Regulatory Guide 1.226: Difference between revisions

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{{Adams
{{Adams
| number = ML16301A128
| number = ML19058A012
| issue date = 11/30/2016
| issue date = 06/30/2019
| title = (New Regulatory Guide, Draft Was Issued as DG-1301, Dated November 2015) Flexible Mitigation Strategies for Beyond-Design-Basis Events
| title = Rev. 0, Flexible Mitigation Strategies for Beyond-Design-Basis Events
| author name = Bowman E, Orr M, Reed T
| author name = Bowman E
| author affiliation = NRC/NRR/JLD
| author affiliation = NRC/NRR
| addressee name =  
| addressee name =  
| addressee affiliation =  
| addressee affiliation =  
| docket =  
| docket =  
| license number =  
| license number =  
| contact person = Orr M
| contact person = Doyle, Daniel
| case reference number = DG-1301
| case reference number = 10 CFR Part 50, 10 CFR Part 52, NRC-2011-0189, NRC-2014-0240, PRM-50-97, PRM-50-98, RG-1.226, RIN 3150-AJ49, SRM-SECY-16-0142
| document report number = RG-1.226
| package number = ML19058A006
| package number = ML16301A100
| document type = Regulatory Guide
| document type = Regulatory Guide
| page count = 24
| page count = 22
}}
}}
{{#Wiki_filter:U.S. NUCLEAR REGULATORY COMMISSION November 2016OFFICE OF NUCLEAR REGULATORY RESEARCH
{{#Wiki_filter:Code of Federal Regulations
Revision 0
REGULATORY GUIDE
Technical LeadEric Bowman Written suggestions regarding this guide or development of new guides may be submitted through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/contactus.html.    Electronic copies of this regulatory guide, previous versions of this guide, and other recently issued guides are available through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/. The regulatory guide is also available through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under ADAMS Accession No. ML16301A128 The regulatory analysis may be found in ADAMS under Accession No. ML16301A009 and the staff responses to the public comments on the final rule and DG-1301 may be found under ADAMS Accession No. ML16271A063.


REGULATORY GUIDE 1.226 (New Regulatory Guide, draft was issued as DG-1301, dated November 2015)
*
FLEXIBLE MITIGATION STRATEGIES FOR 
*
BEYOND-DESIGN-BASIS EVENTS


==A. INTRODUCTION==
Code of Federal Regulations
Purpose  This regulatory guide (RG) identifies methods and procedures the staff of the U.S. Nuclear Regulatory Commission (NRC) considers acceptable for nuclear power reactor applicants and licensees to demonstrate compliance with NRC regulations covering integrated planning and preparedness for beyond-design-basis events as required by U.S. Code of Federal Regulations, Title 10, "Energy," Part 50, "Domestic Licensing of Production and Utilization Facilities," (10 CFR 50) (Ref. 1), Section 50.155, "Mitigation of Beyond-Design-Basis Events," (10 CFR 50.155).   
This RG endorses, with clarifications, the methods and procedures promulgated by the Nuclear Energy Institute (NEI) in technical document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 4 (NEI 12-06, Revision 4) dated December, 2016 (Ref. 2) as a process the NRC considers acceptable for meeting, in part, the regulations in 10 CFR 50.155. Additionally, this RG provides guidance in areas that are not covered in NEI 12-06, for meeting the regulations in 10 CFR 50.15


===5.      ===
Federal Register
Applicability This RG applies to applicants and licensees subject to 10 CFR Part 50, "Domestic Licensing of Production and Utilization Facilities," and all applicants and licensees for a power reactor combined license under 10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants" (Ref. 3). 


Applicable Regulations
Federal Register


* 10 CFR 50.155, "Mitigation of Beyond-Design-Basis Events," requires nuclear power reactor licensees to develop, implement, and maintain an integrated response capability that includes strategies and guidelines to mitigate a Beyond-Design-Basis External Event (BDBEE) 
Federal RegisterFederal Register Federal Register


RG 1.226, Page 2 Purpose of Regulatory Guides The NRC issues RGs to describe methods that the NRC considers acceptable for use in implementing specific parts of the agency's regulat ions, to explain techniques that the NRC uses in evaluating specific problems or postulated accidents, and to provide guidance to applicants. Regulatory guides are not substitutes for regulations and compliance with them is not required. Methods and solutions that differ from those set forth in RGs will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a permit or license by the Commission.
*
***


Paperwork Reduction Act This RG contains information collection requirements covered by 10 CFR 50 and 10 CFR Part 52 that the Office of Management and Budget (OMB) approved under OMB control numbers 3150-0011, 3150-151, and 3150-0155 respectively.
****


Public Protection Notification The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control number.
U.S. Code of Federal Regulations


List of Abbreviations    The following abbreviations are used in this RG
An Integrated, Safety-Focused Approach to Expediting Implementation of Fukushima Dai-ichi Lessons Learned}}
 
ac alternating current  ADAMS NRC Agencywide Documents Access and Management System AFW auxiliary feedwater  AMS alternate mitigating strategy  ASCE American Society of Civil Engineers  BDBEE beyond-design-basis external event  CFR U.S. Code of Federal Regulations DG draft regulatory guide EFW emergency feedwater  ELAP extended loss of alternating current power  EOP emergency operating procedure  EPRI Electric Power Research Institute  ESBWR economic simplified boiling-water reactor  ESEP expedited seismic evaluation process  FLEX diverse and flexible coping strategies  FR federal register FSAR final safety analysis report  FSG FLEX support guidelines  GL generic letter  GMRS ground motion response spectrum  HF high frequency  HPCI  high pressure core injection RG 1.226, Page 3 IAEA International Atomic Energy Agency  IHS IPEEE high-confidence-of-low-probability-of-failure spectrum  IPEEE individual plant examination of external events  ISG interim staff guidance  LLNL Lawrence Livermore National Laboratory  LUHS loss of normal access to the ultimate heat sink  NEA Nuclear Energy Agency  NEI Nuclear Energy Institute  NRC U.S. Nuclear Regulatory Commission  NTTF Near-Term Task Force OECD Organization for Economic Co-operation and Development  PGA peak ground acceleration  RCIC reactor core isolation cooling  RG regulatory guide  RLE review level earthquake  RLGM review level ground motion  SAMGs severe accident management guidelines SEI Structural Engineering Institute  SEL seismic equipment list  SFP spent fuel pool  SMA seismic margin assessment SPID  screening, prioritization, and implementation details  SRM staff requirement memorandum  SPRA seismic probabilistic risk assessment  SSC structure, system, and component  THMS targeted hazard mitigating strategy 
 
==B. DISCUSSION==
Reason for Issuance    One of the primary lessons learned from the accident at the Fukushima Dai-ichi nuclear power plant was the significance of the challenge presented by a loss of multiple safety-related systems following the occurrence of a BDBEE. In the case of the Fukushima Dai-ichi accident, the loss of all alternating current power led to loss of core cooling, and ultimately to core damage and a loss of containment integrity. The design basis for U.S. nuclear plants includes bounding analyses with margin for external events expected at each site. Extreme external events (e.g., seismic events, external flooding, etc.) beyond those accounted for in the design basis, while unlikely, could present challenges to nuclear power plants.
 
In response to lessons learned from the Fukushima Dai-ichi accident, the NRC promulgated 10 CFR 50.155, "Mitigation of Beyond-Design-Basis Events," to improve the capability of nuclear power plants to address BDBEEs. As one method of addressing the challenges that may be presented by these types of events, this RG endorses, with clarifications as detailed in this RG, the principles and processes in NEI 12-06, Revision 4, as acceptable for use by applicants and licensees to define and deploy strategies that will enhance their ability to cope with conditions resulting from BDBEEs.
 
RG 1.226, Page 4 Background Following the March 11, 2011, accident at the Fukushima Dai-ichi nuclear power plant, the NRC established a senior-level agency t ask force referred to as the Near-Term Task Force (NTTF). The NTTF conducted a systematic and methodical review of the NRC regulations and processes to determine whether the agency should make additional improvements in NRC regulations or processes in light of the events at Fukushima Dai-ichi. As a result of this review, the NTTF developed a comprehensive set of recommendations, documented in SECY-11-0093, "Near-Term Report and Recommendations for Agency Actions Following the Events in Japan," dated July 12, 2011 (Ref. 4). In staff requirement memorandum (SRM) to SECY-11-0093 (Ref. 5), the Commission directed the NRC staff to identify any actions that could, and in the staff's judgment should, be taken in the near term given consideration to the wide range of regulatory tools available, and to prioritize those actions. The staff's response to this Commission direction is contained in SECY-11-0124, "Recommended Actions To Be Taken without Delay from the Near-Term Task Force Report," dated September 9, 2011(Ref. 6), and SECY-11-0137, "Prioritization of Recommended Actions To Be Taken in Response to Fukushima Lessons Learned," dated October 3, 2012 (Ref. 7).
 
