Small Modular Reactors The Real Nuclear Renaissance?

Transcription

1 Small Modular Reactors The Real Nuclear Renaissance? Institute of Physics, Nuclear Industry Group Birchwood, 25 May 2016 Juan Matthews FInstP Dalton Nuclear Institute and School of Materials The University of Manchester Presentation to IOP 25 May

2 In the beginning there were just small reactors GEN I GEN II GEN III Reactor power (MWe) Large reactors Medium reactors Small reactors Compact reactors Presentation to IOP 25 May

3 Small reactor markets There are are essentially two markets for small reactors: 1. Small Modular Reactors (SMRs) Sizes from ~20 to 300 MWe Designed for grid connection Need to compete with other grid generation 2. Very small reactors (compact reactors) Sizes from ~1 to 20 MWe Designed mainly for off-grid and isolated generation but could be integrated into a grid Need to be easily transportable and installed Need to compete with diesel and other off-grid generation The U-Battery is an example of 2, in this presentation we look at 1. Presentation to IOP 25 May

4 USA interest in SMRs The American interest in the 1980s for SMRs was driven by EPRI and the US Department of Energy on a strategic basis, looking at requirements for nuclear power both domestically and for export. Around 2000 the focus had changed to the need to replace coal fired power stations in a fragmented deregulated generation industry. This momentum has, at least temporarily, been broken by the availability of cheap shale gas. The US DoE is currently running an SMR Technical Licensing Support Program Presentation to IOP 25 May

5 USDOE view of SMR benefits Modularity: in two senses factory fabrication of modules for a simpler assembly on site and reactor units as modules that can be added to match demand; Lower Capital Investment: lower unit of investment and lower investment per unit power from factory fabrication and shorter construction times; Siting Flexibility: smaller footprint, less demanding infrastructure and possibility of siting on existing fossil sites nearer habitation; Gain Efficiency: use of heat for industry and other applications and coupling with other generation sources for more efficiency; Non-proliferation: Depending on type of SMR could lead to reduced transport and handling of nuclear materials and longer refuelling times, possibility of sealed fuel units; International Marketplace: Opens a new nuclear market. Presentation to IOP 25 May

6 Other potential advantages of SMRs Multiple build enables reduced costs through learning; Enables existing licensed sites to be used where space is limited; Small reactors can fit into limited electrical grid in remote regions, islands and in developing countries; Small reactors are simpler and more able to use natural convection and passive safety features and to be located underground. Presentation to IOP 25 May

7 UK INTEREST IN SMRS Presentation to IOP 25 May

8 UK first interest in SMRs UK Interest in SMRs dates back to the late 1980s when it was realised that the privatisation of the electricity supply industry would make the investment in large reactors difficult. Studies at that time looked at the effect of scale on cost and the industry was still firmly looking at large reactors. The UK (Rolls Royce and AEA Technology) joined the SIR project (Safe Integral Reactor) with ABB and Stone & Webster, but in the end the dash for gas won. Presentation to IOP 25 May

9 UK current interest in SMRs UK Nuclear Industrial Strategy, March 2013: To be a key partner of choice in commercialising Generation III+, IV and Small Modular Reactor (SMR) technologies worldwide. NIRAB (Nuclear Innovation and Research Advisory Board) initiated a feasibility study with BIS support in The feasibility study was published in December 2014 by the National Nuclear Laboratory and focussed on the integral PWR design. In May 2015, DECC commissioned an in-depth Techno- Economic Assessment, which has just reported. This covers: the economic case; grid integration, market assessment and future trends; safety and manufacturing. Presentation to IOP 25 May

10 UK current interest in SMRs A report by the Energy Technologies Institute published in October 2015 looks at SMR siting and identifies SMRs as a solution to the shortage of new nuclear sites and the lack of a low carbon solution to energy for heating. The Government Spending Review in November 2015, specifically mentioned small modular reactors in the context of 250 million increased funding for nuclear. The 2016 Budget also mentioned small modular reactors. The Government is now moving to assess designs and lead companies to decide if is will support an SMR project. A 30 million Phase One of a competition was announced on 17 March 2016 and bids had to be in place by 6 May. A roadmap will be published in September Presentation to IOP 25 May

