Fuel-Cladding Issues in Postulated Spent Fuel Pool Accidents, 29761-29765 [2016-11212]

Download as PDF 29761 Rules and Regulations Federal Register Vol. 81, No. 93 Friday, May 13, 2016 This section of the FEDERAL REGISTER contains regulatory documents having general applicability and legal effect, most of which are keyed to and codified in the Code of Federal Regulations, which is published under 50 titles pursuant to 44 U.S.C. 1510. The Code of Federal Regulations is sold by the Superintendent of Documents. Prices of new books are listed in the first FEDERAL REGISTER issue of each week. NUCLEAR REGULATORY COMMISSION 10 CFR Part 50 [Docket Nos. PRM–50–108; NRC–2014– 0171] Fuel-Cladding Issues in Postulated Spent Fuel Pool Accidents Nuclear Regulatory Commission. ACTION: Petition for rulemaking; denial. AGENCY: The U.S. Nuclear Regulatory Commission (NRC) is denying a petition for rulemaking (PRM or the petition), PRM–50–108, submitted by Mr. Mark Edward Leyse (the petitioner). The petitioner requested that the NRC require power reactor licensees to perform evaluations to determine the potential consequences of various postulated spent fuel pool (SFP) accident scenarios. The evaluations would be required to be submitted to the NRC for informational purposes. The NRC is denying the petition because the NRC does not believe the information is needed for effective NRC regulatory decisionmaking with respect to SFPs or for public safety, environmental protection, or common defense and security. DATES: The docket for the petition, PRM–50–108, is closed on May 13, 2016. SUMMARY: Please refer to Docket ID NRC–2014–0171 when contacting the NRC about the availability of information for this petition. You may obtain publicly-available information related to this petition by any of the following methods: • Federal Rulemaking Web site: Go to https://www.regulations.gov and search for Docket ID NRC–2014–0171. Address questions about NRC dockets to Carol Gallagher; telephone: 301–415–3463; email: Carol.Gallagher@nrc.gov. For ehiers on DSK5VPTVN1PROD with RULES ADDRESSES: VerDate Sep<11>2014 14:42 May 12, 2016 Jkt 238001 technical questions, contact the individual listed in the FOR FURTHER INFORMATION CONTACT section of this document. • The NRC’s Agencywide Documents Access and Management System (ADAMS): You may obtain publiclyavailable documents online in the ADAMS Public Document collection at https://www.nrc.gov/reading-rm/ adams.html. To begin the search, select ‘‘ADAMS Public Documents’’ and then select ‘‘Begin Web-Based ADAMS Search.’’ For problems with ADAMS, please contact the NRC’s Public Document Room (PDR) reference staff at 1–800–397–4209, 301–415–4737, or by email to pdr.resource@nrc.gov. The ADAMS accession number for each document referenced (if it is available in ADAMS) is provided the first time that it is mentioned in the SUPPLEMENTARY INFORMATION section. For the convenience of the reader, instructions about obtaining materials referenced in this document are provided in Section IV, ‘‘Availability of Documents,’’ of this document. • The NRC’s PDR: You may examine and purchase copies of public documents at the NRC’s PDR, O1–F21, One White Flint North, 11555 Rockville Pike, Rockville, Maryland 20852. FOR FURTHER INFORMATION CONTACT: Daniel Doyle, Office of Nuclear Reactor Regulation; U.S. Nuclear Regulatory Commission, Washington, DC 20555– 0001; telephone: 301–415–3748; email: Daniel.Doyle@nrc.gov. SUPPLEMENTARY INFORMATION: Table of Contents I. The Petition II. Reasons for Denial III. Conclusion IV. Availability of Documents I. The Petition Section 2.802 of title 10 of the Code of Federal Regulations (10 CFR), ‘‘Petition for rulemaking—requirements for filing,’’ provides an opportunity for any interested person to petition the Commission to issue, amend, or rescind any regulation. The NRC received a petition dated June 19, 2014, from Mr. Mark Edward Leyse and assigned it Docket No. PRM–50–108 (ADAMS Accession No. ML14195A388). The NRC published a notice of docketing in the Federal Register (FR) on October 7, 2014 (79 FR 60383). The NRC did not request public comment on the petition PO 00000 Frm 00001 Fmt 4700 Sfmt 4700 because sufficient information was available for the NRC staff to form a technical opinion regarding the merits of the petition. The petitioner requested that the NRC develop new regulations requiring that: (1) SFP accident evaluation models use data from multi-rod bundle (assembly) severe accident experiments for calculating the rates of energy release, hydrogen generation, and fuel cladding oxidation from the zirconium-steam reaction; (2) SFP accident evaluation models use data from multi-rod bundle (assembly) severe accident experiments conducted with pre-oxidized fuel cladding for calculating the rates of energy release (from both fuel cladding oxidation and fuel cladding nitriding), fuel cladding oxidation, and fuel cladding nitriding from the zirconiumair reaction; (3) SFP accident evaluation models be required to conservatively model nitrogen-induced breakaway oxidation behavior; and (4) licensees be required to use conservative SFP accident evaluation models to perform annual SFP safety evaluations of: postulated complete loss-of-coolant accident (LOCA) scenarios, postulated partial LOCA scenarios, and postulated boil-off accident scenarios. The petitioner referenced recent NRC post-Fukushima MELCOR simulations of boiling-water reactor Mark I SFP accident/fire scenarios. The petitioner stated that the conclusions from the NRC’s MELCOR simulations are nonconservative and misleading because their conclusions underestimate the probabilities of large radiological releases from SFP accidents. The petitioner asserted that in actual SFP fires, there would be quicker fuelcladding temperature escalations, releasing more heat, and quicker axial and radial propagation of zirconium (Zr) fires than MELCOR simulations predict. The petitioner stated that the NRC’s philosophy of defense-in-depth requires the application of conservative models, and, therefore, it is necessary to improve the performance of MELCOR and any other computer safety models that are intended to accurately simulate SFP accident/fire scenarios. The petitioner stated that the new regulations would help improve public and plant-worker safety. The petitioner asserted that the first three requested regulations, regarding zirconium fuel cladding oxidation and nitriding, as E:\FR\FM\13MYR1.SGM 13MYR1 29762 Federal Register / Vol. 81, No. 93 / Friday, May 13, 2016 / Rules and Regulations ehiers on DSK5VPTVN1PROD with RULES well as nitrogen-induced breakaway oxidation behavior, are intended to improve the performance of computer safety models that simulate postulated SFP accident/fire scenarios. The petitioner stated that the fourth requested regulation would require that licensees use conservative SFP accident evaluation models to perform annual SFP safety evaluations of postulated complete LOCA scenarios, postulated partial LOCA scenarios, and postulated boil-off accident scenarios. The petitioner stated that the purpose of these evaluations would be to keep the NRC informed of the potential consequences of postulated SFP accident/fire scenarios as fuel assembles were added, removed, or reconfigured in licensees’ SFPs. The petitioner stated that the requested regulations are needed because the probability of the type of events that could lead to SFP accidents is relatively high. The NRC staff reviewed the petition and, based on its understanding of the overall argument in the petition, identified and evaluated the following three issues: • Issue 1: The requested regulations pertaining to SFP accident evaluation models are needed because the probability of the type of events that could lead to SFP accidents is relatively high. • Issue 2: Annual licensee SFP safety evaluations and submission of results to the NRC is necessary so that the NRC is aware of potential consequences of postulated SFP accident/fire scenarios as fuel assemblies are added, removed, or reconfigured in licensees’ SFPs. • Issue 3: MELCOR is not currently sufficient to provide a conservative evaluation of postulated SFP accident/ fire scenarios for use in the PRMproposed annual SFP evaluations. Detailed NRC responses to the three issues are provided in Section II, ‘‘Reasons for Denial,’’ of this document. II. Reasons for Denial The NRC is denying the petition because the petitioner failed to present any significant information or arguments that would warrant the requested regulations. The first three requested regulations would establish requirements for how the detailed annual