L-2020-094, Supplemental Response to Request for Additional Information Regarding License Amendment Request to Modify the Reactor Coolant Pump (RCP) Flywheel Inspection Program Requirements

Supplemental Response to Request for Additional Information Regarding License Amendment Request to Modify the Reactor Coolant Pump (RCP) Flywheel Inspection Program Requirements

ML20178A463
Person / Time
Site:	Saint Lucie
Issue date:	06/26/2020
From:	Deboer D Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2020-094
Download: ML20178A463 (5)

Text

June 26, 2020 L-2020-094 10 CFR 50.90 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington D C 20555-0001 RE: St. Lucie Unit 2 Docket No. 50-389 Renewed Facility Operating Licenses NPF-16 Supplemental Response to Request for Additional Information Regarding License Amendment Request to Modify the Reactor Coolant Pump (RCP) Flywheel Inspection Program Requirements

References:

1. Florida Power & Light Company letter, L-2019-091, License Amendment Request to Modify the Reactor Coolant Pump CRCP) Flywheel Inspection Program Requirements, October 9, 2019 (ADAMS Accession No. ML19282D338)

2. NRC electronic memorandum, RAIs for LAR to Revise Technical Specifications 6.8.4.o, "Reactor Coolant Pump Flywheel Inspection Program" March 31, 2020 (ADAMS Accession No. ML20092G344)

3. Florida Power & Light Company letter, L-2020-061, Response to Request for Additional Information Regarding License Amendment Request to Modify the Reactor Coolant Pump (RCP) Flywheel Inspection Program Requirements, April 30, 2020 (ADAMS Accession No. ML20121A170)

4. NRC electronic memorandum, Request for Supplemental Information for the First Round RAI Responses Regarding the License Amendment Request to Revise Technical Specifications 6.8.4.o, "Reactor Coolant Pump Flywheel Inspection Program", May 25, 2020 In Reference 1, Florida Power & Light Company (FPL) requested an amendment to Renewed Facility Operating License NPF-16 for St. Lucie Nuclear Plant Unit 2. The proposed license amendment modifies the St. Lucie Unit 2 Technical Specifications (TS) by revising the Reactor Coolant Pump Flywheel Inspection Program requirements consistent with the conclusions and limitations specified in NRC safety evaluation (SE), Acceptance for Referencing of Topical Report SIR-94-080, "Relaxation of Reactor Coolant Pump Flywheel Inspection Requirements", dated May 21, 1997.

In Reference 2, the NRC requested additional information necessary to complete its review. In Reference 3, FPL provided its response to the request for additional information (RAI). In Reference 4, the NRC requested information clarifying the response to RAI #2 provided in Reference 3.

The enclosure to this letter provides supplemental information supporting FPLs response to RAI #2. The supplemental information clarifies the application, does not expand the scope of the application as originally noticed, and does not alter the conclusion in Reference 1 that the changes do not involve a significant hazards consideration pursuant to 10 CFR 50.92 and there are no significant environmental impacts associated with the changes.

This letter contains no new or revised regulatory commitments.

Should you have any questions regarding this submittal, please contact Mr. Wyatt Godes, St. Lucie Licensing Manager, at (772) 467-7435.

Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957

St. Lucie Unit 2 L-2020-094 Docket No. 50-389 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on June 26, 2020.

Sincerely, Daniel DeBoer Site Director - St. Lucie Nuclear Plant Florida Power & Light Company

Enclosure:

FPL Supplemental Response to RAI #2 cc: USNRC Regional Administrator, Region II USNRC Project Manager, St. Lucie Nuclear Plant, Units 1 and 2 USNRC Senior Resident Inspector, St. Lucie Nuclear Plant, Units 1 and 2

St. Lucie Unit 2 L-2020-094 Docket No. 50-389 Enclosure Page 1 of 3 ENCLOSURE St. Lucie Unit 2 Supplemental Response to Request for Additional Information Regarding License Amendment Request to Modify the Reactor Coolant Pump (RCP) Flywheel Inspection Program Requirements

St. Lucie Unit 2 L-2020-094 Docket No. 50-389 Enclosure Page 2 of 3 In Reference 1, Florida Power & Light Company (FPL) requested an amendment to modify the St. Lucie Unit 2 Technical Specifications (TS) by revising the Reactor Coolant Pump RCP) Flywheel Inspection Program requirements consistent with the conclusions and limitations specified in NRC safety evaluation (SE), Acceptance for Referencing of Topical Report SIR-94-080, "Relaxation of Reactor Coolant Pump Flywheel Inspection Requirements" (Reference 2). In Reference 3, the NRC requested supplemental information clarifying FPLs response to request for additional information (RAI) #2 provided in Reference

5. Specifically, the NRC requests detail clarifying how the fracture toughness values of 69.5 ksiin and 50 ksiin were calculated using the ASME Section XI, Appendix A equations. FPLs response follows.

