BSEP 17-0020, Supplement - License Amendment Request Regarding Relocation of Specific Surveillance Frequency Requirements to a Licensee-Controlled Program

Supplement - License Amendment Request Regarding Relocation of Specific Surveillance Frequency Requirements to a Licensee-Controlled Program

ML17059C189
Person / Time
Site:	Brunswick
Issue date:	02/27/2017
From:	William Gideon Duke Energy Progress
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BSEP 17-0020
Download: ML17059C189 (22)

Text

William R. Gideon Vice President Brunswick Nuclear Plant P.O. Box 10429 Southport, NC 28461 o: 910.457.3698 February 27, 2017 Serial: BSEP 17-0020 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Brunswick Steam Electric Plant, Unit Nos. 1 and 2 Renewed Facility Operating License Nos. DPR-71 and DPR-62 Docket Nos. 50-325 and 50-324 Supplement - License Amendment Request Regarding Relocation of Specific Surveillance Frequency Requirements to a Licensee-Controlled Program

References:

1. Letter from William R. Gideon (Duke Energy) to U.S. Nuclear Regulatory Commission, Application For Technical Specification Change Regarding Risk-Informed Justification for the Relocation of Specific Surveillance Frequency Requirements to a Licensee-Controlled Program, dated December 21, 2015, ADAMS Accession Number ML16004A249

2. Letter from William R. Gideon (Duke Energy) to U.S. Nuclear Regulatory Commission, Response to Request for Additional Information, Revision to Requested Implementation Schedule, and Status Update - License Amendment Request Regarding Relocation of Specific Surveillance Frequency Requirements to a Licensee-Controlled Program, dated November 17, 2016, ADAMS Accession Number ML16348A548 Ladies and Gentlemen:

By letter dated December 21, 2015 (i.e., Reference 1), Duke Energy Progress, LLC, submitted a license amendment request (LAR) for the Brunswick Steam Electric Plant (BSEP), Unit Nos. 1 and 2. The proposed amendment would modify the Technical Specifications (TSs) by relocating specific surveillance frequencies to a licensee-controlled program with the implementation of Nuclear Energy Institute (NEI) 04-10, "Risk-Informed Technical Specification Initiative 5b, Risk-Informed Method for Control of Surveillance Frequencies." Additionally, the change would add a new program, the Surveillance Frequency Control Program, to TS Section 5.5, "Programs and Manuals." The changes are consistent with Nuclear Regulatory Commission (NRC) approved Technical Specification Task Force (TSTF) Standard Technical Specifications (STS) Change TSTF-425, "Relocate Surveillance Frequencies to Licensee Control - RITSTF Initiative 5b,"

Revision 3.

U.S. Nuclear Regulatory Commission Page 2 of 3 By letter dated November 17, 2016 (i.e., Reference 2), Duke Energy requested that review of the proposed TSTF-425 LAR be temporarily placed on hold pending completion of the following action.

Duke Energy will conduct a focused-scope peer review in accordance with Regulatory Guide 1.200, Revision 2, for the internal flooding technical elements based on the enhancements made since the 201 O peer review. All finding-level F&Os from the 201 O peer review, as well as any finding-level F&Os from the new focused-scope peer review itself, will be resolved.

This action has been completed. Therefore, Duke Energy requests that the NRC resume review of the proposed TSTF-425 LAR. The results of the review, including discussion of the resolutions of finding-level Findings and Observations (F&Os), are provided in the attached enclosure.

No new regulatory commitments are contained in this letter.

Please refer any questions regarding this submittal to Mr. Lee Grzeck, Manager - Regulatory Affairs, at (910) 457-2487.

I declare, under penalty of perjury, that the foregoing is true and correct. Executed on February 27, 2017.

s~

William R. Gideon MAT/mat

Enclosure:

Focused-Scope Peer Review Results

U.S. Nuclear Regulatory Commission Page 3 of 3 cc (with enclosure):