11 What is the UK looking for SMRs present an opportunity for the UK to have a stake in the development of a system that may lead eventually to involvement in GEN IV reactor construction and to be global nuclear player again. The hope is to find a project partner that will make space for UK participation and IP generation perhaps on the model of how aircraft are built. There are currently too many SMRs designs. Inevitably most will fail but the winners could eventually pick up 100s of orders. The trick is to pick the winner. The number of sites suitable for large reactors is limited and SMRs are an opportunity to use smaller sites, often nearer centres of population, to expand nuclear capacity. Presentation to IOP 25 May

12 Potential market for SMRs Source: NNL SMR feasibility study 2014 The more recent ETI study suggests this may be an underestimate as the estimate up to 21 GWe for the UK by 2050 worth 60 billion. Presentation to IOP 25 May

13 Energy Technologies Institute Study Small Modular Reactors UK Energy System Requirements For Cogeneration (October 2015) Need for nuclear power to contribute to heat supply as well as electricity generation Need for more flexible generation - load following Need to use sites too small for GWe stations Need to remove dependence on cooling water Need to site smaller stations closer to conurbations to allow the use of heat for industry and homes Potential to use over 20 GWe of SMR capacity by 2040! Presentation to IOP 25 May

14 Current and historic thermal power station locations in England and Wales From Power plant siting study August 2015, prepared for the ETI by Atkins. Presentation to IOP 25 May

15 WHAT SMR DESIGNS ARE WE CONSIDERING? Presentation to IOP 25 May

16 Range of SMR concepts In addition to small versions of current reactors, there are over 60 SMR concepts that have been studied in the last 10 years but few are likely to be built. The main thrust of recent SMR development is with Integral PWRs PWRs where the steam generator is integrated into the reactor pressure vessel (RPV). We will focus on this direction as several designs are close to market High temperature gas cooled reactors are inherently small reactors to enable heat removal in loss of coolant accidents. We have the UK U-Battery very small reactor project and China is building a twin 105 MWe pebble bed reactor station. A number of small sodium and lead alloy cooled fast reactor designs at one time looked like they might be built but currently are seen as a step too far for SMR development. There is a recent interest in molten salt reactors, which would be in the SMR range. Presentation to IOP 25 May

17 The basic components of a PWR Primary circuit Secondary circuit Core To coastal, river or cooling tower heat sink Primary pump Presentation to IOP 25 May 2016 Source 17USNRC

18 Integral PWR (origin marine reactors - Otto Hahn, submarines) Pressurizer Steam generator Control rods Steam outlet Primary circuit Core Primary pump Water inlet Secondary circuit Secondary pump Apologies to USNRC for merging their PWR and BWR animated GIFs Presentation to IOP 25 May

19 Integral PWR concepts Power MWth MWe RPV size (m) Diameter Height Core size (m) Diameter Height Primary circuit SIR (UK, USA) Forced IRIS (international) Forced CAREM (Argentina) Natural ACP-100* (China) Forced SMART (S Korea) Forced mpower (USA) Forced NuScale (USA) Natural Westinghouse SMR Forced SMR 160** (USA) Natural IMR (MHI) (Japan Natural RITM 200* (Russia) Forced *External pressuriser **Steam generators and pressurizer section of RPV offset with a dog-leg Presentation to IOP 25 May

20 Advantages of the integral PWR concept Careful design will give a considerable reduction in the NSSS cost but the main advantages are related to the safety of the system The primary circuit is kept entirely within the RPV, so no primary pipework and no active circuit outside RPV No penetrations of the RPV larger than 50 mm diameter so no large break loss of coolant accidents Increased shielding of RPV from fast neutrons Lower core power density and larger volume of water in RPV Larger surface area to power ratio, making passive decay heat removal easier Uses standard PWR fuel, but with shorter fuel rods. Presentation to IOP 25 May