RAI-2

In Section 3.5 of the enclosure to the submittal, the licensee calculated fracture toughness (KIC) using empirical formulas and stated that the resulting KIC values are of greater toughness than the lower bound ASME KIC vs. T-RTNDT curve. The staff noted that this conclusion is inconsistent with the licensees calculation of KIC in Section 3.4 of the enclosure to the submittal using equation A-4000 of ASME Code,Section XI. This is based on the fact that all the KIC values using the empirical formulas were less than the ASME Code KIC value.

Request: Explain the inconsistency between the statement in Section 3.5 of the enclosure to the submittal that the KIC using the empirical formulas are of greater toughness than the lower bound ASME KIC vs. T-RTNDT curve and the ASME Code KIC calculation in Section 3.4 of the enclosure to the submittal.

FPL Response (Reference 5):

The statement in question is technically accurate but requires clarification. The values obtained by the empirical correlations exceed the ASME XI Appendix A curve at the temperatures used for the correlations (room temperature and 110°F.) It would be inappropriate to compare these values to those from section 3.4, which calculates KIC using the derived RTNDT of -50°F. The result of applying the correlation temperatures to the ASME Curve is summarized by the table below.

Result for PSL Unit 2 (ksiin)

Correlation Name Equation CVN at Room CVN at Temp. (~72oF) +110oF Corten and Sailors 15.5 (CVN)0.5 139.5 147.0 Roberts and Newton 9.35(CVN)0.63 149.0 159.2 ASME XI, Appendix A 33.2 + 20.734 exp[0.02(T - RTNDT)] 69.5 50 While not a direct comparison to the KIC calculated in 3.4, the correlations do result in values that exceed both the 90 ksiin at +100°F required by the SIA topical report (Reference 2), and ASME XI Appendix A values for similar temperatures.

Note 1 - Section 3.4 of the LAR reported a KIC of 449 ksiin. However, the ASME KIC vs. T-RTNDT curve is truncated above 200 ksiin, and 200 ksiin is considered the maximum attainable KIC using the ASME XI, Appendix A, curve.

Note 2 - A similar justification was accepted by the NRC for Millstone Nuclear Power Station, Unit 2 (Reference 4), albeit with a higher RTNDT (+40oF versus -50oF for St. Lucie Unit 2), which correlates to lower toughness.

St. Lucie Unit 2 L-2020-094 Docket No. 50-389 Enclosure Page 3 of 3 FPL Supplemental Response:

The reviewer is using the temperature at which corollary Charpy V Notch (CVN) test values are obtained as the operating temperature T in the (T - RTNDT) portion of the KIC equation, and the resulting values do not align with the response statement that they exceed the ASME KIC curve.

Please note that the values in the response reflect the result when these temperatures are used for RTNDT and not the operating temperature. See below:

KIC = 33.2 + 20.734exp[0.02(T - RTNDT)] = 33.2 + 20.734exp[0.02(100 - 72)] = 69.5ksiin AND KIC = 33.2 + 20.734exp[0.02(T - RTNDT)] = 33.2 + 20.734exp[0.02(100 - 110)] = 50ksiin This makes a very conservative assumption that RTNDT is the temperature at which CVN values were obtained (72oF and 110oF), and shows that the correlation derived KIC values exceed the corresponding ASME KIC curve values for that value of RTNDT and an operating temperature of 100oF.

References:

1. Florida Power & Light Company letter, L-2019-091, License Amendment Request to Modify the Reactor Coolant Pump CRCP) Flywheel Inspection Program Requirements, October 9, 2019 (ADAMS Accession No. ML19282D338)

2. NRC letter to Director, Nuclear Safety Division, Entergy Operations, Inc., Acceptance for Referencing of Topical Report SIR-94-080, Relaxation of Reactor Coolant Pump Flywheel Inspection Requirements, May 21, 1997 (ADAMS Legacy Accession Nos. 9706230099 and 9706240192).

3. NRC electronic memorandum, Request for Supplemental Information for the First Round RAI Responses Regarding the License Amendment Request to Revise Technical Specifications 6.8.4.o, "Reactor Coolant Pump Flywheel Inspection Program", May 25, 2020

4. NRC letter to Dominion Nuclear Connecticut, Inc. Millstone Nuclear Power Station, Unit No. 2 -

Issuance of Amendment RE: Reactor Coolant Pump Flywheel Inspection; February 1, 2002 (ADAMS Accession No. ML013370406)

5. Florida Power & Light Company letter, L-2020-061, Response to Request for Additional Information Regarding License Amendment Request to Modify the Reactor Coolant Pump (RCP) Flywheel Inspection Program Requirements, April 30, 2020 (ADAMS Accession No. ML20121A170)