ML15320A287

NRR E-mail Capture - NRC Staff Comments on NEI 12-06 Appendix H Paths 1, 2, and 3

ML15320A287
Person / Time
Issue date:	11/13/2015
From:	Nicholas Difrancesco Japan Lessons-Learned Division
To:	Mauer A Nuclear Energy Institute
References
Download: ML15320A287 (14)

Text

NRR-PMDAPEm Resource From: DiFrancesco, Nicholas Sent: Friday, November 13, 2015 12:10 PM To: MAUER, Andrew (anm@nei.org); TSCHILTZ, Michael (mdt@nei.org)

Cc: Shams, Mohamed; 50.54f_Seismic Resource

Subject:

NRC Staff Comments on NEI 12-06 Appendix H Paths 1, 2, and 3 Attachments: NRC Staff Comments on Appendix H to NEI 12-06 final.docx Mike, Andrew, Attached are NRC staff comments on Paths 1, 2, and 3 for consideration ahead of the November 17, 2015, public meeting.

Please let us know if you have any questions.

Sincerely, Nick Sr. Project Manager - Seismic Reevaluations U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Japan Lesson Learned Project Division nicholas.difrancesco@nrc.gov l Tel: (301) 415-1115 1

Hearing Identifier: NRR_PMDA Email Number: 2494 Mail Envelope Properties (159c63d9cf894b7c8b884d0588578cb4)

Subject:

NRC Staff Comments on NEI 12-06 Appendix H Paths 1, 2, and 3 Sent Date: 11/13/2015 12:10:00 PM Received Date: 11/13/2015 12:09:00 PM From: DiFrancesco, Nicholas Created By: Nicholas.DiFrancesco@nrc.gov Recipients:

"Shams, Mohamed" <Mohamed.Shams@nrc.gov>

Tracking Status: None "50.54f_Seismic Resource" <50.54f_Seismic.Resource@nrc.gov>

Tracking Status: None "MAUER, Andrew (anm@nei.org)" <anm@nei.org>

Tracking Status: None "TSCHILTZ, Michael (mdt@nei.org)" <mdt@nei.org>

Tracking Status: None Post Office: HQPWMSMRS07.nrc.gov Files Size Date & Time MESSAGE 467 11/13/2015 12:09:00 PM NRC Staff Comments on Appendix H to NEI 12-06 final.docx 232753 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

NOVEMBER 13, 2015 NEI 12-06 APPENDIX H H.1 INTRODUCTION The purpose of this appendix is to provide guidance for a mitigation strategies assessment (MSA) of the impact of the seismic hazard information developed in response to the U.S.

Nuclear Regulatory Commissions 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 from the Fukushima Dai-Ichi Accident [1]. As a result of the information request, all licensees reevaluated the seismic hazard at their sites using updated seismic hazard information and present-day regulatory guidance and methodologies.

The mitigation strategies developed in response to EA-12-049 [2] assumed an extended loss of Commented [A1]: Please ensure consistency with Appendix G in the usage of mitigation strategies, mitigating strategies and FLEX alternating current (AC) power (ELAP) with a loss of normal access to the ultimate heat sink strategies.

(LUHS) from an unspecified event. EA-12-049 [2] was issued to help address beyond-design--

basis external events prior to the time the information concerning the re-evaluated hazards was available. Specifically, since the information concerning the re-evaluated seismic hazards was not available to determine the impact on the facility, an unspecified event was used which Commented [A2]: A significant contributor to ? CDF, presumed the event resulted in a loss of all AC power (a significant contributor for externally maybe?

initiated events) combined with a loss of normal access to the ultimate heat sink, as described in Commented [A3]: Editorial comment: this sentence uses the EA-12-049 [2]. Now that the seismic hazards have been re-evaluated for all sites, more detailed word rely twice and ends with the word reliable. The repetition seems a bit overdone. Could this word be replaced with evaluations of a plants ability to withstand the re-evaluated seismic hazard can be performed dependable to make it read better?

and additional strategies for plant responses that preferably rely upon permanent installed plant Commented [A4]: This entire portion of the paragraph is equipment, which in some instances have been bolstered to withstand beyond-design-basis unnecessary because it does not provide guidance to licensees on how to proceed. It also introduces concepts that may be antithetical seismic events, can be developed. The use of permanently installed plant equipment for these to crediting FLEX in risk-informed decision making, which could strategies can reduce the need to rely on operator manual actions outside of the control room and include addressing the outcomes of SPRAs.

instead rely on operator actions within the control room, which are more reliable. Commented [A5]: There seems to be something missing from this sentence, perhaps the word or to indicate that MSSHI is the The MSA determines whether the mitigation strategies as developed to meet EA-12-049 [2] can term that will be used for the updated seismic hazard information resulting from the 50.54(f) request.

be implemented for the updated seismic hazard information resulting from the 50.54(f) request Commented [A6]: This phrase can probably be eliminated

[1] mitigation strategy seismic hazard information (MSSHI). If it is determined that mitigation because its the title of the document the appendix is being added to strategies developed to meet EA-12-049 [2] have not been evaluated or cannot be implemented and the term FLEX equipment is a defined term for the document.

