NOC-AE-15003257, Notification of Compliance with Orders EA-12-049 for Mitigation Strategies for Beyond-Design-Basis External Events and EA-12-051 for Reliable Spent Fuel Pool Instrumentation

Notification of Compliance with Orders EA-12-049 for Mitigation Strategies for Beyond-Design-Basis External Events and EA-12-051 for Reliable Spent Fuel Pool Instrumentation

ML15196A031
Person / Time
Site:	South Texas
Issue date:	07/02/2015
From:	Gerry Powell South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-12-049, EA-12-051, NOC-AE-15003257, TAC MF0826, TAC MF0828
Download: ML15196A031 (21)

Text

Nuclear Operating Company South Texas project Electric Gencating,Station P.O. Box 289 Wadsworth, Texas 77483 *¢V -

July 2, 2015 NOC-AE-1 5003257 10 CFR 2.202 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Unit 2 Docket No. STN 50-499 Notification of Compliance with Orders EA-12-049 for Mitigation Strategies for Beyond-Design-Basis External Events and EA-12-051 for Reliable Spent Fuel Pool Instrumentation (TAC Nos. MF0826 and MF0828)

References:

1. NRC Order Number EA-12-049, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events",

March 12, 2012 (AE-NOC-1 2002268)(ML12073A195)

2. NRC Order Number EA-12-051, "Issuance of Order to Modify Licenses with Regard to Requirements for Reliable Spent Fuel Pool Instrumentation," March 12, 2012 (AE-NOC-1 2002271) (MLI12054A679)

3. Letter from D.L. Koehl, STPNOC, to NRC Document Control Desk, "STPNOC Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)", February 28, 2013 (NOC-AE- 13002963) (ML13070A011)

4. Letter from D. L. Koehl, STPNOC, to NRC Document Control Desk, "Overall Integrated Plan Regarding Commission Order Modifying Licenses with Regard to Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051)," February 28, 2013 (NOC-AE-1 3002959) (ML13070A006)

5. Letter from T. Brown, NRC, to D.L. Koehl, STPNOC, "South Texas Project, Units 1 and 2 - Report for the Onsite Audit Regarding Implementation of Mitigating Strategies and Reliable Spent Fuel Instrumentation Related to Orders EA-12-049 and EA-12-051 (TAC Nos. MF0825, MF0826, MF0827, and MF0828)", May 6, 2015 (AE-NOC- 15002661 ) (ML1511I1A465)

MPq4 STI 34120923

NOC-AE-1 5003257 Page 2 of 3 The purpose of this letter is to fulfil the requirement to report to the NRC that STP Unit 2 is in full compliance with Order EA-12-049 (Reference 1) regarding mitigation strategies for beyond-design-basis external events and Order EA-12-051 (Reference 2) regarding reliable spent fuel pool instrumentation.

Orders EA-12-049 and EA-12-051 require full implementation no later than two refueling cycles after submittal of the Overall Integrated Plans (References 3 and 4) or December 31, 2016, whichever comes first.

The enclosure provides a brief summary of the key elements associated with compliance with the Orders including a completed milestone accomplishment schedule. The attachment to the enclosure provides a summary response for each of the open and pending items being tracked by the NRC staff in the Safety Evaluation (SE) Tracker as documented in the Onsite Audit Report (Reference 5).

There are no regulatory commitments in this letter.

If there are any questions, please contact Wendy Brost at (361) 972-8516 or me at (361) 972-7566.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on: 2. OI G. T. Powell Site Vice President web

Enclosure:

Summary of Compliance with NRC Orders Regarding Mitigation Strategies for Beyond-Design-Basis External Events (EA-12-049) and Reliable Spent Fuel Pool Instrumentation (EA-12-051) for STP Unit 2

Attachment:

Summary of Responses for Open and Pending Items on the Safety Evaluation Tracker

NOC-AE-1 5003257 Page 3 of 3 Cc:

(paper copy) (electronic copy)

Regional Administrator, Region IV Morgqan, Lewis & Bockius LLP U.S. Nuclear Regulatory Commission Steve Frantz, Esquire 1600 East Lamar Boulevard Arlington, TX 76011-4511 U.S. Nuclear Regqulatory Commission Lisa M. Regner Lisa M. Regner Tony Brown Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (08 H04) NRG South Texas LP 11555 Rockville Pike John Ragan Rockville, MD 20852 Chris O'Hara Jim von Suskil NRC Resident Inspector U. S. Nuclear Regulatory Commission CPS Enerqy P. O. Box 289, Mail Code: MN116 Kevin Polio Wadsworth, TX 77483 Cris Eugster L. D. Blaylock Eric Leeds Director, Office of Nuclear Reactor Regulation Cramn Caton & James, P.C.