evaluations that would be required by the fourth requested regulation would be performed. It is not necessary to require detailed annual evaluations of the progression of SFP severe accidents because the risk of an SFP severe accident is low. The NRC defines risk as the product of the probability and the consequences of an accident. The requested annual VerDate Sep<11>2014 14:42 May 12, 2016 Jkt 238001 evaluations are not needed for regulatory decisionmaking, and the evaluations would not prevent or mitigate an SFP accident. The petitioner described multiple ways that an extended loss of offsite electrical power could occur and how this could lead to an SFP fire. In order for an SFP fire to occur, all SFP systems, backup systems, and operator actions that are intended to prevent the spent fuel in the pool from being uncovered would have to fail. The NRC does not agree that more detailed accident evaluation models need to be developed for this purpose, as requested by the petitioner, because the requested annual evaluations are not needed for regulatory decisionmaking. The NRC recognizes that the consequences of an SFP fire could be large and that is why there are numerous requirements in place to prevent a situation where the spent fuel is uncovered. This section provides detailed NRC responses to the three issues identified in the petition. Issue 1: The Requested Regulations Pertaining to SFP Accident Evaluation Models Are Needed Because the Probability of the Type of Events That Could Lead to SFP Accidents Is Relatively High The petitioner stated that the requested regulations pertaining to SFP accident evaluation models are needed because the probability of the type of events that could lead to SFP accidents is relatively high. The petitioner stated that an SFP accident could happen as a result of a leak (rapid drain down) or boil-off scenario. Furthermore, the petitioner notes that in the event of a long-term station blackout, emergency diesel generators could run out of fuel and SFP cooling would be lost, resulting in a boil-off of SFP water inventory and a subsequent release of radioactive materials from the spent fuel. The petitioner also provided several examples of events that could lead to a long-term station blackout and, ultimately, an SFP accident, such as a strong geomagnetic disturbance, a nuclear device detonated in the earth’s atmosphere, a pandemic, or a cyber or physical attack. NRC Response Spent nuclear fuel offloaded from a reactor is initially stored in an SFP. The SFPs at all nuclear plants in the United States are robust structures constructed with thick, reinforced, concrete walls and welded stainless-steel liners. They are designed to safely contain the spent fuel discharged from a nuclear reactor under a variety of normal, off-normal, and hypothetical accident conditions PO 00000 Frm 00002 Fmt 4700 Sfmt 4700 (e.g., loss of electrical power, loss of cooling, fuel or cask drop incidents, floods, earthquakes, or extreme weather events). Racks fitted in the SFPs store the fuel assemblies in a controlled configuration so that the fuel is maintained in a sub-critical and coolable geometry. Redundant monitoring, cooling, and water makeup systems are provided. The spent fuel assemblies are typically covered by at least 25-feet of water, which provides passive cooling as well as radiation shielding. Penetrations to pools are limited to prevent inadvertent drainage, and the penetrations are generally located well above spent fuel storage elevations to prevent uncovering of fuel from drainage. Studies conducted over the last four decades have consistently shown the risk of an accident causing a zirconium fire in an SFP to be low. The risk of an SFP accident was examined in the 1980s as Generic Issue 82, ‘‘Beyond Design Basis Accidents in Spent Fuel Pools,’’ in light of increased use of highdensity storage racks and laboratory studies that indicated the possibility of zirconium fire propagation between assemblies in an air-cooled environment (Section 3 of NUREG–0933, ‘‘Resolution of Generic Safety Issues,’’ https:// nureg.nrc.gov/sr0933/). The risk assessment and cost-benefit analyses developed through this effort, Section 6.2 of NUREG–1353, ‘‘Regulatory Analysis for the Resolution of Generic Issue 82, Beyond Design Basis Accidents in Spent Fuel Pools’’ (ADAMS Accession No. ML082330232), concluded that the risk of a severe accident in the SFP was low and appeared to meet the objectives of the Commission’s Safety Goal Policy Statement public health objectives (51 FR 30028; August 21, 1986) and that no new regulatory requirements were warranted. The risk of an SFP accident was reassessed in the late 1990s to support a risk-informed rulemaking for permanently shutdown, or decommissioned, nuclear power plants in the United States. The study, NUREG–1738, ‘‘Technical Study of Spent Fuel Pool Accident Risk at Decommissioning Nuclear Power Plants’’ (ADAMS Accession No. ML010430066), conservatively assumed that if the water level in the SFP dropped below the top of the spent fuel, an SFP zirconium fire involving all of the spent fuel would occur, and thereby bounded those conditions associated with air cooling of the fuel (including partial-drain down scenarios) and fire propagation. Even with this conservative assumption, the study E:\FR\FM\13MYR1.SGM 13MYR1 Federal Register / Vol. 81, No. 93 / Friday, May 13, 2016 / Rules and Regulations found the risk of an SFP fire to be low and well within the Commission’s Safety Goals. Additional mechanisms to mitigate the potential loss of SFP water inventory were implemented following the terrorist attacks of September 11, 2001, which have enhanced spent fuel coolability and the potential to recover SFP water level and cooling prior to a potential SFP zirconium fire (73 FR 76204; August 8, 2008). Based on the implementation of these additional strategies, the probability and, accordingly, the risk of an SFP zirconium fire initiation has decreased and is expected to be less than previously analyzed in NUREG–1738 and previous studies. Following the 2011 accident at Fukushima Dai-ichi, the NRC took extensive actions to ensure that portable equipment is available to mitigate a loss of cooling water in the SFP. On March 12, 2012, the NRC issued Order EA–12– 049, ‘‘Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events’’ (ADAMS Accession No. ML12054A735). This order required licensees to develop, implement, and maintain guidance and strategies to maintain or restore core cooling, containment, and SFP cooling capabilities following a beyond-designbasis external event. The NRC endorsed the Nuclear Energy Institute (NEI) guidance to meet the requirements of this order.1 That guidance establishes additional mechanisms for mitigating a loss of SFP cooling water beyond the requirements in 10 CFR 50.54(hh)(2), such as installing a remote connection for SFP makeup water that can be accessed away from the SFP refueling floor. Also, in 2014, the NRC documented a regulatory analysis in COMSECY–13– 0030, ‘‘Staff Evaluation and Recommendation for Japan Lessons Learned Tier 3 Issue on Expedited Transfer of Spent Fuel’’ (ADAMS Accession No. ML13329A918), which considered a broad history of the NRC’s oversight of spent fuel storage, SFP operating experience (domestic and international), as well as information compiled in NUREG–2161, ‘‘Consequence Study of a BeyondDesign-Basis Earthquake Affecting the ehiers on DSK5VPTVN1PROD with RULES 1 See NEI 12–06, ‘‘Diverse and Flexible Coping Strategies (FLEX) Implementation Guide,’’ dated August 2012 (ADAMS Accession No. ML12242A378), and JLD–ISG–2012–01, ‘‘Compliance with Order EA–12–049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events,’’ dated August 2012 (ADAMS Accession No. ML12229A174). VerDate Sep<11>2014 14:42 May 12, 2016 Jkt 238001 Spent Fuel Pool for a U.S. Mark I Boiling Water Reactor’’ (ADAMS Accession No. ML14255A365). In COMSECY–13–0030, the NRC staff concluded that SFPs are robust structures with large safety margins and recommended to the Commission that assessments of possible regulatory actions to require the expedited transfer of spent fuel from SFPs to dry cask storage were not warranted. The Commission subsequently approved the staff’s recommendation in the Staff Requirements Memorandum to COMSECY–13–0030 (ADAMS Accession No. ML14143A360). As supported by numerous evaluations referenced in this document, the NRC has determined that the risk of an SFP severe accident is low. While the risk of a severe accident in an SFP is not negligible, the NRC believes that the risk is low because of the conservative design of