for the MSSHI , the MSA considers other options such as performing additional evaluations, Commented [A7]: The distinguishing characteristic between a modifying existing mitigation strategies and/or diverse and flexible coping strategies (FLEX) FLEX strategy as originally developed under EA-12-049 or as modified to meet a new hazard, and an AMS is the assumption of equipment, or development of an alternate mitigation strategy (AMS) that addresses the MSSHI. occurrence of an ELAP/LUHS without regard to the causation of the If a mitigation strategy is developed that does not rely on FLEX, a basis for choosing the selected ELAP/LUHS. This is captured in the definition in Appendix A, but might be worth mentioning here.

strategy should be provided. In those instances where an AMS is provided, FLEX equipment Commented [A8]: This sentence is somewhat vague as to its should provide for additional defense-in-depth through the provision of the FLEX equipment intent. Understand it means that a licensee should provide a basis stored on site as described in section 5.3.1 and/or FLEX equipment transported to the site from for developing an AMS rather than demonstrating that the FLEX strategies will work or modifying the FLEX strategies to make them the National SAFER Response Centers. The MSA will either demonstrate that the mitigation work, but its not terribly clear here.

strategies can be implemented as currently developed or modified, or that an AMS can be Commented [A9]: Further details on what this means would be developed for the MSSHI which provides for indefinite coping following a beyond-design-basis helpful. As it is written, a licensee would not need to have any portable FLEX equipment on site.

seismic event.

Commented [A10]: This sentence should specify that it is Licensees will use the guidance for performing an MSA in this Appendix to do the following: limited to a BDBEE at the MSSHI; otherwise it doesnt provide sufficient context to convey what capability is really being provided.

N.B., it doesnt contain any information that is not in the bulleted list immediately below.

1

• Confirm mitigating strategies, as currently implemented, are not rendered ineffective by Commented [A11]: This is intended to indicate that it is the mitigating strategies described in the EA-12-049 Overall Integrated the MSSHI; Plan as modified in the audit and review process to date, right? As written, it is a bit imprecise.

• Develop and implement modifications necessary to ensure mitigating strategies are able Commented [A12]: This appears to be a list of different options, to address the MSSHI; or so I believe there should be an or at the end of this item.

• Develop and implement alternate mitigating strategies that are able to address the MSSHI.

A brief description of the MSA approach (and associated sections in this appendix) is as follows:

• Section H.2 establishes the characterization of the MSSHI.

• Section H.3 provides an approach for comparison of the seismic design basis used for mitigation strategy development to the MSSHI to determine if the MSSHI is bounded.

• Section H.4 provides guidance for the evaluation of mitigation strategies with respect to the MSSHI.

• Section H.5 provides performance criteria used to establish adequate seismic ruggedness requirements for structures, systems, and components (SSCs) that support mitigation strategies.

• Section H.6 provides requirements for documentation of the results.

H.2 CHARACTERIZATION OF THE MITIGATION STRATEGY SEISMIC HAZARD INFORMATION (MSSHI)

The MSSHI is the licensees reevaluated seismic hazard information at the plants site, developed using probabilistic seismic hazard analysis (PSHA). It includes a performance-based ground motion response spectrum (GMRS), uniform hazard response spectra (UHRS) at various annual probabilities of exceedance, and a family of seismic hazard curves at various frequencies and fractiles developed at the plants control point elevation. Licensees typically submitted the reevaluated MSSHI including the UHRS, GMRS and the hazard curves at their plants to the Commented [A13]: This is redundant - the MSSHI represents the output of the reevaluation of the seismic hazards and hasnt NRC in March 2014, in response to the NRC 50.54(f) letter dated March 12, 2012. Figure 1 really been reevaluated. Additionally, it needs to be clear the hazard below describes the use of GMRS, UHRS and/or seismic hazard curves for the various curve the staff found acceptable should be used in the MSA. No necessarily what was submitted.

mitigation strategy paths described in Section H.4.

Commented [A14]: The reference number was included in the first two citations of the RFI, but not here. The first 5 EA-12-049 citations include the reference number. What is the rule of usage for this document for reference numbers?

2

Figure 1: MSSHI Use for Appendix H Paths As shown in Figure 1, the GMRS curve is used in paths 1 through 4. The hazard curves are used, in addition to UHRS and GMRS, in path 5 when the MSA is based on a probabilistic evaluation such as a seismic probabilistic risk assessment (SPRA). Detailed descriptions of the use of MSSHI for each of the five paths are discussed in the sections below.

H.3 APPROACH FOR COMPARISON OF EXISTING SEISMIC DESIGN Commented [A15]: Nit-picky editorial comment: references are out of order.

BASIS / PLANT CAPACITY TO MSSHI Commented [A16]: Does this provide sufficient clarity as to the MCE used for ASCE 7-10? NEI 12-06, section 5 is silent on that This section provides the approach for comparing the GMRS (consistent with the screening subject.

criteria in Electric Power Research Institute (EPRI) 1025287 [6]) to the seismic design basis Commented [A17]: The term SSE is actually defined in 10 CFR spectrum used for developing the FLEX mitigation strategies. In most cases, FLEX was designed part 100, Appendix A,Section III.(c). The SARs dont actually define the term, but instead specify the hazard curve for the SSE (or or evaluated using the safe shutdown earthquake (SSE)1. In some cases, FLEX equipment DBE, depending on the nomenclature used when the plant was storage structures were designed using American Society of Civil Engineers (ASCE) 7-10 [5] or licensed). The discussion of this sentence muddies the waters and doesnt really add value. This discussion could be improved by storage was outside a structure and evaluated for seismic interactions. The term SSE is defined in aligning it with the discussion of Appendix G by defining a different the safety analysis reports (SAR) of plants, but is broadly used in this appendix to encompass the term, e.g., SSEFLEX, to refer to the seismic design basis of the FLEX strategies.