U.S. Nuclear Regulatory Commission Peter Nemeth One White Flint North (MS 13 H 16M) 11555 Rockville Pike Rockville, MD 20852 City of Austin Cheryl Mele John Wester Texas Dept. of State Health Services Richard A. Ratliff Robert Free

Enclosure NOC-AE-1 5003257 ENCLOSURE Summary of Compliance with NRC Orders Regarding Mitigation Strategies for Beyond-Design-Basis External Events (EA-12-049) and Reliable Spent Fuel Pool Instrumentation (EA-12-051) for STP Unit 2

Enclosure NOC-AE-1 5003257 Page 1 of 8

1. Introduction STP Nuclear Operating Company (STPNOC) developed an Overall Integrated Plan (OIP)

(Reference 3) to provide diverse and flexible coping (FLEX) strategies in response to Order EA-12-049 (Reference 1). The final FLEX strategies differ substantially from the strategies described in the OIP - strategy updates have been submitted through periodic six-month update letters (References 6 - 9). STP also developed an OIP (Reference 4) to address reliable spent fuel pool level instrumentation (SFPLI) in response to Order EA-12-051 (Reference 2), also supplemented by periodic six-month updates (References 10 - 13).

The information provided in this submittal documents compliance with Orders EA-12-049 and EA-12-051 for STP Unit 2.

2. Milestone Accomplishments Issues from the NRC Interim Staff Evaluation (ISE) for FLEX and SEPLI Order compliance (References 10 and 11) and Audit Report (Reference 5) have been addressed by STPNOC.

The issues that were identified as open and pending in the NRC tracking system are listed below:

ISE Open Item (ISE 01)- ISE 01 3.2.1.1.B ISE Confirmatory Items (ISE Cl) - ISE Cl 3.2.1.2.C, ISE Cl 3.2.1.3.A, ISE Cl 3.2.1.4.A Audit Questions (AQ) - AQ #25 Additional Safety Evaluation (SE) needed information - SE #9, SE #10, SE #11, SE #17 STPNOC has no remaining open or pending Licensee Identified Open Items or SFPLI Requests for Additional Information (RAIs).

A summary of the response to each of the open and pending issues is provided in the attachment to this enclosure. The open and pending items do not affect the STPNOC compliance with Order EA-12-049 nor Order EA-12-051 for STP Unit 2.

Enclosure NOC-AE-1 5003257 Page 2 of 8

3. Milestone Schedule - Items Complete Unit 2 FLEX Unit 2 SFPLI Unit 2 FLEX and SFPLI MilestoneCopeinDt Cmltonae Submit Overall Integrated Plan February 28, 2013 February 28, 2013 Submit 6 Month Updates_________

1 st Update August 26, 2013 August 27, 2013 2 nd Update February 27, 2014 February 27, 2014 3 rd Update August 27, 2014 August 27, 2014 4 th Update February 26, 2015 February 26, 2015 Walk-throughs or Demonstrations April 30, 2015 N/A Perform Staffing Analysis Phase 1 Staffing Assessment June 3, 2013 N/A Phase 2 Staffing Assessment November 25, 2014 N/A Revised Phase 2 Staffing Assessment July 2, 2015 N/A Modifications Unit 2 Modifications Design Completion April 30, 2015 April 18, 2015 Unit 2 Final Modification Implementation May 1, 2015 May 1, 2015 Storage Equipment Storage Complete April 30, 2015 N/A National SAFER Response Center (NSRC) ________

NSRC Plan Requirements Complete April 18, 2015 N/A Procedures Issue Site-Specific FSGs April 30, 2015 N/A Issue Operations/Maintenance Procedures April 30, 2015 April 30, 2015 Training_______ ___

Training Complete March 2015 January 2015 Unit 2 FLEX & SFPLI Compliance Date May 7, 2015 May 7, 2015 Submit Compliance Letter 1 July 2, 2015 July 2, 2015