SFPs; operational criteria to control spent fuel movement, monitor pertinent parameters, and maintain cooling capability; mitigation measures in place if there is loss of cooling capability or water; and emergency preparedness measures to protect the public. The information proposed to be provided to the NRC is not needed for the effectiveness of NRC’s approach for ensuring SFP safety. The NRC notes that the issue of long-term cooling of SFPs is the subject of PRM–50–96, which was accepted for consideration in the rulemaking process (77 FR 74788; December 18, 2012) and is being addressed by the NRC’s rulemaking regarding mitigation of beyond designbasis events (RIN 3150–AJ49; NRC– 2014–0240). Issue 2: Annual Licensee SFP Safety Evaluations and Submission of Results to the NRC Is Necessary So That the NRC Is Aware of Potential Consequences of Postulated SFP Accident/Fire Scenarios as Fuel Assemblies Are Added, Removed, or Reconfigured in Licensees’ SFPs The petitioner stated that the purpose of the proposed requirement is to keep the NRC informed of the potential consequences of postulated SFP accident/fire scenarios as fuel assemblies are added, removed, or reconfigured in licensees’ SFPs. NRC Response The NRC does not agree that this is necessary because the NRC already evaluates SFP systems and structures during initial licensing and license amendment reviews. In addition, baseline NRC inspections provide ongoing oversight to ensure adequate PO 00000 Frm 00003 Fmt 4700 Sfmt 4700 29763 protection. There are not sufficient benefits that would justify the new requirement proposed in the petition for SFP accident evaluations. The proposed new requirement for licensees to perform SFP evaluations would not prevent or mitigate an SFP accident or provide information that is necessary for regulatory decisionmaking. The annual licensee SFP safety evaluations and their results proposed to be provided to the NRC are not needed for the effectiveness of the NRC’s approach to ensuring SFP safety. The NRC issues licenses after reviewing and approving the design and licensing bases contained in the plant’s safety analysis report. Licensees are required to operate the plant, including performing operations and surveillances related to spent fuel, in accordance with technical specifications and established practices and procedures for that plant. Any licensee changes to design, operational or surveillance practices, or approved spent fuel inventory limits or configuration changes must be evaluated using the criteria in 10 CFR 50.59, documented and retained for the duration of the operating license, and, if warranted, submitted to the NRC for prior approval. The general design criteria (GDC) in appendix A to 10 CFR part 50 establish general expectations that licensees must meet through compliance with their plant-specific licensing basis. Several GDC apply to SFPs: • Protecting against natural phenomena and equipment failures (GDC 2 and GDC 4); • Preventing a substantial loss-ofcoolant inventory under accident conditions (e.g., equipment failure or loss of decay and residual heat removal) (GDC 61); • Preventing criticality of the spent fuel (GDC 62); and • Adequately monitoring the SFP conditions for loss of decay heat removal and radiation (GDC 63). Additionally, emergency procedures and mitigating strategies are in place to address unexpected challenges to spent fuel safety. Multiple requirements in 10 CFR part 50, as well as recent NRC orders following the Fukushima Dai-ichi accident, require redundant equipment and strategies to address loss of cooling to SFPs and protective actions for plant personnel and the public to limit exposure to radioactive materials. The NRC provides oversight of the licensee’s overall plant operations and the SFP in several ways. The NRC inspectors ensure that spent fuel is stored safely by regularly inspecting reactor and equipment vendors; inspecting the design, construction, and E:\FR\FM\13MYR1.SGM 13MYR1 ehiers on DSK5VPTVN1PROD with RULES 29764 Federal Register / Vol. 81, No. 93 / Friday, May 13, 2016 / Rules and Regulations use of equipment; and observing ‘‘dry runs’’ of procedures. At least two NRC resident inspectors are assigned to each site to provide monitoring and inspection of routine and special activities. They are aware of, and routinely observe, SFP activities involving fuel manipulation. The NRC inspectors use inspection procedures to guide periodic inspection activities, and the results are published in publiclyavailable inspection reports. Special inspections may be conducted, as necessary, to evaluate root causes and licensee corrective actions if sitespecific events occur. Special inspections may also evaluate generic actions taken by some or all licensees as a result of an NRC order or a change in regulations. In accordance with 10 CFR part 21, the NRC is informed of defects and noncompliances associated with basic components, which include SFPs and associated drain pipes and safety-related systems, structures, and components for makeup water. This information allows the NRC to take additional regulatory action as necessary with respect to defects and noncompliances. The NRC is also informed of events and conditions at nuclear power plants, as set forth in §§ 50.72 and 50.73. Depending upon the nature of the event or condition, a nuclear power plant licensee must inform the NRC within a specified period of time of the licensee’s corrective action taken or planned to be taken. These reports also facilitate effective and timely NRC regulatory oversight. Finally, information identified by a nuclear power plant applicant or licensee as having a significant implication for public health and safety or common defense and security must be reported to the NRC within 2 days of the applicant’s or licensee’s identification of the information. The annual evaluations requested in the petition would not provide information that is necessary for regulatory decisionmaking. The evaluations requested in the petition would postulate scenarios in which the normal cooling systems, the backup cooling methods, and the mitigation strategies have all failed to cool the stored fuel and would require the calculation of the time it would take for the stored fuel to ignite and how much of it would ignite. Due to the robustness of this equipment, the NRC views this sequence of events as extremely unlikely to occur. Since the current regulations require that the pool be designed to prevent the loss-of-coolant and subsequent uncovering of the fuel, the information that would be obtained VerDate Sep<11>2014 14:42 May 12, 2016 Jkt 238001 from the proposed requirement in the petition would not impact the current design basis. Moreover, as discussed previously, the NRC’s current regulatory infrastructure relevant to SFPs at nuclear power plants in the United States already contains information collection and reporting requirements that support effective NRC regulatory oversight of SFPs. The NRC does not agree that it is necessary to impose a new requirement for licensees to perform annual evaluations of their SFPs because existing requirements and oversight are sufficient to ensure adequate protection of public health and safety. Issue 3: MELCOR Is Not Currently Sufficient To Provide a Conservative Evaluation of Postulated SFP Accident/ Fire Scenarios The petitioner requested that the NRC establish requirements for SFP accident evaluation computer models to be used in the annual SFP evaluations requested in Issue 2. The petitioner stated that there are serious flaws with MELCOR, which has been used by the NRC to model severe accident progression in SFPs, and, therefore, MELCOR is not sufficient. NRC Response The NRC does not agree that it is necessary to establish requirements for SFP accident evaluation computer models because the annual SFP evaluations requested in Issue 2 are not necessary for regulatory decisionmaking. Therefore, it is not necessary for the NRC to establish requirements for how such an evaluation should be conducted. Furthermore, the NRC disagrees with the petitioner’s statements that MELCOR is flawed. There are inherent uncertainties in the progression of severe accidents. There are many interrelated phenomena that need to be properly understood; otherwise, conservatism in one area may lead to overall non-conservative results. Conservatism can be meaningfully introduced into the relevant analysis after the best estimate analysis is done and uncertainties are properly taken into account. The important question for a severe accident analysis is whether the uncertainties are appropriately considered in the