previous mitigation strategy seismic design bases, including FLEX storage structures designed Commented [A18]: Recommend removing the discussion on the using ASCE 7-10, which was deemed an acceptable alternative design criteria in Section 5.3.1. acceptability of ASCE 7-10 hazard level from this document. This For path 3, the GMRS is compared to a plant capacity spectrum derived from the individual plant issue is being addressed separately under the mitigation strategies order compliance.

examination of external events (IPEEE) program using plants high-confidence-of-low-probability-of-failure (HCLPF) capacity. The development of the IPEEE HCLPF spectrum or Commented [A19]: This is not really true. The SPID provides screening criteria. Also, this discussion should be in the path 3 IHS is described in EPRI 1025287 [6]. section.

The GMRS at frequencies 1 Hz and higher is compared to the SSE (or IHS) to determine Commented [A20]: The proposed rule language does not reference the IHS. Including the parenthetical option to compare the whether the SSE (or IHS) bounds the GMRS, or identify any areas of exceedance of the SSE (or GMRS to the IHS runs the risk of a gap if the IHS bounds the SSE or DBE because the use of this test at this point in the process would show that the GMRS is bounded. Also, if you look at the flow chart in Figure 2, the only spot where there is a comparison to the IHS is in the decision block that initiates Path 3: in that instance the test is 1 not disjunctive, but instead both comparisons are made. This Some plants have used the term Design Basis Earthquake or DBE, which is synonymous to SSE.

parenthetical would more accurately reflect the process if it read SSE (and IHS for Path 3).

3

IHS). The results of the comparison are used as input to the evaluation of mitigation strategies in Section H.4. The assessment process is illustrated in Figure 2 and described in detail below.

Path 1 Path 2 Path 3 Path 4 Path 5 Characterization GMRS > SSE GMRS < SSE GMRS > SSE GMRS 2X SSE GMRS > 2X SSE of MSSHI Only > 10Hz But < IHS (1-10 Hz) (1-10 Hz)

(1-10 Hz)

OR OR Reasonable Additional actions Additional actions Additional actions TBD- demonstrate protection of to demonstrate to demonstrate to demonstrate reasonable mitigation strategies reasonable reasonable reasonable protection of equipment protection of protection of protection of mitigation strategies demonstrated mitigation strategies mitigation strategies mitigation strategies equipment equipment equipment: equipment:

demonstrated 1) Describe AMS 1) Perform HF

1) Perform HF based on IPEEE review review 2) Perform HF 2) Address SFP review cooling

3) Address SFP 3) Perform cooling assessment of FLEX strategy for the MSSHI NEI 12-06 Mitigation Strategies and/or Alternate Mitigation Strategies valid for MSSHI Figure 2: Mitigation Strategy Assessment Process for the MSSHI H.4 EVALUATION OF MITIGATION STRATEGIES The mitigation strategies are evaluated with respect to the MSSHI, using the process illustrated in Figure 2.

Commented [A21]: It might be worth indicating that this is If the SSE spectrum bounds the GMRS at frequencies 1 Hz and greater, licensees should follow discussing the mitigating strategies as originally developed for EA-the process described in Section H.4.1 (Path 1 in Figure 2) and document completion of the 12-049.

MSA, demonstrating that the mitigating strategies are reasonably protected to the MSSHI. In the Commented [A22]: This sentence needs work. The MSA doesnt actually look at any BDB seismic event, but only at the event that the GMRS is not bounded by the SSE, an assessment of the impacts on mitigation specific one under consideration (e.g., the MSSHI, or potentially the strategies is required. The purpose of the assessment is to determine the adequacy of strategies in IHS). Also, it would not be a case of the site coping, but instead the plant coping, and the plant would be coping with the seismic event consideration of the MSSHI. Sections H.4.2 through H.4.5 of this appendix provide guidance for under consideration, not coping due to the seismic event under development of an MSA to demonstrate that the FLEX strategies or AMS are reasonably consideration.

protected for the MSSHI. Commented [A23]: This is probably true for the typical AMS, but isnt necessarily true for all of them. For example, we have allowed some licensees to install additional diesel generators to use The MSA evaluates the plant equipment, operator actions and procedures required to for their FLEX strategies. If these new generators were installed to a successfully implement the mitigation strategies so that a site may cope indefinitely due to the higher seismic hazard than the original ones and the licensee proposed to rely on them to prevent occurrence of an ELAP, it beyond design-basis seismic event. Sections H.4.2 and H.4.4 provide approaches to evaluate would likely be acceptable as an AMS.

implementation of the mitigation strategies with respect to the MSSHI. Section H.4.3 provides an Commented [A24]: Consider stating An AMS typically relies approach for evaluation of an AMS that is capable of demonstrating plant safety with respect to upon permanently installed plant equipment, but in some instances may rely on FLEX equipment that has been evaluated to the the MSSHI. An AMS primarily relies upon permanent installed plant equipment and in some MSSHI. Using and here sounds awkward.