'Action completed with this submittal

Enclosure NOC-AE-1 5003257 Page 3 of 8

4. Order EA-1 2-049 Compliance Elements - Summary STPNOC has completed implementation of Order EA-12-049 for Unit 2 including the following elements:

Strategies - Complete STP Unit 2 FLEX strategies are in compliance with Order EA-12-049. To meet the intent of the Order, STPNOC followed the guidance provided in NEI 12-06 (Reference 12) with the exception of the Alternate Approaches listed below. These Alternate Approaches have been presented to and discussed with the NRC review staff and are noted in the Onsite Audit Report (Reference 5):

-STP pre-staged some of the FLEX response equipment including two diesel generators in protected structures on top of the Mechanical Auxiliary Building (MAB) roof, and pumps, hoses, associated equipment inside existing Class 1 plant structures protected against design-basis external events. The primary reason for pre-staging this equipment is due to difficulties in retrieving and deploying equipment following a design-basis flooding event.

-STP utilizes two pre-staged pumps with separate injection pathways for Reactor Coolant System (RCS) fill instead of a single pump with primary and alternate connection points and injection pathways supplemented by a portable pump. In the STP strategy, the failure of a pre-staged pump would render one of the two injection pathways unavailable as opposed to the two pathways that would be available using the portable pump strategy. As a compensatory measure, STP reduced the allowed out of service time for both the positive displacement pump (PDP) and FLEX RCS makeup pump and their associated connections and flowpaths. STP FLEX strategies also rely on pre-staged pumps for Steam Generator (SG) makeup and SFP makeup, however, STP has the ability to makeup to these systems using a portable pump.

Further details and justifications for these alternate approaches to the approved NEI 12-06 guidance will be included in the Final Integrated Plan (FIP) to be submitted following the compliance outage for STP Unit 1 in the Fall of 2015.

Modifications - Complete All modifications required to support the FLEX strategies for STP Unit 2 have been fully implemented in accordance with station processes.

Enclosure NOC-AE-1 5003257 Page 4 of 8 Equipment - Procuredand Maintenance and Testing Performed - Complete The equipment required to implement the FLEX strategies for STP Unit 2 has been procured, received, initially tested and performance verified as recommended in accordance with NEI 12-06 (Reference 12) and is available for use.

Maintenance and testing requirements for FLEX equipment are included in the STP Preventative Maintenance Program such that equipment reliability is monitored and maintained.

Procedures- Complete STPNOC has developed FLEX Support Guidelines (FSGs) for Unit 2 and the FSGs have been integrated into existing procedures. Other affected procedures required for FLEX implementation have also been revised. The FSGs and applicable procedures have been verified and are available for use and are being controlled in accordance with station processes.

Training - Complete All necessary training has been completed in accordance with the Systematic Approach to Training (SAT) as recommended in NEI 12-06.

Staffing - Complete The STPNOC Phase 1 Staffing Assessment (Reference 17) was completed in accordance with the 10 CFR 50.54(f) request for information with respect to Near-Term Task Force (NTTF) Recommendation 9.3 for Emergency Preparedness (Reference 18).

The STPNOC Phase 2 Staffing Assessment (Reference 19) was also completed in accordance with the 10 CFR 50.54(f) letter.

Following the development of the FSGs, STP performed a revalidation of the Phase 2 assessment to ensure the FLEX strategies could be implemented as written. STP determined that two additional maintenance personnel are required to implement the FLEX strategies for a two unit event in addition to the minimum on-shift staff required by the Emergency Plan for a single unit event. The needed personnel are currently procedurally obligated to be onsite at all times and STP has implemented administrative controls to ensure these staffing levels are maintained.

The results of the revalidation were communicated to the NRC and the Revised Phase 2 Staffing Assessment that resulted from the revalidation efforts was submitted to the NRC on July 2, 2015 (Reference 20).

Enclosure NOC-AE-1 5003257 Page 5 of 8 National SAFER Response Center (NSRC) - Complete STPNOC has joined the Strategic Alliance for FLEX Emergency Response (SAFER)

Team Equipment Committee for off-site facility coordination. A site-specific SAFER Response Plan has been developed (Reference 21) and the requisite equipment is available at the NSRCs to support Phase 3 FLEX implementation in the event that it is needed.