analysis results. For example, Section 9 of the SFP study (NUREG–2161) is devoted to discussing the major uncertainties that can affect the radiological releases (e.g., hydrogen combustion, core concrete interaction, multi-unit or concurrent accident, or fuel loading). In addition, the regulatory PO 00000 Frm 00004 Fmt 4700 Sfmt 4700 analysis in COMSECY–13–0030 only relied on SFP study insights for the boiling-water reactors with Mark I and II containments, and, even then, the results were conservatively biased towards higher radiological releases. For other designs, the release fractions were based on previous studies (i.e., NUREG– 1738) that used bounding or conservative estimates. The MELCOR computer code is the NRC’s best estimate tool for severe accident analysis. It has been validated against experimental data, and it represents the current state of the art in severe accident analysis. In NUREG– 2161, the NRC stated that ‘‘MELCOR has been developed through the NRC and international research performed since the accident at Three Mile Island in 1979. MELCOR is a fully integrated, engineering-level computer code and includes a broad spectrum of severe accident phenomena with capabilities to model core heatup and degradation, fission product release and transport within the primary system and containment, core relocation to the vessel lower head, and ex-vessel core concrete interaction.’’ Furthermore, MELCOR has been benchmarked against many experiments, including separate and integral effects tests for a wide range of phenomena. Therefore, the NRC has determined that MELCOR is acceptable for its intended use. Additional information about the capabilities of the MELCOR code to model SFP accidents can be found in the NRC response to stakeholder comments in Appendix E to NUREG– 2161. The NRC also addressed questions regarding MELCOR in Appendix D to NUREG–2157, Volume 2, ‘‘Generic Environmental Impact Statement for Continued Storage of Spent Nuclear Fuel’’ (ADAMS Accession No. ML14196A107). III. Conclusion For the reasons described in Section II, ‘‘Reasons for Denial,’’ of this document, the NRC is denying the petition under 10 CFR 2.803. The petitioner failed to present any information or arguments that would warrant the requested amendments. The NRC does not believe that the information that would be reported to the NRC as requested by the petitioner is necessary for effective NRC regulatory decisionmaking with respect to SFPs. The NRC continues to conclude that the current design and licensing requirements for SFPs provide adequate protection of public health and safety. E:\FR\FM\13MYR1.SGM 13MYR1 Federal Register / Vol. 81, No. 93 / Friday, May 13, 2016 / Rules and Regulations IV. Availability of Documents interested persons as indicated. For more information on accessing ADAMS, The documents identified in the following table are available to see the ADDRESSES section of this document. ADAMS accession number/ Federal Register citation Date Document August 21, 1986 ................................. Safety Goals for the Operations of Nuclear Power Plants; Policy Statement; Republication. NUREG–1353, ‘‘Regulatory Analysis for the Resolution of Generic Issue 82, Beyond Design Basis Accidents in Spent Fuel Pools’’. NUREG–1738, ‘‘Technical Study of Spent Fuel Pool Accident Risk at Decommissioning Nuclear Power Plants’’. EA–12–049, ‘‘Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events’’. NEI 12–06, ‘‘Diverse and Flexible Coping Strategies (FLEX) Implementation Guide’’. JLD–ISG–2012–01, ‘‘Compliance with Order EA–12–049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events’’. Long-Term Cooling and Unattended Water Makeup of Spent Fuel Pools ... COMSECY–13–0030, ‘‘Staff Evaluation and Recommendation for Japan Lessons Learned Tier 3 Issue on Expedited Transfer of Spent Fuel’’. SRM–COMSECY–13–0030, ‘‘Staff Requirements—COMSECY–13–0030— Staff Evaluation and Recommendation for Japan Lessons-Learned Tier 3 Issue on Expedited Transfer of Spent Fuel’’. Incoming Petition (PRM–50–108) from Mr. Mark Edward Leyse ................. NUREG–2157, ‘‘Generic Environmental Impact Statement for Continued Storage of Spent Nuclear Fuel,’’ Volume 2. NUREG–2161, ‘‘Consequence Study of a Beyond-Design-Basis Earthquake Affecting the Spent Fuel Pool for a U.S. Mark I Boiling-Water Reactor’’. Notice of Docketing for PRM–50–108 ........................................................... April 1989 ........................................... February 2001 .................................... March 12, 2012 .................................. August 2012 ....................................... August 2012 ....................................... December 18, 2012 ............................ November 12, 2013 ............................ May 23, 2014 ..................................... June 19, 2014 .................................... September 2014 ................................. September 2014 ................................. October 7, 2014 ................................. Dated at Rockville, Maryland, this 5th day of May, 2016. For the Nuclear Regulatory Commission. Annette L. Vietti-Cook, Secretary of the Commission. [FR Doc. 2016–11212 Filed 5–12–16; 8:45 am] BILLING CODE 7590–01–P PENSION BENEFIT GUARANTY CORPORATION 29 CFR Parts 4010, 4041, 4071, and 4302 RIN 1212–AB33 Adjustment of Civil Penalties Pension Benefit Guaranty Corporation. ACTION: Interim final rule. AGENCY: The Pension Benefit Guaranty Corporation is amending its regulations to adjust the penalties provided for in sections 4071 and 4302 of the Employee Retirement Income Security Act of 1974. This action is being taken in accordance with the Federal Civil Penalties Inflation Adjustment Act Improvements Act of 2015 and Office of Management and Budget memorandum M–16–06. The regulations being amended are those on Penalties for Failure to Provide Certain Notices or Other Material Information (29 CFR part 4071) and ehiers on DSK5VPTVN1PROD with RULES SUMMARY: VerDate Sep<11>2014 16:59 May 12, 2016 Jkt 238001 Penalties for Failure to Provide Certain Multiemployer Plan Notices (29 CFR part 4302). Conforming amendments are also being made to the regulations on Annual Financial and Actuarial Information Reporting (29 CFR part 4010) and Termination of SingleEmployer Plans (29 CFR part 4041). DATES: The amendments are effective August 1, 2016. Also see Applicability, below. FOR FURTHER INFORMATION CONTACT: Deborah C. Murphy, Deputy Assistant General Counsel for Regulatory Affairs (murphy.deborah@pbgc.gov), Office of the General Counsel, Pension Benefit Guaranty Corporation, 1200 K Street NW., Washington, DC 20005–4026; 202– 326–4400 extension 3451. (TTY and TDD users may call the Federal relay service toll-free at 800–877–8339 and ask to be connected to 202–326–4400 extension 3451.) SUPPLEMENTARY INFORMATION: Executive Summary Purpose of the Regulatory Action This rule is needed to carry out the requirements of the Federal Civil Penalties Inflation Adjustment Act Improvements Act of 2015. The rule adjusts the maximum civil penalties that PBGC may assess for failure to provide certain notices or other material information. PO 00000 Frm 00005 Fmt 4700 Sfmt 4700 29765 51 FR 30028. ML082330232. ML010430066. ML12054A735. ML12242A378. ML12229A174. 77 FR 74788. ML13329A918. ML14143A360. ML14195A388. ML14196A107. ML14255A365. 79 FR 60383. PBGC’s legal authority for this action comes from the Federal Civil Penalties Inflation Adjustment Act of 1990 as amended by the Federal Civil Penalties Inflation Adjustment Act Improvements Act of 2015 and from sections 4002(b)(3), 4071, and 4302 of the Employee Retirement Income Security Act of 1974. Major Provisions of the Regulatory Action This rule adjusts the maximum civil penalties that PBGC may assess under sections 4071 and 4302 of ERISA. The new maximum amounts are $2,063 for section 4071 penalties and $275 for section 4302 penalties. Background The Pension Benefit Guaranty Corporation (PBGC) administers title IV of the Employee Retirement Income Security Act of 1974 (ERISA). Title IV has two provisions that authorize PBGC to assess civil monetary penalties.1 Section 4302, added to ERISA by the Multiemployer Pension Plan 1 Under the Federal Civil Penalties Inflation Adjustment Act of 1990, a penalty is a civil monetary penalty if (among other things) it is for a specific monetary amount or has a maximum amount specified by Federal law. Title IV also provides (in section 4007) for penalties for late payment of premiums, but those penalties are neither in a specified amount nor subject to a specified maximum amount. E:\FR\FM\13MYR1.SGM 13MYR1

