ML15022A239

Request for Additional Information- National Fire Protection Association Standard NFPA 805

ML15022A239
Person / Time
Site:	Waterford
Issue date:	02/06/2015
From:	Michael Orenak Plant Licensing Branch IV
To:	Entergy Operations
Wang A
References
TAC ME7602
Download: ML15022A239 (27)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 February 6, 2015 Vice President, Operations Entergy Operations, Inc.

Waterford Steam Electric Station, Unit 3 17265 River Road Killona, LA 70057-3093

SUBJECT:

WATERFORD STEAM ELECTRIC STATION, UNIT 3- REQUEST FOR ADDITIONAL INFORMATION- NATIONAL FIRE PROTECTION ASSOCIATION STANDARD NFPA 805 (TAC NO. ME7602)

Dear Sir or Madam:

By letter dated November 17, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML113220230), as supplemented by letters dated January 26, September 27, and October 16, 2012 (ADAMS Accession Nos. ML12027A049, ML12272A099, and ML12272A099, respectively); May 16, and December 18, 2013 (ADAMS Accession Nos.

ML13137A128 and ML13365A325, respectively); and June 11, 2014 (ADAMS Accession No. ML14162A506), Entergy Operations, Inc. (Energy, the licensee), submitted a license amendment request (LAR) for Waterford Steam Electric Station, Unit 3 (Waterford). The proposed amendment would transition Waterford's fire protection licensing basis from Section 50.48(b) of Title 10 of the Code of Federal Regulations (10 CFR) to 10 CFR 50.48(c),

National Fire Protection Association Standard NFPA 805, "Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants."

The NRC staff has reviewed the information provided by the licensee in the December 18, 2013, and June 11, 2014, submittals and determined that a request for additional information (RAI) is needed to complete the review of the proposed amendment.

To support the clarification of the RAis and further the staff's understanding of the licensee's NFPA 805 methodologies, a review team, consisting of U.S. Nuclear Regulatory Commission (NRC) staff and contractors from Pacific Northwest National Laboratory (PNNL) and the Southwest Research Institute (SWRI) participated in a regulatory audit at Waterford in Killona, Louisiana, from January 12- 14, 2015. The enclosed RAI is the result of discussions held during the audit.

Please respond to the RAI within the dates identified in Enclosure 2.

If you have any questions, please contact me at 301-415-3229 or by e-mail at Michaei.Orenak@nrc.gov.

Sincerely, Michael D. Orenak, Project Manager Plant Licensing IV-2 and Decommissioning Transition Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-382

Enclosures:

1. Request for Additional Information

2. Response Times cc w/encls: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO ADOPT NATIONAL FIRE PROTECTION ASSOCIATION STANDARD 805 ENTERGY OPERATIONS, INC WATERFORD STEAM ELECTRIC STATION. UNIT 3 DOCKET NO. 50-382 By letter dated November 17, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML113220230), as supplemented by letters dated January 26, September 27, and October 16, 2012 (ADAMS Accession Nos. ML12027A049, ML12272A099, and ML12272A099, respectively); May 16, and December 18, 2013 (ADAMS Accession Nos.

ML13137A128 and ML13365A325, respectively); and June 11, 2014 (ADAMS Accession No. ML14162A506), Entergy Operations, Inc. (Energy, the licensee), submitted a license amendment request (LAR) for Waterford Steam Electric Station, Unit 3 (Waterford). The proposed amendment would transition Waterford's fire protection licensing basis from Section 50.48(b) of Title 10 of the Code of Federal Regulations (1 0 CFR) to 10 CFR 50.48(c),

National Fire Protection Association Standard NFPA 805, "Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants."

The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing the LAR and requests the following additional information.

Fire Protection Engineering (FPE) Request for Additional Information (RAil 501 LAR Attachment A, identifies both "open items" and "confirmatory items" that are necessary to achieve compliance with NFPA 805. In the RAI dated July 18, 2012 (ADAMS Accession No. ML12185A212), FPE RAI 07 had requested the licensee to confirm which "open items" are closed and which should be included as implementation items in the licensee's LAR application AttachmentS. By letter dated September 27, 2012, the licensee responded to FPE RAI 07 and stated that "confirmatory items" are identified as implementation items because these items are solely required for NFPA 805 implementation. The licensee also stated that "open items" are those required for the current Appendix R licensing basis, as well as NFPA 805, and must be corrected regardless of transitioning to NFPA 805. These "open items" are tracked in the plant corrective action program. The licensee further stated that the "open items" are considered as required actions to transfer to NFPA 805, but do not rise to the level of being categorized as "confirmatory items" needing to be listed in Attachment S.

Enclosure 1

Since the "open items" are required to comply with NFPA 805, and LAR AttachmentS is used to document items necessary to complete NFPA 805 implementation, per the proposed licensee condition, provide the following:

a. A revised LAR Attachment S that includes these "open items" as implementation items, or justification for their exclusion.

b. LAR Section 4.1.2.1, "NFPA 805 Chapter 3 Requirements Met or Previously Approved by the NRC," indicates that the "confirmatory items" and "open items" are associated with the "Complies" compliance statement. However, in the LAR, Attachment A, several of these items are included with elements that state "Complies with use of EEEEs [Existing Engineering Equivalency Evaluations]." For these cases, which include NFPA 805 Chapter 3 Sections: 3.3.1.2(5), 3.3.7.1, 3.4.1(a)(1),

3.5.3, 3.7, 3.8.1, 3.8.2, 3.9.1 (1), 3.9.1 (2), 3.11.3(2), and 3.11.5, clarify if these "confirmatory items" and "open items" are necessary to comply directly with the NFPA 805 Chapter 3 sections, or if they are associated with the EEEEs that are cited in the compliance basis.

FPE RAI 502 Position C.2.3.1 of Regulatory Guide (RG) 1.205, "Risk-Informed, Performance-Based Fire Protection for Existing Light-Water Nuclear Power Plants," Revision 1, dated December 2009 (ADAMS Accession No. ML092730314), and Section 4 of Nuclear Energy Institute (NEI) 04-02, "Guidance for Implementing a Risk-Informed, Performance-Based Fire Protection Program Under 10 CFR 50.48(c)," Revision 2, dated April2008 (ADAMS Accession No. ML081130188),

provide guidance regarding transition of previously approved alternatives to NFPA 805 Chapter 3 elements. The guidance describes that the basis for previously approved elements be assessed for continued applicability and validity, including consideration of any modifications that may have altered the original basis for approval. In addition, the guidance in NEI 04-02, Figure 4-2, as repeated in the LAR, Section 4.1.1, Figure 4-1, describes the insertion of verbatim excerpts from the approval documentation in the compliance basis field (of LAR Attachment A, Table B-1). LAR, Attachment A contains several elements that cite "Complies via Previous Approval," and although references are made to the associated NRC safety evaluations for these elements, with the exception of Element 3.6.4, 1) the licensee has not provided the applicable excerpts, 2) has not provided a statement of continued validity, and

3) does not discuss any potential impacts from plant changes over time.