After receiving the Commission's direction in SRM-SECY-11-0124 (Ref. 8) and SRM-SECY-11-0137 (Ref. 9), the NRC conducted public meetings to discuss enhanced mitigation strategies intended to maintain or restore core cooling, containment, and spent fuel pool (SFP) cooling capabilities following a BDBEE. At these meetings, the industry described its proposal for a diverse and flexible mitigation capability (FLEX), as documented in a letter from NEI dated December 16, 2011 (Ref. 10). FLEX was proposed as a strategy to fulfill the key safety functions of core cooling, containment integrity, and spent fuel cooling.
 
On February 17, 2012, the NRC staff provided SECY-12-0025, "Proposed Orders and Requests for Information in Response to Lessons Learned from Japan's March 11, 2011, Great Tohoku Earthquake and Tsunami" (Ref. 11), to the Commission, including a proposed order to implement enhanced mitigation strategies for BDBEEs. As directed by SRM-SECY-12-0025 (Ref. 12), the NRC issued Order EA-12-049,  "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," (Ref. 13) on March 12, 2012. On March 30, 2012, the Commission issued Memorandum and Order CLI-12-09 (Ref. 14), which included the requirements for
 
mitigation strategies as a license condition for Virgil C. Summer Nuclear Station, Units 2 and 3. These requirements were subsequently included as license condition 2.D.(17) on both combined license NPF-93 (Ref. 15) and combined license NPF-94 (Ref. 16) for those units.
 
On May 4, 2012, NEI submitted NEI 12-06, Revision B (Ref. 17), to provide specifications for an industry proposed method for the development, implementation, and maintenance of guidance and strategies in response to Order EA-12-049. On May 13, 2012, NEI submitted NEI 12-06, Revision B1 (Ref. 18). The strategies and guidance described in NEI 12-06 expand on those developed and implemented by the nuclear industry to address the limited set of BDBEEs involving the loss of a large area of the plant due to explosions and fire required pursuant to paragraph (hh)(2) of 10 CFR 50.54, "Conditions of licenses." 
 
On May 31, 2012, the NRC issued a draft version of an interim staff guidance document, JLD-ISG-2012-01 (Ref. 19), and published a notice of its availability for public comment in the Federal Register (77 FR 33779), with the 30 day comment period running through July 7, 2012. The NRC received seven comments during this time, with the NRC addressing the comments as documented in "NRC Response to Public Comments, JLD-ISG-2012-01 (Docket ID NRC-2012-0068)" (Ref. 20). 
 
RG 1.226, Page 5 On July 3, 2012, NEI submitted Revision C to NEI 12-06 (Ref. 21), incorporating many of the exceptions and clarifications included in the draft version of JLD-ISG-2012-01. On August 3, 2012, NEI submitted Draft Revision 0 to NEI 12-06 (Ref. 22) incorporating many of the remaining exceptions and clarifications. On August 21, 2012, NEI submitted Revision 0 to NEI 12-06, (Ref. 23) making various editorial corrections. The NRC reviewed the August 21, 2012 submittal of Revision 0 of NEI 12-06 dated August 2012 and endorsed it in JLD-ISG-2012-01 (Ref. 24) as a process the NRC considers acceptable for meeting the regulatory requirements with noted clarifications.
 
On August 25, 2015, NEI submitted Revision 1 to NEI 12-06 (Ref. 25), incorporating lessons learned in the implementation of Order EA-12-049 and alternative approaches taken by licensees for compliance to that order.  Following a public webina r discussion of potential exceptions and clarifications on September 21, 2015, NEI submitted Revision 1A to NEI 12-06 (Ref. 26).
 
On October 30, 2015, the NRC staff issued a draft revision (Draft Revision 1) to JLD-ISG-2012-01 (Ref. 27) and published a notice of its availability for public comment in the Federal Register
(80 FR 69702; November 10, 2015), with the comment period running through December 10, 2015
(30 days from its publication).  The staff received four comments during this time, which it addressed as documented in "NRC Response to Public Comments, Revision to Japan Lessons-Learned Division Interim Staff Guidance 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 January 22, 2016 (Ref. 28).
 
On November 13, 2015, the NRC staff issued Draft Regulatory Guide (DG)-1301, "Flexible Mitigation Strategies for Beyond-Design-Basis Events" (Ref. 29), and published a notice of its availability for public comment in the Federal Register (80 FR 70609; November 13, 2015), with the comment period running through February 11, 2016 (90 days from its publication).  The staff received three comments during this time, which it addr essed as documented in "NRC Response to Public Comments, Mitigation of Beyond-Design-Basis Events Rule" dated December 2016 (Ref. 30).
On December 10, 2015, NEI submitted Revision 2 to NEI 12-06 (Ref. 31), incorporating many of the clarifications and additions included in the draft version of the revision to JLD- ISG-2012-01. Section H.4.5 of NEI 12-06, Revision 2, notes that detailed guidance for mitigating strategies assessments (MSAs) for licensees having reevaluated seismic hazards more than twice their safe-shutdown earthquake is under development and expected to be available to support MSAs for those licensees.  The NRC reviewed the December 10, 2015, submittal of Revision 2 of NEI 12-06 dated December 2015, and endorsed it in JLD-ISG-2012-01, Revision 1, (Ref. 32) dated January 22, 2016, with clarifications and additions, as a process the NRC considers acceptable for meeting the regulatory requirements.
 
On September 22, 2016, NEI submitted Revision 3 to NEI 12-06 (Ref. 33) to address certain lessons learned in the implementation of Order EA-12-049.  These lessons learned relate to the timing of out-of-service periods for equipment supporting the required strategies, the location of guidance for the performance of drills, documentation and configuration control, and the provision of guidance in Section H.4.5 for the performance of MSAs for plants with reevaluated seismic hazard information greater than twice the plant's safe-shutdown earthquake.  In addition, Revision 3 incorporates the guidance from JLD-ISG-2012-01, Revision 1, on the SFP spray strategy.
 
On November 10, 2016, the NRC staff issued a draft revision (Draft Revision 2) to JLD-ISG-2012-01 (Ref. 34) and published a notice of its availability for public comment in the Federal Register
(81 FR 79056; November 10, 2016), with the comment period running through December 12, 2016
(30 days from its publication).  The staff received 6 comments during this time, which it addressed as documented in "NRC Response to Public Comments, Revision to Japan Lessons-Learned Division RG 1.226, Page 6 Interim Staff Guidance 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 January xx, 2017 (Ref. 35).
On December 12, 2016, NEI submitted Revision 4 to NEI 12-06 [Reference 2] to clarify the provisions on availability/functionality of equipment relied upon for the mitigating strategies, while retaining the changes that had been proposed in Revision 3 to NEI 12-06.  The NRC reviewed the December 12, 2016, submittal of Revision 4 of NEI 12-06 and endorsed it in JLD-ISG-2012-01, Revision 2, (Ref. 36) dated January xx, 2017, with clarifications, as a process the NRC considers acceptable for meeting the regulatory requirements of Order EA-12-049.
 
The NRC is issuing 10 CFR 50.155 to, among other things, make the requirements of Order EA-12-049 generically applicable, taking into account lessons learned during the implementation of the orders and input from stakeholders. This RG endorses, with clarif ications and additions, NEI 12-06, Revision 4 as an acceptable method for applicants and licensees to demonstrate compliance with certain aspect of these regulatory requirements. NEI 12-06, Revision 4 was developed by NEI to incorporate lessons learned and additional alternative approaches to meet the requirements of Order EA-12-049. The guidelines in NEI 12-06, Revision 4 recommend a three-phase approach for mitigating BDBEE
 
====s.  The ====
 
initial phase makes use of installed equipment and resources to maintain or restore key safety functions including core cooling, containment, and SFP coolin g. The transition phase incl udes providing sufficient, portable, onsite equipment and consumables to maintain or restore these functions until they can be accomplished with resources brought from offsite. The final phase includes obtaining sufficient offsite resources to sustain these functions indefinitely.
 
