SBK-L-21033, Response to Request for Additional Information (RAI) Regarding License Amendment Request (LAR) 20-02, Resolve Non-Conservative Heat Flux Hot Channel Factor (Fo(Z)) Requirements

Response to Request for Additional Information (RAI) Regarding License Amendment Request (LAR) 20-02, Resolve Non-Conservative Heat Flux Hot Channel Factor (Fo(Z)) Requirements

ML21083A250
Person / Time
Site:	Seabrook
Issue date:	03/24/2021
From:	Booth B NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-21033
Download: ML21083A250 (10)

Text

NEXTera*

EN~

March 24, 2021 SBK-L-21033 10 CFR 50.90 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington DC 20555-0001 RE: Seabrook Station Docket No. 50-443 Renewed Facility Operating License No. NPF-86 Response to Request for Additional Information (RAI) Regarding License Amendment Request (LAR) 20-02, Resolve Non-Conservative Heat Flux Hot Channel Factor (Fo(Z)) Requirements References :

1. License Amendment Request 20-02 , Resolve Non-Conservative Heat Flux Hot Channel Factor (FQ(Z)) Requirements, August 17, 2020 (ADAMS Accession No. ML20230A425)

2. NRR Email Capture, Request for Additional Information Regarding Seabrook Heat Flux Hot Channel Requirement Amendment Request (L-2020-LLA-0187), February 23 , 2021 In Reference 1, NextEra Energy Seabrook, LLC (NextEra) requested an amendment to Renewed Facility Operating License (RFOL) NPF-86 for Seabrook Nuclear Plant Unit 1 (Seabrook) . The proposed license amendment revises the Seabrook Technical Specifications (TS) to resolve non-conservative requirements associated with the nuclear heat flux hot channel factor, Fo(Z) [RAOC-W(Z) Methodology], as reported in Westinghouse Nuclear Safety Advisory Letter (NSAL) 09-5, Revision 1, "Relaxed Axial Offset Control Fo Technical Specification Actions", dated September 23, 2009, and NSAL 15-1 , "Heat Flux Hot Channel Factor Technical Specification Surveillance", dated February 3, 2015.

In Reference 2, the NRC requested additional information determined necessary to complete its review.

The enclosure to this letter provides NextEra's response to the request for additional information (RAJ) . In addition, and as discussed in the enclosure, NextEra is proposing an additional change to the Seabrook TS. Attachment 1 to the enclosure provides the additional TS page marked up to show the proposed change. The TS marked up page in Attachment 1 is to be added to the corresponding TS marked up pages provided in Reference 1. No changes are proposed to the TS Bases pages provided in Reference 1.

The supplements included in this RAI response provide additional information that clarifies the application, do not expand the scope of the application as originally noticed, and should not change the NRC staffs original proposed no significant hazards consideration determination as published in the Federal Register.

This letter contains no new regulatory commitments.

Should you have any questions regarding this submission , please contact Mr. Ken Browne, Safety Assurance and Learning Site Director, at 603-773-7932.

NextEra Energy Seabrook, LLC P.O. Box 300, Lafayette Road , Seabrook, NH 03874

Seabrook Station SBK-L-21033 Docket Nos. 50-443 Page 2 of2 I declare under penalty of perjury that the foregoing is true and correct.

).d.

Executed on the

"°'day of March 2021.

Sincerely,

~~

Brian Booth Nuclear Site Vice President - Seabrook Nuclear Power Station NextEra Energy Enclosure cc: USNRC Region I Administrator USNRC Project Manager USNRC Senior Resident Inspector Director Homeland Security and Emergency Management New Hampshire Department of Safety Division of Homeland Security and Emergency Management Bureau of Emergency Management 33 Hazen Drive Concord, NH 03305 Katharine Cederberg, Lead Nuclear Planner The Commonwealth of Massachusetts Emergency Management Agency 400 Worcester Road Framingham, MA 01702-5399

Seabrook Station SBK-L-21033 Docket Nos. 50-443 Enclosure Page 1 of 8 Seabrook Station Response to Request for Additional Information (RAI) Regarding LAR 20-02.

