ML24352A118

NRR E-mail Capture - Request for Additional Information GL 2004-02 Closure (L-2017-LRC-0000)

ML24352A118
Person / Time
Site:	Turkey Point
Issue date:	12/11/2024
From:	Perry Buckberg NRC/NRR/DORL/LPL2-2
To:	Mack J Florida Power & Light Co
Buckberg P
References
L-2017-LRC-0000
Download: ML24352A118 (5)

Text

From:

Perry Buckberg Sent:

Wednesday, December 11, 2024 3:54 PM To:

Mack, Jarrett (Jarrett.Mack@fpl.com)

Subject:

Turkey Point Nuclear Plant, Units 3 and 4 - Request for Additional Information Regarding Final Response to close Generic Letter (GL) 2004 L-2017-LRC-0000 Attachments:

Final RAIs - GL 2004-02 Closeout Turkey Point 3 and 4 L-2017-LRC-0000.docx Good afternoon Jarrett.

On December 29, 2017, (Agencywide Documents Access and Management System (ADAMS)

Accession No. ML17363A265), Florida Power and Light Company (FPL), the licensee, submitted final responses to close Generic Letter (GL) 2004-02, dated September 13, 2004 (ADAMS Accession No. ML042360586), Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors, for Turkey Point Nuclear Units 3 and 4 (Turkey Point).

The U.S. Nuclear Regulatory Commission (NRC) and NextEra have been working on closing GL 2004-02 at Turkey Point for an extended time. The licensee provided closure information for Turkey Point and later provided follow up information intended to address the in-vessel question and also address issues that had been identified in other areas by the NRC reviewers. The questions in this Request for Additional Information (RAI) represent the extent of NRC open issues associated with GL 2004-02 at Turkey Point.

Consistent with your e-mail today, the NRC requests that the response to the attached final RAI be issued within 60 days of this email.

Thanks, Perry Buckberg Senior Project Manager / Agency 2.206 Petition Coordinator U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation office: (301)415-1383 perry.buckberg@nrc.gov Mail Stop O-8B1a, Washington, DC, 20555-0001

Hearing Identifier:

NRR_DRMA Email Number:

2673 Mail Envelope Properties (PH0PR09MB76749FD4D20ACFB4A393579E9A3E2)

Subject:

Turkey Point Nuclear Plant, Units 3 and 4 - Request for Additional Information Regarding Final Response to close Generic Letter (GL) 2004 L-2017-LRC-0000 Sent Date:

12/11/2024 3:54:23 PM Received Date:

12/11/2024 3:54:00 PM From:

Perry Buckberg Created By:

Perry.Buckberg@nrc.gov Recipients:

"Mack, Jarrett (Jarrett.Mack@fpl.com)" <Jarrett.Mack@fpl.com>

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REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING GENERIC LETTER 2004-02 CLOSEOUT FLORIDA POWER AND LIGHT COMPANY TURKEY POINT NUCLEAR GENERATING STATION, UNITS 3 AND 4 FLORIDA POWER AND LIGHT COMPANY DOCKET NOS. 50-250 AND 50-251 EPID NO. L-2017-LRC-0000

Background

In letter dated December 29, 2017, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17363A265), Florida Power and Light Company (FPL), the licensee, submitted final responses to close Generic Letter (GL) 2004-02, dated September 13, 2004 (ADAMS Accession No. ML042360586), Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors, for Turkey Point Nuclear Units 3 and 4 (Turkey Point). The December 29, 2017, letter was supplemented by additional information related to the closure of GL 2004-02 on April 14, 2021 (ML21104A139).

The NRC and NextEra have been working on closing GL 2004-02 at Turkey Point for an extended time. The licensee provided closure information for Turkey Point and later provided follow up information intended to address the in-vessel question and also address issues that had been identified in other areas by the NRC reviewers. The questions in this RAI represent the extent of NRC open issues associated with GL 2004-02 at Turkey Point.

NRC Staff Requests for Additional Information (RAIs)

RAI -1 For Region II breaks at Turkey Point 4, the NPSH margin calculation credits Containment Accident Pressure (CAP). The NRC staff understands that the plant licensing basis for NPSH assumes that, for NPSH calculations, the surface pressure of the sump is assumed to be the saturation pressure of the sump fluid. Refer to the NextEra Audit Plan, dated November 26, 2018 (ML18331A033), for details on the NRCs original questions. Also, refer to the response to a request for additional information (RAI) for its extended power uprate (EPU), as documented in ADAMS Accession No. ML11151A204 for the NRC staff understanding of the Turkey Point 4 current licensing basis.

During the audit, the NRC staff understood that Turkey Point would evaluate the potential for use of a 50.59 evaluation to justify the change to credit CAP for the NPSH evaluations. The NRC staff did not find additional information regarding this evaluation in the most recent submittal.