Validation - Complete STPNOC has completed validation of the FLEX strategies using station processes and in accordance with industry developed guidance to assure required tasks, manual actions and decisions for FLEX strategies are feasible and may be executed within the constraints identified in the FLEX strategy timeline.

FLEX Program Document - Established The STPNOC FLEX Program Document (Reference 22) has been developed in accordance with the requirements of NEI 12-06 and will be controlled in accordance with station processes.

5. Order EA-12-051 Compliance Elements - Summary STPNOC has completed implementation of the SFP level monitoring system in Unit 2 which includes: independent level sensors in the SFP area, battery backup and level indicators in the radwaste control room area. Modifications and training are complete and applicable procedures have been verified and are available for use in accordance with the site procedure control program.

Enclosure NOC-AE-1 5003257 Page 6 of 8 References

1. NRC Order Number EA-12-049, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events',

March 12, 2012 (AE-NOC-1 2002268) (ML12073A195)

2. NRC Order Number EA-12-051, "Issuance of Order to Modify Licenses with Regard to Requirements for Reliable Spent Fuel Pool Instrumentation," March 12, 2012 (AE-NOC-12002271 ) (ML12054A679)

3. Letter from D.L. Koehi, STPNOC, to NRC Document Control Desk, "STPNOC Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)", February 28, 2013 (NOC-AE-1 3002963)

(ML13070A0 1)

4. Letter from D. L. Koehl, STPNOC, to NRC Document Control Desk, "Overall Integrated Plan Regarding Commission Order Modifying Licenses with Regard to Reliable Spent Fuel Pool Instrumentation (Order Number EA-12-051)," February 28, 2013 (NOC-AE-13002959) (ML13070A006)

5. Letter from T. Brown, NRC, to D.L. Koehl, STPNOC, "South Texas Project, Units 1 and 2

- Report for the Onsite Audit Regarding Implementation of Mitigating Strategies and Reliable Spent Fuel Instrumentation Related to Orders EA-12-049 and EA-12-051 (TAC Nos. MF0825, MF0826, MF0827, and MF0828)", May 6, 2015 (AE-NOC-1 5002661)

(ML1511I1A465)

6. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "STPNOC First Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)", August 26, 2013 (NOC-AE-I13003027) (M L 13249A060)

7. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "STPNOC Second Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)", February 27, 2014 (NOC-AE-14003089)(ML14073A458)

8. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "STPNOC Third Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)(TAC Nos. MF0825 and MF0826)",

August 27, 2014 (NOC-AE-14003162)(ML14251A029)

9. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "STPNOC Fourth Six-Month Status Report in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)(TAC Nos. MF0825 and. MF0826)",

February 26, 2015 (NOC-AE-1 5003224)(ML15075A019)

Enclosure NOC-AE-1 5003257 Page 7 of 8

10. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, 'Six-Month Status Update of Overall Integrated Plan in Response to Order EA-12-051, 'Reliable Spent Fuel Pool Instrumentation' (TAC Nos. MF0827 and MF0828)", August 27, 2013 (NOC-AE-I 3003020)(ML13249A078)

11. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "2 nd Six-Month Status Update of Overall Integrated Plan in Response to Order EA-1 2-051, 'Reliable Spent Fuel Pool Instrumentation' (TAC Nos. MF0827 and MF0828)", February 27, 2014 (NOC-AE-1 4003089)(MLI14066A388)

12. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "3r Six-Month Status Update of Overall Integrated Plan in Response to Order EA-12-051, 'Reliable Spent Fuel Pool Instrumentation' (TAC Nos. MF0827 and MF0828)", August 27, 2014 (NOC-AE-140031 64)(ML14251A028)

13. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "4 th Six-Month Status Update of Overall Integrated Plan in Response to Order EA-12-051, 'Reliable Spent Fuel Pool Instrumentation' (TAC Nos. MF0827 and MF0828)", February 26, 2015 (NOC-AE- 15003225) (MLL5069A220)

14. Letter from J.S. Bowen, NRC, to D.L. Koehl, STPNOC, "interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049 (Mitigation Strategies) (TAC Nos. MF0825 and MF0826)", January 29, 2014 (AE-NOC-14002494)(ML13339A736)

15. Letter from B.K. Singal, NRC, to D.L. Koehl, STPNOC, "South Texas Project, Units 1 And 2 - Interim Staff Evaluation and Request For Additional Information Regarding the Overall Integrated Plan for Implementation of Order EA-12-051, Reliable Spent Fuel Pool Instrumentation (TAC Nos. MF0827 AND MF0828)", September 19, 2013 (AE-NOC-1 3002466)(ML13254A210)