4

instances may include certain aspects of FLEX mitigation strategies that that have been evaluated to the MSSHI.

For each of the paths identified in H.4.1 through H.4.5, the MSA should be appropriately documented per Section H.6 of this appendix.

H.4.1 PATH 1: GMRS < SSE If the GMRS described in Section H.2 is bounded by the SSE spectrum at frequencies 1 Hz and greater, then additional evaluation is unnecessary, consistent with Path 1 of Figure 2.

Section 3.2.1 of EPRI 1025287 describes two Special Screening Considerations for plants with low seismic ground motions or narrow banded exceedances in the frequency range between 1-10 Hz that can be applied in this Path 1 evaluation. In addition, minor Commented [A25]: Consider providing criteria for this path such as:

GMRS exceedances accepted by the NRC as not significant in the site specific NRC NTTF 2.1 final determination letter (October 2015 reference TBD), can be considered to meet the 1.The GMRS is bounded by the SSE at 1 Hz and greater with the exception of low seismic ground motions or narrow banded path 1 screening assessment. For plants meeting these criteria, the FLEX strategies are exceedances as described in EPRI 1025287, Section 3.2.1, or reasonably protected to the MSSHI based on the underlying process used to develop the 2.The GMRS is bounded by the SSE at 1 Hz and greater with the exception of minor exceedances accepted by the NRC as not FLEX strategies. significant in the .

Commented [A26]: This is covered in the second of the two H.4.2 PATH 2: GMRS < SSE WITH HIGH FREQUENCY EXCEEDANCES criteria in my comment above.

If the GMRS described in Section H.2 is less than the SSE in the 1 to 10 Hz range consistent with Section 3.2 of EPRI 1025287 [6], but is not bounded at frequencies >10 Hz, Commented [A27]: Citation in H.4.1 doesnt have a reference number; why is it included here (or absent there)?

an MSA should be performed as illustrated in Path 2 of Figure 2. Section 3.2.1 of EPRI 1025287 describes two Special Screening Considerations for plants with low seismic ground motions or narrow banded exceedances that can be applied in this Path 2 evaluation. In addition, minor GMRS exceedances accepted by the NRC as not significant in the site specific NRC NTTF 2.1 final determination letter (October 2015 reference TBD), can be considered to meet the path 1 screening assessment in H.4.1. Commented [A28]: Why is this discussion here? Are there, or will there be, plants with minor insignificant exceedances that have HF exceedance that need to be considered? If so, this sentence

Introduction:

should be revised to be applicable to path 2 and H.4.2; otherwise it should be deleted.

For plants where the GMRS spectrum above 10 Hz exceeds the SSE spectrum, licensees Commented [A29]: Why is there an introductory paragraph can demonstrate adequacy of the mitigation strategy with respect to the MSSHI by before the introduction?

performing an MSA that consists of an evaluation of HF sensitive in-plant SSCs required for mitigation strategy implementation.

Basis:

FLEX equipment has been evaluated to demonstrate adequacy following the guidance in Section 5. The SSE exceedances (i.e., >10 Hz) can be evaluated by performing an MSA to Commented [A30]: The parenthetical does not really explain the text that precedes it. This could be corrected by modifying it to read show that mitigation strategies can be implemented as planned using the guidance in SSE exceedances in the high frequency range (i.e., >10 Hz).

Sections 3 and 4 of EPRI 3002004396 [7] and the acceptance criteria in Section H.5 to Commented [A31]: a limited-scope evaluation as address the effect of the HF exceedances on sensitive components.

Commented [A32]: that equipment that is sensitive to high frequency vibration will not prevent performance of the mitigating Background and Discussion: strategies using the guidance in Sections 3 .

FLEX equipment has been evaluated to demonstrate adequacy following the guidance in Section 5. This evaluation can be supplemented to consider HF GMRS exceedances above 5

the SSE using the process as follows. Section 4 of EPRI 3002004396 [7] describes a HF evaluation process focusing on contact control devices subject to intermittent states (e.g.,

relay chatter) in seal-in and lockout circuits. For the MSA HF evaluation, the acceptance criteria from Section H.5 can be used and the scope of circuits to be reviewed include installed FLEX SSCs credited for the Phase 1 response as well as permanently installed Commented [A33]: Does this include SSCs that could prevent an expected protective action?

Phase 2 or 3 SSCs that have the capability to begin operation without operator manual actions.

Therefore, the MSA HF evaluation scope is focused on seal-in and lock out circuits in the Commented [A34]: Lockout or lock out? See usage in third sentence of prior paragraph and in second and third bullet below.

following systems and equipment.

• Devices whose chatter could cause malfunction of a reactor SCRAM.2

• Devices in seal-in or lockout circuits whose chatter could cause a reactor coolant system (RCS) leakage pathway that was not considered in the mitigation strategy.

Examples include the automatic depressurization system (ADS) actuation relays in boiling-water reactors (BWRs) and relays that could actuate pressurizer power-operated relief valves (PORVs).