Consistent with the approach used by the licensee for LAR Attachment A, Element 3.6.4, provide the compliance basis for the previously approved elements, including statements of continued applicability and validity and the impacts of plant changes over time.

FPE RAI 503 LAR Attachment A, Section 3.4.1 (c) states compliance with NFPA 805 Section 3.4.1 (c) which requires that the fire brigade leader and at least two brigade members have sufficient training and knowledge of nuclear safety systems to understand the effects of fire and fire suppressants on nuclear safety performance criteria. In RG 1.189, "Fire Protection for Nuclear Power Plants,"

Revision 2, dated October 2009 (ADAMS Accession No. ML092580550), Section 1.6.4.1 "Qualifications," the NRC staff acknowledged the following example for the fire brigade leader as sufficient that states, in part:

The brigade leader should be competent to assess the potential safety consequences of a fire and advise control room personnel. Such competence by the brigade leader may be evidenced by possession of an operator's license or equivalent knowledge of plant systems.

Provide additional detail regarding the training provided to the fire brigade leader and brigade members that addresses their ability to assess the effects of fire and fire suppressants on NFPA 805 nuclear safety performance criteria. Include the justification for how the training meets NFPA 805 Section 3.4.1.

FPE RAI 504 NFPA 805 Section 3.4.1 (a) requires a minimum fire brigade staff of five persons on duty at all times. LAR Attachment A, the licensee states it complies with clarification that the fire brigade may be less than the minimum complement of five persons for a maximum of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to accommodate unexpected absences. As described in NEI 04-02, Section 4.3.1, "Complies with Clarification," statements are intended to address compliance differences that are generally editorial in nature. The less-than-minimum staffing statement in the LAR is not considered editorial.

NFPA 805 states that previously approved alternatives to the fundamental fire protection program attributes, identified in Chapter 3, take precedence over the requirements in NFPA 805, Chapter 3.

Clarify whether the NRC has previously approved less-than-minimum fire brigade staffing for Waterford, for this 2-hour grace period, and if so, confirm that this approval has been assessed for "continued applicability and validity." If not, specifically request NRC staff approval of this condition and provide adequate justification.

FPE RAI 505 LAR Attachment A, Element 3.11.3(2) refers toLAR Attachment T, for clarification in the Compliance Basis column. In the LAR supplement dated December 18, 2013, the content of LAR Attachment Twas reported as "deleted." Clarify the compliance basis for NFPA 805 Element 3.11.3(2).

Safe Shutdown Analysis RAI S01

. By letter dated December 18, 2013, the LAR supplement provided a revised Attachment S.

Clarify or provide a revised status regarding the following Implementation Items:

a. The updated response in the licensee's letter dated June 11, 2014, to RAI SSA 12 states that Implementation Item S2-17 has been revised to ensure that all feasibility criteria in FAQ 07-0030, "Establishing Recovery Actions," are addressed for Nuclear Safety Capability Assessment (NSCA) recovery actions (RAs). The updated response to RAI SSA 08.01, however, states that the only RAs in Attachment G of the revised LAR are associated with tripping Reactor Coolant Pumps, and the RAs were confirmed to be feasible based on all11 criteria of FAQ 07-0030. From the above RAI responses, it is unclear if all RAs feasibility analysis to FAQ 07-0030 have been completed or if there will be some that are completed during the implementation period. Confirm the time period for the feasibility analyses for Waterford NSCA and non-power operations RAs that are completed and those to be completed per Implementation Item S2-17.

b. Implementation Item S2-20 also involves evaluating a revised list of RAs for feasibility using the criteria of FAQ 07-0030 (see Item a. above) and revising LAR Attachments C, G, S, and W. This implementation item references SSA RAis 08.01 and 13. However, the licensee's letter dated June 11, 2014, indicates that the actions described in this implementation item have been completed. Clarify the status of which items have been revised and which items remain to be revised per Implementation Item S2-20.

SSA RAI S02 By letter dated December 18, 2013, the LAR supplement, Attachment C, VFDR 1-045 does not have a disposition. Provide the disposition of this variance from deterministic requirements (VFDR).

SSA RAI S03 By letter dated December 18, 2013, the LAR supplement, Attachment G, the recovery action for RAB 7 references VFDR 7-074. In Attachment C of the LAR supplement, the recovery action for RAB 7 references VFDR 7-070. Confirm which VFDR should be referenced.

SSA RAI S04 By letter dated December 18, 2013, the LAR supplement, Attachment C, Tables C-1 and C-2, identifies the Fire Suppression and Detection Systems required for compliance by an EEEE or to meet a licensing action. In particular, Fire Areas RAB 15A, RAB 16A, RAB 40 and RAB 41 each reference "Attachment A, Section 3.3.8." However, the LAR supplement revised a number of Attachment A, Section 3.3.8, compliance statements from "Complies with EEEE" and "Complies by Previous Approval," to "Complies." Therefore, in Attachment C, clarify the basis for the required Fire Suppression and Detection Systems to align with Attachment A.

88A RAI 805 In the LAR, Section 4.8.1 and Attachment C, the licensee designates the basis for requiring a fire protection system or feature as follows: S (Separation), L (Licensing Action), E (EEEE Criteria), R (Risk Criteria), and D (Defense-in-Depth). LAR Attachment C, Table C-2, provides the compilation of required systems and features for all fire areas and follows the Section 4.8.1 designations described above. However, in LAR Attachment C, Table C-1, systems or features required for licensing action or EEEE in individual fire areas are designated "LNEEEE." Because the LNEEEE designation in Table C-1 does not follow the same convention as Section 4.8.1 and Table C-2, confirm the designations (i.e., S, L, E, R, D) for the required features and systems in Table C-2 are correct and appropriate for use in determining if the systems and features are required for either a licensing action or an EEEE.

88A RAI 806 By letter dated December 18, 2013, the LAR supplement, Attachment G, states, "Once control of the plant has been established at the primary control station (PCS), operators will use available controls as dictated by operations procedures to maintain the plant in a safe and stable condition. The location of the fire and impact on specific equipment will determine which equipment and actions will be available to the operators." Provide the following clarifications:

a. Clarify whether additional local actions are necessary outside the PCS (i.e., remote shutdown station) to maintain safe and stable conditions once control of the plant has been established at the PCS.

b. If additional actions are necessary to control the plant beyond those performed at the PCS, describe these actions and either: 1) include them in a revised Table G-1 and assess the risk of the additional actions, or 2) provide justification for not including these actions in Table G-1.

Fire Modeling (FM) RAI 801 NFPA 805, Section 2.4.3.3 states that the Probabilistic Risk Assessment (PRA) approach, methods, and data shall be acceptable to the NRC. The NRC staff noted that fire modeling comprised the following:

• The algebraic equations implemented in FDTs [Fire Dynamics Tools] were used to characterize flame radiation (heat flux), flame height, plume temperature, ceiling jet temperature, and hot gas layer (HGL) temperature, the latter of which is used in the multi-compartment analysis.