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[Federal Register Volume 81, Number 93 (Friday, May 13, 2016)]
[Rules and Regulations]
[Pages 29761-29765]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-11212]



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Federal Register / Vol. 81, No. 93 / Friday, May 13, 2016 / Rules and 
Regulations

[[Page 29761]]



NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

[Docket Nos. PRM-50-108; NRC-2014-0171]


Fuel-Cladding Issues in Postulated Spent Fuel Pool Accidents

AGENCY: Nuclear Regulatory Commission.

ACTION: Petition for rulemaking; denial.

-----------------------------------------------------------------------

SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is denying a 
petition for rulemaking (PRM or the petition), PRM-50-108, submitted by 
Mr. Mark Edward Leyse (the petitioner). The petitioner requested that 
the NRC require power reactor licensees to perform evaluations to 
determine the potential consequences of various postulated spent fuel 
pool (SFP) accident scenarios. The evaluations would be required to be 
submitted to the NRC for informational purposes. The NRC is denying the 
petition because the NRC does not believe the information is needed for 
effective NRC regulatory decisionmaking with respect to SFPs or for 
public safety, environmental protection, or common defense and 
security.

DATES: The docket for the petition, PRM-50-108, is closed on May 13, 
2016.

ADDRESSES: Please refer to Docket ID NRC-2014-0171 when contacting the 
NRC about the availability of information for this petition. You may 
obtain publicly-available information related to this petition by any 
of the following methods:
     Federal Rulemaking Web site: Go to https://www.regulations.gov and search for Docket ID NRC-2014-0171. Address 
questions about NRC dockets to Carol Gallagher; telephone: 301-415-
3463; email: Carol.Gallagher@nrc.gov. For technical questions, contact 
the individual listed in the FOR FURTHER INFORMATION CONTACT section of 
this document.
     The NRC's Agencywide Documents Access and Management 
System (ADAMS): You may obtain publicly-available documents online in 
the ADAMS Public Document collection at https://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``ADAMS Public Documents'' and 
then select ``Begin Web-Based ADAMS Search.'' For problems with ADAMS, 
please contact the NRC's Public Document Room (PDR) reference staff at 
1-800-397-4209, 301-415-4737, or by email to pdr.resource@nrc.gov. The 
ADAMS accession number for each document referenced (if it is available 
in ADAMS) is provided the first time that it is mentioned in the 
SUPPLEMENTARY INFORMATION section. For the convenience of the reader, 
instructions about obtaining materials referenced in this document are 
provided in Section IV, ``Availability of Documents,'' of this 
document.
     The NRC's PDR: You may examine and purchase copies of 
public documents at the NRC's PDR, O1-F21, One White Flint North, 11555 
Rockville Pike, Rockville, Maryland 20852.

FOR FURTHER INFORMATION CONTACT: Daniel Doyle, Office of Nuclear 
Reactor Regulation; U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001; telephone: 301-415-3748; email: Daniel.Doyle@nrc.gov.

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. The Petition
II. Reasons for Denial
III. Conclusion
IV. Availability of Documents

I. The Petition

    Section 2.802 of title 10 of the Code of Federal Regulations (10 
CFR), ``Petition for rulemaking--requirements for filing,'' provides an 
opportunity for any interested person to petition the Commission to 
issue, amend, or rescind any regulation. The NRC received a petition 
dated June 19, 2014, from Mr. Mark Edward Leyse and assigned it Docket 
No. PRM-50-108 (ADAMS Accession No. ML14195A388). The NRC published a 
notice of docketing in the Federal Register (FR) on October 7, 2014 (79 
FR 60383). The NRC did not request public comment on the petition 
because sufficient information was available for the NRC staff to form 
a technical opinion regarding the merits of the petition.
    The petitioner requested that the NRC develop new regulations 
requiring that: (1) SFP accident evaluation models use data from multi-
rod bundle (assembly) severe accident experiments for calculating the 
rates of energy release, hydrogen generation, and fuel cladding 
oxidation from the zirconium-steam reaction; (2) SFP accident 
evaluation models use data from multi-rod bundle (assembly) severe 
accident experiments conducted with pre-oxidized fuel cladding for 
calculating the rates of energy release (from both fuel cladding 
oxidation and fuel cladding nitriding), fuel cladding oxidation, and 
fuel cladding nitriding from the zirconium-air reaction; (3) SFP 
accident evaluation models be required to conservatively model 
nitrogen-induced breakaway oxidation behavior; and (4) licensees be 
required to use conservative SFP accident evaluation models to perform 
annual SFP safety evaluations of: postulated complete loss-of-coolant 
accident (LOCA) scenarios, postulated partial LOCA scenarios, and 
postulated boil-off accident scenarios.
    The petitioner referenced recent NRC post-Fukushima MELCOR 
simulations of boiling-water reactor Mark I SFP accident/fire 
scenarios. The petitioner stated that the conclusions from the NRC's 
MELCOR simulations are non-conservative and misleading because their 
conclusions underestimate the probabilities of large radiological 
releases from SFP accidents.
    The petitioner asserted that in actual SFP fires, there would be 
quicker fuel-cladding temperature escalations, releasing more heat, and 
quicker axial and radial propagation of zirconium (Zr) fires than 
MELCOR simulations predict. The petitioner stated that the NRC's 
philosophy of defense-in-depth requires the application of conservative 
models, and, therefore, it is necessary to improve the performance of 
MELCOR and any other computer safety models that are intended to 
accurately simulate SFP accident/fire scenarios.
    The petitioner stated that the new regulations would help improve 
public and plant-worker safety. The petitioner asserted that the first 
three requested regulations, regarding zirconium fuel cladding 
oxidation and nitriding, as

[[Page 29762]]

well as nitrogen-induced breakaway oxidation behavior, are intended to 
improve the performance of computer safety models that simulate 
postulated SFP accident/fire scenarios. The petitioner stated that the 
fourth requested regulation would require that licensees use 
conservative SFP accident evaluation models to perform annual SFP 
safety evaluations of postulated complete LOCA scenarios, postulated 
partial LOCA scenarios, and postulated boil-off accident scenarios. The 
petitioner stated that the purpose of these evaluations would be to 
keep the NRC informed of the potential consequences of postulated SFP 
accident/fire scenarios as fuel assembles were added, removed, or 
reconfigured in licensees' SFPs. The petitioner stated that the 
requested regulations are needed because the probability of the type of 
events that could lead to SFP accidents is relatively high.
    The NRC staff reviewed the petition and, based on its understanding 
of the overall argument in the petition, identified and evaluated the 
following three issues:
     Issue 1: The requested regulations pertaining to SFP 
accident evaluation models are needed because the probability of the 
type of events that could lead to SFP accidents is relatively high.
     Issue 2: Annual licensee SFP safety evaluations and 
submission of results to the NRC is necessary so that the NRC is aware 
of potential consequences of postulated SFP accident/fire scenarios as 
fuel assemblies are added, removed, or reconfigured in licensees' SFPs.
     Issue 3: MELCOR is not currently sufficient to provide a 
conservative evaluation of postulated SFP accident/fire scenarios for 
use in the PRM-proposed annual SFP evaluations.
    Detailed NRC responses to the three issues are provided in Section 
II, ``Reasons for Denial,'' of this document.