Resolve Non-Conservative Heat Flux Hot Channel Factor (Fa(Z)) Requirements In Reference 1, NextEra requested an amendment to Renewed Facility Operating License (RFOL) NPF-86 for Seabrook Nuclear Plant Unit 1 (Seabrook). The proposed license amendment revises the Seabrook Technical Specifications (TS) to resolve non-conservative requirements associated with the nuclear heat flux hot channel factor, FQ(Z) [RAOC-W(Z) Methodology], as reported in Westinghouse NSAL 09-5, Revision 1 (Reference 2), and NSAL 15-1 (Reference 3).

In Reference 4, the NRC requested additional information determined necessary to complete its review, as provided below. NextEra's RAI response follows:

RAl#1 Justify the validity of the adoption of the Rj factor in light of the fact that doing so will result in COLR specifications that do not adhere to the methods referenced in 6.8.1.6.b.14, as required by the Seabrook TS. As necessary, consider proposing a revised TS citation that specifies, with adequate accuracy, the Seabrook-specific methods that would be used.

NextEra Response:

The current Fa Technical Specifications (TS) surveillance requirement includes the application of the greater of a 1.02 factor or a factor specified in the COLR to account for potential increases in FaW(Z) between surveillances. As stated in WCAP-17661-P-A, (Reference 5), Section 3.2.5, this penalty factor, which is now referred to as Ri, will continue to be applied, with no minimum of 2%, whenever the minimum margin to the Faw(z) limit is predicted to decrease.

The penalty factor, Ri, is generated in the same manner as for the current Fa TS surveillance, except for the elimination of 2% minimum penalty. This penalty factor, Ri, is determined using the WCAP-10216-P-A, Revision1A (Reference 6), methodology, as discussed in WCAP-17661-P-A, Section 3.2.5 and Section 5.5 (page 5-6). WCAP-10216-P-A, Revision 1A, is listed as an approved COLR methodology in TS 6.8.1.6.b. To implement the proposed methodology related to the elimination of minimum penalty of 2% and the application of the Ri penalty based on the predicted margin trends, the license amendment proposed by this amendment request will be added to the listing of COLR approved methodologies referenced in Seabrook TS 6.8.1.6.b, consistent with the NRC staffs recommendation.

Attachment 1 provides the existing TS 6.8.1.6.b page marked up to show the change proposed in this RAI response. The TS marked up page is in addition to the corresponding TS marked up pages provided in Reference 1. No changes are proposed to the TS Bases pages provided in Reference 1.

RAl#2 Justify the applicability of the Rj factor, in light of the fact that the Seabrook licensee does not intend to adopt the broader surveillance formulation described in WCAP-17661-P-A.

Seabrook Station SBK-L-21033 Docket Nos. 50-443 Enclosure Page 2 of 8 NextEra Response:

The penalty factor Ri is unrelated to the adoption of new Fa surveillance formulation and remains applicable to the current Fa formulation, based on W(z), as seen in the example of flux map application in Section 6.7 of WCAP-17661-P-A, Equation 6-1.

A note in the current Fa TS, which requires application of the greater of a 1.02 factor or a factor specified in the COLR, is to account for potential increases in Faw(z) between surveillances. As stated in WCAP-17661-P-A, Section 3.2.5, the note will be eliminated but application of the penalty factor, which is now referred to as Ri, will continue to be required whenever the minimum margin to the FaW(Z) limit is predicted to decrease. Additionally, a minimum penalty of 2% in the current TS is eliminated and the magnitude of the penalty factor is based on the predicted margin which is set to 1.0 when the margin is predicted to increase.

RAl#3 Justify the implementation of RAOC Operating Spaces as consistent with WCAP-10216-P-A, Revision 1A, or provide additional information to describe how the RAOC Operating Spaces would be formulated. As necessary, consider proposing a revised TS citation that specifies, with adequate accuracy, the Seabrook-specific methods that would be used.