• The Consolidated Model of Fire Growth and Smoke Transport (CFAST) was used to assess main control room (MCR) habitability and to calculate HGL temperature in selected multi-compartment scenarios.

LAR Section 4.5.1.2, "Fire PRA" states, in part, that "[f]ire modeling was performed as part of the Fire PRA development (NFPA 805 Section 4.2.4.2)." Reference is made toLAR Attachment J, "Fire Modeling V&V [verification and validation]," for a discussion of the acceptability of the fire models that were used.

Regarding the acceptability of the PRA approach, methods, and data:

a. Identify whether any fire modeling tools and methods have been used in the development of the LAR that are not discussed in LAR Attachment J. Conversely, identify any fire modeling tools and methods discussed in LAR Attachment J that have not been used in the fire modeling analyses performed at Waterford.

b. In the updated response by letter dated June 11, 2014, to previous FM RAis 01.m and 01.01, it is stated that secondary combustibles are considered in the revised analysis. However, it is not clear from the supporting documentation that this is the case. Clarify how this issue has been resolved in the updated analysis.

Alternatively, provide justification for ignoring the effect of flame spread and fire propagation in secondary combustibles (cable trays) and the corresponding heat release rate (HRR) on the calculated zone of influence (ZOI) and HGL temperature.

c. In the updated response by letter dated June 11, 2014, to previous FM RAI 01.p, it is stated that non-cable intervening combustibles are considered in the revised analysis. However, it is not clear from the supporting documentation that this is the case. Clarify how this issue has been resolved in the updated analysis and provide information on how non-cable intervening combustibles were identified and accounted for in the fire modeling analyses.

d. Typically, during maintenance or measurement activities in the plant, electrical cabinet doors are opened for a certain period of time. Explain what administrative controls are in place to minimize the likelihood of fires involving such an open cabinet, and describe how cabinets with temporarily open doors were treated in the fire modeling analyses.

e. Describe the criteria that were used to decide whether a cable tray in the vicinity of an electrical cabinet will ignite following a high energy arcing fault (HEAF) event in the cabinet. Explain how the ignited area was determined and subsequent fire propagation was calculated. If applicable, describe and justify the effect of tray covers and fire-resistant wraps on HEAF-induced cable tray ignition and subsequent fire propagation.

f. For calculation of fixed ignition source ZOis, the fire area for all cabinet fires was fixed at 0.5 m2 . Justify why using a fixed area is representative of all fixed ignition sources in the plant or demonstrate that the findings from this analysis are not sensitive to the fire area size or that the obtained results are bounding.

In addition, provide justification for the assumed fire areas and elevations that were used in the transient ZOI calculations. Explain how the model assumptions in terms of location and HRR of transient combustibles in a fire area or zone will not be violated during and post-transition.

g. Explain how wall and corner effects were accounted for in all of the fire modeling calculations, or provide the technical justification for not doing so.

h, Specifically, regarding the use of CFAST in the MCR abandonment calculations:

i. The licensee assumed that half of the electrical cabinet fire scenarios will involve single cable bundle fires and half will involve multiple cable bundle fires. The licensee stated that this assumption is conservative as all fires initiate as a single bundle cable fire, which need to propagate to become multiple bundle cable fires, and that most of the electrical cabinet fires will not involve multiple bundles as the MCR will be equipped with a rapid detection system.

Provide justification for the assumed fraction of single cable bundle and multiple cable bundle electrical cabinet fires. Provide technical justification for the assumption that the growth rate and peak HRR recommended in NUREG/CR-6850, "EPRI [Electric Power Research lnstitute]/NRC-RES

[Office of Nuclear Regulatory Research] Fire PRA Methodology for Nuclear Power Facilities, Volume 2: Detailed Methodology," dated September 2005 (ADAMS Accession No. ML052580118), for electrical cabinet fires involving a single bundle fire can be applied to a fraction of electrical cabinets in the MCR with multiple cable bundles.

Describe the detection and suppression devices used in the electrical cabinets or main control boards in the control room and demonstrate their capability to suppress single cable bundle fires before they propagate to additional cable bundles.

ii. During the audit walkdown of the MCR, the NRC staff noted several cabinets that do not appear to be separated by a double wall and an air gap. Provide

the technical justification for not considering electrical cabinet fires that propagate to adjacent cabinets.

iii. The licensee indicates that for transient fires, the most conservative scenario involves an operational heating, ventilation, and air conditioning (HVAC) system. However the analysis indicates that 13 HRR bins cause abandonment with non-functional HVAC as opposed to 12 bins with functional HVAC. Also, it appears that the scenarios with operational HVAC and doors opening at 15 minutes are used to calculate the probability for control room abandonment.

Provide the technical justification for selecting the scenarios with operating HVAC and doors opening at 15 minutes to calculate the probability for control room abandonment and explain why the cases without HVAC and doors not opening were not considered in the Fire PRA.

iv. Provide the technical basis for the material properties that were specified in CFAST for the transient combustibles in the MCR. Provide confirmation that the assumed soot yield and heat of combustion values are representative of the transient materials that are present in the MCR, or lead to conservative estimates of the soot generation rate.

v. It appears that the cables in the electrical cabinets are assumed to be an equal mix of ethylene propylene rubber (EPR), Hypalon, and Neoprene.

Confirm that this assumption is consistent with the actual cable mixture present in the plant. Provide the technical basis for the material properties that were specified in CFAST for the cables inside the cabinets in the MCR.

Provide confirmation that the assumed soot yield and heat of combustion values lead to conservative estimates of the soot generation rate.

i. Specifically, regarding the use of CFAST in the RAB 7A, 78, 7C and 70 calculations:

i. The soot yield, carbon monoxide (CO) yield, and radiation fraction parameters used in the CFAST analysis for both the transient fires and electrical cabinet fires are the same. Justify using the same parameters for all types of fires and also provide detail about why the values of these parameters used in the analysis are conservative or are consistent with actual plant conditions.

ii. The licensee indicated that most of the cables in RAB-7 are routed through covered cable trays and that the majority of the remaining cables are routed through conduits. Explain if there are any cables that are not enclosed in either covered cable trays or conduits, and describe how the fire propagation in these cables is accounted for in the CFAST analyses.

iii. Provide the technical justification for not excluding the volume of different obstructions, such as electrical cabinets and equipment, from the overall

volume used in the CFAST calculations, or demonstrate that the analysis is conservative and adequate for the stated purpose.

iv. Temperature values obtained from the CFAST analysis were used to determine whether a cabinet or sub-PAU [Physical Analysis Unit] fails.