• Relays and contactors that may lead to circuit seal-ins or lockouts that could impede the FLEX capabilities for mitigation of seismic events, including credited installed Phase 1 direct current (DC) systems and alternating current (AC) systems supported through the inverters and any permanently installed Phase 2 or 3 SSCs that have the capability to Commented [A35]: Does this mean ac systems supplied with power from the dc systems through inverters? (Consider usage of begin operation without operator manual actions. ac and dc following NUREG-0544, Revision 4 for NRC abbreviations and acronyms.)

H.4.3 PATH 3: GMRS < IHS If the high-confidence-of-low-probability-of-failure (HCLPF) plant capacity spectrum (IHS) developed from the evaluations for Individual Plant Examination of External Event Commented [A36]: Improperly defined acronym. It really means IPEEE HCLPF spectrum, doesnt it? That isnt the usage that (IPEEE) envelops the SSE between 1 and 10 Hz with the exception of small narrow band precedes it.

exceedances that meet the criteria of EPRI 1025287 [6], an AMS may be used based upon Commented [A37]: Prior usage is narrow banded the IPEEE, consistent with Path 3 of Figure 2. IPEEE safe-shutdown paths would be used exceedances. Not sure what it is in EPRI 1025287, Section 3.2.1.

to demonstrate reasonable protection of SSCs relied upon for this AMS. Alternatively, Commented [A38]: This is the section 3.2.1 criteria used before, licensees may elect to perform an MSA of the impacts of MSSHI on mitigation strategies right? Why not include the section number here for clarity?

consistent with Path 4 of Figure 2 or perform an SPRA-informed MSA consistent with Path Commented [A39]: Why is a discussion of the GMRSs relationship to the IHS delayed until prerequisite 1? Why is this the 5 of Figure 2. entering argument for Path 3? Do we have cases where the IHS doesnt envelop the SSE? If not, then this sentence adds no value to the discussion and is misleading.

The following prerequisites apply in order to use the IPEEE evaluations for H.4.3:

1. Licensees using this approach should have previous seismic evaluations that were conducted under the IPEEE effort and accepted by NRC per Enclosure 2 of their May 9, 2014 letter [8] or in a subsequent determination, provided the IHS completely envelops the GMRS between 1 and 10 Hz, with the exception of small narrow band Commented [A40]: Band or banded?

exceedances that meet EPRI 1025287 [6] criteria. Commented [A41]: Section 3.2.1?

2 A SCRAM is a manually-triggered or automatically-triggered rapid insertion of all control rods into the reactor, causing emergency shutdown.

6

2. Licensees using this approach should have conducted a full scope IPEEE or, if a plant Commented [A42]: Should this be MSA? The IPEEE was in the focused scope bin, the licensee can bring the focused scope IPEEE assessment isnt the AMS, instead the AMS is the safe-shutdown paths demonstrated to be reasonably protected by the IHS.

assessment in line with a full scope assessment as defined in GL 88-20 Supplements 4 Commented [A43]: This guidance to licensees that used an

[10] and 5 [11] and NUREG-1407 [9] in accordance with the guidance in EPRI NRC SMA or SPRA seems a bit buried in the weeds of the 1025287[6]. Plants that conducted a reduced scope IPEEE assessment cannot use prerequisites for the MSA. Is it truly a pre-requisite or is it part of the MSA or could be included in the background and discussion Path 3 for their AMS. portion. Please clarify how and where will this be documented?

Commented [A44]: Potential edit:

3. For IPEEEs, the EPRI SMA approach was based on EPRI NP-6041-SL Rev. 1 [15].

This approach defined the SEL for evaluation of safe shutdown success paths to be Licensees that are eligible to use this path rely on the previous seismic evaluations that were conducted under the IPEEE effort comprised of those SSCs required to bring the plant to a stable condition (either hot and accepted by NRC per Enclosure 2 of their May 9, 2014 letter or cold shutdown) and maintain that condition for at least 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Therefore, for [8] or in a subsequent screening determination that was issued through October 2827, 2015, provided that the IPEEE HCLPF plants with an IPEEE based on the SMA described in EPRI 1025287 [6] approach, spectrum (IHS) envelops the GMRS between 1 and 10 Hz, with the exception of small narrow band exceedances that meet the the IPEEE results must be evaluated for limitations that are based on the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> criteria in the Screening, Prioritization and Implementation Details coping duration. Plants that performed a seismic PRA or the NRC margin method for report (EPRI 1025287 [6]. For those eligible plants an AMS may be used based upon the IPEEE, consistent with Path 3 of Figure 2.

IPEEE may have limitations based on coping durations of less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> that also IPEEE safe-shutdown paths would be used to demonstrate reasonable protection of SSCs relied upon for this AMS.

must be evaluated. Generally, the conclusions of the SMAs and SPRAs are not Alternatively, licensees may elect to perform an MSA of the sensitive to coping duration. However, certain consumable items, such as water and impacts of MSSHI on mitigation strategies consistent with Path 4 of Figure 2 or perform an SPRA-informed MSA consistent with fuel oil inventories, may have been evaluated based on a limited onsite supply. The Path 5 of Figure 2.