External Documents Endorsed in This Guide This RG endorses, in part, the use of one or more codes, standards, or guidance documents developed by external organizations. These codes, standards, and third party guidance documents may contain references to other codes, standards, or third party guidance documents ("secondary references"). If a secondary reference has itself been incorporated by reference into NRC regulations as a requirement, then licensees and applicants must comply with that standard as set forth in the regulation. If the secondary reference has been endorsed in an RG as an acceptable approach for meeting an NRC requirement, then the standard constitutes a method acceptable to the NRC for meeting that regulatory requirement as described in the specific RG. If the secondary reference has neither been incorporated into NRC regulations nor endorsed in an RG, the secondary reference is neither a legally-binding requirement nor a "generic" NRC-approved acceptable approach for meeting an NRC requirement. However, licensees and applicants may consider and use the information in the secondary reference, if appropriately justified, consistent with current regulatory practice, and consistent with applicable NRC requirements.
 
Harmonization with International Standards The International Atomic Energy Agency (IAEA) has established a series of technical reports, safety guides and standards constituting a high level of safety for protecting people and the environment. IAEA guides present international good practices and identify best practices to help users striving to achieve high levels of safety. This RG and the NEI technical document endorsed by it contain guidance about BDBEE mitigation similar to guidance under revision by the IAEA.
 
C.  STAFF REGULATORY GUIDANCE
 
RG 1.226, Page 7 This RG endorses, with clarifications, the met hods described in NEI 12-06, Revision 4, dated December 2016. The NRC staff has determined that the methods described in the NEI 12-06, Revision 4, constitute procedures and processes generally acceptable to the NRC for demonstrating compliance with the regulatory requirements in 10 CFR 50.155, subject to the following clarifications and addition
 
====s.      ====
1. Development and Implementation Process Paragraphs 50.155(b) and (b)(1) require that applicants or licensees develop and implement an integrated response capability that includes strategies and guidelines to mitigate beyond-design-basis external events from natural phenomena that result in an loss of all alternating current power concurrent with either a loss of normal access to the ultimate heat sink (LUHS) or, for nuclear power plants with passive reactor designs, a loss of normal access to the normal heat sink.
 
The strategies and guidelines developed and implemented under those sections must be capable of being implemented site-wide and must include maintaining or restoring core cooling, containment, and spent fuel pool cooling capabilities; and the acquisition and use of offsite assistance and resources to support those functions.
 
1.1. Establishment of Baseline Coping Capability
 
Section 1.3 of NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 4, provides the objectives and guiding principles of the FLEX program that are responsive to 10 CFR 50.155(b) and (b)(1) and provide that plant-specific analyses will determine the duration of each phase, as described below in Section 1.1.1..
 
Section 2 of NEI 12-06, Revision 4, provides a high-level discussion of the site-specific nature of the actions required by each licensee to properly implement the performance-based requirements in 10 CFR 50.155(b) and (b)(1).  Sections 2.1 through 2.5 of NEI 12-06, Revision 4, discuss the coping capacities, types of external hazards, strategies, and controls each licensee should implement to meet the requirements of the rule.
 
Section 3 of NEI 12-06, Revision 4, provides performance attributes, general criteria, and baseline assumptions for use in the development and implementation of the strategies and guidelines under 10 CFR 50.155(b) and (b)(1).  NEI 12-06, Revision 4, further provides that licensees should use these criteria and assumptions for analyses used to establish a baseline coping capability.  The assumptions include the initial conditions listed in Section 3.2.1.3 of NEI
12-06, Revision 4, that include an extended loss of ac power (ELAP) consisting of a loss of offsite power (LOOP) affecting all units at a plant site and the specification that "[a]ll design-basis installed sources of emergency on-site ac [alternating current] power and SBO [station blackout] alternate ac power sources [as defined in 10 CFR 50.2, "Definitions" are assumed to be not available and not imminently recoverable."
 
Section 3.2.1.7 of NEI 12-06, Revision 4, specifies that "[s]trategies that have a time constraint to be successful should be identified and a basis provided that the time can reasonably be met."  Section 11.4.3 of NEI 12-06, Revision 4, specifies that FLEX support guidelines (FSGs) will be developed to provide guidance that can be employed for a variety of conditions and that the FSGs will be reviewed and validated to ensure they ar e feasible.  Appendix E to NEI 12-06, Revision 4, provides a method for validating the FSGs.
 
Section 3.2.1.13 of NEI 12-06, Revision 4, specifies that best-estimate analyses are appropriate for the purpose of establishing the baseline coping capabilities.
 
RG 1.226, Page 8 Staff Position: Sections 1, 2 and 3 and Appendix E of NEI 12-06, Revision 4 provide an acceptable method for licensees to follow to develop a baseline coping capability for mitigating an ELAP concurrent with either an LUHS or, for nuclear power plants with passive reactor designs, a loss of normal access to the normal heat sink with the following clarifications and addition:
 
a) An element of a set of strategies to maintain or restore core and SFP cooling and containment functions includes knowledge of the time a licensee or applicant can withstand challenges to these key safety functions using installed equipment during a BDBEE.  This knowledge provides an input to the choice of storage locations and conditions of readiness of the equipment required for the follow-on phase.  This duration is related to, but distinct from, the specified duration for the requirements of 10 CFR
 
50.63(a), because it represents the current cap abilities of the licensee or applicant rather than a required capability.  Licensees and applicants should (1) account for the SFP
cooling function, which is not addressed by 10 CFR 50.63(a), and (2) assume that alternate ac sources, which may be included in meeting the specified durations of 10 CFR 50.63(a), are unavailable,. This is imp licit in the principles described in Section 3.2.1.7, paragraph (6), and Section 3.2.2, paragraph (1), of NEI 12-06, Revision 4.
 
b) The use of best-estimate analyses for establishing the baseline coping capabilities is appropriate in the context of the BDBEEs for 10 CFR 50.155(b).  This includes the use of normal fluid levels for tanks that are maintained by procedure or administrative controls rather than the minimum levels allowed by technical specifications.
 
c) Consistent with the goal of mitigation strategies for BDBEE, the NRC endorses the validation method documented in Appendix E to NEI 12-06, Revision 4, as a method to (1) assess whether it is "feasible" (as the term is used in risk-informed decision making),
considering design-basis or reevaluated hazard conditions determined under the 10 CFR
50.54(f) request for information letter issued on March 12, 2012 (Ref. 37) (as applicable), to execute tasks, manual actions, and decisions (i.e., human actions) required by the mitigation strategies described in NEI 12-06, Revision 4, and (2) support a conclusion that the strategies mitigate, to the extent practical, the adverse effects of BDBEEs on the ability of personnel to perform the required human actions.  However, Appendix E to NEI 12-06, Revision 4, does not propose a method to assess whether required human actions are reliable, nor does the NRC endorse it as such.
 
1. Tasks, manual actions, or decisions performed more than 24 hours after the initiation of the event that have time constraints may be validated using a Level A or Level B method that results in an estimate of the time required to complete the task or manual action or to make and communicate the decision in order to confirm that the time constraint can reasonably be met as specified in Section 3.2.1.7, principle 6, of NEI 12 06, Revision 4.  Section 3.2.1.7, principle 6, states that "[s]trategies that have a time constraint to be successful should be identified and a basis provided that the time can reasonably be met." 
1.1.1. Phased Approach The regulations in 10 CFR 50.155 do not contain specific requirements for a multiple phase approach to mitigating and recovering from a BDBEE as had been the case under Order EA-12-049. NEI 12-06, Revision 4, carries the definitions of the phases from that order forward as a conceptual framework for the development of the FLEX strategies. Maintenance of core and RG 1.226, Page 9 SFP cooling and containment functions requires overlap between the initiating times for the phases with the duration for which each licensee can perform the prior phase
 
====s. The NRC ====
recognizes that for certain BDBEEs, the damage state could prevent maintenance of key safety functions using the equipment intended for particular phases. Under such circumstances, prompt initiation of the follow-on phases to restore core and SFP cooling and containment functions is appropriate.
 
Staff Position: NEI 12-06, Revision 4 provides an acceptable method for developing an approach to mitigate and cope with BDBEEs.
 