U. S. Nuclear Regulatory Commission, Region II ATTN: Ms. Catherine Haney, Regional Administrator 245 Peachtree Center Ave, NE, Suite 1200 Atlanta, GA 30303-1257 U.S. Nuclear Regulatory Commission ATTN: Mr. Andrew Hon (Mail Stop OWFN 8G9A) (Electronic Copy Only) 11555 Rockville Pike Rockville, MD 20852-2738 Andrew.Hon@nrc.gov U.S. Nuclear Regulatory Commission ATTN: Ms. Michelle P. Catts, NRC Senior Resident Inspector 8470 River Road Southport, NC 28461-8869 Chair - North Carolina Utilities Commission (Electronic Copy Only) 4325 Mail Service Center Raleigh, NC 27699-4300 swatson@ncuc.net Mr. W. Lee Cox, III, Section Chief (Electronic Copy Only)

Radiation Protection Section North Carolina Department of Health and Human Services 1645 Mail Service Center Raleigh, NC 27699-1645 lee.cox@dhhs.nc.gov

BSEP 17-0020 Enclosure Page 1 of 19 Focused-Scope Peer Review Results

Background

By letter dated December 21, 2015, Duke Energy Progress, LLC, submitted a license amendment request (LAR) for the Brunswick Steam Electric Plant (BSEP), Unit Nos. 1 and 2.

The proposed amendment would modify the Technical Specifications (TSs) by relocating specific surveillance frequencies to a licensee-controlled program with the implementation of Nuclear Energy Institute (NEI) 04-10, "Risk-Informed Technical Specification Initiative 5b, Risk-Informed Method for Control of Surveillance Frequencies." Additionally, the change would add a new program, the Surveillance Frequency Control Program (SFCP), to TS Section 5.5, "Programs and Manuals." The changes are consistent with Nuclear Regulatory Commission (NRC) approved Technical Specification Task Force (TSTF) Standard Technical Specifications (STS) Change TSTF-425, "Relocate Surveillance Frequencies to Licensee Control - RITSTF Initiative 5b," Revision 3.

By letter dated November 17, 2016, Duke Energy requested that review of the proposed TSTF-425 LAR be temporarily placed on hold pending completion of the following action.

Duke Energy will conduct a focused-scope peer review in accordance with Regulatory Guide 1.200, Revision 2, for the internal flooding technical elements based on the enhancements made since the 2010 peer review. All finding-level F&Os from the 2010 peer review, as well as any finding-level F&Os from the new focused-scope peer review itself, will be resolved.

This action has been completed. Therefore, Duke Energy requests that the NRC resume review of the proposed TSTF-425 LAR. The results of the review, including discussion of the resolutions of finding-level Findings and Observations (F&Os), are provided below.

Based on completion of this action, Duke Energy requests that the NRC resume review of the proposed TSTF-425 LAR.

BSEP IFPRA Focused-Scope Peer Review The BSEP internal flooding probabilistic risk assessment (IFPRA) review consisted of a focused peer review of the updated IFPRA sections that pertained to the supporting requirements (SR) addressed in the F&Os generated in the 2010 peer review. These SR requirements were evaluated to determine if they adequately met Capability Category II (CC-II) of the 2009 ASME PRA Standard (i.e., Reference 1). It was noted by the peer review team that, although the previous F&Os were used in part to identify the SRs on which to focus, the review was considered a stand-alone peer review that will become the document of record for the current PRA internal flooding analysis. All F&Os from 2010 peer review are considered closed, with new F&Os having been generated from the 2016 review.

The BSEP IFPRA was assessed against the requirements of the 2009 ASME PRA Standard (i.e., Reference 1) with considerations from any Clarifications and Qualifications provided in Regulatory Guide (RG) 1.200, Revision 2 (i.e., Reference 2). As a result of the review, 10 SRs were assessed to be Met to Capability Category II with no finding; 9 SRs met Capability Category II with a finding; and 1 SR met Capability Category I (CC-1). Nine SRs were

BSEP 17-0020 Enclosure Page 2 of 19 evaluated as Not Met. Table 1 provides a summary of the F&Os generated for each of the high level requirements (HLR) of the Standard.

Table 1. Summary of Results for BSEP IFPRA Focused-Scope Peer Review High Level SR's Met w/o SR's Met SR's Met Cat I SR's Not Met Requirement Finding w/Finding IFPP 1 IFSO 3 2 IFSN 4 5 2 IFEV 1 1 2 IFQU 1 2 5 Total 10 9 1 9 Duke Energy's resolution of the identified F&Os are provided in Tables 2 through 4. Table 2 contains the 9 F&O's that were considered to be Not Met. The resolution of the finding, and the impact on the SFCP are provided. Table 3 provides the resolution of the single F&O met at CC-I, and Table 4 contains the resolution of the Met with Finding F&Os. All findings from the IFPRA focused-scope peer review are considered to be resolved.