II. Reasons for Denial

    The NRC is denying the petition because the petitioner failed to 
present any significant information or arguments that would warrant the 
requested regulations. The first three requested regulations would 
establish requirements for how the detailed annual evaluations that 
would be required by the fourth requested regulation would be 
performed. It is not necessary to require detailed annual evaluations 
of the progression of SFP severe accidents because the risk of an SFP 
severe accident is low. The NRC defines risk as the product of the 
probability and the consequences of an accident. The requested annual 
evaluations are not needed for regulatory decisionmaking, and the 
evaluations would not prevent or mitigate an SFP accident. The 
petitioner described multiple ways that an extended loss of offsite 
electrical power could occur and how this could lead to an SFP fire. In 
order for an SFP fire to occur, all SFP systems, backup systems, and 
operator actions that are intended to prevent the spent fuel in the 
pool from being uncovered would have to fail. The NRC does not agree 
that more detailed accident evaluation models need to be developed for 
this purpose, as requested by the petitioner, because the requested 
annual evaluations are not needed for regulatory decisionmaking. The 
NRC recognizes that the consequences of an SFP fire could be large and 
that is why there are numerous requirements in place to prevent a 
situation where the spent fuel is uncovered.
    This section provides detailed NRC responses to the three issues 
identified in the petition.

Issue 1: The Requested Regulations Pertaining to SFP Accident 
Evaluation Models Are Needed Because the Probability of the Type of 
Events That Could Lead to SFP Accidents Is Relatively High

    The petitioner stated that the requested regulations pertaining to 
SFP accident evaluation models are needed because the probability of 
the type of events that could lead to SFP accidents is relatively high. 
The petitioner stated that an SFP accident could happen as a result of 
a leak (rapid drain down) or boil-off scenario. Furthermore, the 
petitioner notes that in the event of a long-term station blackout, 
emergency diesel generators could run out of fuel and SFP cooling would 
be lost, resulting in a boil-off of SFP water inventory and a 
subsequent release of radioactive materials from the spent fuel. The 
petitioner also provided several examples of events that could lead to 
a long-term station blackout and, ultimately, an SFP accident, such as 
a strong geomagnetic disturbance, a nuclear device detonated in the 
earth's atmosphere, a pandemic, or a cyber or physical attack.

NRC Response

    Spent nuclear fuel offloaded from a reactor is initially stored in 
an SFP. The SFPs at all nuclear plants in the United States are robust 
structures constructed with thick, reinforced, concrete walls and 
welded stainless-steel liners. They are designed to safely contain the 
spent fuel discharged from a nuclear reactor under a variety of normal, 
off-normal, and hypothetical accident conditions (e.g., loss of 
electrical power, loss of cooling, fuel or cask drop incidents, floods, 
earthquakes, or extreme weather events). Racks fitted in the SFPs store 
the fuel assemblies in a controlled configuration so that the fuel is 
maintained in a sub-critical and coolable geometry. Redundant 
monitoring, cooling, and water makeup systems are provided. The spent 
fuel assemblies are typically covered by at least 25-feet of water, 
which provides passive cooling as well as radiation shielding. 
Penetrations to pools are limited to prevent inadvertent drainage, and 
the penetrations are generally located well above spent fuel storage 
elevations to prevent uncovering of fuel from drainage.
    Studies conducted over the last four decades have consistently 
shown the risk of an accident causing a zirconium fire in an SFP to be 
low. The risk of an SFP accident was examined in the 1980s as Generic 
Issue 82, ``Beyond Design Basis Accidents in Spent Fuel Pools,'' in 
light of increased use of high-density storage racks and laboratory 
studies that indicated the possibility of zirconium fire propagation 
between assemblies in an air-cooled environment (Section 3 of NUREG-
0933, ``Resolution of Generic Safety Issues,'' https://nureg.nrc.gov/sr0933/). The risk assessment and cost-benefit analyses developed 
through this effort, Section 6.2 of NUREG-1353, ``Regulatory Analysis 
for the Resolution of Generic Issue 82, Beyond Design Basis Accidents 
in Spent Fuel Pools'' (ADAMS Accession No. ML082330232), concluded that 
the risk of a severe accident in the SFP was low and appeared to meet 
the objectives of the Commission's Safety Goal Policy Statement public 
health objectives (51 FR 30028; August 21, 1986) and that no new 
regulatory requirements were warranted.
    The risk of an SFP accident was re-assessed in the late 1990s to 
support a risk-informed rulemaking for permanently shutdown, or 
decommissioned, nuclear power plants in the United States. The study, 
NUREG-1738, ``Technical Study of Spent Fuel Pool Accident Risk at 
Decommissioning Nuclear Power Plants'' (ADAMS Accession No. 
ML010430066), conservatively assumed that if the water level in the SFP 
dropped below the top of the spent fuel, an SFP zirconium fire 
involving all of the spent fuel would occur, and thereby bounded those 
conditions associated with air cooling of the fuel (including partial-
drain down scenarios) and fire propagation. Even with this conservative 
assumption, the study

[[Page 29763]]

found the risk of an SFP fire to be low and well within the 
Commission's Safety Goals.
    Additional mechanisms to mitigate the potential loss of SFP water 
inventory were implemented following the terrorist attacks of September 
11, 2001, which have enhanced spent fuel coolability and the potential 
to recover SFP water level and cooling prior to a potential SFP 
zirconium fire (73 FR 76204; August 8, 2008). Based on the 
implementation of these additional strategies, the probability and, 
accordingly, the risk of an SFP zirconium fire initiation has decreased 
and is expected to be less than previously analyzed in NUREG-1738 and 
previous studies.
    Following the 2011 accident at Fukushima Dai-ichi, the NRC took 
extensive actions to ensure that portable equipment is available to 
mitigate a loss of cooling water in the SFP. On March 12, 2012, the NRC 
issued Order EA-12-049, ``Order Modifying Licenses with Regard to 
Requirements for Mitigation Strategies for Beyond-Design-Basis External 
Events'' (ADAMS Accession No. ML12054A735). This order required 
licensees to develop, implement, and maintain guidance and strategies 
to maintain or restore core cooling, containment, and SFP cooling 
capabilities following a beyond-design-basis external event. The NRC 
endorsed the Nuclear Energy Institute (NEI) guidance to meet the 
requirements of this order.\1\ That guidance establishes additional 
mechanisms for mitigating a loss of SFP cooling water beyond the 
requirements in 10 CFR 50.54(hh)(2), such as installing a remote 
connection for SFP makeup water that can be accessed away from the SFP 
refueling floor.
---------------------------------------------------------------------------