1.1.1.1. Initial Response Phase The initial response phase will be accomplished using installed equipment.  Licensees and applicants should establish and maintain current estimates of their capabilities to maintain core and SFP cooling and containment functions assuming a loss of all ac electric power to the essential and nonessential switchgear buses, except for those fed by station batteries through inverters. These estimates provide the time period in which the licensee should be able to initiate the transition phase and maintain or restore the key safety functions using portable onsite equipment.  These estimates should be considered in selecting the storage locations for that equipment and the prioritization of resources to initiate their use.
 
Staff Position: NEI 12-06, Revision 4, Section 3.0, provides an acceptable method for determining the baseline coping capab ilities for the initial response phase.
 
1.1.1.2. Transition Phase The transition phase will be accomplished by supplementing installed equipment with onsite equipment.  The strategies for this phase must be capable of maintaining core cooling, containment, and SFP cooling capabilities (after their restoration, if applicable) from the time they are implemented until they can be supplemented by offsite resources in the final phase.  The duration of the transition phase should provide sufficient overlap with both the initial and final phases to account for the time it takes to in stall equipment and for uncertainties.
 
Staff Position: NEI 12-06, Revision 4, Section 3.0, provides an acceptable method for determining the baseline coping capabilities for the transition phase.
 
1.1.1.3. Final Phase The final phase will be accomplished using the onsite equipment augmented with additional equipment and consumables obtained from off-s ite until power, water, and coolant injection systems are restored or commissioned.
 
Staff Position: NEI 12-06, Revision 4, Section 3.0, provides an acceptable method for determining the baseline coping capabilities fo r the final phase. NEI 12-06, Revision 4, Section 12.2, provides an acceptable method for establishing the capability to obtain equipment and consumables from off-site until power, water, and coolant injection systems are restored or commissioned.  This provides an acceptable method to sustain the listed functions indefinitely when coupled with the restoration or commissioning of power, water, and coolant injection systems.
 
RG 1.226, Page 10
1.2. Contingencies for Loss of All Alternating Current Power Section 1.3 of NEI 12-06, Revision 4, defines an ELAP as a "loss of off-site power, emergency diesel generators and any alternate ac source but not the loss of ac power from buses fed by station batteries through inverters."  (Footnote omitted.)  Section 1.1 of this RG discusses an acceptable approach to mitigating the effects of an ELAP.  10 CFR 50.155(b)(1) requires "[s]trategies and guidelines to mitigate beyond-design-basis external events from natural phenomena that are developed assuming  a loss of all ac power-" rather than an ELAP.  The difference between the conditions described in NEI 12-06 and those in 10 CFR 50.155(b)(1) is addressed through the development of contingency actions. Specifically, the damage state of a loss of all ac power condition concurrent with LUHS was implemented first through the assumption of an ELAP to the onsite emergency ac buses, while allowing ac power from the inverters to be assumed available, in order to establish event sequence and the associated times for when mitigation actions would be assumed to be required.  Secondly, to address the 10 CFR 50.155(b)(1) requirement for a loss of all ac power, including ac power from the batteries (through inverters), contingencies are included in the mitigation strategies to enable actions to be taken under those circumstances (e.g., sending operators to immediately take manual control over a non-ac-powered core cooling pump).  These contingencies, which are discussed below, could be implemented if ac power fed by station batteries through inverters is not available.
 
NEI 12-06, Revision 4, Section 3.2.2 provides 17 guidelines for use in the development of the guidance and strategies under 10 CFR 50.155(b)(1). Guideline (2) of this sections states:
Plant procedures/guidance should recognize the importance of AFW/HPCI/RCIC/IC during the early stages of the event and direct the operators to invest appropriate attention to assuri ng its initiation and continued, reliable operation throughout the transient since this ensures decay heat removal.
 
The risk of core damage due to ELAP can be significantly reduced by assuring the availability of auxiliary feedwater (AFW) (emergency feedwater (EFW) at some plants), high pressure core injection (HPCI), reactor core isolation cooling (RCIC), or isolation condensers (IC), particularly in the first 30 minutes to one hour of the event. Assuring that one of these systems has been initiated to provide early core heat removal, even if local initiation and control is required is an important initial action. A substantial portion of the decay and sensible reactor heat can be removed during this period. The availability of AFW/HPCI/RCIC/IC can be improved by providing a reliable supply of water, monitoring turbine conditions (particularly lubricating oil flow and temperature), bypassing automatic trips, and maintaining nuclear boiler/steam generator water levels. These actions help ensure that the core remains adequately covered and cooled during an [ELAP] event.
 
Appendices C and D of NEI 12-06, Revision 4 contain summaries of performance attributes for boiling-water and pressurized-water reactors respectively, and address Guideline (2) of NEI 12-06, Revision 4, Section 3.2.2 by specifying that procedures/guidance will include local manual initiation of AFW/EFW/HPCI/RCIC/IC.
 
Section 5.3.3 of NEI 12-06, Revision 4, describes interface considerations for seismic events and expands on this contingency to specify that the strategies and guidelines should include the following:
 
RG 1.226, Page 11 -a reference source for the plant operators that provides approaches to obtaining necessary instrument readings to support the implementation of the coping strategy. Such a resource could be provided as an attachment to the plant procedures/guidance. Guidance should include critical actions to perform until alternate indications can be connected and on how to control critical equipment without associated control power.
 
This reference source should include control room and non-control room readouts and should also provide guidance on how and where to measure key instrument readings using a portable instrument (e.g., a Fluke meter) at a location that does not rely on the functioning of intervening electrical equipment (e.g. I/E convertors, analog to digital converters, relays, etc.) that could be adversely affected by BDB seismic events. An instrument reading should be obtained at the closest accessible termination point to the containment penetration or parameter of measurement, as practical.
 
Staff Position: Guideline (2) of Section 3.2.2 of NEI 12-06, Revision 4, and the provisions in Appendices C and D to NEI 12-06, Revision 4, for manual initiation of AFW/EFW/HPCI/RCIC/IC, coupled with the provisions in Section 5.3.3 of NEI 12-06, Revision 4, for the development of guidance on obtaining instrument readings and controlling critical equipment without the associated power, provide an acceptable method for licensees to develop
 
the contingencies for the loss of all ac power, which are necessary to comply with the requirement in 10 CFR 50.155(b)(1) to mitigate a loss of all ac power. The need for the contingencies in Section 5.3.3 of NEI 12-06, Revision 4, to show compliance with the condition of loss of all ac power is not limited to seismically-induced events; it is a necessary element of compliance for that requirement regardless of the initiating event.  Because Section 5 of NEI 12-06, Revision 4, is applicable to all power reactor licensees, conformance to Section 5.3.3 of NEI
12-06, Revision 4, can provide the capabilities necessary to meet that element regardless of the initiating event.
 
2. Equipment Capacity and Capability Paragraph 50.155(c)(1) requires that the equipment relied upon for the mitigation strategies, guidelines, and event-specific approaches required by § 50.155(b)(1) and (b)(2) have sufficient capacity and capability to perform the functions required by § 50.155(b)(1) and (b)(2).
Section 3.2.1.12 of NEI 12-06, Revision 4 provides that there should be a basis for plant equipment relied upon to support implementation of the mitigating strategies to perform its function.
 
Guideline (16) in Section 3.2.2 of NEI 12-06, Revision 4, provides guidance for the minimum number of sets of equipment a licensee should have in order to achieve reasonable assurance that the equipment will be available in sufficient qua ntity to have the capacity necessary to comply with the rule.  This includes guidance for the provision of spare hoses and cables in a quantity that is either (1) equivalent to 10 percent of the total length of each type of hose or cable necessary or (2) of sufficient length and sizing to replace the single longest run needed to support any single strategy.
 
Sections 11.1 and 11.2 of NEI 12-06, Revision 4, provide guidance on the quality attributes and equipment design a licensee may use to achieve reasonable assurance that the individual pieces of RG 1.226, Page 12 equipment have the capability to perform the functions they are intended for in the FLEX
strategies.
 
Staff Position: Section 3.2.1.12, Guideline (16) of Section 3.2.2 and Sections 11.1 and 11.2 of NEI 12-06, Revision 4, provide an acceptable method to demonstrate compliance with § 50.155(c)(1). 
3. Reasonable Protection Paragraph 50.155(c)(2) and (c)(3) require that the equipment relied upon for the mitigation strategies required by § 50.155(b)(1) and (b)(2) be reasonably protected from the effects of natural phenomena.
 