References

1. ASME/ANS RA-Sa-2009, Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications, Addendum A to RA-S-2008, ASME, New York, NY, American Nuclear Society, La Grange Park, Illinois, February 2009.

2. Regulatory Guide 1.200, An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk- Informed Activities, Revision 2, U.S.

Nuclear Regulatory Commission, March 2009.

BSEP 17-0020 Enclosure Page 3 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact IFSN-A3 Automatic or operator response to The original analysis included two bounding, generic An additional, terminate or contain floods was not operator actions that were applied to all appropriate scenario-specific Not Met identified for the significant sequences. sequences based on similar timing and operator action to Only two operator actions were characteristics of the flood sequences. The terminate or developed, based on timing, and significant flooding scenarios have been re-analyzed, contain floods generally applied to flooding scenarios. and an additional, scenario-specific operator action was added to the that would terminate or contain the flood has been model, and the developed in accordance with SR HR-F1 from risk was section 2-2.5 of the Standard. reassessed and documented.

Specifically, the flooding model was run with no credit There is no risk-for operator action to determine the risk significant significant impact scenarios. "Risk significant" was taken to mean, on PRA results in "contributing more than 1% to Internal Flooding Core the SFCP.

Damage Frequency (CDF)." This returned three flood scenarios that initially contributed 97% to flooding CDF; all other scenarios contributed approximately 0.5% or less to CDF.

The three top scenarios are all similar - large diameter service water breaks in the lower elevations of the Reactor Building which cause submergence failure of Core Spray, Residual Heat Removal (RHR) and High Pressure Coolant Injection (HPCI). Timing of the three scenarios was compared, and the more limiting timing was chosen as a system window for a new operator action. The model was re-quantified with the scenario-specific operator action, and additional, similar scenarios (i.e., for both CDF and Large Early Release Frequency (LERF)) were identified and included. The generic operator actions

BSEP 17-0020 Enclosure Page 4 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact were retained for other appropriate scenarios. The accident sequences were assessed in the cutset review and determined to be appropriate. Updated documentation was developed in the human reliability analysis (HRA) Calculator.

IFSN-A11 Multi-Unit Scenarios are discussed in Multi-unit flood propagation is modeled and Multi-unit floods in section F.2.1 and F.4.8.5 with discussed for the cable spreading rooms. the battery rooms Not Met assumptions in F.1.3. There are no Specifically, Section 4.8.6 of BSEP's internal flooding have been validated modeled multi-unit Floods. However, analysis discusses floods originating in one cable to be modeled cable spreading room MCC's fail at 3 ft., spreading room which propagate to the opposite correctly. A bounding but the doors adjacent to the MCC's and unit's cable spreading room, as well as to the battery analysis for a 3 foot curb fail at 2.3 to 2.5 ft., rooms. Table F.B.1 of the calculation identifies 68 potential multi-unit depending on direction of propagation; retained flood initiating events with propagation propagation pathway therefore, this would seem to be a multi- pathways involving the two cable spreading rooms in the turbine building unit flood that was not accounted for or and four battery rooms. A sampling of the scenarios has been assessed discussed. documented as propagating to the opposite unit was and incorporated in performed to verify that they are included in the flood the model. There is Metal doors between U1 & U2 turbine PRA. No discrepancies were identified. Note that the no risk-significant buildings are not credited to fail creating doors adjacent to the motor control centers (MCCs) impact on PRA a multi-unit turbine building flood; and the 3-foot curb referenced in the F&O are results in the SFCP.

however, other doors in the U1 and U2 actually located in the 20 foot elevation of the turbine turbine buildings fail at 4 inches, and buildings, not in the cable spreading room.

there is no justification for not evaluating turbine building multi-unit flood This F&O also addresses propagation pathways for propagation through these doors. internal floods originating in the turbine buildings.

Drawings do not match the doors in the Specifically, the F&O questions why the exterior roll-space (roll up vs opposing swing doors). up doors are assumed to fail at 4 inches water level while the roll-up door between units is not.

Investigation of this issue determined that a propagation pathway between the Unit 1 and Unit 2

BSEP 17-0020 Enclosure Page 5 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact turbine buildings cannot be excluded.