NextEra Response:

The implementation of RAOC Operating Spaces remains consistent with WCAP-10216-P-A, Revision 1A. The proposed Fa margin improvement by reducing RAOC Axial Flux Difference (AFD) Operating Space, including reduction in power if necessary, is discussed in WCAP-17661-P-A in Section 3.2.3, specifically on top of page 3-14, as applicable to the current TS Faw(z) formulation with an example in Figure 3-6.

The required limits on thermal power and required reductions on AFD limits will be determined using the standard RAOC methodology of WCAP-10216-P-A, Revision 1A, which is the current method used to analyze RAOC Operating Spaces. The WCAP-10216-P-A, Revision 1A methodology is referenced in the current Seabrook TS 6.8.1.6.b.14.

RAl#4 Describe how the required margin improvements contained in Table 3 of the COLR were formulated, demonstrate that they provide the required, additional margin to justify continued operation in the event FQW(Z) exceeds its limit, and as necessary, consider proposing a revised TS citation that specifies, with adequate accuracy, the Seabrook-specific methods that would be used.

NextEra Response:

The proposed COLR changes include sample data in Table 3, which is not considered to be representative of any Seabrook cycle design. For the Seabrook cycle-specific COLR, Seabrook core design specific data will continue to be generated using the RAOC WCAP-10216-P-A, Revision 1A methodology with the discrete maximum power levels and reduced AFD limits, as required, to quantify the margin improvements. The methodology used (WCAP-10216-P-A, Revision 1A) is the same as that used in the current RAOC analysis and is in the Seabrook list of approved COLR methods for Fa referenced in TS 6.8.1.6.b.14. If more than one Operating Space is specified in the COLR, cycle specific data similar to Table 3 of the sample COLR will be generated for each of the Operating Spaces.

Seabrook Station SBK-L-21033 Docket Nos. 50-443 Enclosure Page 3 of 8 RAl#5 Discuss the applicability of LIMITATION 2 imposed in the NRG safety evaluation approving WGAP-17661-P-A to Seabrook specific methods. If the licensee determines that LIMITATION 2 is not applicable, please provide rationale for the basis of the determination. If LIMITATION 2 is applicable, please justify a value, other than 50 percent, that would be "specified in cycle specific GOLR," as stated in the LAR.

NextEra Response:

LIMITATION 2 is applicable to Seabrook and the final power decrease to 50% will be specified in the Seabrook GOLR based on the NRG's prior approval of this power level in WGAP-17661-P-A. The intent of the "as specified in cycle specific GOLR" was to allow change in the event of any future NRG approved changes. For the GOLR, implementing the changes proposed in this amendment request, Seabrook will comply with LIMITATION 2 imposed in the SE for WGAP-17661-P-A to use 50 percent as the final power level reduction.

RAl#6 Discuss how the effect of terms, such as [T(z)]GOLR and AXY(z), on the proposed FQW formulation in the GOLR were determined to involve low safety significance, and justify the adequacy of the proposed surveillance formulations in GOLR with use of FQ(Z) instead of FXY(Z) in the NRG-approved formulations (Equations 5-1 and 5-2) in WGAP-17661-P-A.

NextEra Response:

The proposed Faw formulation in the GOLR is the same as the current formulation in the TS, which is based on W(z). The acceptability/adequacy of this W(z) formulation is discussed below.

WGAP-17661-P-A states the following in RAI 15.a response:

"However, the option of using Method 1 to set Axv(z) factor to unity (as discussed in Section 4.3.1 of the TR) will still be retained as an alternative to using Method 2 to explicitly calculate the Axv(z) factor at the time of the surveillance. Setting the Axv(z) factor to 1.0 is effectively the same as not using it at all. In this respect, using Method 1 is consistent with the current Fa Surveillance methodology, which makes no correction for surveillances that are performed at conditions different than were assumed in generating the Fa surveillance factors."