ability to continue coping would require re-supply of consumables. Site access is The following conditions apply in order to use the IPEEE restored to a near-normal status and/or augmented transportation resources are evaluations for H.4.3:

available within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> consistent with NEI 12-01 [16] to allow for additional 1.As noted above, these plants have an IHS that completely supplies to be brought in and allow for continuation of coping strategies and maintain envelops the GMRS between the frequency range of 1 and 10 Hz, with the exception of small narrow band exceedances the plant in a stable condition. FLEX Phase 3 deployment could replenish that meet the Screening, Prioritization and Implementation consumables beyond the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> coping duration and a plant-specific evaluation Details report EPRI 1025287 [6] criteria. To apply this approach, licensees conducted a full scope IPEEE or, if a should be performed to conclude that SSCs that limit the EPRI SMA-based IPEEE licensee conducted a plant focused- scope IPEEE, the coping duration to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> are available for an indefinite period following the licensee brought the focused-scope IPEEE assessment to be consistent with a full-scope IPEEE assessment as defined in beyond design-basis seismic event to support continued maintenance of the safe GL 88-20 Supplements 4 [10] and 5 [11] and NUREG-1407 [9]

shutdown condition. in accordance with the guidance in EPRI 1025287[6]. If additional evaluations (e.g., full-scope relay review) to bring the IPEEE to be consistent with a full scope IPEEE was identified but not yet completed, then the successful demonstration must be completed to use this path.

==

Introduction:==

2.For those plants for which the IHS has been already determined to be acceptable and used the EPRI SMA An IPEEE-based AMS relies on the comprehensive seismic evaluation of plant equipment approach based on EPRI NP-6041-SL Rev. 1 [15], the SEL for evaluation of safe shutdown success paths was comprised to demonstrate reasonable protection for the re-evaluated MSSHI. Licensees that choose of those SSCs required to bring the plant to a stable condition this path can rely on the previous seismic evaluations that were conducted under the IPEEE (either hot or cold shutdown) and maintain that condition for at least 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Therefore, for those plants with an IPEEE effort and accepted by NRC per Enclosure 2 of their May 9, 2014 letter [8] or in a based on the SMA described in EPRI 1025287 [6] approach, subsequent determination, provided that the IPEEE HCLPF spectrum (IHS) envelops the the IPEEE results must be evaluated for limitations that are based on the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> coping duration. Plants that performed a GMRS between 1 and 10 Hz, with the exception of small narrow band exceedances that seismic PRA or the NRC margin method for IPEEE may meet the criteria in EPRI 1025287 [6]. The development of the IHS is described in have limitations based on coping durations of less than 72 ... [1]

EPRI 1025287 [6]. Commented [A45]: Too much stuff before the introduction.

This also reads more like basis discussions than like an introduction..

IPEEEs relied on the results of an SPRA, an EPRI seismic margins assessment (SMA) Commented [A46]: Band or banded?

methodology, or an NRC SMA methodology to demonstrate the capability to bring the Commented [A47]: Section 3.2.1?

plant to a safe shutdown condition following a review level earthquake (RLE) as described Commented [A48]: Hyphenated or not? This conflicts with the in NUREG-1407 [9]. These seismic evaluation approaches evaluated multiple redundant usage in the paragraph immediately following the header for H.4.3.

safe shutdown success paths. The safe shutdown success paths provide independent means Commented [A49]: Hyphenated?

7

of achieving a safe shutdown condition following a severe seismic event (e.g., core cooling by heat removal from the steam generators and core cooling by RCS feed and bleed).

To provide a complete MSA seismic evaluation, the IPEEE evaluation is supplemented by reviews of spent fuel pool cooling functions and high frequency exceedances (as applicable).

Basis:

Seismic evaluations performed under IPEEE included SSCs in multiple redundant safe-shutdown success paths. Therefore, based on the results of the IPEEE, safe-shutdown of the Commented [A50]: I dont think it gets hyphenated here. Its not a compound modifier.

plant following a seismic event can be accomplished, and consequences can be mitigated, for a seismic event up to the plant capacity level (i.e., the IHS) for which SSCs in the IPEEE were evaluated.

In addition, seismic evaluations for spent fuel pool cooling should be performed using the MSSHI to demonstrate that spent fuel would remain cooled following a seismic event, and a review of HF sensitive components should be performed, as needed.

Background and Discussion:

IPEEE Evaluations The IPEEEs were completed by plants in the 1990s under NRC Generic Letter (GL) 88-20 Supplements 4 [10] and 5 [11] in accordance with the guidance of NUREG-1407 [9].

Acceptable approaches to perform IPEEE included the NRC seismic margin assessment (SMA) method, the EPRI SMA method, or an SPRA. For each approach, a seismic equipment list (SEL) was developed that included multiple redundant safe shutdown success paths and/or accident sequences. The evaluation of SSCs in these redundant safe shutdown success paths demonstrates reasonable protection of the capability to maintain or Commented [A51]: Hyphenated?

restore core cooling and containment capabilities for a beyond design-basis seismic event Commented [A52]: hyphenate up to the level of the IHS, which envelopes the GMRS in the 1 to 10 Hz range (see Section H.2). Commented [A53]: Why the cross-reference?

NUREG-1407 [9] categorized plants performing IPEEE in three bins - reduced scope, focused scope and full scope. Commented [A54]: Why is this sentence here? What does it mean? Is it important to include in this section?