Appendix A to NEI 12-06, Revision 4, defines reasonable protection as- "[s]toring on-site FLEX equipment in configurations such that no one external event can reasonably fail the site FLEX capability (N) when the required FLEX equipment is available."
 
Staff Position: NEI 12-06, Revision 4, provides an acceptable approach for reasonably protecting equipment from the effects of natural phenomena. This approach includes the following:
 
* Identification of the natural phenomena for which reasonable protection is necessary,
* Determination of the method of protection to be used,
* Establishment of controls on f unctionality of the equipment, and
 
* Provision of a method of transporting the portable equipment from its storage location to the site in which it will be used.
 
Individual elements of reasonable protection are discussed below.
 
3.1. Evaluation of External Hazards Section 4 of NEI 12-06, Revision 4, discusses the overall methodology for identifying external hazards and evaluating their impact. Appendix B of NEI 12-06, Revision 4, discusses the identification of external hazards for which licensees should provide reasonable protection. Sections 5 through 9 of NEI 12-06, Revision 4, discuss the evaluation of the effects of natural phenomena to meet the baseline coping capability.
 
Staff Position: Sections 5 through 9 and Appendix B of NEI 12-06, Revision 4, provide an acceptable method for the evaluation and equipmen t considerations to address the effects of external hazards in order to satisfy that element of reasonable protection.
 
3.2. Protection from External Hazards
 
Sections 5 through 9 of NEI 12-06, Revision 4, discuss methodologies for the protection of the equipment.  The methods of protection comprise (1) physical protection of the equipment, (2)
protection by relocation of the equipment from a position in which a licensee may have indication of an impending hazard, and (3) provision of multiple, redundant pieces of equipment or methods to accomplish a function, stored in diverse locations to ensure that at least one method of RG 1.226, Page 13 accomplishing that function will survive an event of a localized nature such as a tornado missile impact.
 
Section 11.5.4.b.i provides that in the event of non-functionality of equipment that is reasonably protected from tornado winds and/or missiles by means of separation from redundant or alternate equipment, that redundant or alternate equipment continues to be deemed reasonably protected by means of separation.
 
Section 11.5.4.e and f discuss the programmatic controls for the protection of the equipment from external hazards, providing limited durations for which equipment may be out of its normal reasonable protection configuration for maintenance, testing, risk reduction for plant maintenance or outage activities, or other reasons.
 
Staff Position: Sections 5 through 9, 11.5.4.b.i, 11.5.4.e, and 11.5.4.f of NEI 12-06, Revision 4 provide an acceptable method for protecting the equipment from the effects of external hazards in order to satisfy that element of reasonable protection.
 
3.3. Deployment of Equipment Sections 5 through 9 of NEI 12-06, Revision 4, discuss methods for transporting the equipment from the location in which it is stored to the location in which it would be used. These sections additionally discuss the connection of the equipment to structures, systems, and components (SSCs) necessary for completion of the deployment of the equipment from storage to a state in which it can supplement the functions of the installed SSCs.
 
Staff Position: Sections 5 through 9 and Appendix B of NEI 12-06, Revision 4 provide an acceptable method for deployment of the equipment in order to satisfy that element of reasonable protection.
 
3.4. Programmatic Controls for Functionality Section 11.5.4 of NEI 12-06, Revision 4, discusses the programmatic controls for equipment and connections between that equipment and permanently installed SSCs.  These controls include limited time periods in which the equipment and connection points may be non-functional for any reason, with the duration of the acceptable time period being based on the ability of the licensee to accomplish the intended function of the equipment by other means.
 
When a licensee cannot accomplish the intended function of the equipment by other means, durations for which the equipment is non-functional are limited to periods comparable to those allowed by technical specifications for safety-related SSCs with similar functions (e.g., the completion times allowed for restoration of turbine-driven auxiliary feedwater trains in Limiting Condition for Operation 3.7.5, "Auxiliary Feedwater (AFW) System," of NUREG-1431, "Standard Technical Specifications-Westinghouse Plants," Volume 1, "Specifications," Revision 4.0, issued April 2012 (Ref. 38), which range from 24 hours to 7 days.
 
When a licensee can accomplish the intended function of the equipment by other means (e.g., the equipment is spare equipment beyond the minimum necessary to accomplish the intended function), durations for which the equipment is non-functional are limited to 90 days based on a normal plant work cycle of 12 weeks to avoid displacing maintenance actions for other safety- significant equipment or SSCs.
 
RG 1.226, Page 14 When a licensee is able to accomplish the intended function of the equipment by other means, but that means is not protected from all possible effects of natural phenomena, durations for which the equipment is non-functional are limited to 14 days in order to avoid displacing maintenance actions for other safety-significant equipment or SSCs.
 
Similar controls are applied to connection points for the equipment to installed SSCs.
 
Section 11.5.4.e of NEI 12-06, Revision 4, stipulates that the unavailability of equipment does not constitute a loss of reasonable protection from the standpoint of a diverse storage location protection strategy.  Section 7.3.1.b gives the diverse storage location protection strategy, which allows for the reasonable protection of equipment from the tornado missile hazard by storing multiple sets of equipment in locations that are unlikely to be damaged by missiles from the same tornado.  Staff Position: Section 11.5.4 of NEI 12-06, Revision 4, provides an acceptable method for controlling unavailability of the equipment to satisfy that element of reasonable protection.
 
4. Equipment Maintenance Paragraph 50.155(b) requires that licensees maintain guidance and strategies to maintain or restore core cooling, containment, and SFP c ooling capabilities.  This necessitates that the equipment relied on for the mitigation strategies under § 50.155(b) receive adequate maintenance such that it is capable of fulfilling its intended function.
 
Section 11.5 of NEI 12-06, Revision 4 discusses the maintenance and testing of the equipment. Section 3.2.1.13 discusses the Electric Power Res earch Institute (EPRI)
program developed for maintenance of the equipment, which is documented in the EPRI technical report 3002000623, "Applications Center: Preventive Maintenance Basis for FLEX Equipment - Project Overview Report" (Ref. 39). The EPRI technical report 3002000623 was endorsed by NRC letter dated October 7, 2013 (Ref. 40). 
Staff Position: Sections 11.5 and 3.2.1.13 of NEI 12-06, Re vision 4, provide an acceptable method for maintaining the equipment relied on for the mitigation strategies under § 50.155(b)(1).
5. Configuration Control Paragraph 50.155(b), (b)(1) and (b)(2) require that applicants or licensees maintain an integrated response capability that includes strategies and guidelines to mitigate beyond-design-basis external events from natural phenomena that result in a loss of all ac power concurrent with either an LUHS or, for nuclear power plants with passive reactor designs, a loss of normal access to the normal heat sink.
 
Paragraph 50.155(g) allows licensees to make changes to the implementation of the requirements of 10 CFR 50.155 without NRC approval provided that the licensee demonstrates that
10 CFR 50.155 continues to be met prior to making the change and maintains document of
 
changes.  Section 11.8 of NEI 12-06, Revision 4 discusses the configuration control of the strategies and guidelines as well as the maintenance of an overall program document and record of changes.
 
RG 1.226, Page 15 Staff Position: Section 11.8 of NEI 12-06, Revision 4 provides an acceptable method for maintaining configuration control of an integrated response capability under 10 CFR 50.155(b)(1), (b)(2), and (g).
 
6. Treatment of Reevaluated Hazards under the Requests for Information of March 12, 2012 Paragraph CFR 50.155(b)(2) requires that each licensee that received the March 12, 2012, NRC letter issued under § 50.54(f) concerning reevaluations of seismic and flooding hazard levels consider the effects of the reevaluated hazards information developed in response to that request if the magnitude of those hazards exceeds the external design basis of the facility.  Licensees with exceedances are required to address the effects of the reevaluated hazard information by showing that the mitigation strategies and guidelines required by 10 CFR 50.155(b)(1), as implemented or as modified, will mitigate the hazards, or by developing and implementing event-specific approaches.
 
Paragraph 50.155(c)(3) requires that licensees provide reasonable protection for the equipment relied upon by the strategies and guidelines under 10 CFR 50.155(b)(2) from the effects of the reevaluated hazards determined in response to the March 12, 2012 NRC letter issued under 10 CFR 50.54(f).
 