21 Safe Integral Reactor (SIR) Power 300 MWe Power density 55 MW/m3 (similar to BWR) Special design features 12 modular steam generators, integral with RPV There is an extremely low fast neutron dose to the reactor pressure vessel because of the large water gap between the reactor core and the vessel wall. Vessel diameter 5.8 m Vessel height 19.2 m Source: Matzie et al, Nucl. Eng. and Design 136 (1992) 73 Presentation to IOP 25 May

22 Primary pumps Steam generators 8 helical once through modules Pressurizer CRDM Core IRIS (International Secure and Innovative) was a collaboration led by Westinghouse that included BNFL in the UK and organisations in Italy, Spain, Russia, Brazil and Japan. The main design work was done in the early 2000s, but the influence of the project can be seen in all current integral PWR designs. The design is just outside the normal definition of an SMR at 335 MWe. IRIS has the features that can be seen in designs like the Westinghouse SMR, mpower, SMART, CAREM and some Russian designs IRIS is clearly influenced by the SIR design (Westinghouse acquired ABB Combustion Engineering) but the main innovation is the sealed CRDM inside the RPV. Source: IAEA Presentation to IOP 25 May

23 Westinghouse Electric Co Source: Westinghouse Westinghouse has moved on from its role in IRIS to create its own 225 MWe SMR design Claimed to be derived from the AP1000 design but clearly built on the IRIS experience The design is much longer and thinner than IRIS and a second flange is added below the steam generators to allow easier access to the core for fuel reloading. The coolant pumps are also located lower. The Westinghouse design is well developed and has advanced along the USNRC approval but there are no specific plans to build a first plant. Westinghouse have been lobbying the UK Government since the 2015 Spending Review. Presentation to IOP 25 May

24 Generation mpower LLC The mpower design comes from B&W in the USA and was being developed as a JV with Bechtel. It is said to be based on its experience with US naval reactors, but the influence of IRIS is obvious The design has been rated at various powers but currently aims to deliver MWe. In many respects the design is very similar 180 to that of Westinghouse but the coolant pumps are still located at the top of the RPV. The containment concept is less ambitious than Westinghouse, NuScale or ACP-1000, with a larger dry containment. Discussion on construction on the TVA Clinch River Site. Plan to submit Design Certification application to the NRC After a very bullish start, several US DoE grants and substantial by late-2014 investment for approval by B&W, by the 2018projects is now essentially mothballed. B&W are looking for a partner to take a majority stake, but still hopes to be the main manufacturer. Source: Generation mpower LLC Presentation to IOP 25 May

25 NuScale Power LLC Source: NuScale NuScale started as a concept at of Oregon State University and Idaho National Laboratory but is now being developed by Fluor. From the point of view of containment and heat removal it is the most innovative of the new designs. As the only design the UK is looking at, that uses natural convection during normal operation, the reactor power is just 50 MWe. It is intended to be used in blocks of up to 12 modules (a total of only 600 MWe). Despite this an overnight cost of only $5000/kWe is claimed The CRDM system is external using conventional technology, which means the linkages are very long Rolls Royce has given support to NuScale in its US DoE funding applications. Currently the plans are to build the first plant at Idaho and it is expected that the construction and operation licence application to USNRC will be made in 2017, NuScale are lobbying the UK Government since the 2015 Spending Review. Presentation to IOP 25 May

26 ACP-100 and ACP-100+ (CNNC, China) Steam generators ACP-100+ Pressurizer Core CRDM Primary pumps The Integral PWR project closest to implementation is the the Chinese ACP-100 design which is currently being assessed for safety by the IAEA and construction is waiting Central Committee approval. The design for a 100 MWe reactor is being replaced with a 120 MWe development with several important design improvements, notably placing the CRDM and pressurizer inside the RPV. The new reactor is designated for the time being as ACP 100+ and this design is the one that the UK is looking at a possible development partnership. Source: CNNC Presentation to IOP 25 May