Clarify where (location within the surface or volume of the cabinets) these temperature values were recorded and provide the basis for selecting these particular locations.

j. Specifically regarding the multi-compartment analysis (MCA):

i. Describe the criteria that were used to qualitatively screen multi-compartment scenarios.

ii. Explain how the methods described in Chapter 2 of NUREG-1805, "Fire Dynamics Tools (FDTs) Quantitative Fire Hazard Analysis Methods for the U.S. Nuclear Regulatory Commission Fire Protection Inspection Program,"

dated December 2004 (ADAMS Accession No. ML043290075) were used in the calculations to screen an ignition source based on insufficient HRR to generate a HGL condition in the exposing compartment.

iii. Explain how the possibility of damaging hot gases spreading to a third compartment was considered.

FM RAI 802 American Society of Mechanical Engineers/American Nuclear Society (ASME/ANS) Standard RA-Sa-2009, "Standard for Levei1/Large Early Release Frequency Probabilistic Risk Assessments for Nuclear Power Plant Applications," Part 4, requires damage thresholds be established to support the Fire PRA. Thermal impact(s) must be considered in determining the potential for thermal damage of structures, systems, and components and appropriate temperature and critical heat flux criteria must be used in the analysis.

In the updated response by letter dated June 11, 2014, to previous FM RAI 02.a, the licensee stated, in part, "[t]he design specifications for Waterford 3 cables required IEEE [Institute of Electrical and Electronics Engineers]-383 qualification. The materials of construction of the cables are consistent with thermoset performance which was the basis for the determination for the Fire PRA."

However, it appears that a damage threshold of 380 °Centigrade (C) was used for thermoset cable, as opposed to 330 °C, which is the NUREG/CR-6850-recommended bounding value for thermoset cable.

a. Describe how the installed cabling in the power block was characterized, specifically with regard to the critical damage/ignition threshold temperatures and critical heat fluxes for thermoset and thermoplastic cables as described in NUREG/CR-6850.

Confirm that the ignition/damage criteria for raceways with a mixture of different

types of cables were based on the cables with the lowest damage/ignition threshold in the target raceway, as recommended in Section H.1.4 of NUREG/CR-6850. If the characterization of cabling in the power block in terms of damage/ignition thresholds is not consistent with NRC guidance, then justify this deviation or replace this treatment with an acceptable approach in the integrated analysis provided in response to PRA RAI S 18.

b. Explain how the damage thresholds for non-cable components (i.e., pumps, valves, electrical cabinets, etc.) were determined. Identify any non-cable components that were assigned damage thresholds different from those for thermoset and thermoplastic cables, and provide a technical justification for these damage thresholds.

c. Explain how exposed temperature-sensitive equipment was treated, and provide the technical justification for the damage criteria that were used.

FM RAI 503 Regarding the V&V of fire models, NFPA 805, Section 2.7.3.2, states that each calculational model or numerical method used shall be verified and validated through comparison to test results or comparison to other acceptable models.

The LAR Section 4.5.1.2 states that fire modeling was performed as part of the Fire PRA development (NFPA 805, Section 4.2.4.2). Reference is made toLAR Attachment J, for a discussion of the V&V of the fire models that were used. Furthermore LAR Section 4.7.3, "Compliance with Quality Requirements in Section 2.7.3 of NFPA 805," states, in part, that "Calculational models and numerical methods used in support of compliance with 10 CFR 50.48(c) were verified and validated as required by Section 2.7.3.2 of NFPA 805."

For any tool or method identified in the response to FM RAI S01.a above, provide the V&V basis if not already explicitly provided in the LAR (for example in LAR Attachment J). Provide technical details to demonstrate that these models were applied within the validated range of input parameters, or justify the application of the model outside the validated range in the V&V basis documents.

FM RAI 504 NFPA 805, Section 2.7.3.3, states that acceptable engineering methods and numerical models shall only be used for applications to the extent these methods have been subject to V&V.

These engineering methods shall only be applied within the scope, limitations, and assumptions prescribed for that method. The LAR, Section 4.7.3, states, in part, that "Engineering methods and numerical models used in support of compliance with 10 CFR 50.48(c) were applied appropriately as required by Section 2.7.3.3 of NFPA 805."

Regarding the limitations of use:

a. The NRC staff notes that algebraic models cannot be used outside the range of conditions covered by the experiments on which the model is based. NUREG-1805, includes a section on assumptions and limitations that provides guidance to the user in terms of proper and improper use for each FDT.

Identify uses, if any, of the FDTs outside the limits of applicability of the model and for those cases explain how the use of the FDT was justified.

b. Identify uses, if any, of CFAST outside the limits of applicability of the model and for those cases, explain how the use of CFAST was justified.

FM RAI 505 The LAR, Section 4.7.3, states, in part, that, "[u]ncertainty analyses were performed as required by Section 2.7.3.5 of NFPA 805 and the results were considered in the context of the application. This is of particular interest in fire modeling and Fire PRA development." The updated responses to FM RAis 05.a & 05.b by letter dated June 11, 2014, states, "[u]ncertainty associated with specific fire modeling parameters is addressed through the use of a conservative and bounding analysis," and makes reference to several supporting documents for additional details.

Regarding the uncertainty analysis for fire modeling:

a. Describe how the uncertainty associated with the fire model input parameters was accounted for in the fire modeling analyses.

b. Describe how the "model" and "completeness" uncertainties were accounted for in the fire modeling analyses.

Probabilistic Risk Assessment (PRA) RAI 801 By letter dated June 11, 2014, the responses to PRA RAI 01 and PRA RAI 21 explain that secondary ignition and subsequent fire spread beyond the initial ZOI is modeled in the updated Fire PRA, and that the resulting fire impact to secondary targets and associated change to the HRR is addressed. The response to PRA RAI 01 states that walkdowns were performed and locations of plausible secondary ignition sources were recorded. The response stated that only two PAUs were determined to require the additional analysis.

Explain the characteristics of the Waterford plant that cause such a low number of areas that require additional analysis.

PRA RAI 802 By letter dated June 11, 2014, the response to PRA RAI 04, in which the NRC staff asks about how defense-in-depth was evaluated, did not describe the criteria used to determine when there was a "substantial imbalance between echelons" and did not describe the types of improvements made in response to the evaluation. Also, though the licensee presents criteria used to address safety margin, description of how that criteria was applied to specific parts of Fire Risk Evaluation (FRE) was not provided. Please explain the method used in the FREs to determine when a substantial imbalance between echelons was determined to exist and describe the improvements that were made as a result of the defense-in-depth evaluation. Also provide a description of how criteria used in the FREs to evaluate safety margin criteria was applied to specific elements of the FREs consistent with guidelines/criteria in NEI 04-02.

PRA RAI 803 By letter dated June 11, 2014, the response to PRA RAI 06 explains that a detailed sensitivity study was completed to examine the impact of using NUREG/CR-6850, Supplement 1 frequencies instead of those in Table 6-1 of NUREG/CR-6850 Volume 2. The response explains that a sensitivity study was performed using the mean of the fire frequency bins contained in Table 6-1 of NUREG/CR-6850 for those bins with an alpha value less than or equal to one. The response, however, does not provide the sensitivity study results but does state that individual PAU core damage frequencies (CDFs) and large early release frequencies (LERFs) fall within Region II or Ill of the risk guidelines in RG 1.174, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," Revision 2, dated May 2011 (ADAMS Accession No. ML100910006). Given that PRA RAI S18 asks for an integrated analysis using acceptable methods, the NRC staff notes that risk estimates may change.

