SMALL MODULAR REACTORS: SAFETY AND SECURITY CONCERNS
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SMALL MODULAR REACTORS: SAFETY AND SECURITY CONCERNS

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UCS and Nuclear Power. UCS has been a nuclear safety and security watchdog for more than 40 yearsUCS is neither pro- nor anti-nuclear, but believes that nuclear power will take itself off the table unless its safety, security and proliferation problems can be contained. Nuclear power after Fukushim
SMALL MODULAR REACTORS: SAFETY AND SECURITY CONCERNS

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1. SMALL MODULAR REACTORS: SAFETY AND SECURITY CONCERNS Edwin Lyman Senior Scientist, UCS Presentation to the Secretary of Energy Advisory Board SMR Subcommittee May 30, 2012

2. UCS and Nuclear Power UCS has been a nuclear safety and security watchdog for more than 40 years UCS is neither pro- nor anti-nuclear, but believes that nuclear power will take itself off the table unless its safety, security and proliferation problems can be contained

3. Nuclear power after Fukushima The Fukushima disaster revealed serious deficiencies in the design, regulation and operation of nuclear power plants Nuclear power in the future must attain a significantly higher level of safety than is currently the case This principle should apply equally to any new nuclear reactor, no matter the size

4. Safety and SMRs In general, SMRs (< 300 MWe) are not intrinsically safer than larger reactors Although heat removal for some SMR designs may be easier, safety benefits are not automatically realized Fukushima Daiichi Unit 1 was 460 MWe: not significantly greater than the upper SMR limit Unit 4 SFP was only ~ 3 MW, yet presented a major heat removal challenge Far more important are the criteria that will govern SMR design, licensing and operation: post-Fukushima requirements will be key Weakening regulatory requirements for SMRs could erode any inherent safety features provided by their design

5. Offsetting the SMR cost burden All other things equal, SMRs come out of the starting gate with a major capital cost disadvantage compared to larger reactors Major cost savings from factors such as economies of mass production and reduced upfront financing are speculative Consequently, SMR vendors seek to achieve cost savings through regulatory relief from certain operating cost requirements, including operator staffing, security and emergency planning will ?directly influence the operating cost, which will be a large determinant into the economic feasibility of these plants.? John Kelly, Deputy Assistant Secretary for Nuclear Energy, March 2011

6. Multi-module effects One SMR deployment scenario would essentially replace one large unit with multiple smaller units If the units are completely independent and core damage frequency is the same, site risk (probability times consequences) will be the same In fact, overall site risk could actually increase units will not be independent because of common-cause failures and inter-module interactions (as seen at Fukushima) Although many new reactor vendors claim that internal event core damage frequencies are lower than for current reactors, external event core damage frequency will likely dominate

7. Fukushima lessons learned A number of multi-module issues that arose during Fukushima must be addressed: Adequate operator staffing to cope with the complexities of multiple units in distress Adequate emergency equipment and personnel Adequate separation between units (both physical location and independence of support equipment) Modeling deficiencies (PRA, plume behavior)

8. Security There is an ongoing terrorist threat to domestic infrastructure that requires the utmost vigilance However, DOE and SMR vendors have emphasized that reducing security staffing is critical Whether SMRs get deployed in large numbers or not is going to come down to O&M. And the biggest variable that we can attack directly ? is the security issue.? -- Christofer Mowry, B&W, March 2011. ?Optimal security staffing levels [for SMRs] may appreciably differ from current levels.?? NEI. NRC staff believe that current regulations allow for alternative approaches that credit security by design Features like underground siting may enhance protection against some, but not all, scenarios

9. Emergency planning DOE and SMR vendors have argued that SMRs need not satisfy current emergency planning requirements because they are safer and/or smaller than current reactors NRC staff have proposed an approach by which the 10 mile evacuation planning zone could be scaled for SMRs based on analysis using mechanistic source terms However, Fukushima has shown that the current 10 mile zone provides inadequate severe accident protection NRC worst case projections found EPA evacuation criteria could be exceeded at least 50 miles away Actual release led to exceeding EPA criteria at least 13 miles away and probably much further in certain directions Long-term land contamination presents additional challenges far from the site of origin

10. Emergency planning A technically sound, source term-based methodology for emergency planning requirements is likely to lead to expanded EPZs for both large and small reactors

11. Containment performance A truly passive containment would have sufficient strength and volume to be able to withstand the internal forces generated in worst-case severe accidents by hydrogen explosions The need to reduce SMR capital cost almost certainly will drive containments to be smaller and less robust Neither active (igniters) nor passive (recombiners) means of hydrogen control are likely to be as effective as large containments

12. Conclusions SMRs are not a panacea for the economic and safety problems faced by nuclear power The ultimate level of safety provided by SMRs will strongly depend on the regulatory framework DOE and its SMR industry partners should halt their drive to weaken SMR regulatory requirements


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