6.1. Treatment of Reevaluated Seismic Hazards Appendix H to NEI 12-06, Revision 4, discusses a method to assess the results of the seismic hazard reevaluations with respect to the strategies and guidelines or event-specific approaches required by 10 CFR 50.155(b)(2).
6.1.1.  (Modified) Mitigating Strategies Sections H.4.1, H.4.2, and H.4.4 of Appendix H to NEI 12-06, Revision 4, discuss a method to assess or modify the mitigating strategies to meet the requirements of 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3).
 
Section H.4.5 of Appendix H to NEI 12-06, Revision 4, discusses several methods to assess the capability of a facility to meet the requirements of 10 CFR 50.155(b)(2) and 10 CFR
50.155(c)(3).
 
Staff Position:  Sections H.4.1, H.4.2, H.4.4, and H.4.5.2 (when combined with Section H.4.5.6) of Appendix H to NEI 12-06, Revision 4, provide appropriate methods to assess or modify the mitigating strategies to show that they remain capable of mitigating the new seismic hazard information, referred to as mitigating strategies seismic hazard information, with the following clarification.  In addition to the raceways (cable trays and conduit) and nuclear steam supply system components (piping and vessels) listed as classes of high-capacity equipment and systems established in EPRI NP-6041-SL, "A Methodology for Assessment of Nuclear Plant Seismic Margin," Revision 1, dated August 1, 1991 (Ref. 41), as having sufficient seismic capacities relative to the ground motion response spectrum (GMRS) for Path 4 plants and therefore not requiring additional evaluations to demonstrate ruggedness, Table 2-4 of EPRI NP-6041-SL provides that buried tanks also have sufficient seismic capacity and limits evaluations of those tanks to evaluation of piping connections.  The potential for misalignment of piping connections due to soil failures impacting buried tanks associated with the Expedited Seismic Evaluation Process equipment list should be considered in Section H.4.4, Step 3, as a seismic failure mechanism that could potentially affect the FLEX
strategies.  Soil failure evaluations are not RG 1.226, Page 16 needed for structures that are considered inherently or sufficiently rugged relative to the GMRS
levels for Path 4 plants.
 
The method described in Section H.4.4 of NEI 12-06, Revision 4, is applicable for the following types of facilities:
 
* those facilities for which Section H.4.3 is applicable as documented in Section 6.1.2 of this RG
* Beaver Valley Power Station, Units 1 and 2, Renewed License Nos. DPR-66 and NPF-73
 
* Calvert Cliffs Nuclear Power Plant, Units 1 and 2, Renewed License Nos. DPR-53 and DPR-69
* Catawba Nuclear Station, Units 1 and 2, Renewed License Nos. NPF-35 and NPF-52
 
* Cooper Nuclear Station, Renewed License No. DPR-46
 
* Davis-Besse Nuclear Power Station, Unit 1, License No. NPF-3
 
* Donald C. Cook Nuclear Plant, Units 1 and 2, Renewed License Nos. DPR-58 and DPR-
74
* Dresden Nuclear Power Station, Units 2 and 3, Renewed License Nos. DPR-19 and DPR-
25
* Edwin I Hatch Nuclear Plant, Units 1 and 2, Renewed License Nos. DPR-57 and NPF-5
 
* Fermi, Unit 2, Facility Operating License No. NPF-43
 
* LaSalle County Station, Units 1 and 2, Facility Operating License Nos. NPF-11 and NPF-
18
* McGuire Nuclear Station, Units 1 and 2, Renewed License Nos. NPF-9 and NPF-17
 
* Monticello Nuclear Generating Plant, Unit 1, License No. DPR-22
 
* Perry Nuclear Power Plant, Unit 1, License No. NPF-58
 
* Point Beach Nuclear Plant, Units 1 and 2, Renewed License Nos. DPR-24 and DPR-27
 
* Seabrook Station, Unit 1, Facility Operating License No. NPF-86
 
* Three Mile Island Nuclear Station, Unit 1, Renewed License No. DPR-50
 
* Watts Bar Nuclear Plant, Units 1 and 2, Facility Operating License Nos. NPF-90 and NPF-96
* Wolf Creek Generating Station, Unit 1, Renewed License No. NPF-42
 
RG 1.226, Page 17 Sections H.4.5.4 and H.4.5.5, of NEI 12-06, Revision 4 (for instances in which the seismic probabilistic risk assessment incorporates the strategies and guidelines required by 10 CFR 50.155(b)(1)), in combination with Section H.4.5.6, provide appropriate methods to assess or modify the mitigating strategies to meet the requirements of 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3).
6.1.2.  Alternate Mitigating Strategies Section H.4.3 of Appendix H to NEI 12-06, Revision 4, discusses a method to develop an alternate mitigating strategy (AMS) to meet the requirements of 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3).  This includes a modification of the general criteria and baseline assumptions included in Section 3.2.1 of NEI 12-06 to exclude consideration of losses such as an ELAP, LOOP, or LUHS unless caused by the seismic hazard.
 
Sections H.4.5.3, H.4.5.4, and H.4.5.5, in combination with Section H.4.5.6, of NEI 12-06, Revision 4, discuss methods to develop an AMS to meet the requirements of 10 CFR
50.155(b)(2) and 10 CFR 50.155(c)(3). 
 
Staff Position:  The method described in Section H.4.3 of NEI 12-06, Revision 4, for development of an AMS that provides a capability to mitigate the BDBEE is an acceptable method to meet the requirements of 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3).  The protection of onsite power sources and normal access to the ultimate heat sink from the seismic hazard is an acceptable method of mitigating a simultaneous loss of all ac power and loss of normal access to the ultimate (normal) heat sink.
 
The method described in Section H.4.3 of NEI 12-06, Revision 4, is applicable for the following types of facilities:
 
* Arkansas Nuclear One, Units 1 and 2, Renewed License Nos. DPR-51 and NPF-6
 
* Brunswick Steam Electric Plant, Units 1 and 2, Renewed License Nos. DPR-71 and DPR-62
* Byron Station, Units 1 and 2, Renewed License Nos. NPF-37 and NPF-66
 
* Fort Calhoun Station, Unit 1, Renewed License No. DPR-40
 
* James A. FitzPatrick Nuclear Power Plant, Renewed License No. DPR-59
 
* Millstone Power Station, Units 2 and 3, Renewed License Nos. DPR-65 and NPF-49
 
* Salem Nuclear Generating Station, Units 1 and 2, Renewed License Nos. DPR-70 and DPR-75Susquehanna Steam Electric Station, Units 1 and 2, Renewed License Nos. NPF-14 and NPF-22
 
The methods described in Sections H.4.5.3, H.4.5.4, and H.4.5.5, in combination with Section H.4.5.6, of NEI 12-06, Revision 4, to develop an AMS that provides a capability to mitigate the BDBEE are acceptable methods of providing reasonable protection when the hazard level for the AMS is identified.  The protection of onsite power sources and normal access to the ultimate heat RG 1.226, Page 18 sink from the seismic hazard is an acceptable method of mitigating a simultaneous loss of all ac power and loss of normal access to the ultimate (normal) heat sink.
 
6.2. Treatment of Reevaluated Flooding Hazards Appendix G of NEI 12-06, Revision 4 discusses a method to assess the results of the flooding hazard reevaluations with respect to the guidance and strategies required by 10 CFR 50.155(b)(2). 
6.2.1.  (Modified) Mitigating Strategies Sections G.4.1 and G.4.2 of Appendix G of NEI 12-06, Revision 4 discuss a method to assess or modify the mitigating strategies to show they comply with the requirements of 10 CFR
50.155(b)(2) and 10 CFR 50.155(c)(3) by using the new flooding hazard information, referred to as mitigating strategies flood hazard information.
 
Staff Position: Sections G.4.1 and G.4.2 of Appendix G of NEI 12-06, Revision 4, provide acceptable methods to show that the existing strategies and guidelines comply with the requirements of 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3) for the new flooding hazard information or for developing modified strategies and guidelines.
 
6.2.2.  Alternate Mitigating Strategies Section G.4.3 of Appendix G to NEI 12-06, Revision 4, discusses a method to develop an AMS to meet the requirements of 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3) to address the mitigating strategies flood hazard information.  This includes a modification of the general criteria and baseline assumptions included in Section 3.2.1 of NEI 12-06 to exclude consideration of losses such as an ELAP, LOOP, or LUHS unless caused by the flood hazard.
 