    \1\ See NEI 12-06, ``Diverse and Flexible Coping Strategies 
(FLEX) Implementation Guide,'' dated August 2012 (ADAMS Accession 
No. ML12242A378), and JLD-ISG-2012-01, ``Compliance with Order EA-
12-049, Order Modifying Licenses with Regard to Requirements for 
Mitigation Strategies for Beyond-Design-Basis External Events,'' 
dated August 2012 (ADAMS Accession No. ML12229A174).
---------------------------------------------------------------------------

    Also, in 2014, the NRC documented a regulatory analysis in COMSECY-
13-0030, ``Staff Evaluation and Recommendation for Japan Lessons 
Learned Tier 3 Issue on Expedited Transfer of Spent Fuel'' (ADAMS 
Accession No. ML13329A918), which considered a broad history of the 
NRC's oversight of spent fuel storage, SFP operating experience 
(domestic and international), as well as information compiled in NUREG-
2161, ``Consequence Study of a Beyond-Design-Basis Earthquake Affecting 
the Spent Fuel Pool for a U.S. Mark I Boiling Water Reactor'' (ADAMS 
Accession No. ML14255A365). In COMSECY-13-0030, the NRC staff concluded 
that SFPs are robust structures with large safety margins and 
recommended to the Commission that assessments of possible regulatory 
actions to require the expedited transfer of spent fuel from SFPs to 
dry cask storage were not warranted. The Commission subsequently 
approved the staff's recommendation in the Staff Requirements 
Memorandum to COMSECY-13-0030 (ADAMS Accession No. ML14143A360).
    As supported by numerous evaluations referenced in this document, 
the NRC has determined that the risk of an SFP severe accident is low. 
While the risk of a severe accident in an SFP is not negligible, the 
NRC believes that the risk is low because of the conservative design of 
SFPs; operational criteria to control spent fuel movement, monitor 
pertinent parameters, and maintain cooling capability; mitigation 
measures in place if there is loss of cooling capability or water; and 
emergency preparedness measures to protect the public. The information 
proposed to be provided to the NRC is not needed for the effectiveness 
of NRC's approach for ensuring SFP safety. The NRC notes that the issue 
of long-term cooling of SFPs is the subject of PRM-50-96, which was 
accepted for consideration in the rulemaking process (77 FR 74788; 
December 18, 2012) and is being addressed by the NRC's rulemaking 
regarding mitigation of beyond design-basis events (RIN 3150-AJ49; NRC-
2014-0240).

Issue 2: Annual Licensee SFP Safety Evaluations and Submission of 
Results to the NRC Is Necessary So That the NRC Is Aware of Potential 
Consequences of Postulated SFP Accident/Fire Scenarios as Fuel 
Assemblies Are Added, Removed, or Reconfigured in Licensees' SFPs

    The petitioner stated that the purpose of the proposed requirement 
is to keep the NRC informed of the potential consequences of postulated 
SFP accident/fire scenarios as fuel assemblies are added, removed, or 
reconfigured in licensees' SFPs.

NRC Response

    The NRC does not agree that this is necessary because the NRC 
already evaluates SFP systems and structures during initial licensing 
and license amendment reviews. In addition, baseline NRC inspections 
provide ongoing oversight to ensure adequate protection. There are not 
sufficient benefits that would justify the new requirement proposed in 
the petition for SFP accident evaluations. The proposed new requirement 
for licensees to perform SFP evaluations would not prevent or mitigate 
an SFP accident or provide information that is necessary for regulatory 
decisionmaking. The annual licensee SFP safety evaluations and their 
results proposed to be provided to the NRC are not needed for the 
effectiveness of the NRC's approach to ensuring SFP safety.
    The NRC issues licenses after reviewing and approving the design 
and licensing bases contained in the plant's safety analysis report. 
Licensees are required to operate the plant, including performing 
operations and surveillances related to spent fuel, in accordance with 
technical specifications and established practices and procedures for 
that plant. Any licensee changes to design, operational or surveillance 
practices, or approved spent fuel inventory limits or configuration 
changes must be evaluated using the criteria in 10 CFR 50.59, 
documented and retained for the duration of the operating license, and, 
if warranted, submitted to the NRC for prior approval.
    The general design criteria (GDC) in appendix A to 10 CFR part 50 
establish general expectations that licensees must meet through 
compliance with their plant-specific licensing basis. Several GDC apply 
to SFPs:
     Protecting against natural phenomena and equipment 
failures (GDC 2 and GDC 4);
     Preventing a substantial loss-of-coolant inventory under 
accident conditions (e.g., equipment failure or loss of decay and 
residual heat removal) (GDC 61);
     Preventing criticality of the spent fuel (GDC 62); and
     Adequately monitoring the SFP conditions for loss of decay 
heat removal and radiation (GDC 63).
    Additionally, emergency procedures and mitigating strategies are in 
place to address unexpected challenges to spent fuel safety. Multiple 
requirements in 10 CFR part 50, as well as recent NRC orders following 
the Fukushima Dai-ichi accident, require redundant equipment and 
strategies to address loss of cooling to SFPs and protective actions 
for plant personnel and the public to limit exposure to radioactive 
materials.
    The NRC provides oversight of the licensee's overall plant 
operations and the SFP in several ways. The NRC inspectors ensure that 
spent fuel is stored safely by regularly inspecting reactor and 
equipment vendors; inspecting the design, construction, and

[[Page 29764]]

use of equipment; and observing ``dry runs'' of procedures. At least 
two NRC resident inspectors are assigned to each site to provide 
monitoring and inspection of routine and special activities. They are 
aware of, and routinely observe, SFP activities involving fuel 
manipulation. The NRC inspectors use inspection procedures to guide 
periodic inspection activities, and the results are published in 
publicly-available inspection reports. Special inspections may be 
conducted, as necessary, to evaluate root causes and licensee 
corrective actions if site-specific events occur. Special inspections 
may also evaluate generic actions taken by some or all licensees as a 
result of an NRC order or a change in regulations.
    In accordance with 10 CFR part 21, the NRC is informed of defects 
and noncompliances associated with basic components, which include SFPs 
and associated drain pipes and safety-related systems, structures, and 
components for makeup water. This information allows the NRC to take 
additional regulatory action as necessary with respect to defects and 
noncompliances. The NRC is also informed of events and conditions at 
nuclear power plants, as set forth in Sec. Sec.  50.72 and 50.73. 
Depending upon the nature of the event or condition, a nuclear power 
plant licensee must inform the NRC within a specified period of time of 
the licensee's corrective action taken or planned to be taken. These 
reports also facilitate effective and timely NRC regulatory oversight. 
Finally, information identified by a nuclear power plant applicant or 
licensee as having a significant implication for public health and 
safety or common defense and security must be reported to the NRC 
within 2 days of the applicant's or licensee's identification of the 
information.
    The annual evaluations requested in the petition would not provide 
information that is necessary for regulatory decisionmaking. The 
evaluations requested in the petition would postulate scenarios in 
which the normal cooling systems, the backup cooling methods, and the 
mitigation strategies have all failed to cool the stored fuel and would 
require the calculation of the time it would take for the stored fuel 
to ignite and how much of it would ignite. Due to the robustness of 
this equipment, the NRC views this sequence of events as extremely 
unlikely to occur. Since the current regulations require that the pool 
be designed to prevent the loss-of-coolant and subsequent uncovering of 
the fuel, the information that would be obtained from the proposed 
requirement in the petition would not impact the current design basis. 
Moreover, as discussed previously, the NRC's current regulatory 
infrastructure relevant to SFPs at nuclear power plants in the United 
States already contains information collection and reporting 
requirements that support effective NRC regulatory oversight of SFPs.
    The NRC does not agree that it is necessary to impose a new 
requirement for licensees to perform annual evaluations of their SFPs 
because existing requirements and oversight are sufficient to ensure 
adequate protection of public health and safety.