27 SIZE MATTERS Presentation to IOP 25 May

28 Effect of economies of scale on reactor size Source: Locatelli et al, Prog. in Nucl. Energy, 73 (2014) 75. Presentation to IOP 25 May

29 Is reactor construction time related to reactor power? 12 Timeform start of construction to ccommercial operation (years) Japanese construction times PWR BWR Reactor net power (MWe) Presentation to IOP 25 May

30 Claimed construction times (from first concrete to grid connection) Main vendor offerings VVER 1200 EPR NuScale RITM 200 IMR (MHI) ATMEA AP 1000 APR1400 ABWR Smart mpower SMR 160 Westinghouse SMR DMR (Hitachi) Current SMRs concepts Presentation to IOP 25 May

31 Variation of reactor vessel diameter with power PWR Integral PWR SMRs Reactor vessel inner diameter (m) 10 ABV 6M CAREM ACP100 SMART mpower SMR160 NuScale Westinghouse RITM 200 IRIS IMR SIR 1 P µr 3 P µr Thermal Power (MW) Presentation to IOP 20 April

32 Variation of reactor vessel diameter with power PWR BWR Integral PWR HTGR LMFBR SMRs Reactor vessel inner diameter (m) 10 1 P r 3 P r Thermal Power (MW) Presentation to IOP 25 May

33 Comparison of size of NSSS of an SMR to a regular PWR SMART NSSS Net power 100 MWe mpower NSSS Net power 180 MWe AP 1000 NSSS net power 1117 MWe 27m 18.5m 12m 6.5m OD 4m OD 4.4m OD Presentation to IOP 25 May Source: IAEA ARIS data and images

34 Comparison of size of primary containment for integral and regular PWRs. Westinghouse unit 225 MWe AP MWe NuScale unit 45 MWe mpower unit 180 MWe Source: IAEA ARIS data Presentation to IOP 25 May

35 Primary containment of Westinghouse SMR Westinghouse Electric Co Source: Westinghouse Presentation to IOP 25 May

36 NuScale Power LLC Containment NuScale Reactor vessel Modules with own containment in water pond in concrete cells SMR Containment One of the opportunities for SMR safety design is to choose a small-volume pressure suppression containment more usually found with BWR systems. The NuScale, Westinghouse and ACP-100+ designs have below ground tight steel high pressure containments. Westinghouse and NuScale can operate with the containment under vacuum, so that the reactor has no insulation and is easier to cool by flooding the containment in a loss of cooling accident. The Westinghouse and ACP-100+ containments have internal water reservoirs for pressure suppression. The NuScale design has up to 12 reactors sitting in a large fuel handling pool. Source: NuScale Presentation to IOP 25 May

37 Footprint of SMRs are they smaller? Reactor Nuclear island area Nuclear and nonnuclear Island area Total area m 2 m 2 /MWe m 2 m 2 /MWe Hectares m 2 /MWe Current designs relevant to UK EPR ~ ~ Twin 170 ~500 AP1000 ~ ~ Twin 125 ~560 ABWR ~ ~ Twin 50 ~185 SMR designs mpower ~ ~ Twin 16 ~450 Westinghouse SMR ~ ~ Single 6.5 ~290 NuScale ~ ~ x12 18 ~333 SMART ~ ~ Single ~9 ~900 HTR-PM ~ ~ Twin ~2 ~100 SMRs occupy less land in absolute terms but are comparable relatively Presentation to IOP 25 May

38 WHAT ARE THE SMR CHALLENGES FOR THE UK? Presentation to IOP 25 May

39 Overnight costs of US nuclear plant Range of US SMR claims AP 1000 US EIS data Presentation to IOP 25 May

40 SMR overnight capital cost estimates /kwe Data from SMR feasibility study, National Nuclear Laboratory, December 2014 The study had access to 4 of the best developed SMR design, the adjusted data is where the original vendor data was reassessed by the study team. Presentation to IOP 25 May