"Section 4.3.1 of the TR states that setting Axv(z) to 1.0, "is a reasonable option that will in all likelihood result in conservative surveillances at off-normal conditions."

NRG SE (Section 4.1.1) on page 18, states:

"Several considerations justify an allowance to keep the RAOG surveillance uncorrected. First among these is the fact that the vast majority of surveillances are performed in a Hot Full Power (HFP), All Rods Out configuration, such that there would be little deviation from the reference condition. Stated differently, in most cases, the Axy factor would seldom deviate from unity, and deviations are usually expected to be minor. Second, the existing methodology does not include this correction. Third, in response to RAI 15.e, several tables were provided for a demonstration plant with several successive surveillances completed slightly above BO-percent RTP, with a 14-percent D-bank control rod insertion. These tables show that the Axy factor removes a small amount of conservatism from the uncorrected surveillance, meaning that, in these conditions, a unity-value Axy is conservative."

Seabrook Station SBK-L-21033 Docket Nos. 50-443 Enclosure Page 4 of 8 Based on the above conclusions documented in WCAP-17661-P-A, where the Method 1 of the new formulation is considered to be consistent with the current Fa Surveillance methodology, the use of the current Fa surveillance formulation is considered to be an acceptable method with no identified safety concerns. Also, Seabrook operates essentially with all rods out (ARO) conditions, which further justifies the use of the current Fa surveillance methodology.

References:

1. License Amendment Request 20-02, Resolve Non-Conservative Heat Flux Hot Channel Factor (FQ(Z)) Requirements, August 17, 2020 (ADAMS Accession No. ML20230A425)

2. Westinghouse Nuclear Safety Advisory Letter 09-5, Revision 1, Relaxed Axial Offset Control Fa Technical Specification Actions, September 23, 2009.

3. Westinghouse Nuclear Safety Advisory Letter 15-1, Heat Flux Hot Channel Factor Technical Specification Surveillance, February 3, 2015.

4. NRR Email Capture, Request for Additional Information Regarding Seabrook Heat Flux Hot Channel Requirement Amendment Request (L-2020-LLA-0187), February 23, 2021

5. Westinghouse WCAP-17661-P-A, Revision 1, Improved RAOC and CAOC Fa Surveillance Technical Specifications, February 2019 (ADAMS Accession No. ML18298A314)

6. Westinghouse WCAP-10216-P-A, Revision 1A, Relaxation of Constant Axial Offset Control Fa Surveillance Technical Specification, February 1994 (ADAMS Accession No. ML20063L185)

Seabrook Station SBK-L-21033 Docket No. 50-443 Enclosure Page 5 of 8 ATTACHMENT 1 PROPOSED TECHNICAL SPECIFICATION PAGES (MARKUP)

(3 pages follow)

jThis page is provided for information only. No changes are proposed on this page. j ADMINISTRATIVE CONTROLS 6.8.1.6.b The analytical methods used to determine the core operating limits shall be those previously reviewed and approved by the NRC in:

1. WCAP-12945P-A, "Code Qualification Document for Best Estimate LOCA Analysis," Volume 1, Revision 2, and Volumes 2 through 5, Revision 1; Bajorek, S. M., et al, 1998.

Methodology for Specification:

3.2.2 Heat Flux Hot Channel Factor

2. WCAP-10079-P-A, (Proprietary) and WCAP-10080-A (Nonproprietary),

"NOTRUMP: A Nodal Transient Small Break and General Network Code",

August 1985.

Methodology for Specification:

3.2.2 Heat Flux Hot Channel Factor

3. YAEC-1363-A, "CASM0-3G Validation," April, 1988.

YAEC-1659-A, "SIMULATE-3 Validation and Verification,"

September, 1988.

WCAP-11596-P-A, (Proprietary), "Qualification of the PHOENIX-P/ANC Nuclear Design System for Pressurized Water Reactor Cores", June, 1988.