In order to account for this potential propagation pathway, a conservative bounding analysis was developed and included in the flood PRA. This bounding analysis takes no credit for the roll-up door between the two turbine buildings for preventing flood propagation above 4 inches of water accumulation.

Therefore, it effectively assumes that any flood in either turbine building that can accumulate 4 inches of water on the floor of that turbine building within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> becomes a 3 foot flood in both units.

IFEV-A4 See IFSN-A11 Same Finding This SR requires that, for multi-unit sites with shared The multi-unit systems or structures, multi-unit impacts on impacts on SSCs Not Met structures, systems and components (SSCs) and and initiating events plant initiating events caused by internal flood from flooding scenario groups be included. This is essentially the scenarios are same as SR IFSN-A11 which requires that multi-unit included in the scenarios be included. model, and documentation has SSCs impacted by multi-unit spray initiating events been updated. There are modeled, as documented in Tables F.C.1 and is no risk-significant F.C.2 of BSEP's internal flooding analysis. Table impact on PRA F.C.1 contains service water pipe spray initiating results in the SFCP.

events that fail both the Unit 1 and Unit 2 service water pumps.

Multi-unit flood propagation is modeled and discussed for the cable spreading rooms in section 4.8.6 and Table F.B.1. These sections address SSCs impacted by floods originating in one cable spreading

BSEP 17-0020 Enclosure Page 6 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact room which propagate to the opposite unit's cable spreading room, as well as to the battery rooms. This is discussed in more detail in the response to F&O IFSN-A11.

Multi-unit turbine building scenarios and their impact on SSCs/initiating events have been incorporated into the PRA via the bounding analysis discussed in the response to F&O IFSN-A11.

IFEV-A5 New Methodology was applied to use The existing flood scenario frequencies have been The flood scenario pipe length and flood and major flood adjusted to include both the Electric Power Research frequencies have Not Met frequency based on diameter and flow Institute (EPRI) Flood and Major Flood initiating been adjusted to rate. The analysis should have event frequencies. include the Flood evaluated flood frequency for small pipe frequency for large and flows, and Flood frequency AND Table F.15 of the internal flooding calculation pipes and flows.

Major Flood frequency for large pipe and provides a mapping of piping frequencies and their There is no risk-flows. However, the analysis only associated system designation. The updated EPRI significant impact on applied major flood frequencies to large values are from TR 3002000079. Since the flooding PRA results in the pipe, omitting flood frequency from large frequency data in the calculation and the EPRI data SFCP.

pipe which is the dominant frequency. have different pipe size breakpoints, the pipe size intervals were adjusted to match. The corresponding Table F.15 provides the different frequencies were then adjusted by the ratio of new frequencies from the EPRI Tech Report, EPRI flood and major flood frequency to existing but they are applied incorrectly in the major flood frequency. The appropriate multiplier was analysis as shown in Table F.16. then applied to each scenario based on pipe size and fluid system type. This assumes all floods are Major Floods that bound both Flood and Major Flood frequency contributions.

BSEP 17-0020 Enclosure Page 7 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact IFQU-A5 The HRA Analysis provided does not A scenario-specific human error probability (HEP) A new, scenario-meet the applicable requirements for that meets the requirements of the Standard was specific HEP to Not Met HRA Analysis. developed (i.e., see response to F&O IFSN-A3) and mitigate the top included in the updated model and quantification. flooding scenarios The BSEP internal flooding model uses The guidance in SR HR-F1 of Section 2-2.5 of the has been developed only two flood isolation HEPs, Standard for developing human failure events (HFEs) and included in the XOPER_F25 and XOPER_F60. The first was followed, and the HRA Calculator, v5.1, which quantification of the is based on minimum time of 25 min meets the requirements of the Standard, was used. model. The HEP needed to respond to a flooding event. It An operator interview was conducted on February 6, meets the is not clear what the basis is for 60 min 2017, to validate the procedures and assumptions requirements of the time used for the second HEP or its used as the basis for the modeling. All assumptions Standard, so there is assumed value of 1E-3. These two and bases for the performance shaping factors no risk-significant HEPs are applied to model isolation of (PSFs) were documented in the HRA Calculator. impact on PRA all initiators with greater than 25 minutes results in the SFCP.

critical damage time, therefore the model Dependency analysis was considered for both CDF is overly simplified with the potential of and LERF in regards to the new flooding operator producing both overly conservative and action, and documentation of dependency levels has non-conservative results. In the HRA been included in the assessment. The accident Calculator, the alarm time used is 1 min, sequences were assessed in the cutset review, and and cognition time is 5 min, which may descriptions of the top cutsets were included in the not be bounding since this HEP is documentation.

applied to numerous flood scenarios of differing delay times which is not considered.