Provide an indication of whether the acceptance guidelines of RG 1.174 may be exceeded if this sensitivity study would be applied to the integrated analysis requested in PRA RAI S 18. If these guidelines may be exceeded, provide a description of fire protection, or related measures that can be taken to provide additional defense-in-depth as discussed in FAQ 08-0048, "Revised Fire Ignition Frequencies" (ADAMS Accession No. ML091590457).

PRA RAI 504 By letter dated June 11, 2014, the response to PRA RAI 07 explains that a screening value of 0.1 is no longer used as the conditional core damage probability (CCDP) for failure of alternate shutdown on loss of MCR habitability. The response explains that based on updated assessment including detailed Human Reliability Analysis (HRA), the original CCDP value of 0.1 was found not to be bounding. The assessment of MCR abandonment is not described in the response to PRA RAI 01, but the licensee's analysis appears to indicate that a single CCDP of 3.87E-1 was determined and used in all MCR abandonment scenarios. Table W-1 of the LAR supplement lists MCR abandonment scenarios for which the CCDP value is shown to be 1.0, which is not consistent with the licensee's analyses. It is not clear from the LAR and the licensee's analysis whether a single CCDP/CLERP (conditional large early release probability) value was determined for MCR abandonment, what the MCR abandonment CCDP/CLERP values are, and how single values can be representative of the CCDPs in MCR abandonment scenarios for which different fire-induced impacts are possible.

The response for PRA RAI 07 also states that "[a]ll [Fire PRA] abandonment scenarios are associated with [the Fire Area) RAB-1 which includes the control room proper as well as the cable vault." This statement appears to indicate that MCR abandonment may be credited for the cable vault, and therefore, MCR abandonment is credited for loss of control as well as loss of habitability in the MCR. The NRC staff notes that for MCR abandonment on loss of control, the cues to abandon the MCR, the timing associated with those cues, and the time allowed to complete required actions are different than for abandonment of the MCR on loss of habitability.

It is not clear whether MCR abandonment is credited for loss of control, or how MCR abandonment was modeled for loss of habitability and if applicable for loss of control.

In light of the observations made above, please provide the following:

a. Describe how MCR abandonment was modeled for loss of habitability.

b. Identify in Table G-1 in Appendix Gall operator actions required to bring the plant into a safe and stable state, including those that must be performed before and after leaving the MCR. Operator actions taken at a PCS should be identified as PCS actions.

c. Explain how the operator actions were modeled in the HRA and incorporated into the Fire PRA for both loss of habitability and loss of control.

d. Explain how the CCDPs/CLERPs are estimated for fires that lead to abandonment due to loss of habitability and how they address various possible fire-induced failures. Specifically include in this explanation, discussion of how the following scenarios are addressed:

i. Scenarios where fire fails only a few functions aside from forcing MCR abandonment and successful alternate shutdown is straightforward;

ii. Scenarios where fire could cause some recoverable functional failures or spurious operations that complicate the shutdown, but successful alternate shutdown is likely; and, iii. Scenarios where the fire-induced failures cause great difficulty for shutdown by failing multiple functions and/or complex spurious operations that make successful shutdown unlikely.

e. If MCR abandonment is credited for loss of control (i.e., non-habitability cases),

please:

i. Describe when MCR abandonment on loss of control is credited and how it was modeled.

ii. Discuss the bases for the timing assumed in the HRA performed for MCR abandonment scenarios on loss of control, including the results of thermal-hydraulics analyses. Include discussion of the cues to abandon the MCR, the timing associated with those cues, and the basis for time available to complete required actions. Include explanation of how fire-induced impacts, including spurious operations are accounted for in determining the timing associated with the cue to abandon and the time available to perform operator actions.

iii. If the timing of the cues to abandon the MCR and the available time for performing operator actions does not take into account fire-induced impacts, then justify the current approach or replace this approach with an acceptable approach in the integrated analysis provided in response to RAI S18.

f. Explain how the abandonment scenario frequencies due to loss of habitability and/or loss of control were determined. Include explanation of how the fire ignition frequencies contributing to this scenario and non-suppression probabilities were determined.

PRA RAI 505 By letter dated June 11, 2014, the response to PRA RAI 08 explains that Attachment W of the LAR was entirely revised as part of the LAR supplement, and that calculation of b.CDF and b.LERF is discussed in the updated Section W.2.1 of the LAR. The discussion in the updated Section W.2.1 of the LAR primarily references an internal Waterford document instead of providing the requested description of the calculations for b.CDF and b.LERF used at Waterford.

The response to PRA RAI 57 a is also related to the calculation of b.CDF and b.LERF because it states, in part, "LAR Supplement Attachment C (Table B-3) provides detailed dispositions for non-modeled VFDRs." The NRC staff reviewed the updated Attachment C of the LAR and notes that in 187 instances VFDR dispositions state: "[t]his condition has no corresponding PRA basic event and by definition has insignificant risk" and references an internal Waterford document. Review of the referenced internal Waterford document indicates that some

component failure modes were selected for exclusion from the PRA (e.g., control indication, component cooling water makeup to emergency diesel generators, HVAC and Feed Tank level),

but the rationale and justification for exclusion is not always clear. Provide the following information:

a. Summary of the model adjustments made to remove VFDRs from the compliant plant model, such as adding events or logic, or use of surrogate events.

b. Identify any risk-reduction modifications credited in the change-in-risk calculations and explain how these are included in the post-transition and compliant plant models.

c. Discussion of the rationale used for excluding VFDRs from the calculation of flCDF and flLERF. Include justification of why so many VFDRs were excluded from the change-in-risk calculations.

d. Summary of how the change in risk was determined for MCR abandonment scenarios, including a summary of how the CCDP was determined for the compliant and for the variant plant models.

e. Provide separately the total risk increase associated with retained VFDRs and the total risk decrease associated with risk reduction modifications.

PRA RAI 506 By letter dated June 11, 2014, the response to PRA RAI 09 explains that the peer reviews of the Internal Events and Fire PRAs were performed in accordance with the guidelines in NEI 05-04 and NEI 07-12, which reference the clarifications and qualifications of RG 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities." The response does not explicitly state which revision of RG 1.200 (i.e.,

Revision 1 or 2) was used in the peer reviews. The licensee's Internal Events PRA peer review appears to indicate that it was performed in 2009 against PRA Standard ASME RA-Sb-2005 as clarified by RG 1.200 Revision 1, dated January 2007. The current guidance for using PRA for risk-informed applications is RG 1.200 Revision 2, dated March 2009 (ADAMS Accession No. ML090410014), which is based on PRA Standard ASME/ANS RA-Sa-2009.

