L-2020-061, Response to Request for Additional Information Regarding License Amendment Request to Modify the Reactor Coolant Pump (RCP) Flywheel Inspection Program Requirements

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

ML20121A170
Person / Time
Site:	Saint Lucie
Issue date:	04/30/2020
From:	Deboer D Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2020-061
Download: ML20121A170 (6)

Text

• F=PL.

U. S. Nuclear Regulatory Commission APR 3 0 2020 L-2 020-061 10 CFR 50.90 Attn: Document Control Desk Washington D C 20555-0001 RE: St. Lucie Unit 2 Docket No. 50-389 Renewed Facility Operating Licenses NPF-16 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, RAls for LAR to Revise Technical Specifications 6.8.4.o, "Reactor Coolant Pump Flywheel Inspection Program", March 31, 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 determined necessary to complete its review.

The enclosure to this letter provides FPL's response to the NRC's request for additional information (RAI).

The RAI response provides supplemental information that 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 Gades, St. Lucie Licensing Manager, at (772) 467-7435.

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

Executed on APR *3 0 2020 Sincerely, Daniel DeBoer Site Director - St. Lucie Nuclear Plant Florida Power & Light Company Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957

St. Lucie Unit 2 L-2020-061 Docket No. 50-389 Page 2 of 2

Enclosure:

FPL Response to Request for Additional Information 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-2020-061 Docket No. 50-389 Enclos ure Page 1 of 4 ENCLOSURE St. Lucie Unit 2 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-2020-061 Docket No. 50-389 Enclos ure Page 2 of 4 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 staff requested additional information (RAI) determined necessary to complete its review, as indicated below. FPL's response follows:

Background

By letter dated October 9, 2019 (ADAMS Accession No. ML19282D338), Florida Power & Light Company (FPL, the licensee), submitted to the United States Nuclear Regulatory Commission (NRC) , a license amendment request (LAR) to revise Technical Specification (TS) 6.8.4.o "Reactor Coolant Pump Flywheel Inspection Program" of the St. Lucie Nuclear Plant, Unit 2 (St. Lucie, Unit 2), pursuant to Title 10 of the Code of Federal Regulations (10 CFR) , Part 50, Paragraph 50.90. Specifically, the licensee proposed to modify the St. Lucie, Unit 2 Reactor Coolant Pump (RCP) Flywheel Inspection Program requirements to be consistent with the conclusions and limitations specified in the NRC's safety evaluation (SE) of topical report SIR-94-080, Revision 1 (ADAMS Legacy Accession Nos. 9706230099 and 9706240192).

Regulatory Basis General design criterion (GDC) 4 of Appendix A to 10 CFR 50 states that structures, systems, or components (SSCs) important to safety be designed to accommodate the effects of and be compatible with the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents, including loss-of-coolant accidents. GDC 4 further states that SSCs shall be appropriately protected against dynamic effects, which include the effects of missiles, pipe whipping , and discharging fluids , that may result from equipment failures. The RCP flywheel is a large solid metallic disk and is part of the RCP motor to provide rotational inertia when the RCP motors are turned off to ensure slow decrease in reactor coolant flow. If the RCP flywheel fails during normal operation , it has sufficient kinetic energy to produce high-energy missiles that could damage SSCs important to safety in the reactor coolant system.

Structural integrity of the RCP flywheels thus must be maintained in order to meet the design criterion of GDC 4. Therefore, NRC staff (the staff) determined that the following requests for additional information (RAls) pertaining to the structural integrity of St. Lucie, Unit 2 RCP flywheels is needed to complete the review of the LAR.

The staff noted that conclusion (1) in Section 4 of the staff's SE of SIR-94-080, Revision 1 specifies that licensees meeting the first condition stated in the SE should either conduct a volumetric examination through a "qualified in-place [ultrasonic testing (UT)] examination" or surface examination . In the markup of St. Lucie, Unit 2 TS 6.8.4.o in the licensee's LAR, however, the licensee stated that the RCP flywheel be inspected "100% volumetric inspection" but did not state the type of volumetric inspection to be a "qualified in-place UT examination ," as specified in the staff's SE of SIR-94-080, Revision 1.

Request: State the type of volumetric inspection for the St. Lucie Unit 2 RCP flywheels proposed in the LAR. If the stated volumetric inspection is not" a "qualified in-place UT examination, " as specified in the staff's SE of SI R-94-080, Revision 1, justify how the stated volumetric inspection is equivalent to a "qualified in-place UT examination ."

FPL Response:

The term "qualified in place" refers the process of calibrating the search unit on the component at a known location. FPL employs qualified volumetric procedure NDE 5.15, "Ultrasonic Examination of Reactor Coolant Pump Flywheels" for examining the RCP flywheels . The procedure calls for calibration of the complete ultrasonic examination system by placing the search unit transducer on

St. Lucie Unit 2 L-2020-061 Docket No. 50-389 Enclos ure Page 3 of 4 the flywheel peripheral edge with the sound beam aimed at the bore hole and maximizing the signal response from a keyway to set the search unit sensitivity level. Any change in search units, ultrasonic instruments, cables, wedges, or Level 111111 personnel is cause for a calibration check.

NOE 5.15 requires peripheral scanning of the flywheels 360 degrees in two directions using a 25-degree longitudinal, 2.25 MHz, 1/2" x 1" transducer with a 40-inch screen distance.

RAI- -2 In Section 3.5 of the enclosure to the submittal, the licensee calculated fracture toughness (Kie) using empirical formulas and stated that the resulting Kie values "are of greater toughness than the lower bound ASME Kie vs. T-RTNoT curve. " The staff noted that this conclusion is inconsistent with the licensee's calculation of Kie 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 Ki e values using the empirical formulas were less than the ASME Code Kie value.

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

FPL Response:

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 Kie using the derived RTNOT 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 (ksiv'in)

Correlation Name Equation CVN at Room CVN at Temp. (-72°F) +110°F Carten and Sailors 15.5 (CVN) 0 *5 139.5 147.0 Roberts and Newton 9.35(CVN) 063 149.0 159.2 ASME XI , Appendix A 33.2 + 20.734 exp[0.02(T - RTNoT)] 69.5 50 While not a direct comparison to the Kie calculated in 3.4, the correlations do result in values that exceed both the 90 ksiv'in 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 Kie of 449 ksiv'in . However, the ASME Kie vs. T-RT NOT curve is truncated above 200 ksiv'in , and 200 ksiv'in is considered the maximum attainable Kie 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 RTNOT (+40°F versus -50°F for St. Lucie Unit 2) , which correlates to lower toughness.

St. Lucie Unit 2 L-2020-061 Docket No. 50-389 Enclosure Page 4 of 4

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, RAls for LAR to Revise Technical Specifications 6.8.4.o, "Reactor Coolant Pump Flywheel Inspection Program", March 31 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)