The IPEEEs were generally performed using input motions based on the following:

a. Median-centered response spectrum using the NUREG/CR-0098 [12] shape, anchored to 0.3g peak ground acceleration (PGA).

b. For SPRAs, plants generally used the mean Uniform Hazard Response Spectra (UHRS) and hazard curves developed by Lawrence Livermore National Laboratory Commented [A55]: This is a different UHRS than the one discussed in H.2, isnt it? How should they be distinguished, or is it (LLNL) in NUREG-1488 [13] and/or EPRI in EPRI NP-6395-D [14]. really necessary?

c. In some cases, past SPRAs were submitted for IPEEE closure that used input motions and hazard curves that preceded the LLNL and EPRI hazard curves of NUREG-1488

[13] and EPRI NP-6395-D [14] respectively.

Consistent with the input spectrum shape used in an IPEEE, an IHS can be developed, as described in EPRI 1025287 [6]. Commented [A56]: This portion does not seem to add value as guidance.

Spent Fuel Pool Cooling Evaluation 8

Equipment needed to accomplish the spent fuel pool (SFP) cooling function (SFP cooling system components, SFP makeup capability, and SFP level instrumentation etc.) should be evaluated for seismic adequacy to the MSSHI. For developing in-structure response Commented [A57]: Would this mean that the equipment is robust as defined in NEI 12-06, Appendix A?

spectrum (ISRS) corresponding to the GMRS, it is acceptable to scale the SSE-based ISRS by the highest ratio of GMRS/SSE in the 1 to 10 Hz range for these evaluations. A high Commented [A58]: Is this true for GMRS > 2xSSE?

frequency evaluation of the SFP cooling key safety functions is not warranted since operators would have a significant amount of time to restore SFP cooling. Commented [A59]: Some basis for this assertion would be helpful, such as the large amount of water over the fuel and the High Frequency Evaluation: known maximum boil off rates. You could point to the times for initiation of SFP makeup documented in OIPs and accepted by the Licensees following this path that also have high frequency exceedances (GMRS > IHS NRC in the ISEs.

above 10 Hz) should perform a high frequency evaluation of relays in the IPEEE scope consistent with the criteria in Sections 3 and 4 of EPRI 3002004396 [7], using the acceptance criteria in H.5 .

Availability of FLEX Equipment s: Commented [A60]: This portion is difficult to follow because there doesnt seem to be an established formatting convention.

The alternate mitigation strategies described in H.4.3 do not generally rely upon Consider using the type of wording that exists in Appendix G here in order to simplify this.

availability of FLEX equipment. In these cases where the alternate mitigation strategies do Commented [A61R60]: I agree this portion would benefit from not rely upon the availability of FLEX equipment, availability of FLEX equipment should a re-write to clarify the actions (if any) to be taken by a licensee to still be treated in the MSA as a means of additional defense in depth. protect the phase 2 equipment. Our suggestion to start with App G language and modify as necessary to account for the complex nature Portable FLEX Equipment of the problem under seismic events is just a simplification first step to help us arrive at the appropriate answer for phase 2 if the licensee Portable FLEX equipment is stored onsite and available for deployment to support the does not rely on it.

maintenance of core cooling, containment, and spent fuel cooling functions. Phase 3 is protected by the separation and it is probably not necessary to go into too much justification beyond that. It is Portable FLEX equipment is stored in accordance with Section 5.3.1 and is considered important, however, to clearly address the deployment strategy for portable equipment in general and Phase 3 in particular. Recommend rugged with respect to an increased seismic hazard. The portable FLEX equipment are tying back to the main body of 12-06 on the subject of deployment located in an area where ground motion amplification through a structure is not expected and also crediting onsite/off-site debris removal equipment and the available time before the need to deploy portable equipment to (i.e., structure located on grade, equipment stored on the ground elevation of the building) layout a sound deployment strategy.

and the equipment is restrained. As previously established in Section 11, Portable Commented [A62]: AMSs?

towable equipment that is designed for over the road transport typically used in Commented [A63]: AMSs?

construction/remote sites are deemed sufficiently rugged to function following a BDB Commented [A64]: How does the MSA treat non-portable seismic event. FLEX equipment?

Offsite Resources Commented [A65]: What about the buildings housing the equipment?

Portable FLEX equipment is also available from offsite. The industry has established two (2) National SAFER Response Centers (NSRCs) to support utilities during beyond-design- Commented [A66]: Acronym should be defined in third paragraph of page 1.

basis events. Each plant has established contracts with the Pooled Equipment Inventory Company (PEICo) to participate in the process for support of the NSRCs as required. Each NSRC will hold five (5) sets of equipment, four (4) of which will be able to be fully deployed when requested, the fifth set will have equipment in a maintenance cycle. In the event of a beyond-design-basis seismic event, equipment can be moved from an NSRC to a local assembly area established by the Strategic Alliance for FLEX Emergency Response (SAFER) team. From there, equipment can be taken to the site and staged at the SAFER Commented [A67]: Acronym used in first sentence of this paragraph.

onsite Staging Area by helicopter if ground transportation is unavailable. Communications will be established between the site and the SAFER team via satellite phones and required equipment moved to the site as needed. First arriving equipment will be delivered to the site within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> from the initial request. The order in which equipment is delivered is identified in the SAFER Response Plan.

9

Therefore, additional defense-in-depth to provide reasonable protection against the MSSHI is expected to be available from on-site and/or off-site portable equipment.