Explain whether the gap assessment was performed for the Internal Events PRAto ASME/ANS RA-Sa-2009 and RG 1.200 Revision 2; if not, determine whether the differences between RG 1.200 Revision 1 and RG 1.200 Revision 2 have any impact on the LAR, and provide a summary of the evaluation.

PRA RAI 507 By letter dated June 11, 2014 the responses to PRA RAI13 and PRA RAI45.h explain that the fire event Human Error Probabilities (HEPs) used in the Fire PRA were calculated by multiplying Internal Event HEPs by a factor of 10 to account for effects of fire on operator performance and equipment. The response to PRA RAI 45.h explains that operator actions taken outside the

MCR are assumed to fail. The response to PRA RAI 45.h also states that this "methodology is different from the previous revision, which more closely resembled NUREG-1921, "EPRI/NRC-RES Fire Human Reliability Analysis Guideline," Final Report, Appendix C, (ADAMS Accession No. ML12216A104) and is considered a "more simplified approach."

The NRC staff notes that this approach is similar to the screening approaches described in Section 5.1.1 of NUREG-1921. NUREG-1921 screening approaches are similar in that for specified cases a factor of 10 times the internal event HEP could be used as a screening HEP for the corresponding fire Human Failure Events (HFE) to account for effects not covered in the internal events PRA such as fire brigade action, increased work load, and distraction. However, a number of criteria are identified in NUREG-1921 for using the screening approaches. For example, the Set 1 and Set 2 screening approaches cannot be used if there is a potential for fire damage to safe shutdown equipment that is being credited, instrumentation needed (e.g., no-readings, off-scale readings, and incorrect/misleading readings), or environmental impact that significantly impacts the MCR crew. The NRC staff notes that fire impact might preclude particular operator events from being successful by failing instrumentation needed for the action or by interfering with the operator action, and in these cases the use of the "multiplier approach" could lead to under-prediction of the HEPs associated with credited operator actions.

It is not clear how the licensee's HRA accounts for dependencies between HFEs in the same cut set. By letter dated June 11, 2014, the response to PRA RAI 13 states, in part, "[a] factor of 10 was chosen for the adjustment at the individual and combination level for actions where the probability of failure was less than 1.0E-2 and in particular combination with 1.0E-5 or lower probabilities." It is not clear what this statement means and whether the "multiplier approach" accounts for dependencies between HFEs in the same cut set.

Additionally, it is not clear whether new HFEs not used in the Internal Events PRA were added to the Fire PRA. If new HFEs were added, it is not clear how the HEPs for these HFEs are determined using the current multiplier approach. Provide the following:

a. Explain how the screening criteria discussed in Section 5.1.1 of NUREG-1921 for Sets 1 and 2 are considered. If not considered, provide further justification.

b. Explain how the HRA accounts for dependencies between HFEs in the same cut sets.

c. Explain whether or not plant procedures contain additional operator manual actions outside the control room that are currently credited in the PRA but are not listed in Table G-1 of the LAR. If so, explain why these actions are not included in Table G-1.

PRA RAI 508 By letter dated June 11, 2014, the response to PRA RAI 16 explains that the updated Fire PRA was revised to address sensitive electronics rather than screening them from the analysis. The response to PRA RAI 16 indicates that expanded ZOis were used to account for sensitive electronics, but the approach was not described in the response. Although the treatment of sensitive electronics may be consistent with recent guidance on modeling sensitive electronics,

the licensee's analysis does not cite FAQ 13-0004 (Clarifications on Treatment of Sensitive Electronics, issued December 3, 2013 (ADAMS Accession No. ML13322A085), as one of the FAQs used in the Fire PRA. Explain the updated treatment of sensitive electronics used in the Fire PRA. Include explanation of whether the treatment of sensitive electronics performed for the Fire PRA is consistent with the guidance in FAQ 13-0004, including the caveats about configurations that can invalidate the approach (i.e., sensitive electronics mounted on the surface of cabinets or in the presence of louvers or vents). If the approach cannot be justified using available NRC guidance, then replace the current approach with an acceptable approach as part of the integrated analysis performed in response to PRA RAI S 18.

PRA RAI 809 By letter dated June 11, 2014, the response to PRA RAI 22 explains that assessment of the MCR Main Control Board (MCB) was updated using the NUREG/CR-6850 Appendix L method but does not describe the new treatment. Based on the review of the licensee's updated analysis, the NRC staff makes the following observations.

The first observation is that the licensee's description of applying the Appendix L approach states that the MCB fire ignition frequency was "apportioned into different fire scenarios", and that the approach "allowed for approximately 88.3% of the of the MCB frequency to be discarded" as not significant. When applying the NUREG/CR-6850 Appendix L method, as per guidance in FAQ 14-0008, the frequency of a scenario involving specific target damage in the MCB should be determined by multiplying the probability of target damage, such as specified by Figure L-1 of NUREG/CR-6850, by the entire MCB frequency. Subdividing the MCB frequency is not intended by Appendix L guidance unless accompanied by recalculation of Appendix L, Figure L-1, target damage probabilities.

The second observation is that the analysis credited additional non-suppression probability for scenarios where fire propagates from one MCB panel to another based on the licensee's characterization of the MCB as "not an open construct," but rather "individual panels abutted together". The MCB configuration that justifies reducing the likelihood of fire propagation between MCB panels is not completely clear.

The third observation is that it appears from information presented in the licensee's analysis that there may be control functionality located on the rear side of the MCB. It is not clear from description of the licensee's analysis whether this functionality is included in the target sets addressed in the MCB fire evaluation. Note that guidance in FAQ 14-0008 provides discussion of MCB configurations in which the rear side of the MCB should also be considered an integral part of the MCB and analyzed as such.

Based on the observations above please provide the following:

a. Clarify how the MCB fire ignition was applied to MCB fire scenarios. If the entire MCB frequency is not multiplied by the target damage for each MCB fire scenario, per guidance in FAQ 14-0008, then justify the approach using NRC guidance on application of the Appendix L method, or remove this approach and replace it with an

acceptable approach as part of the integrated analysis provided in response to PRA RAI S18.

b. Describe the MCB panel configuration that provides the basis for reducing the likelihood of fire propagation between MCB panels. Indicate whether there are partitions between the panels and if there are, whether there are any openings in the partitions. If the Waterford MCB panel configuration cannot justify reducing the likelihood of fire propagation between MCB panels using guidance in NUREG/CR-6850, then remove the additional non-suppression credit applied to fire scenarios between MCB panels as part of the integrated analysis provided in response to PRA RAI S18.

c. Clarify whether there is control functionality located on the rear side of the MCB and whether it included as part of the target sets addressed in application of the NUREG/CR-6850 Appendix L approach. If there is functionality on the rear side that must be considered an integral part of the MCB that was not assessed, then justify this exclusion or include consideration of fire damage to these functions as part of application of the NUREG/CR-6850 Appendix L approach in the integrated analysis provided in response to PRA RAI S18.