2 Since the time of the audit, Regulatory Guide 1.82 has been updated to Revision 5 and now contains the most recent guidance on acceptable methods to evaluate the use of CAP credit for NPSH margin calculations. The NRC Staff SE for NEI 04-07 allows relaxed evaluation for some aspects of Region II breaks. However, it states that license amendments may be required to change the licensing basis to allow relaxations. The Turkey Point letter dated April 14, 2021, regarding closure of GL 2004-02 did not address the CAP issue including the proposed 50.59 evaluation discussed above.

Regarding the need for a license amendment to credit CAP for NPSH evaluations, the NRC staff identified the following from the statements of consideration from a 1999 rule change to 10 CFR 50.59. (Reference Federal Register/Vol. 64, No. 191/Monday, October 4, 999/Rules and Regulations 53599).

Example 4: The licensee wishes to change an analysis described in the FSAR which states that adequate net positive suction head (NPSH) is verified by analysis without crediting containment overpressure. The new analysis will assume that five pounds of overpressure is credited in calculation of available NPSH. The revised analysis predicts more (five additional pounds of) available NPSH for the pumps, a result further from the limit (the required NPSH) for an analysis that establishes part of the design bases for the pumps as being capable of performing their required function under the range of expected conditions. This change cannot be made without prior NRC approval because a change in an element of a method described in the FSAR, used to establish the design basis, that is not conservative, or essentially the same, is a departure.

Provide a license amendment request to incorporate the use of CAP into the Turkey Point 4 licensing basis for Region II breaks or provide an alternate evaluation that justifies that this is not required by regulations and has been adequately analyzed for Turkey Point 4.

RAI-2

The NRC staff reviewed the methods for calculation of void fraction and NPSH required calculations provided in the Turkey Point, April 14, 2021, submittal and have identified the following issues:

a. The use of the Rayleigh-Plesset equation is not applicable to degasification because it is focused on bubbles formed by water vapor, instead of non-condensable gasses. While the NRC staff agrees that gas bubbles will be compressed as they travel to the pump suction it is unlikely that they will collapse as described for the water vapor voids in the submittal. The NRC staff also noted that the pressure changes during cavitation can be significantly more abrupt than those being evaluated for the strainer. The reference indicates that the experiments used to reach the conclusions for Rayleigh-Plesset equation used extreme care to degasify the water prior to the experiments. This provides additional evidence that the theory is not applicable to conditions where degasification is predicted to occur.

b. The NRC staff reviewed the referenced GL 04-02 submittals from other licensees and determined that those submittals were evaluated based on plant-specific conditions that contained significant margins. In addition, both plants corrected the NPSH required for the pumps based on the results of the analyses. The

3 licensee should provide an evaluation for Turkey Point that is valid for the plant-specific conditions, including margins and conservatism as appropriate.

c. The NRC staff also noted that the "acceptance limit" in RG 1.82 is only part of the guidance. Demonstration that the void fraction is less than 2 percent is a part of the guidance. In addition, void fractions between 0 and 2 percent are used to calculate a penalty in NPSH required for the pumps. The submittal did not make the corrections to NPSH required as the methodology in the guidance suggests.

The NRC staff understands that the plants are not licensed to RG 1.82 and that the guidance is only one way to demonstrate compliance with regulations.

Licensees do not have to follow the guidance in RG 1.82. However, in lieu of using the guidance, a different methodology for showing adequate pump operation with the calculated void fraction over the required period is needed.

d. For calculating void fractions, it is acceptable to use the strainer mid-height if the strainer is vertically symmetric and the degasification occurs over the entire height of the strainer. Other conditions may lead to significantly inaccurate calculation of void fraction. The NRC staff noted that for Region II breaks, more realistic assumptions may be used for the void fraction analysis.

Provide a degasification evaluation that addresses the issues as noted above.

RAI-3

According to FPL letter Updated Final Response to NRC Generic Letter 2004-02, dated December 29, 2017, the sump strainer chemical effects analysis for Turkey Point 3 and Turkey Point 4 uses the same buffer, pH, and post-LOCA temperature profile. Page E1-260 states that the total amount of aluminum that would precipitate in the containment sump pool based on reactor cavity breaks for Turkey Point 3 and Turkey Point 4 is 413.1 kilograms and 341.7 kilograms, respectively. The total amount of aluminum precipitate for the break locations outside the reactor cavity are also different between the two units. The maximum temperature where aluminum precipitation could occur is stated as 247.8 degrees Fahrenheit for both Turkey Point 3 and Turkey Point 4. The NRC staff would expect different precipitation temperatures for Turkey Point 3 and Turkey Point 4 if the pH assumptions are the same and there are different quantities of aluminum in solution.

Please confirm the maximum precipitation temperature.