16. Nuclear Energy Institute (NEI) Guidance 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide," Revision 0, August 21, 2012 (ML12242A378)

17. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "Revised Phase 1 Staffing Assessment Submitted in Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 9.3 of the Near-Term Task Force Review of Insights", June 3, 2013 (NOC-AE-1 3003004)(MLI 31 82A021)

18. Letter from E.J. Leeds, NRC, to All Power Reactor Licensees, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-lchi Accident", March 12, 2012 (AE-NOC-12002269)

(ML12053A340)

19. Letter from A. Capristo, STPNOC, to NRC Document Control Desk, "Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-lchi Accident -

Phase 2 Staffing Assessment", November 25, 2014 (NOC-AE-14003189)

Enclosure NOC-AE-1 5003257 Page 8 of 8

20. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk, "Supplement to Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-lchi Accident - Phase 2 Staffing Assessment", July 2, 2015 (NOC-AE-1 5003255)

21. STPNOC Vendor Technical Document, VTD-A977-0003, "SAFER Response Plan for South Texas Project Electric Generating Station", Revision 0 (STI 34077493)

22. STPNOC Document, FLEX-0001, "Diverse and Flexible Coping Strategies (FLEX)

Program Document", Revision 0 (STI 33759523)

23. STPNOC Calculation, STP-CP-006, "ELAP Analysis with the South Texas Project RETRAN-02 Input Model", Revision 1, April 15, 2015 (STI 34064235)

24. AREVA Nuclear Products Advisory Bulletin, NPAB-024-201 5 RCP-001, "RCP Seal Testing at ELAP Temperatures - High Temperature 0-Rings", January 7, 2015

25. NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, Chapter 9, Section 9.2.5, Revision 2, 'Ultimate Heat Sink", July 31, 1981 (ML052350549)

26. Westinghouse Nuclear Safety Advisory Letter, NSAL 15-2, "Impact of a Break in the Reactor Coolant Pump No. 1 Seal Leak-off Line Piping on Seal Leakage During a Loss of Seal Cooling Event", March 23, 2015 (ML15105A346)

27. Westinghouse InfoGram, IG-15-1, "Elevated Transient Pressure in Reactor Coolant Pump No. 1 Leak-Off Line Following a Loss of All Seal Cooling", March 19, 2015 (WN-N OC-1 5000010)

28. Westinghouse Nuclear Safety Advisory Letter, NSAL 14-1, Revision 1, "impact of Reactor Coolant Pump No. 1 Seal Leakoff Piping on Reactor Coolant Pump Seal Leakage During a Loss of All Seal Cooling", February 10, 2014 (WN-NOC-14000003)

29. STPNOC Procedure, 0POP05-EO-EC00, "Loss of All AC Power", Revision 24 (STI 34116305)

30. STPNOC FLEX Support Guideline Procedure, 0POPI2-ZO-FSG04, "ELAP DC Bus Load Shed/Management", Revision 0 (STI 34093163)

31. Westinghouse Report by L.R. Gussenbauer, PWROG 14015-P, Revision 2, Task 2, "Determine Seal Flow Rates", April 2015

32. STP White paper by P. Jensen and C.R., Albury, "White Paper demonstrating the Applicability of the RETRAN-3D Code for Analysis of the ELAP", August 21, 2014

33. Westinghouse Report by L.R. Gussenbauer, PWROG 14074-P, Task 8, "Benchmarking the ITCHSEAL Code", April 2015

Attachment NOC-AE-1 5003257 ATTACHMENT Summary of Responses for Open and Pending Items on the Safety Evaluation Tracker

Attachment NOC-AE-1 5003257 Page 1 of 8 STPNOC provides the following responses to the Open and Pending items identified in the NRC Safety Evaluation (SE) Tracker.

The NRC identified information needed from STP to resolve these open items in the Onsite Audit Report (Reference 5):

Item Description Information Needed by NRC Summary Response Provide analysis of the ELAP transient that is applicable to STP and which demonstrates the adequacy of the mitigating strategy proposed for STP. This Tesafrvee T' includes specification of an acceptable calculation during the audit.

definition for the transition to reflux condensation cooling to ensure that the The staff is developingSTNCpoiethrqusdcaulinTP ISE 01 analysis is not credited beyond this prvdeithoseqetion the licese CP-0006, during the onsite audit (Reference 23).