PRA RAJ 810 By letter dated June 11, 2014 the response to PRA RAI 28 states, in part, that "the updated analysis no longer uses a floor for joint HEP values," because a simple multiplier approach is used to determine the HEP of fire event HFEs based on the HEP of Internal Events HFEs. The response indicates that joint HEPs with probabilities lower than 1E-05 are used. NUREG-1921 discusses the need to consider a minimum value for the joint probability of multiple HFEs, and NUREG-1792, "Good Practices for Implementing Human Reliability Analysis (HRA)," issued April 2005 (ADAMS Accession No. ML051160213), Table 2-1 recommends that joint HEP values should not be below 1E-5. Table 4-3 of EPRI 1021081, "Establishing Minimum Acceptable Values for Probabilities of Human Failure Events," provides a lower limiting value of 1E-6 for sequences with a very low level of dependence.

a. Confirm that each joint HEP value used in the Fire PRA below 1E-5 includes its own justification that demonstrates the inapplicability of the NUREG-1792 lower value guideline.

b. Provide an estimate of the number of these joint HEPs below 1E-5 and at least two different examples of the justification.

PRA RAJ 811 By letter dated June 11, 2014 the response to PRA RAI 30 explains that as a result of the revised Fire PRA the "generic" non-suppression factors originally used were removed and non-suppression probability values from NUREG/CR-6850, Supplement 1, were incorporated. The updated approach is not described in the response; however, the NRC staff reviewed the description in the licensee's analysis and notes potential inconsistencies. The licensee's

analysis identifies several PAUs (i.e., FPH, RAB 15A, RAB 16A, RAB 20, RAB 40, and RAB 41) for which automatic suppression systems are used as the bases for non-suppression probabilities credited in the Fire PRA. However, these suppression systems appear not to be required in Table C-2 of the LAR supplement for risk reduction. Please explain this apparent inconsistency.

PRA RAI 512 By letter dated June 11, *2014, the response to PRA RAI 32 explains that the MCR analysis has been revised by differentiating between single and multiple bundles of cables affecting abandonment times for MCR abandonment scenarios. Though the RAI response does not provide further description of the new approach, the NRC staff reviewed the description of the updated approach in the licensee's analysis. This description explains that 50 percent of fire scenarios are assumed to involve single cable bundles and 50 percent are assumed to involve multiple cable bundles. The licensee's analysis further explains that "this assumption is conservative because all fires initiate as a single bundle," and in the MCR "50% of the fires are likely to be single cable bundles prior to detection and suppression." The NRC staff notes that without supporting fire modeling or event data, it is not clear what the opportunity for suppression is before cables in multiple bundles are involved in a fire, and whether this assumption is conservative compared to, for example, specifically identifying and modeling single and multiple cable bundles based on a walkdown. The NRC staff also notes that this assumption is a deviation from NUREG/CR-6850 guidance, which treats individual electrical panels as containing either a single cable bundle or multiple cable bundles.

Provide further justification that the assumption is conservative based on characterization of the actual cable bundle configurations in the MCR cabinets, or update risk results as part of the integrated analysis requested in PRA RAI S18.

PRA RAI 513 By letter dated June 11, 2014, the response to PRA RAI 33 explains that though guidance to limit fire propagation from "sealed" cabinets is acknowledged, that for the Waterford Fire PRA, the licensee states, in part, "all cabinets are treated as having the ability to propagate a fire based on their resultant zone of influence impacts .... " This statement seems to imply that fire propagation was considered for all electrical cabinets included in the fire frequency bin count for Bin 15 (i.e., Electrical Cabinets). In contrast to this statement, however, description of the licensee's analysis associated with fixed ignition sources states that "[c]abinet fires surrounded by only non-vented cabinets can be screened if no smoke effects are expected."

Explain how fire propagation outside of a cabinet and subsequent damage was modeled for electrical cabinets.

a. How is fire propagation outside of the cabinet modeled for electrical cabinets and motor control centers (MCCs) greater than 440 V?

b. How is fire propagation outside of well-sealed, robustly-secured cabinets modeled for electrical cabinets and MCCs greater than 440 V?

c. Is fire propagation outside of the cabinet modeled for electrical cabinets less than 440V?

d. Are well-sealed cabinets below 440 V excluded from the counting process for Bin 15? If not, justify that this does not dilute the fire ignition frequency per cabinet leading to an underestimation of risk.

PRA RAI 514 By letter dated June 11, 2014 the responses to PRA RAI 48 and 43.f identifying modifications that are credited in the PRAdo not appear to be fully consistent with the updated Table S-1 in the LAR supplement. Please identify which modifications in the updated Table S-1 are credited in the PRA.

PRA RAI 515 By letter dated June 11, 2014 the responses to PRA RAI 49 and PRA RAI 45.e explain that quantitative uncertainty analysis was developed for the updated Fire PRA. However, neither these responses nor the licensee's analysis discuss whether or how state of knowledge correlation (SOKC) is accounted for in the quantitative uncertainty analysis. Mean CDF and LERF values can be affected by SOKC and should be accounted for as part of statistical parametric uncertainty analysis. It is not clear whether SOKC was taken into account in the quantitative uncertainty analysis performed for the updated Fire PRA. PRA Standard Supporting Requirement (SR) QU-A3 (referenced by FQ-A4) and QU-E4 (referenced by FQ-E4) require that the CDF be estimated accounting for the SOKC between event probabilities. The SOKC should include consideration of correlation between probability distributions for Internal Event and Fire PRA parameters (i.e., component type failure mode probabilities, hot short probabilities, and non-suppression probabilities). Summarize the impact of the SOKC correlation on the results reported in Attachment W.

PRA RAI 516 By letter dated June 11, 2014, the response to PRA RAI 51 explains that the new MCA was "substantially revised" and that the current analysis does not screen out all MCA scenarios. The response and the licensee's analysis indicates that the updated MCA retains several scenarios, but do not explain the revision made to the MCA or the reason for the significantly different MCA results. Please explain the revision made to the MCA and the reasons for the significantly different MCA results.

PRA RAI 517 Section 2.4.3.3 of NFPA-805 states that the PRA approach, methods, and data shall be acceptable to the NRC. Section 2.4.4.1 of NFPA-805 further states that the change in public health risk arising from transition from the current fire protection program to an NFPA-805 based program, and all future plant changes to the program, shall be acceptable to the NRC.

RG 1.174 provides quantitative guidelines on CDF, LERF, and identifies acceptable changes to

these frequencies that result from proposed changes to the plant's licensing basis and describes a general framework to determine the acceptability of risk-informed changes. The NRC staff review of the information in the LAR has identified additional information that is required to fully characterize the risk estimates.