Assessment of AMS where FLEX Equipment Relied Upon An AMS utilizes any configuration of FLEX equipment and/or plant equipment to maintain or restore core cooling, spent fuel pool cooling, and containment capabilities for the duration of the event. Therefore, some portion of the AMS developed under H.4.3 may utilize FLEX equipment.

Equipment stored on-site or off-site whose primary function is to support an AMS will be considered to be FLEX equipment in accordance with the definition in Appendix A. Such equipment should be designed and implemented to the same standards (e.g., programmatic controls) to which the FLEX strategies were designed and implemented.

To the extent that FLEX equipment is relied upon within the AMS, the MSA should address the following:

• The sequence of events should be established based on the MSSHI as the initiating event.

• The MSA should use the General Criteria and Baseline Assumptions in Section 3.2.1 with the exception that the only losses that need to be considered (e.g., ELAP, LOOP, LUHS) are those that would be caused by the MSSHI.

• The impacts of the MSSHI should be used in place of the SSE to perform the screening and evaluation per Section 6. Reasonable protection from the MSSHI should be provided for the FLEX equipment which is being used in the AMS.

• If deployment locations of FLEX equipment are changed as a result of the evaluation per Section 6, the design considerations for the strategy should be reevaluated per Section 11.2.1.

• The equipment storage guidance of Section 11.3 should be reassessed based on the impacts of the MSSHI.

• The impacts of the MSSHI should be used in place of the SSE in the consideration of robustness of plant equipment as defined in Appendix A. For determining robustness only the GMRS should be used as the applicable hazard.

• The impacts of the MSSHI should be used to evaluate the applicability of the Minimum Baseline Capabilities of Section 3.2.2 with the only losses (e.g., ELAP, LOOP, LUHS) needing to be considered being those that would be caused by the MSSHI.

Additionally, the AMS may use plant equipment, FLEX equipment, or any combination of the two.

• The seismic protection features relied upon for the AMS should meet the performance criteria provided in Section H.5.

• New or modified actions to FLEX should be validated in accordance with Appendix E. Commented [A68]: Should there be a qualitative assessment of existing actions to account for differences between the SSE and the GMRS?

10

Page 7: [1] Commented Author Potential edit:

Licensees that are eligible to use this path rely on the previous seismic evaluations that were conducted under the IPEEE effort and accepted by NRC per Enclosure 2 of their May 9, 2014 letter [8] or in a subsequent screening determination that was issued through October 2827, 2015, provided that the IPEEE HCLPF spectrum (IHS) envelops the GMRS between 1 and 10 Hz, with the exception of small narrow band exceedances that meet the criteria in the Screening, Prioritization and Implementation Details report (EPRI 1025287

[6]. For those eligible plants an AMS may be used based upon the IPEEE, consistent with Path 3 of Figure 2. IPEEE safe-shutdown paths would be used to demonstrate reasonable protection of SSCs relied upon for this AMS. Alternatively, licensees may elect to perform an MSA of the impacts of MSSHI on mitigation strategies consistent with Path 4 of Figure 2 or perform an SPRA-informed MSA consistent with Path 5 of Figure 2.

The following conditions apply in order to use the IPEEE evaluations for H.4.3:

1. As noted above, these plants have an IHS that completely envelops the GMRS between the frequency range of 1 and 10 Hz, with the exception of small narrow band exceedances that meet the Screening, Prioritization and Implementation Details report EPRI 1025287 [6] criteria. To apply this approach, licensees conducted a full scope IPEEE or, if a licensee conducted a plant focused- scope IPEEE, the licensee brought the focused-scope IPEEE assessment to be consistent with a full-scope IPEEE assessment as defined in GL 88-20 Supplements 4 [10] and 5 [11] and NUREG-1407 [9] in accordance with the guidance in EPRI 1025287[6]. If additional evaluations (e.g., full-scope relay review) to bring the IPEEE to be consistent with a full scope IPEEE was identified but not yet completed, then the successful demonstration must be completed to use this path.

2. For those plants for which the IHS has been already determined to be acceptable and used the EPRI SMA approach based on EPRI NP-6041-SL Rev. 1 [15], the SEL for evaluation of safe shutdown success paths was comprised of those SSCs required to bring the plant to a stable condition (either hot or cold shutdown) and maintain that condition for at least 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Therefore, for those plants with an IPEEE based on the SMA described in EPRI 1025287 [6]

approach, the IPEEE results must be evaluated for limitations that are based on the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> coping duration. Plants that performed a seismic PRA or the NRC margin method for IPEEE may have limitations based on coping durations of less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> that also need to be further evaluated for meeting the intent of mitigating strategies. Generally, the conclusions of the SMAs and SPRAs are not sensitive to coping duration. However, certain consumable items, such as water and fuel oil inventories, may have been evaluated based on a limited onsite supply. The ability to continue coping would require re-supply of consumables. It is assumed that site access is restored to a near-normal status and/or augmented transportation resources are available within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> consistent with NEI 12-01 [16] to allow for additional supplies to be brought in and allow for continuation of coping strategies and maintain the plant in a stable condition. FLEX Phase 3 deployment could replenish consumables beyond the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> coping duration and a plant-specific evaluation should be performed to conclude that SSCs that limit the EPRI SMA-based IPEEE coping duration to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> are available for an indefinite period following a beyond design-basis seismic event at the reevaluated seismic hazard to support continued maintenance of the safe shutdown condition.