3.2.1.1.B juncture. A sufficient number of cases sparatiel ahse patofthe lcne (Fending) should be included in the analysis to ongoingel audi parocess.tNo As stated in the Onsite Audit Report, no additional demonstrate the acceptability of different additional information from the information is needed at this time.

strategies that may be necessary toliesesrqutdaths mitigate an ELAP (e.g., as discussed in tie Section 3.2.1.6, in some cases "N"and "N+1" pumps have different capabilities, which may substantially affect the sequence of events in the integrated plan).

Attachment NOC-AE-1 5003257 Page 2 of 8 Item fDescription Information Needed by NRC jSummary Response in some plant designs, such as those with 1200 to 1300 psia SG design pressures The high temperature 0-rings used in the STP Reactor Coolant Pump (RCP) seals are for the and no accumulator backing of the main Model 100A pump.

steam system PORV actuators, the cold legs could experience temperatures As described in Nuclear Products Advisory Bulletin exceeding 580 degrees °F before The staff requests the licensee (NPAB) 024-2015, "RCP Seal Testing at ELAP cooldown commences. This is beyond the make available for audit Temperatures - High Temperature 0-Rings" qualification temperature (550 degrees 0F) documentation that identifies (Reference 24), ARE VA modified its test procedures of the 0-rings used in the RCP seals. For the types of 0-rings that are and retested multiple batches of 0-ring material ISE Cl such Westinghouse designs, a discussion installed, or will be installed in 3.2.1.2.C incorporating the higher temperature of 5820°F and of the information (including applicable future operating cycles, and increasing stay time from 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> to 58 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br />. All analysis and relevant seal leakage testing justification for their tested 0-rings passed using these higher test data) should be provided to justify that (1) survivability during the ELAP values with sufficient margin. The STP 0-rings meet the integrity of the associated 0-rings will event. the higher temperature requirements.

be maintained at the temperature conditions experienced during the ELAP This NPAB was made available to the NRC review event, and (2) the seal leakage rate of 21 team electronically via the Inspection Management gpm/seal used in the ELAP is adequate System (IMS) portal.

and acceptable.

Attachment NOC-AE-1 5003257 Page 3 of 8 Item Description Information Needed by NRC Summary Response Section 3.5 of STP calculation STP-CP-006 (Reference 23) demonstrates that the decay heat assumed in the RETRAN-3D analysis bounds the The licensee should address the following The staff requests the licensee decay heat used for design basis events issues associated with decay heat make available for audit documented in the UFSAR. The decay heat modeling: (1) specify the value of the documentation that presented in UFSAR Table 6.2.1.3-6 is based on multiplier applied to the ANS 5.1 - 1979 demonstrates the the 1979 American National Standards Institute decay heat standard for the ELAP event thermal/hydraulic analysis (ANSI) decay heat standard.

and its basis. (2) Clarify whether the assumptions are bounding, or multiplier would be capable of accounting are well representative of the This calculation was made available to the NRC for the residual heat contribution from current licensing basis for review team electronically via the IMS portal.

actinides (e.g. plutonium, neptunium) and long-term decay heat (i.e.

ISE Cl 3.2.1.3.A neutron absorption in fission products or Updated Final Safety Analysis An additional comparison of the RETRAN-3D whether these residual heat sources were Report (UFSAR) Revision 16, calculated decay heat and the decay heat accounted for explicitly. (3) Clarify whether Table 6.2.1.3-6a); or determined by Branch Technical Position (BTP) the discussion applies to the RETRAN-3D justification that UFSAR Auxiliary Systems Branch (ASB) 9-2, "Residual thermal-hydraulic analysis or whether it Revision 16, Table 6.2.1.3-6, Decay Energy for Light-Water Reactors for Long-applies to auxiliary calculations (e.g., the is reasonable to use for ELAP Term Cooling" (Reference 25) has also been made determination of steam generator makeup event, even if it is not the STP available to the NRC review team electronically via required during various phases of the licensing basis for long-term the IMS portal. Over a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> evaluation period, ELAP coping analysis). decay heat. RETRAN-3D over predicts decay heat, which is conservative for the determination of Auxiliary Feedwater usage.