BSEP 17-0020 Enclosure Page 8 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact IFQU-A6 See IFQU-A5 Finding A new, scenario-specific Internal Flooding operator Scenario-specific action was developed (i.e., see response to F&O impacts on PSF's Not Met IFSN-A3) and included in the quantification of the have been assessed model (i.e., see response to SR IFQU-A5). The HRA in the scenario-Calculator, v5.1, was used to develop the HEP, and it specific HEP. There included assessment of scenario-specific PSFs. is no risk-significant Documentation of the PSFs is included in the HRA impact on PRA Calculator documentation: results in the SFCP.

Workload and stress during a large service water break are assessed and validated in an operator interview.

Cue availability has been verified for the sump alarms, which are the cue for this action.

Accessibility restrictions have been taken into account, given the sump alarms, even if accessibility is restricted due to flood level in the core spray room, a header low-pressure alarm should cue operators to the flood source.

The procedures used for this action are flood-specific. That is, they deal directly with pipe leakage/rupture.

IFQU-A9 Though Direct Effects and Submergence The BSEP PRA screens pipe whip and jet Pipe whip and jet were evaluated, indirect effects of Pipe impingement failures for HELB events in the reactor impingement will Not Met Whip and Jet Impingement have not building based on the plant design considerations, as have minimal impact been fully identified; therefore, no documented in BSEP's Updated Final Safety on the PRA results quantified effects were evaluated. Analysis Report (UFSAR). The UFSAR describes based on design design elements for pipe restraints to prevent pipe requirements in the In order to quantify the effects of pipe whip and jet impingement impact on SSCs in the reactor and whip and jet impingement, first one reactor building and primary containment. High containment

BSEP 17-0020 Enclosure Page 9 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact needs to identify the potential of such energy lines in the turbine building, however, are not buildings, and a events. For flood scenarios involving a explicitly discussed in the UFSAR. screening high energy line break (HELB), the assessment for the evaluation did not IDENTIFY the A review of PRA equipment in the turbine building turbine buildings.

susceptibility of each SSC identified in was performed using information from the fire PRA to There is no risk-IFSN-A5 to jet impingement, pipe whip, assist in identifying potential damage scenarios. The significant impact on temperature, and pressure failure fire PRA provides spatial damage sets throughout the PRA results in the mechanisms. Therefore, no turbine building that can provide insight into potential SFCP.

quantification of these effects was pipe whip scenarios. The fire scenario conditional performed. core damage probabilities (CCDPs) can be used as pipe whip and jet impingement surrogate CCDPs to provide an estimate of the impacts on core damage.

The total contributions to CDF for jet impingement and pipe whip is approximately 1E-07 per year and therefore would not impact PRA conclusions under the SFCP.

Using the fire CCDPs is conservative because the fire PRA includes failure modes such as spurious failures that are not included in HELB mechanical damage. The pipe whip and jet impingement zones of influence are also limited due to the concrete biological shielding in the turbine building that would limit exposed equipment.

IFQU-B1 Information provided for model All of the F&O responses have been incorporated This is a quantification and sequence into the model, and the model has been re-quantified. documentation issue Not Met identification did not facilitate peer A cutset review was completed in accordance with only. Documentation review. the Standard, the accident sequences have been of the cutset set reviewed and documented, and descriptions of the review and Cutsets typically consisted of the top cutsets for CDF and LERF have been included in descriptions of the initiating event identifier and applied the calculation. Significant contributors to CDF and top sequences for

BSEP 17-0020 Enclosure Page 10 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact flags. The descriptions of these cutsets LERF have been identified, and a sampling of non- CDF and LERF have were lacking in sufficient detail regarding significant accident sequences were reviewed for been added to the flooding induced equipment failures and reasonableness. calculation. There is mitigating action failures. no risk-significant impact on PRA results in the SFCP.