Staff Position:  The method described in Section G.4.3 of NEI 12-06, Revision 4, for development of an AMS that provides a capability to mitigate the BDBEE is an acceptable method for complying with 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3).  The protection of onsite power sources and normal access to the ultimate heat sink from the flood hazard is an acceptable method of mitigating a simultaneous loss of all ac power and loss of normal access to the ultimate heat sink.
 
6.2.3.  Targeted Hazard Mitigating Strategies Section G.4.4 of Appendix G to NEI 12-06, Revision 4, discusses a method to develop targeted hazard mitigating strategies (THMS) to meet the requirements of 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3) to address the mitigating strategies flooding hazard information.  This includes a modification of the general criteria and baseline assumptions included in Section 3.2.1 of NEI 12-06, Revision 4, to exclude consideration of losses such as an ELAP, LOOP, or LUHS unless caused by the flood hazard.
 
Staff Position:  The method described in Section G.4.4 of NEI 12-06, Revision 4, for development of a THMS that provides a capability to mitigate the BDBEE is an acceptable method to meet the requirements of 10 CFR 50.155(b)(2) and 10 CFR 50.155(c)(3) to address the mitigating strategies flooding hazard information.
 
The protection of onsite power sources and normal access to the ultimate heat sink from the flood hazard is an acceptable method of mitigating a simultaneous loss of all ac power and loss of normal access to the ultimate heat sink 
 
RG 1.226, Page 19
7. Coordination with Severe Accident Management Guidelines In SRM-COMSECY-15-0065, (Ref. 42) the Commi ssion directed the NRC staff to "-ensure that any NRC-endorsed guidance for the proposed rule will provide for appropriate coordination of the FLEX support guidelines, extreme damage mitigating guidelines, and voluntarily maintained SAMGs [Severe Accident Management Guidelines] with the existing emergency operating procedures (EOPs) at each plant-."
 
Section 3.2.1.10 of NEI 12-06, Revision 4, provides criteria for the selection of parameters to be monitored as part of the minimum set of parameters necessary to support strategy implementation.  These criteria include the ability to demonstrate the success of the strategies at maintaining the key safety functions, as well as indicating imminent or actual core damage to facilitate a decision to manage the response to the event within the EOPs and FSGs or within the SAMGs.  Section 11.4 of NEI 12-06, Revision 4 provides that FSGs will be used to supplement (not replace) the existing procedures that establish the command and control for the event.  This section further provides that the existing command and control procedure structure will be used to transition to SAMGs if FLEX mitigation strategies are not successful.
 
Staff Position:  Sections 3.2.1.10 and 11.4 provide appropriate coordination between the FSGs and SAMGs, retaining command and control direction as defined within the EOPs unless and until a licensee transitions to the use of SAMGs.
 
8. Guidance for AP-1000 Design Appendix F of NEI 12-06, Revision 4 provides specific guidance for licensees with reactors of the AP-1000 design on how to satisfy provisions of the aforementioned regulations for sufficient offsite resources to sustain functions indefinitely.
 
Staff Position: The guidance of NEI 12-06, Revision 4, Appendix F, provides an acceptable means to meet the requirements of the regulations or license conditions imposing similar requirements.
 
==D. IMPLEMENTATION==
.  The purpose of this section is to provide information on how applicants and licensees
1 may use this guide and information regarding the NRC's plans for using this RG. In addition, it describes how the NRC complies with the Backfit Rule found in 10 CFR 50.109(a)(1) or any applicable finality provisions in 10 CFR Part 52.
 
1  In this section, "licensees" refers to holders of, and "applicants" refers to applicants for, licenses for nuclear power plants under 10 CFR Parts 50 and 52.
 
RG 1.226, Page 20 Use by Applicants and Licensees Applicants and licensees may voluntarily
2 use the guidance in this document to demonstrate compliance with the underlying NRC regulations. Methods or solutions that differ from those described in this RG may be deemed acceptable if they provide sufficient basis and information for the NRC to verify that the proposed alternative demonstrates compliance with the appropriate NRC regulations. Current licensees may continue to use guidance the NRC found acceptable for complying with the identified requirements as long as their current licensing basis remains unchanged.
 
Licensees may use the information in this RG for actions that do not require NRC review and approval. Licensees may use the information in this RG or applicable parts to resolve regulatory or inspection issues.
 
Use by NRC   
The NRC does not intend or approve any imposition or backfitting of the guidance in this RG. The NRC does not expect any existing licensee to use or commit to using the guidance in this RG, unless the licensee makes a change to its licensing basis. The NRC does not expect or plan to request licensees to voluntarily adopt this RG to resolve a generic regulatory issue. The NRC does not expect or plan to initiate NRC regulatory action that would require the use of this RG. Examples of such unplanned NRC regulatory actions include issuance of an order requiring the use of the RG, generic communication, or promulgation of a rule requiring the use of this RG without further backfit consideration.
 
During regulatory discussions on plant-specific operational issues, the NRC staff may discuss with licensees various actions consistent with NRC positions in this RG, as one acceptable means of meeting the underlying NRC regulatory requirement. Such discussions would not ordinarily be considered backfitting. However, unless this RG is part of the licensing basis for a facility, the NRC may not represent to the licensee that the licensee's failure to comply with the positions in this RG constitutes a violation.
 
If an existing licensee voluntarily seeks a license amendment or change and (1) the NRC's consideration of the request involves a regulatory issue directly relevant to this RG and (2) the specific subject matter of this RG is an essential consideration in the NRC's determination of the acceptability of the licensee's request, then the NRC may request that the licensee either follow the guidance in this RG or provide an equivalent alternative process that demonstrates compliance with the underlying NRC regulatory requi rements. This is not considered backfitting as defined in 10 CFR 50.109(a)(1) or a violation of any applicable finality provisions in 10 CFR Part 52.
 
If a licensee believes that the NRC is either using this RG or requesting or requiring the licensee to implement the methods or processes in this RG in a manner inconsistent with the discussion in this Implementation section, then the licensee may file a backfit appeal with the NRC in accordance with the guidance in NUREG-1409, "Backfitting Guidelines" (Ref. 43), and the NRC Management Directive 8.4, "Management of Facility-Specific Backfitting and Information Collection" (Ref. 44). 
 
2  In this section, "voluntary" and "voluntarily" means that the licensee is seeking the action of its own accord, without the force of a legally binding requirement or an NRC representation of further licensing or enforcement action.
 
RG 1.226, Page 21 REFERENCES
3    1. U.S. Code of Federal Regulations (CFR), Title 10, "Energy," Chapter 1, "Nuclear Regulatory Commission," Part 50, "Domestic Licensing of Production and Utilization Facilities." 
 
2. Nuclear Energy Institute (NEI) document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 4, dated September 2016, Washington, DC. (ADAMS Accession No. ML16354B421)
4    3. CFR , Title 10, "Energy," Chapter 1, "Nuclear Regulatory Commission," Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants." 
4. U.S. Nuclear Regulatory Commission (NRC), SECY-11-0093, "Near-Term Report and Recommendations for Agency Actions Following the Events in Japan," dated July 12, 2011, Washington, DC. (ADAMS Accession No. ML11186A950)
 
5. NRC, SRM-SECY-11-0093, "Staff Requirements - SECY-11-0093 - Near-Term Report and Recommendations for Agency Actions Following the Events in Japan," dated August 19, 2011, Washington, D.C. (ADAMS Accession No. ML112310021) 
 
6. NRC, SECY-11-0124, "Recommended Actions to be Taken without Delay from the Near-Term Task Force Report," dated September 9, 2011, Washington, DC. (ADAMS Accession No. ML11245A158) 
 
7. NRC, SECY-11-0137, "Prioritization of Recommended Actions to be Taken in Response to Fukushima Lessons Learned," dated October 3, 2011, Washington, DC. (ADAMS Accession No. ML11272A111) 
8. NRC, SRM-SECY-11-0124, "Staff Requirements - SECY-11-0124 - Recommended Actions to be Taken without Delay from the Near-Term Task Force Report," dated October 18, 2011, Washington, DC. (ADAMS Accession No. ML112911571) 
 
9. NRC, SRM-SECY-11-0137, "Staff Requirements - SECY-11-0137 - Prioritization of Recommended Actions to be Taken in Response to Fukushima Lessons Learned," dated December 15, 2011, Washington, DC. (ADAMS Accession No. ML113490055)
10. Letter from Adrian Heymer (Nuclear Energy Institute) to David L. Skeen (NRC), "
An Integrated, Safety-Focused Approach to Expediting Implem entation of Fukushima Dai-ichi Lessons Learned," dated December 16, 2011, NEI, Washington, DC. (ADAMS Accession No. ML11353A008) 
                                                      3  Publicly available documents from the U.S. Nuclear Regulatory Commission (NRC) are available electronically through the NRC Library on the NRC's public Web site at http://www.nrc.gov
/reading-rm/doc-collections/. The documents can also be viewed on-line for free or printed for a fee in the NRC's Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing address is USNRC PDR, Washington, DC 20555; telephone (301) 415-4737 or (800) 397-4209; fax (301) 415 3548; and e-mail pdr.resource@nrc.gov.    4  Publications from the Nuclear Energy Institute (NEI) are available at their Web site: http://www.nei.org/ or by contacting the headquarters at Nuclear Energy Institute, 1776 I Street NW, Washington DC 20006-3708, Phone: 202-739-800, Fax 202-785-4019.
 
