Lessons Learned from the Fukushima Nuclear Accident for Improving Safety and Security of U.S. Nuclear Plants Phase 2 (2016) / Chapter Skim
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4 Reevaluation of Findings and Recommendations from Previous NAS Reports
4 Reevaluation of Findings and Recommendations from Previous NAS Reports
Pages 88-113
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From page 88... ...
2 Completion and release of the public report was delayed because of an extended security review by the sponsoring agency (U.S. Nuclear Regulatory Commission)
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From page 89... ...
2. Safety and security advantages, if any, of dry cask storage versus wet pool storage at these reactor sites.
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From page 90... ...
and the risk these materials might be used to construct a radiological dispersal device."5 The chapter provides background information on risk assessment and a brief discussion of possible terrorist motivations for attacking a nuclear plant and its spent fuel storage facilities. The report concluded that the terrorst attack risks could not be addressed "using quantitative and com i parative risk assessments." Instead, the report examined "a range of possible terrorist attack scenarios in terms of (1)
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From page 91... ...
that the understanding of security risks at nuclear power plants and spent fuel storage facilities can be improved through risk assessment. Assessments that focus on the risk triplet -- scenarios, likelihoods, and consequences -- can contribute useful security insights for improving the protection of facilities and operations.
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From page 92... ...
8 The ACRS has oversight on all safety aspects of nuclear plants including spent fuel storage facilities. A recent example of such oversight is the July 18, 2013, ACRS letter report concerning the USNRC's Spent Fuel Study (see ACRS, 2013)
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From page 93... ...
Several programs have been put into place by the USNRC and the nuclear industry to address the trustworthiness and reliability of indi iduals v with access to nuclear plants to minimize the potential for malevolent actions, including • Fitness for duty, • Access authorization, and • Behavior observation. The committee received written documents10 and briefings on these measures from USNRC staff.
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notes that a terrorist attack that partially or completely drained a spent fuel pool could, under some condi tions, lead to a propagating zirconium cladding fire and the release of large quantities of radioactive materials to the environment. 11 The term zirconium cladding fire is used to describe the self-sustaining oxidation of zirco nium fuel cladding.
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From page 95... ...
• Finding 3E (NRC, 2006) notes that progress has been made by the USNRC and others to understand the potential vulnerabilities and consequences of terrorist attacks on spent fuel pools but that additional work is needed.
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identified particular terrorist attack scenarios that were judged by its authoring committee to have the potential to damage spent fuel pools and result in the loss of water coolant (see Section 2.2 in NRC, 2004)
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The committee finds (Finding 4.5) that these analyses confirm that reconfiguring spent fuel in pools to more evenly distribute heat loads and enhance heat transfer can be an effective strategy for reducing the likelihood of fuel damage and zirconium cladding fires follow ing loss-of-pool-coolant events.
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From page 98... ...
, which calls for an assessment of the "Safety and security advantages, if any, of dry cask storage versus wet pool storage at [commercial] reactor sites." The chapter provides background information on dry cask storage, its potential risks, as well as potential advantages over pool storage.
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From page 99... ...
• Finding 4E (NRC, 2006) notes that the USNRC might determine that earlier-than-planned movements of spent fuel from pools into dry cask storage would be prudent to reduce the potential conse quences of terrorist attacks on pools at some commercial nuclear plants, depending on the outcome of the analyses recommended in NRC (2004)
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From page 100... ...
to determine whether "earlier movements of spent fuel from pools into dry cask storage would be prudent to reduce the potential consequences of terrorist attacks on pools at some commercial nuclear plants." The committee recommends (Recommendation 4.11) that the USNRC should perform a spent fuel storage risk assessment to elucidate the risks and potential benefits of expedited transfer of spent fuel from pools to dry casks.
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From page 101... ...
The present committee received briefings from USNRC staff and the Nuclear Energy Institute (NEI) , which represents nuclear plant operators and dry cask storage vendors, on current practices for sharing securityrelated information.
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Nuclear Regulatory Commission should strengthen their capabilities for identifying, evaluating, and managing the risks from terrorist attacks. Particular attention is needed to broaden scenario identification, including asymmetric attacks; account for the adaptive nature of adversaries; account for the performance of plant security personnel in responding to the identified scenarios; estimate the potential onsite and offsite consequences of attack scenarios, including radioactive releases and psychological impacts; and develop strategies for countering the identified threats.
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From page 103... ...
: The Nuclear improve inventory controls, enhance Regulatory Commission should review inspections, and update regulatory guidance and upgrade, where necessary, its security for control and accounting of spent fuel requirements for protecting spent fuel rods and rod fragments. The Commission is rods not contained in fuel assemblies from also undertaking a rulemaking to clarify and theft by knowledgeable insiders, especially strengthen material control and accounting in facilities where individual fuel rods or requirements for these materials.
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From page 104... ...
Nuclear Regulatory Commission zirconium cladding fire and the release of has not examined the specific terrorist large quantities of radioactive materials to attack scenarios identified in that report (see the environment. Details are provided in Recommendation 3E-1 in NRC [2004]
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From page 105... ...
of spent fuel pools to terrorist attacks are plant-design specific. Therefore, specific vulnerabilities can be understood only by examining the characteristics of spent fuel storage at each plant.
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From page 106... ...
: The addressed the following important issues: Nuclear Regulatory Commission should undertake additional best-estimate • Fuel damage state and timing as a analyses to more fully understand the function of fuel age and pool water loss. vulnerabilities and consequences of loss- • Propagation of zirconium cladding fires to of-pool-coolant events that could lead other assemblies in the pool.
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From page 107... ...
The U.S. Nuclear Regulatory Regulatory Commission should ensure Commission has directed plant licensees to that power plant operators take prompt and effective measures to reduce the • Reconfigure their spent fuel in pools to consequences of loss-of-pool-coolant achieve at least a 1 × 4 dispersion of events in spent fuel pools that could result high- and low-decay-heat assemblies, in propagating zirconium cladding fires.
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From page 108... ...
Nuclear Regulatory taken to make dry casks less vulnerable to Commission is incorporating the results potential terrorist attacks. of its dry cask vulnerability analyses into its regulations through rulemaking.
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From page 109... ...
to determine whether "earlier movements of spent fuel from pools into dry cask storage would be prudent to reduce the potential consequences of terrorist attacks on pools at some commercial nuclear plants." RECOMMENDATION 4.11: The U.S. Nuclear Regulatory Commission should perform a spent fuel storage risk assessment to elucidate the risks and potential benefits of expedited transfer of spent fuel from pools to dry casks.
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From page 110... ...
The Commission has Regulatory Commission should improve sponsored key staff at these organizations the sharing of pertinent information on for national security clearances, regularly vulnerability and consequence analyses shares important security-related information of spent fuel storage with nuclear power and threat-related intelligence with industry plant operators and dry cask storage groups, and is responsive to industry requests system vendors on a timely basis. for information.
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From page 111... ...
for an Independent Spent Fuel Storage Installation1 (ISFSI) either on- or offsite, and 2.
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. Following the September 11, 2001, terrorist attacks on the United States, the USNRC carried out an evaluation of its regulatory program for spent fuel storage and initiated a rulemaking (USNRC, 2009a)
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Nevertheless, the committee recommends (Recommendation 4.10) that the USNRC give high priority to completing its analyses on dry cask storage vulnerabilities and rulemaking.
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