IFQU-B2 The documentation did not justify Documentation of the processes used to determine This is a screening of the flood sources, and did the applicable flooding sequences and the documentation issue Not Met not explain sufficiently the description of quantification of the model has been added in only. Documentation cutsets and sequences for dominant accordance with the requirements of the Standard. of the updated floods. There is an inconsistency in The accident sequences/cutsets were reviewed of quantification and documentation between how consistency and correctness, and the sequence- results of the conventional service water and nuclear specific HEP that was added was validated. The analysis have been service water are identified in the flood basis for this documentation F&O included several included for CDF and analysis, flood database, and PRA specific items that have also been addressed LERF. Descriptions model sequences. individually. of the top cutsets have also been The process that describes how flood sources were added to the screened was documented, and the list of potential calculation. There is flood sources retained for further analysis has been no risk-significant updated (i.e., see F&O responses IFSN-A15 and impact on PRA IFSN-A16). results in the SFCP.

The fault trees and initiating event frequencies have been updated based on changes documented in the other F&O responses, and the model has been re-quantified. The detailed descriptions of the cutsets and accident sequences have been added (i.e., see F&O responses IFQU-B1).

BSEP 17-0020 Enclosure Page 11 of 19 Table 2. Resolution of "Not Met" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact The Conventional Service Water and Nuclear Service Water modeling has been validated and clarified.

BSEP 17-0020 Enclosure Page 12 of 19 Table 3. Resolution of "Met CC1" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact IFEV-A6 The BSEP historical plant-specific flood The Duke Energy Consolidated Asset Suite (CAS) The BSEP operating data is included in section F.1.1 of RSC- was queried to identify Nuclear Condition Reports experience has been Met CC1 10-05, noting it appears to be limited to (NCRs) associated with flood events induced by compiled and major events. The impact from this plant- maintenance activities as well as piping and reviewed, and the specific information on calculation of component failures. A detailed review of 887 BSEP analysis pipe rupture frequencies is not NCRs reveals that the majority of the cases were demonstrates that discussed. It should be demonstrated either a pipe leak or spray whose discharged water there are no events through analysis of plant-specific was insignificant and had no impact on PRA-related that impact the flooding information that it has no impact equipment. There were no direct plant transients as a generic failure rates on generic failure rates. In other words, if result of any events. No maintenance-induced used in the analysis.

Bayesian update of generic data is flooding events were retained due to either not This SR is performed with plant-specific meeting the screening criteria or being a considered to be met information, the generic failure rates will maintenance activity not characteristic of at-power at CC II. There is no not be significantly affected (prior and operation performed during an outage. risk-significant posterior distributions are similar). impact on PRA All of the events were either detected immediately results in the SFCP.

It does not appear that all flooding and the faulted component/piping segment put under events were collected, only major events clearance, or found as a part of routine inspection or were documented. The analysis simply test and appropriate corrective action was taken applies generic information, with no before the leak/sprays escalated to an unacceptable documentation or justification for not level leading to a flooding scenario.

integrating plant specific information.

As a result of this review, it is demonstrated that the BSEP plant-specific experience does not contain significant flooding events that represent an outlier to the generic industry data used in the internal flooding analysis. It is concluded, therefore, that the NCRs reviewed do not impact the plant level and flood compartment level frequencies for the BSEP internal flooding PRA, and that the internal flooding PRA meets the requirements of SR IFEV-A6 at CCII.

BSEP 17-0020 Enclosure Page 13 of 19 Table 4. Resolution of "Met with Finding" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact IFSO-A4 No discussion of fire suppression Inadvertent actuation of fire suppression Inadvertent actuation inadvertent actuation as a source or effects systems has been added to the model, and the of fire suppression were provided in the analysis. In sections model has been re-quantified. has been added to MET with F.5, F.12, and F8.3 they discuss failures of the model. There is pipes and tanks, flexible connections and EPRI Report 3002000079 includes plant level no risk-significant Finding frequencies for inadvertent actuation of fire gaskets, and maintenance induced floods. impact on PRA No discussion of inadvertent actuation of fire suppression systems. The plant level spurious results in the SFCP.

suppression as a source was included. fire protection system actuation mean frequency from Table 7-3 of the EPRI Report is 8.44E-04.

