

17 Primary System Core Flow channels Reactor vessel internals (RVI) Pressurizer Reactor coolant pumps (RCP) Primary heat exchangers (PHX) Decay heat removal heat exchangers (DHR-HX) Flow assisting devices Reactor pressure vessel

18 Core 10.11ft Diameter 12 ft active fuel height 121 Fuel Assemblies 19 x 19 fuel grid Based on Westinghouse 17x17 RFA U 3 Si 2 pellets with SS clad 336 rods per assembly Internal CRDMS with RCCA 33 RCCAs 24 rodlets per RCCA HM Loading of 72.9 MT

19 Reflectors and Core plates Support plate below fuel assemblies 10 cm thick Core barrel supports plate via Chamfered edge Reflector consists of stainless steel rings 10 rings Stacked vertically around core Flow holes to facilitate cooling Upper Alignment plate 10 cm thick Rests on uppermost reflector Fits snugly within vessel

20 No primary piping Flow Channels Hot leg upper core barrel Pressurizer integral Pump under pressurizer, within the RPV itself PWR SG PHX, in annular region

21 Reactor Vessel Internals (RVI) Inside Upper Core Barrel Region Internal CRDMs RCC guide tubes I&C Cabling Instruments Penetrations Sampling systems

22 Integral Pressurizer Same functions as standard PWR Pressurizer Based on IRIS pressurizer Adapted based on Westinghouse SMR learning Individual standard electric heaters Pressurizer

23 Reactor Coolant Pumps Horizontally mounted, radially at top of RPV Hydraulics located in annular region below pressurizer Sealless, canned motor or wet winding pumps Circulating primary fluid cools pump internals

24 Primary Heat Exchangers Dozens of 1 mm flow channels on a 2m thick flat plate No zig-zags, turbulent flow, not laminar flow Parametric studies to find ideal arrangements Micro-channel heat exchangers (mc- HX)

25 Decay Heat Removal Heat Exchangers (DHR-HX) Decay heat removal heat exchangers (DHR-HX) Natural circulation driven Helical Coil Exchanger 115 tubes 12 rows of coils Low thermal expansion stresses Low flow resistance

26 Flow Assisting Devices Designed to mitigate minor flow losses Verified by CFD, experiment, historical use Rounded flow holes below pressurizer Flow skirt for uniform core inlet flow Beveled edges Gradual flow

27 Reactor Pressure Vessel Inner diameter of vessel of 15.4 ft Nominal thickness of 11 in Based on IRIS design Radial support flange between secondary flow nozzels for vessel support Preliminary design/functions

28 Challenges Volume requirements within RPV Water makeup volume Additional components/cabling Maintenance and personnel access Shielding Heat transfer in both SS and transients