Issue 3: MELCOR Is Not Currently Sufficient To Provide a Conservative 
Evaluation of Postulated SFP Accident/Fire Scenarios

    The petitioner requested that the NRC establish requirements for 
SFP accident evaluation computer models to be used in the annual SFP 
evaluations requested in Issue 2. The petitioner stated that there are 
serious flaws with MELCOR, which has been used by the NRC to model 
severe accident progression in SFPs, and, therefore, MELCOR is not 
sufficient.

NRC Response

    The NRC does not agree that it is necessary to establish 
requirements for SFP accident evaluation computer models because the 
annual SFP evaluations requested in Issue 2 are not necessary for 
regulatory decisionmaking. Therefore, it is not necessary for the NRC 
to establish requirements for how such an evaluation should be 
conducted. Furthermore, the NRC disagrees with the petitioner's 
statements that MELCOR is flawed.
    There are inherent uncertainties in the progression of severe 
accidents. There are many interrelated phenomena that need to be 
properly understood; otherwise, conservatism in one area may lead to 
overall non-conservative results. Conservatism can be meaningfully 
introduced into the relevant analysis after the best estimate analysis 
is done and uncertainties are properly taken into account.
    The important question for a severe accident analysis is whether 
the uncertainties are appropriately considered in the analysis results. 
For example, Section 9 of the SFP study (NUREG-2161) is devoted to 
discussing the major uncertainties that can affect the radiological 
releases (e.g., hydrogen combustion, core concrete interaction, multi-
unit or concurrent accident, or fuel loading). In addition, the 
regulatory analysis in COMSECY-13-0030 only relied on SFP study 
insights for the boiling-water reactors with Mark I and II 
containments, and, even then, the results were conservatively biased 
towards higher radiological releases. For other designs, the release 
fractions were based on previous studies (i.e., NUREG-1738) that used 
bounding or conservative estimates.
    The MELCOR computer code is the NRC's best estimate tool for severe 
accident analysis. It has been validated against experimental data, and 
it represents the current state of the art in severe accident analysis. 
In NUREG-2161, the NRC stated that ``MELCOR has been developed through 
the NRC and international research performed since the accident at 
Three Mile Island in 1979. MELCOR is a fully integrated, engineering-
level computer code and includes a broad spectrum of severe accident 
phenomena with capabilities to model core heatup and degradation, 
fission product release and transport within the primary system and 
containment, core relocation to the vessel lower head, and ex-vessel 
core concrete interaction.'' Furthermore, MELCOR has been benchmarked 
against many experiments, including separate and integral effects tests 
for a wide range of phenomena. Therefore, the NRC has determined that 
MELCOR is acceptable for its intended use.
    Additional information about the capabilities of the MELCOR code to 
model SFP accidents can be found in the NRC response to stakeholder 
comments in Appendix E to NUREG-2161. The NRC also addressed questions 
regarding MELCOR in Appendix D to NUREG-2157, Volume 2, ``Generic 
Environmental Impact Statement for Continued Storage of Spent Nuclear 
Fuel'' (ADAMS Accession No. ML14196A107).

III. Conclusion

    For the reasons described in Section II, ``Reasons for Denial,'' of 
this document, the NRC is denying the petition under 10 CFR 2.803. The 
petitioner failed to present any information or arguments that would 
warrant the requested amendments. The NRC does not believe that the 
information that would be reported to the NRC as requested by the 
petitioner is necessary for effective NRC regulatory decisionmaking 
with respect to SFPs. The NRC continues to conclude that the current 
design and licensing requirements for SFPs provide adequate protection 
of public health and safety.

[[Page 29765]]

IV. Availability of Documents

    The documents identified in the following table are available to 
interested persons as indicated. For more information on accessing 
ADAMS, see the ADDRESSES section of this document.

----------------------------------------------------------------------------------------------------------------
                                                                        ADAMS accession number/Federal Register
                 Date                             Document                             citation
----------------------------------------------------------------------------------------------------------------
August 21, 1986......................  Safety Goals for the           51 FR 30028.
                                        Operations of Nuclear Power
                                        Plants; Policy Statement;
                                        Republication.
April 1989...........................  NUREG-1353, ``Regulatory       ML082330232.
                                        Analysis for the Resolution
                                        of Generic Issue 82, Beyond
                                        Design Basis Accidents in
                                        Spent Fuel Pools''.
February 2001........................  NUREG-1738, ``Technical Study  ML010430066.
                                        of Spent Fuel Pool Accident
                                        Risk at Decommissioning
                                        Nuclear Power Plants''.
March 12, 2012.......................  EA-12-049, ``Order Modifying   ML12054A735.
                                        Licenses with Regard to
                                        Requirements for Mitigation
                                        Strategies for Beyond-Design-
                                        Basis External Events''.
August 2012..........................  NEI 12-06, ``Diverse and       ML12242A378.
                                        Flexible Coping Strategies
                                        (FLEX) Implementation
                                        Guide''.
August 2012..........................  JLD-ISG-2012-01, ``Compliance  ML12229A174.
                                        with Order EA-12-049, Order
                                        Modifying Licenses with
                                        Regard to Requirements for
                                        Mitigation Strategies for
                                        Beyond-Design-Basis External
                                        Events''.
December 18, 2012....................  Long-Term Cooling and          77 FR 74788.
                                        Unattended Water Makeup of
                                        Spent Fuel Pools.
November 12, 2013....................  COMSECY-13-0030, ``Staff       ML13329A918.
                                        Evaluation and
                                        Recommendation for Japan
                                        Lessons Learned Tier 3 Issue
                                        on Expedited Transfer of
                                        Spent Fuel''.
May 23, 2014.........................  SRM-COMSECY-13-0030, ``Staff   ML14143A360.
                                        Requirements--COMSECY-13-003
                                        0--Staff Evaluation and
                                        Recommendation for Japan
                                        Lessons-Learned Tier 3 Issue
                                        on Expedited Transfer of
                                        Spent Fuel''.
June 19, 2014........................  Incoming Petition (PRM-50-     ML14195A388.
                                        108) from Mr. Mark Edward
                                        Leyse.
September 2014.......................  NUREG-2157, ``Generic          ML14196A107.
                                        Environmental Impact
                                        Statement for Continued
                                        Storage of Spent Nuclear
                                        Fuel,'' Volume 2.
September 2014.......................  NUREG-2161, ``Consequence      ML14255A365.
                                        Study of a Beyond-Design-
                                        Basis Earthquake Affecting
                                        the Spent Fuel Pool for a
                                        U.S. Mark I Boiling-Water
                                        Reactor''.
October 7, 2014......................  Notice of Docketing for PRM-   79 FR 60383.
                                        50-108.
----------------------------------------------------------------------------------------------------------------


    Dated at Rockville, Maryland, this 5th day of May, 2016.
    For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary of the Commission.
[FR Doc. 2016-11212 Filed 5-12-16; 8:45 am]
 BILLING CODE 7590-01-P
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