This frequency is partitioned over the entire plant to each of the wet pipe fire protection systems based on the quantity of small bore (i.e., less than 2 inch diameter) fire protection piping. The spray scenarios frequency due to inadvertent actuation was added to the pipe spray scenario frequencies where applicable.

IFSO-B2 The IFSO-A section lacks documentation on Documentation has been developed for and This is a several modeling requirements that are added to the Internal Flood calculation for each documentation issue shown to be correct through investigation. of these modeling requirements. only, and the MET with documentation has In IFSO-A1, no drain backflow The system diagrams and system been developed and Finding propagation identification provided in description for the Liquid Radwaste System included in the the documentation. Investigation shows were collected, reviewed, and documented calculation. There is that drains flow to an exterior rad waste in the IFPRA calculation as described in the no risk-significant building floor drain collection tank from response to IFSN-B2. The floor drain flow impact on PRA all locations which would justify the to the Radwaste Building and the results in the SFCP.

assumption in F.1.3; however, there is conclusion that drain backflow is not a no discussion, drawings, or justification flooding concern in the other buildings was provided in the analysis for screening. verified.

BSEP 17-0020 Enclosure Page 14 of 19 Table 4. Resolution of "Met with Finding" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact In IFSO-A1 there is little to no The documentation of door failure critical documentation of doors and door height determination has been included per failures contributing to propagation and the response to IFSN-A2.

critical height determination. A list of all potential flood sources was Capacity of the sources per IFSO-A5 is updated and documented as described in not documented, it was identified this the response to IFSN-A15. The capacities information is in the flooding database of those systems retained for further but it is not discussed in the flooding assessment are included in the updated calculation. documentation and were compared to the capacities from the database table used in the flooding propagation analysis.

Capacities used for all sources in the original propagation analysis bounded the capacities for all systems described in the response to IFSN-A15.

IFSN-A2 There are multiple issues regarding door The basis for this F&O was the lack of detailed This is a failure. These issues directly impact flood discussion in the documentation for three documentation issue propagation both within a unit and multi-unit specific scenarios/assumptions in the model: only, and additional MET with floods. documentation has treatment of propagation through doors on been developed and Finding Though the flood database appears to the 20 foot elevation of the reactor building included. There is no address door failure via critical height, there down stairs to the RHR and core spray risk-significant is very limited documentation and no clear rooms; impact on PRA flood propagation analysis provided to justify propagation through doors in the turbine results in the SFCP.

propagation paths and timing. There is no building that could lead to multi-unit floods, supporting analysis for when different door and types fail depending on the flood door failure as a function of propagation propagation direction. direction.

Each of these was reassessed in the model,

BSEP 17-0020 Enclosure Page 15 of 19 Table 4. Resolution of "Met with Finding" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact and detailed discussions have been included.

Treatment of propagation from the 20 foot elevation to the RHR/core spray rooms was determined to be adequate and conservative. The doors to the RHR rooms are not required to be closed (and in fact, were open during the PRA walkdowns), and they have a large gap (i.e., approximately 1/2 inch) between the bottom of the door and the floor. The doors to the RHR room were conservatively assumed to pass roughly the same amount of water as the openings to the core spray rooms, and no modification is necessary.

Propagation in the turbine building is a multi-unit flood consideration that has been addressed in the response to F&O IFSN-A11. The door failure assumptions for this multi-unit scenario are consistent with other door failures in the model and are conservative with respect to the direction they fail in multi-unit flood scenarios.

Discussion of the basis for door failure as a function flood propagation direction has been added to the documentation. For example, a door failure height of 2.3 feet (approximately 1/3 of door height) was used for hollow metal doors that open outward, while a failure height of 4.6 feet (approximately 2/3 of door height) was

BSEP 17-0020 Enclosure Page 16 of 19 Table 4. Resolution of "Met with Finding" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact assumed for hollow metal doors that open inward. A simplistic finite element model, using a "typical" set of dimensions and materials, was performed to obtain an estimate for door failure, whether against the latch or door jamb. The results show that the door failure heights used in the analysis are reasonable. Other door types are included in the calculation.

Each of the elements in the basis for this finding has been addressed, and the documentation has been added.