New guidance on using conditional probabilities of spurious operation for control circuits was issued in a letter from the NRC to NEI, "Supplemental Interim Technical Guidance on Fire-induced Circuit Failure Mode Likelihood Analysis" (ADAMS Accession Nos. ML14086A165 and ML14017A135) and in NUREG/CR-7150, Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE)," Volume 2: "Expert Elicitation Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure" (ADAMS Accession No. ML14141A129). This guidance included: a) replacement of the conditional hot short probability tables in NUREG/CR-6850 for Option #1 (including removal of credit for Control Power Transformers (CPTs) and conduit) with new circuit failure probabilities for single break and double break control circuits, b) Option #2 in NUREG/CR-6850 is no longer an adequate method and should not be used, c) replacement of the probability of spurious operation duration figure in FAQ 08-0051 (NUREG/CR-6850 Supplement 1) for alternating current control circuits and additional guidance to address duration for direct current control circuits, d) aggregate-values for circuit failure probabilities should be used unless it is demonstrated that a cable is only susceptible to a single failure mode, e) incorporation of the uncertainty values for the circuit failure probabilities and spurious operation duration in the SOKC for developing the mean CDF/LERF, and f) recommendations on the hot short probabilities to use for other cable configurations, including panel wiring, trunk cables, and instrument cables.

Provide an assessment of the assumptions used in the Waterford Fire PRA relative to the updated guidance specifically addressing each of these items. If the Fire PRA assumptions are not bounded by the new guidance, provide justification for each of the differences or provide updated risk results as part of the integrated analysis requested in PRA RAI S 18, utilizing the guidance in NUREG/CR-7150, Volume 2. Justify the proposed treatment of circuit failure probabilities during post transition for self-approval of risk-informed changes.

PRA RAI 518 Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. Section 2.4.4.1 of NFPA-805 further states that the change in public health risk arising from transition from the current fire protection program to an NFPA-805 based program, and all future plant changes to the program, shall be acceptable to the NRC.

RG 1.174 provides quantitative guidelines on CDF and LERF, and identifies acceptable changes to these frequencies that result from proposed changes to the plant's licensing basis and describes a general framework to determine the acceptability of risk-informed changes.

The NRC staff's review of the information in the LAR has identified several PRA methods that require additional review. The PRA methods currently under review include:

• PRA RAI S01 regarding treatment of secondary ignition

• PRA RAI S04 regarding modeling MCR abandonment

• PRA RAI S05 regarding modeling determination of additional risk of recovery actions

• PRA RAI S07 regarding the licensee's multiplier approach for developing fire HEPs

• PRA RAI SOB regarding treatment of sensitive electronics

• PRA RAI S09 regarding use of NUREG/CR-6850 Appendix L

• PRA RAI S 12 regarding single versus multiple bundle cable fires

• PRA RAI S15 regarding the inclusion of SOKC for internal and fire event factors

• PRA RAI S17 regarding new spurious actuation guidance

• FM RAI S02.a regarding critical damage thresholds Provide the following:

a. Results of an aggregate analysis that provides the integrated impact on the fire risk (i.e., the total transition CDF, LERF, ~CDF, ~LERF) of replacing any unacceptable methods identified above with alternative methods, which are acceptable to the NRC.

In this aggregate analysis, for those cases where the individual issues have a synergistic impact on the results, a simultaneous analysis must be performed. For those cases where no synergy exists, a one-at-a-time analysis may be done. For those cases that have a negligible impact, a qualitative evaluation may be done. It should be noted that this list may expand depending on NRC's review of the responses to other RAis in this document.

b. For each method (i.e., each bullet) above, explain how the issue will be addressed in

1) the final aggregate analysis results provided in support of the LAR, and 2) the PRA that will be used at the beginning of the self-approval of post-transition changes. In addition, provide confidence (e.g., with a proposed implementation item) that all changes will be made, that a focused-scope peer review will be performed on changes that are PRA upgrades as defined in the PRA standard, and that any findings will be resolved before self-approval of post-transition changes. Note that any use of unacceptable methods may prohibit the staff from completing its review for self-approval.

c. In the response, explain how the RG 1.205 risk acceptance guidelines are satisfied for the aggregate analysis. If applicable, include a description of any new modifications or operator actions being credited to reduce delta risk as well as a discussion of the associated impacts to the fire protection program.

d. If any of the methods not accepted by the NRC staff will be retained in the PRA that will be used to estimate the change in risk of post-transition changes to support self-approval, explain how the quantification results for each future change will account for the use of these methods.

PRA RAI 519 Section 2.4.3.3 of NFPA 805 states that the PRA approach, methods, and data shall be acceptable to the NRC. RG 1.205 identifies NUREG/CR-6850 as documenting a methodology for conducting a fire PRA and endorses, with exceptions and clarifications, NEI 04-02, Revision 2, as providing methods acceptable to the NRC staff for adopting a fire protection

program consistent with NFPA-805. RG 1.200 describes a peer review process utilizing an associated ASME/ANS standard (currently ASME/ANS-RA-Sa-2009) as one acceptable approach for determining the technical adequacy of the PRA once acceptable consensus approaches or models have been established.

a) Summarize or list all modeling changes made to the Internal Events and Fire PRA since the December 18, 2013 submittal.

b) Indicate if any other methods were employed that deviate from the guidance in NUREG/CR-6850 or other acceptable guidance (e.g., FAQs or interim guidance documents). If so, describe and justify any proposed method that deviates from NRC guidance, or replace the proposed method with an accepted method. Also, include the proposed method as a method "currently under review" as part of the integrated analysis in the response to PRA RAI S 18.

Response Dates for the Request for Additional Information Required Request for Additional Information Response Date FPE S01,S03,S04,S05 SSA S01,S02,S03,S04,S05,S06 03/16/2015 FM S01.a, S01.d, S01.f, S01.h.iv, S01.h.v, S01.i.iv, S01.j, S02.b, S02.c, (60 days*)

S03 PRA S02, S05, S06, S08, S1 0, S11, S14, S15 FPE S02 04/14/2015 FM S01.b, S01.c, S01.e, S01.g, S01.h.iii, S01.i.i, S01.i.iii, S04.b, S05 (90 days*)

PRA S01, SO?, S13, S16, S17 FM S01.h.i, S01.h.ii, S01.i.ii, S02.a, S04.a 05/14/2015 PRA S03, S04, S09, S12, S18, S19 (120 days*)

• from conclusron of audrt on January 14, 2015 Acronyms:

FPE - Fire Protection Engineering SSA - Safe Shutdown Analysis FM - Fire Modeling PRA - Probabilistic Risk Assessment Enclosure 2

ML15022A239 *RAI"mput e-ma1"I OFFICE NRR/DORL/LPL4-2/PM NRR/DORLILPL4-2/LA NRR/DRA/AFPB/BC*

NAME MOrenak PBiechman AKiein DATE 2/5/15 2/5/15 1/16/15 OFFICE NRR/DRA/APLA/BC* NRR/DORL!LPL4-2/BC NRR/DORLILPL4-2/PM NAME HHamzehee DBroaddus (MKhanna for) MOrenak DATE 1/16/15 2/6/15 2/6/15