41 SMR levelised electricity cost estimates Levelised cost estimates are shown for discount rates of 5%, 8% and 10% for FY 2012 s Data from SMR feasibility study, National Nuclear Laboratory, December 2014 Presentation to IOP 25 May

42 Importance of reducing manufacturing costs An Energy Technologies Institute study has show that overturning the economies of scale for SMR is vital to their viability. The use of factory production to reduce costs might be a way of getting substantial cost reduction with production of many units. The use of residual heat for district heat makes the viability of SMR much more attainable. Cost model projections and breakeven capex levels for electricity only generic SMRs From The role of nuclear in a low carbon energy system and Energy Technologies Institute Insight Report October Presentation to IOP 25 May

43 ETI study on cost reduction From: System requirements for alternative nuclear technologies Mott MacDonald Report the Energy Technologies Institute, August (Weighted average capital cost) Presentation to IOP 25 May

44 What can we conclude about SMR costs? SMRs should be built in substantially shorter times than larger reactors SMRs will occupy much less land than larger reactors but the area occupied/kwe is not very different. Overnight costs/kwe of SMRs are similar to those of larger reactors. Levelised costs of electricity from SMRs may be smaller than from larger stations, but there is a large uncertainty which can only be resolved when an SMR building program is started. The unit cost of capital for a twin SMR station is still large for a deregulated electricity industry at around 2 billion. Presentation to IOP 25 May

45 Manufacturing issues The only way the overnight costs for SMRs can compete with larger reactors is to have simple completely modular designs that can be made efficiently in factory conditions and quickly assembled on site. If SMRs are successful then the number of systems built could be hundreds and experience from the aircraft and automotive industry might be useful. It would then be worth making the investment in tooling for automated fabrication Presentation to IOP 25 May

46 Modular construction Modular construction should extend to the whole plant. Experience from the aircraft industry shows that complex modules, weighing >100 tonnes containing multiple services can be made by different factories and assembled on site, but it needs precision. A380 Module Source: Airbus Presentation to IOP 25 May

47 Modular construction for whole plant Replacement of shuttering and rebar setting with structural modules for shield walls and main plant structures. Modules are filled with concrete once in place. Structural modules with built-in piping, cable trays, ductwork, HI-VAC and other services. Functional modules that contain a plant systems, eg water treatment. Modules need to be small enough to be transportable and where possible they should be interchangeable. Presentation to IOP 25 May

48 SMR R&D needs Integral PWRs mostly use the same technology as other LWRs and the same fuel, reduced in length. So the materials, fuel and structural integrity issues are the same ones as being faced in BWRs and PWRs, eg Zr alloy oxidation and radiation damage of the RPV. The really distinct issues for SMRs are related to: specific design features; safety; and manufacture. For lower power SMRs there is the possibility of cassette fuel replacement. Presentation to IOP 25 May

49 NNUMAN and Nuclear AMRC There are two major activities in the UK at the heart of advanced nuclear manufacturing: The EPSRC New Nuclear Manufacturing program (NNUMAN) which is does research at TRL 2-4 with 8 million investment. An 8000m 2 research factory, with 30 million investment, at the Nuclear Advanced Manufacturing Research Centre (AMRC) Manufacturing Technology Research Laboratory The University of Manchester Nuclear AMRC Research Factory University of Sheffield Presentation to IOP 25 May

50 Use of advanced manufacturing technology It has proved very difficult to introduce the latest technologies into current new build, because of barriers of licensing of established designs. SMRs offer an opportunity to avoid the barrier, decreasing costs and manufacturing times, while improving reliability. Technology being developed by NNUMAN and the Nuclear AMRC Electron and laser welding narrow gap, thick section Automatic welding of complex components steam generators Assisted machining cryogenic machining Robotic machining and process to part manufacture Diode laser cladding of primary circuit facing structures Near net shape and additive manufacture eg HIP State-of the-art metrology with virtual and augmented reality Presentation to IOP 25 May