IFSN-A8 From IFSO-A4, the effects of gaskets and The CDF and LERF contributions from gasket Effects of gasket and expansion joint failures were not propagated and expansion joint failures, including effects expansion joint beyond failing the attached equipment. from propagation, have been included in the failures on MET with internal flooding models. Table F.25 of IFPRA propagation have Section F.4.8 discusses the propagation calculation contains the listing of expansion been added to the Finding between rooms, and basis for drain paths. joints and gaskets along with their failure rates. model. There is no No propagation from gaskets or expansion The component failures have been mapped to risk-significant joints was modeled. the associated initiating events in the model. impact on PRA New scenarios and their propagation impacts results in the SFCP.

based on similar pipes in the flood zone have been developed and assessed for the expansion joint and gasket flooding scenarios.

This is a IFSN-A15 Did not provide a comprehensive list of flood The BSEP Internal Flooding analysis identified documentation sources that were screened out with all potential flooding sources and screened issue only, and justification. those sources as required by the Standard. The detailed final listing of the internal flood sources were

BSEP 17-0020 Enclosure Page 17 of 19 Table 4. Resolution of "Met with Finding" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact MET with It does not appear in documentation that captured in the flooding analysis, but the documentation Finding they screen flood sources directly; however, screening process was not clearly documented. has been added it appears they have screened out systems to the calculation.

like potable water and other small water The screening was re-performed, and the There is no risk-systems. For large water systems that they screening process has been provided. All significant impact model they appropriately model down to potential flood sources that were screened have on PRA results in very small pipe and did not screen. been listed. The detailed documentation of the the SFCP.

screening process meets the requirements of IFSN-A15.

IFSN-A16 Insufficient justification is given for screening The analysis met the requirement of the This is only a maintenance induced floods due to operator Standard; however, the documentation was documentation issue, action in section F.8.3. lacking. The documentation has been updated and documentation MET with to describe the approach taken to satisfy the has been added to Analysis screens out flood areas using supporting requirements of the Standard. describe the process Finding human mitigating actions, however sufficient for screening justification is not provided, such as Potential flood sources were not screened potential flood maintenance induced flood mitigation. based on operator actions. Sources/systems sources. There is no were screened if they contained no on-line risk-significant preventive maintenance. This was determined impact on PRA by two methods: by reviewing the on-line results in the SFCP.

Preventive Maintenance schedule, and by eliminating those systems not scheduled to be breached at power. The screened list was verified by interviews with the BSEP on-line work control manager, former BSEP Senior Reactor Operators (SROs), and Subject Matter Experts (SMEs).

Detailed documentation of the screening process has been added. A discussion has also

BSEP 17-0020 Enclosure Page 18 of 19 Table 4. Resolution of "Met with Finding" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact been included that describes the analysis performed for multi-unit flood scenarios from maintenance on a shutdown unit.

IFSN-B2 No documentation of a Drain Backflow System Floor and Equipment drains and Liquid This is a propagation evaluation provided. Radwaste System description and diagrams documentation issue were reviewed and included in the only, and the system Documentation was not provided for drain documentation. The system documentation descriptions and MET with backflow analysis assumption. Investigation Finding validates that the floor drains flow to an exterior drawings have been shows that drains flow to an exterior rad building and that there is no flooding concern added. There is no waste building floor drain collection tank due to backflow through the drains. risk-significant from all locations; however, there is no impact on PRA discussion, drawings, or justification results in the SFCP.

provided in the analysis for screening. This does not affect results of the analysis it is simply lack of sufficient documentation and is assessed in IFSN-B2.

IFQU-A1 See Documentation Finding IFQU-B2 Accident sequences were reviewed as part of This is a the cutset review for the updated CDF results. documentation issue Descriptions of the top flooding sequences have only, and the MET with been added to the documentation of the results accident sequences Finding (i.e., per response to IFQU-B2). have been reviewed and documented.

There is no risk-significant impact on PRA results in the SFCP.

BSEP 17-0020 Enclosure Page 19 of 19 Table 4. Resolution of "Met with Finding" F&Os from BSEP Internal Flooding PRA Focused Peer Review SR Finding Resolution TSTF-425 Impact IFQU-A10 See Documentation Finding IFQU-B2 LERF sequences were reviewed as part of the This is a cutset review for the updated results. documentation issue Descriptions of the top flooding sequences have only, and the MET with been added to the documentation of the LERF accident sequences Finding results (i.e., per response to IFQU-B2). have been reviewed and documented.

There is no risk-significant impact on PRA results in the SFCP.