Confirm that key initial plant parameters Tiitmis open pending staff ISE Cl and assumptions used in the forthcoming Thisitem.N ddtoa As stated in the Audit Report, this item is open 3.2.1.4.A RETRAN-3D analysis are consistent with rve.Nadionlpending NRC staff review and no additional (Pending) the appropriate values from NEI 12-06, information from the licensee information is needed at this time.

Section 3.2, or justify any deviations, is requested at this time.

Attachment NOC-AE-1 5003257 Page 4 of 8 Item Description Information Needed by NRC Summary Response Some information has been provided by the Pressurized Water Reactor Owners Group (PWROG) to attempt to Provide the manufacturer's name and address similarity of ARE VA model number for the reactor coolant and Westinghouse seals. The PWROG is working to address this issue with the pumps and the reactor coolant pump staff has identified questions NRC.

AQ #25 seals. Discuss whether or not the reactor associated with this coolant pump and seal combination information that will require As stated in the Audit Report, no additional complies with a seal leakage model further discussion with information is needed from STPNOC at this time.

described in WCAP-1 7601. PWROG and the licensee as part of the ongoing audit process. No additional information from the licensee is requested at this time.

Questions related to Westinghouse Nuclear Safety Advisory Letter 14-1, This item is open pending staff As stated in the Audit Report, this item is open SE #9 "Impact of Reactor Coolant Pump No. 1 review. No additional pending NRC staff review and no additional (Pending) Seal Leakoff Piping on Reactor Coolant information from the licensee information is needed at this time.

Pump Seal Leakage During a Loss of All is requested at this time.

Seal Cooling".

Attachment NOC-AE-1 5003257 Page 5 of 8 Item Description jInformation Needed by NRC Summary Response Please provide adequate justification for the seal leakage rates calculated according to the Westinghouse seal leakage model that was revised following the issuance of NSAL-14-1. The justification should include a discussion of the following factors:

a. benchmarking of the seal leakage The PWROG is developing model against relevant data from tests and validating documentation or operating events, that leakage rates in PWROG-

b. discussion of the impact on the seal series reports are valid. The leakage rate due to fluid temperature staff is reviewing the PWROG is working to address this issue with the greater than 5500°F resulting in preliminary results of this work NRC.

SE #10 increased deflection at the seal and will require further interface, discussion with the PWROG As stated in the Audit Report, no additional

c. clarification whether the second stage and licensee as part of the information is needed from STPNOC at this time.

reactor coolant pump seal would ongoing audit process. No remain closed under ELAP conditions additional information from the by the revised seal leakage model and licensee is requested at this a technical basis to support the time.

determination, and,

d. justification that the interpolation scheme used to compute the integrated leakage from the reactor coolant pump seals from a limited number of computer simulations (e.g.,

three) is realistic or conservative.

Attachment NOC-AE-1 5003257 Page 6 of 8 Item JDescription Information Needed by NRCj Summary Response The NRC staff understands that STP Design Engineering performed a preliminary Westinghouse has recently recalculated evaluation of pipe stresses in the leakoff lines. The seal leakoff line pressures under loss of evaluation indicates that no failures (i.e. ruptures) will seal cooling events based on a revised occur in the No. 1 seal leakoff line piping in Unit 2.

seal leakage model and additional design- This evaluation was performed using the leakoff line specific information for certain plants. conditions following a loss of all RCP seal cooling

a. Please clarify whether the piping and event: RCS cold leg temperature 582°F and 2500 psia all components (e.g., flow elements, pressure up to the leakoff line orifice. The pressure flanges, valves, etc.) in your seal used in the STP evaluation is greater than the The staff requests the licensee pressure suggested in Westinghouse Nuclear Safety leakoff line are capable of withstanding make available for audit documentation that (1) Advisory Letter (NSAL) 15-2 and InfoGram (IG)15-1 the pressure predicted during an ELAP (References 26 and 27).

event according to the revised seal demonstrates the leakoff line leakage model. piping and components up to The results of the orifice plate evaluation presented in and including the flow orifice NSAL-14-1 (Reference 28) showed that there was

b. Please clarify whether operator actions are robust to the design are credited with isolating low-pressure only negligible erosion to the orifice plate after 16 pressure of the RCS and (2) hours at the worst case conditions used in the NSAL.