51 Modular structure of the RPV in the mpower and Westinghouse designs. Pressurizer Upper flange Mid-flange Steam generator Pumps Steam outlet and feedwater inlet CRDM Core Westinghouse SMR mpower Presentation to IOP 25 May

52 Main components for the mpower NSSS Pressure 14 MPa Max T 320 C Main structural components low alloy SA-508 Gr. 3 steel with primary facing surfaces clad in 308 stainless steel or alloy 57. Currently large structures are likely to be forged and machined. Cladding of surfaces is done by overlay welding. Studies are being done on the use of powder metallurgical methods Steam generator tubes are Alloy 609 or a similar nimonic. The secondary circuit is largely based on low alloy steel so there are no transition welds Source: Sandusky and Lunceford, PNNL Presentation to IOP 25 May

53 Main components for the mpower core structures Core structures are mainly made of 304L or 316 nuclear grade stainless steels, but these have poor radiation resistance, largely through the high nickel content. No alternatives are available yet and this could be a life limiting feature on components. Components like support grids are made by machining large forging with high fractions of material removal, as welded structures may not be acceptable. There are opportunities for new advanced manufacturing methods Source: Sandusky and Lunceford, PNNL Presentation to IOP 25 May

54 Main components for the NuScale NSSS and primary containment Differences from the mpower design include: No recirculating pumps as the system uses natural convection; Control rod drive mechanism (CRDM) is external so the top dome has many penetrations and the control rod extensions are very long The steam generator configuration is the opposite of mpower the secondary circuit passes through the boiler tubes. The primary containment is a steel vessel fitted tightly around the reactor vessel. Source: Sandusky and Lunceford, PNNL Presentation to IOP 25 May

55 Primary coolant pump Design issues The primary pumps are usually fixed externally in a canned design with a penetration through the RPV for the drive to the impellors. Some designs dispense with pumps and operate wholly on natural convection. Control rod drive mechanism (CRDM) The long RPV and the location of steam generators and pressurizer makes design of the CRDM difficult. Some designs use a sealed internal CRDM. Steam generator The steam generators have to be compact and efficient. Many systems use modular steam generators that can be isolated and separately removed if there is a tube leak. Pressurizer The location and small volume available for the pressurizer is a challenge. Presentation to IOP 25 May

56 Westinghouse SMR CRDM The CRDMs are a high-temperature and pressure version of the recently developed AP1000 CRDM, which has already been tested to eight million steps, to be used within the pressure boundary of the SMR integral reactor. Elimination of control rod penetrations through the reactor pressure boundary has resulted in reduced cost of manufacture and the elimination of the normally-postulated rod ejection event. Source: Nuclear Engineering International Presentation to IOP 25 May

57 Safety issues Smaller reactors are easier to cool passively Some designs are very conventional in their approach to safety systems, but others, notably NuScale, take the opportunity to completely rethink heat transfer in accidents. The use of tight low volume containments. Sitting the containment in a large volume fuelhandling water pool. The use of multiple cooling routes and with low power cores the possibility of dry cooling by air convection without the melting of the reactor. Presentation to IOP 25 May

58 NuScale safety features In operation there is a vacuum between the containment vessel and the RPV. There is no need for insulation on the RPV making inspection easier. NuScale Power LLC Decay heat removal from external feed water accumulators and from main water pool. Steam generators are used to cool primary circuit. Emergency core cooling by passive convective cooling by flooding containment vessel. Any primary circuit steam is vented through reactor vent valves Presentation to IOP 25 May Source: NuScale Power LLC

59 Long term cooling in NuScale NuScale Power LLC Presentation to IOP 25 May

60 THAT ALL FOLKS! Presentation to IOP 25 May