WCAP-10965-P-A, (Proprietary), "ANC: A Westinghouse Advanced Nodal Computer Code", September, 1986.

Methodology for Specifications:

3.1.1.1 SHUTDOWN MARGIN for MODES 1,2, 3, and 4 3.1.1.2 SHUTDOWN MARGIN for MODE 5 3.1.1.3 Moderator Temperature Coefficient 3.1.3.5 Shutdown Bank Insertion Limit 3.1.3.6 Control Rod Insertion Limits 3.2.1 AXIAL FLUX DIFFERENCE 3.2.2 Heat Flux Hot Channel Factor 3.2.3 Nuclear Enthalpy Rise Hot Channel Factor

4. Seabrook Station Updated Final Safety Analysis Report, Section 15.4.6, "Chemical and Volume Control System Malfunction That Results in a Decrease in the Boron Concentration in the Reactor Coolant System".

Methodology for Specifications:

3.1.1.1 SHUTDOWN MARGIN for MODES 1, 2, 3, and 4 3.1.1.2 SHUTDOWN MARGIN for MODE 5 SEABROOK - UNIT 1 6-17 Amendment No. 22, 66, 104, 115, 162

ADMINISTRATIVE CONTROLS 6.8.1.6.b (Continued)

12. NYN-95048, Letter from T. C. Feigenbaum (NAESCo) to NRC, "License Amendment Request 95-05: Positive Moderator Temperature Coefficient",

May 30, 1995.

Methodology for Specification:

3.1.1.3 Moderator Temperature Coefficient

13. WCAP-12610-P-A, "VANTAGE+ Fuel Assembly Reference Core Report".

April, 1995, (Westinghouse Proprietary).

WCAP-12610-P-A & CENPD-404-P-A, Addendum 1-A, "Optimized ZIRLO'",

July 2006.

Methodology for Specification:

3.2.2 Heat Flux Hot Channel Factor

14. WCAP-10216-P-A, Revision 1A (Proprietary), "Relaxation of Constant Axial Offset Control Fa Surveillance Technical Specification", February, 1994.

Methodology for Specification:

3.2.1 AXIAL FLUX DIFFERENCE 3.2.2 Heat Flux Hot Channel Factor

15. WCAP-9272-P-A, (Proprietary), "Westinghouse Reload Safety Evaluation Methodology", July, 1985.

Methodology for Specifications:

2.1 Safety Limits 3.1.1.1 SHUTDOWN MARGIN for MODES 1,2,3, and 4 3.1.1.2 SHUTDOWN MARGIN for MODE 5 3.1.1.3 Moderator Temperature Coefficient 3.1.2. 7 Isolation of Un borated Water Sources - Shutdown 3.1.3.5 Shutdown Bank Insertion Limit 3.1.3.6 Control Rod Insertion Limits 3.2.1 AXIAL FLUX DIFFERENCE 3.2.2 Heat Flux Hot Channel Factor 3.2.3 Nuclear Enthalpy Rise Hot Channel Factor 3.2.5 DNB Parameters 3.5.1.1 Accumulators for MODES 1, 2, and 3 3.5.4 Refueling Water Storage Tank for MODES 1, 2, 3, and 4 3.9.1 Boron Concentration

16. WCAP-13749-P-A, (Proprietary) "Safety Evaluation Supporting the Conditional Exemption of the Most Negative Moderator Temperature Coefficient Measurement," March, 1997.

INSERT new"17" from next page. Methodology for Specifications:

3.1.1 .3 Moderator Temperature Coefficient SEABROOK - UNIT 1 6-20 Amendment No. 66, 88, 104, 107, 115, 139, ~

INSERT for TS 6.9.1.6.b

17. License Amendment [XXX] issued [XX/XX/21] (ADAMS Accession No.[MLXXXXXXX])

Methodology for Specification:

3.2.2 - Heat Flux Hot Channel Factor