RG 1.226, Page 22
11. NRC, SECY-12-0025, "Proposed Orders and Requests for Information in Response to Lessons Learned from Japan's March 11, 2011, Great Tohoku Earthquake and Tsunami," dated February
17, 2012, Washington, DC. (ADAMS Accession No. ML12039A103) 
12. NRC, SRM-SECY-12-0025, "Staff Requirements - SECY-12-0025 - Proposed Orders and Requests for Information in Response to Lessons Learned from Japan's March 11, 2011, Great Tohoku Earthquake and Tsunami," dated March 9, 2012, Washington, DC. (ADAMS Accession No. ML120690347) 
 
13. NRC, Order EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," dated March 12, 2012, Washington, DC. (ADAMS Accession No. ML12054A736) 
 
14. NRC, Commission Memorandum and Order, CLI-12-09, dated March 30, 2012, Washington, DC. (ADAMS Accession No. ML12090A531)     
 
15. NRC, "Combined License, Virgil C. Summer Nuclear Station, Unit 2," License No. NPF-93, April 10, 2014 (ADAMS Accession No. ML14100A092)
 
16. NRC, "Combined License, Virgil C. Summer Nuclear Station Unit 3," License No. NPF-94, April 10, 2014 (ADAMS Accession No. ML14100A101)
 
17. NEI, document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision B, dated May 4, 2012, Washington, DC. (ADAMS Accession No.
 
ML12144A419) 
18. NEI, document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision B1, May 13, 2012, Washington, DC. (ADAMS Accession No. ML12143A232) 
 
19. NRC, "Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," Draft JLD-ISG-2012-01, May 31, 2012 (ADAMS Accession No. ML12146A014)
  20. NRC, Response to Public Comments on JLD-ISG-2012-01 (Docket ID NRC-2012-0068), dated August 29, 2012, Washington DC. (ADAMS Accession No. ML12229A253) 
21. NEI, document 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision C, July 3, 2012, Washington, DC. (ADAMS Accession No. ML15027A542) 
 
22. Bauer, Scott A., NEI, letter to Steven D. Bloom, NRC, "Transmittal of Draft Revision 0 of NEI 12-06, 'Diverse and Flexible Coping Strategies (FLEX) Implementation Guide,'" Draft Revision 0, August 3, 2012 (ADAMS Accession No. ML12221A204)
23. NEI, document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 0, dated August 21, 2012, Washington, DC. (ADAMS Accession No. ML12242A378) 
 
24. NRC, JLD-ISG-2012-01, "Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design-Basis External Events," Revision 0, Issued August 2012, NRC, Washington, DC. (ADAMS Accession No.
 
ML12229A174)   
RG 1.226, Page 23
25. NEI, document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 1, dated October, 2015, Washington, DC. (ADAMS Accession No. ML15244B006) 
26. NEI, document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 1A, December 2015 (ADAMS Accession No. ML15279A426)
 
27. NRC, 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," Draft Revision 1, dated October 30, 2015 (ADAMS Accession No. ML15294A078)
  28. NRC, "NRC Responses to Public Comments, Revision to Japan Lessons-Learned Division Interim Staff Guidance 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," Docket ID NRC-2012-0068, January 22, 2016 (ADAMS Accession No.
 
ML15357A147)
 
29. NRC, Draft Regulatory Guide (DG)-1301, "Flexible Mitigation Strategies for Beyond-Design-Basis Events," dated November 30, 2015 (ADAMS Accession No. ML13168A031)
30. NRC, "NRC Response to Public Comments, Mitigation of Beyond-Design-Basis Events Rule" Docket ID (RIN: 3150-AJ49), December 2016 (ADAMS Accession No. ML16271A063)
31. NEI, document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 2, dated December 2015 (ADAMS Accession No. ML16005A625)
32. NRC, 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," Revision 1, dated January 22, 2016 (ADAMS Accession No. ML15357A163)
33. Nuclear Energy Institute (NEI) document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 3, dated September 2016, Washington, DC. (ADAMS Accession No. ML16267A274) 
 
34. NRC, 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," Draft Revision 2, dated November 10, 2016 (ADAMS Accession No. ML16277A617)
  35. NRC, "NRC Responses to Public Comments, Revision to Japan Lessons-Learned Division Interim Staff Guidance 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," Docket ID NRC-2012-0068, January xx, 2017 (ADAMS Accession No.
 
ML16DDDANNN)
 
36. NRC, 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," Revision 2, dated January xx, 2017 (ADAMS Accession No. ML16DDDANNN)
  37. NRC, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights RG 1.226, Page 24 from the Fukushima Dai-ichi Accident," dated March 12, 2012 (ADAMS Accession No. ML12053A340)
 
38. NRC, NUREG-1431, "Standard Technical Specifications - Westinghouse Plants," Revision 4.0, Volume 1, "Specifications," Washington, DC. (ADAMS Accession No. ML12100A222) 
 
39. Electric Power Research Institute (EPRI) tec hnical report 3002000623, "Applications Center: Preventive Maintenance Basis for FLEX Equipment - Project Overview Report," Palo Alto, CA
5 (ADAMS Accession Number ML13276A573) 
40. Letter from Jack R. Davis (NRC) to Joseph E. Pollock (NEI), no subject line, dated October 7, 2013, Washington, DC. (ADAMS Accession Number ML13276A224) 
 
41. EPRI, Report NP-6041-SL, Revision 1, "A Methodology for Assessment of Nuclear Plant Seismic Margin," dated August 1, 1991, Palo-Alto, CA.
 
6  http://www.epri.com/abstracts/Pages/Produc tAbstract.aspx?ProductId=NP-6041-SLR1      42. NRC, SRM-SECY-15-0065, "Proposed Rulemaking: Mitigation of Beyond-Design-Basis Events (RIN 3150-AJ49)," August 27, 2015, Washington, DC (ADAMS Accession No. ML15239A767) 
43. NRC, NUREG-1409, "Backfitting Guidelines," July 1990, Washington, DC. (ADAMS Accession No. ML032230247) 
 
44. NRC, Management Directive 8.4, "Management of Facility specific Backfitting and Information Collection," Washington, DC.
 
5  Copies of Electric Power Research Institute (EPRI) documents may be obtained by contacting the Electric Power Research Institute, 3420 Hillview Avenue, Palo Alto, CA 94304, Telephone: 650-855-2000 or on-line at http://my.epri.com/portal/server.pt.    6  Copies of Electric Power Research Institute (EPRI) documents may be obtained by contacting the Electric Power Research Institute, 3420 Hillview Avenue, Palo Alto, CA 94304, Telephone: 650-855-2000 or on-line at http://my.epri.com/portal/server.pt.}}


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Revision as of 05:22, 16 August 2019

Rev. 0, Flexible Mitigation Strategies for Beyond-Design-Basis Events
ML19058A012
Person / Time
Issue date: 06/30/2019
From: Eric Bowman
Office of Nuclear Reactor Regulation
To:
Doyle, Daniel
Shared Package
ML19058A006 List:
References
10 CFR Part 50, 10 CFR Part 52, NRC-2011-0189, NRC-2014-0240, PRM-50-97, PRM-50-98, RG-1.226, RIN 3150-AJ49, SRM-SECY-16-0142
Download: ML19058A012 (22)
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