portions of the seal leakoff line, and if that credit is not being taken so, please explain how these actions The analysis also showed that there would be minimal SE #11 for calculated leakage rates deflection of the orifice plate. These results apply to will be executed under ELAP where the 1/4" flow orifice the STP orifice plates in the No. 1 seal leakoff lines.

conditions. unchokes (e.g., possible at The preliminary pipe stress evaluation therefore

c. If over-pressurization of piping or RCS pressures below about credits choked flow conditions at the orifice, resulting components could occur under ELAP 300 psia), since these in lower temperatures and pressures downstream of conditions, please discuss any planned flowrates may be the orifice.

modifications to the seal leakoff piping underestimated if a rupture and component design and the STP is in the process of performing and documenting occurs in the piping and associated completion timeline. a final engineering evaluation related to the No.1 seal components downstream of

,.Alternately, please identify the seal leakoff line integrity under the described ELAP the flow orifice. conditions for STP Unit 2. Plant modifications are not leakoff piping or components that would be susceptible to over- planned.

pressurization during ELAP conditions, In the STP emergency operating procedure for Loss of clarify their locations, and provide All AC Power (Reference 29), Operators are directed justification that the seal leakage rate to close the RCP seal water return outside would remain in an acceptable range if containment isolation valve manually at the valve the affected piping or components location outside containment. This action can be were to rupture. performed in an ELAP.

Attach ment NOC-AE-1 5003257 Page 7 of 8 Item Description Information Needed by NRC Summary Response A walkdown of the battery load shed procedure was performed with the NRC review team during the onsite audit.

STPNOC performed a timed simulation of DC load shedding using procedure 0POP12-ZO-FSG04, "ELAP DC Bus Load Shed/Management" The staff requests the licensee make available for audit (Reference 30). The success criterion for the SE #17 ILoad shed validation validation of the battery load simulation is 90 minutes and the operators shed procedure. performed load shedding in 42.5 minutes.

Documentation of the load shed validation demonstrating that the DC load shedding actions can be completed within the required time has been made available to the NRC review team electronically via the IMS portal.

Attachment NOC-AE-1 5003257 Page 8 of 8 The RCP No. 1 seal leakage model used in the analysis to support the FLEX strategy is based on results presented in PWROG 1401 5-P, Revision 2 (Reference 31). PWROG 14015-P defines STP as a Category 6 plant, but STP's analysis conservatively assumes the higher leak rate for a Category I or Category 6 plant. STP input these higher leakage rates into a site-specific model and determined that RCP seal uncovery could occur at 11.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> and reflux cooling could occur at 15.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> following the initiation of an ELAP event. In the current FLEX strategy timeline, flow can be restored to the RCS within four hours when using the positive displacement pump (PDP) or within eight hours using the FLEX RCS makeup pump if the PDP is not available.

While PWROG 14015-P has not been approved by the NRC, the following additional conservatisms provide reasonable assurance that RCP seal uncovery and reflux cooling will not occur during an ELAP event:

• The STP RETRAN-3D White Paper made available to the NRC via the IMS portal (Reference 32) provides a benchmark of the STP RETRAN-3D model compared to a STP RELAP5 model. The model assumed RCP seal leakage of 21 gpm at normal operating pressure and temperature, which was the best available information at the time. The results of the benchmarking show that the STP RETRAN-3D computer model conservatively predicts both the time to RCP seal uncover and the time to reflux cooling compared to a similar RELAP5 computer model. The model-generated times for RCP seal uncovery are 13.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> for RETRAN-3D versus 13.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> for RELAP5, and the times for reflux cooling are 17.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> for RETRAN-3D versus 24.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> for RELAP5.

• The PWROG's ITCHSEAL calculations used to determine RCP seal leakage contain known conservatisms when compared to the results of the generic analysis performed at Electricite de France's Montereau facility. As discussed in PWROG 14074-P (Reference 32), parameters within the ITCHSEAL calculations used for the STP RCP seal leakage values were adjusted to ensure significant margin when compared to the results of the Montereau RCP seal leakage test data.

• The STP FLEX procedures monitor RCS inventory (e.g. reactor pressure vessel water level) during the ELAP event and direct the operators to implement primary makeup more rapidly if signs of increased RCP leakage are detected.

STP will monitor the progress of the ongoing discussions between the NRC and the PWROG regarding RCP seal leakage and continue to answer questions as needed.