ML25092A037

Final Request for Additional Information Regarding Final Response to Generic Letter 2004-02 (EPID L-2017-LRC-0000) (1)

ML25092A037
Person / Time
Site:	Saint Lucie
Issue date:	04/01/2025
From:	Natreon Jordan NRC/NRR/DORL/LPL2-2
To:	Falkiewicz T, Mack J Florida Power & Light Co
References
EPID L-2017-LRC-0000
Download: ML25092A037 (1)

Text

From:

Natreon Jordan To:

Mack, Jarrett; Falkiewicz, Timothy Cc:

Mack, Kenneth

Subject:

St. Lucie Units 1 and 2 - Final Request for Additional Information Regarding Final Response to Generic Letter 2004-02 (EPID L-2017-LRC-0000)

Date:

Sunday, December 29, 2024 10:38:00 PM On August 7, 2024, the U.S. Nuclear Regulatory Commission (NRC) staff issued draft Requests for Additional Information (RAIs) to Florida Power and Light Company (FPL), which are identified below. The RAIs are related to FPLs response to Generic Letter (GL) 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors, dated September 13, 2004 (ML042360586).

On December 9, 2024, the NRC and FPL held a conference call to clarify the draft RAIs. At the conclusion of the call, FPL informed the NRC staff that the information requested was understood and that no additional clarification of the RAIs was necessary. A publicly available version of this final RAI (with the term Draft removed) will be placed in the NRCs Agencywide Documents Access and Management System (ADAMS). As agreed, please provide a response to the specified RAIs within 60 days of this correspondence.

Thanks,

-Nate

Natreon (Nate) Jordan Nuclear Engineer (Project Manager)

Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop O-8B1A Washington, DC 20555 301-415-7410 natreon.jordan@nrc.gov

From: Natreon Jordan Sent: Wednesday, August 7, 2024 12:22 PM To: Mack, Jarrett <Jarrett.Mack@fpl.com>; Falkiewicz, Timothy <Timothy.Falkiewicz@fpl.com>

Cc: Michael Mahoney <Michael.Mahoney@nrc.gov>

Subject:

St. Lucie Units 1 and 2 - Draft Request for Additional Information Regarding Final Response to Generic Letter 2004-02 (EPID L-2017-LRC-0000)

Good Afternoon Tim/Jarrett,

By letter dated December 20, 2017 (Agencywide Documents Access and

Management System (ADAMS) Accession No. ML17362A108), and supplemented by letter dated December 4, 2020 (ML20339A501), Florida Power and Light Company (FPL) submitted its final response to Generic Letter (GL) 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors, dated September 13, 2004 (ML042360586), for the St.

Lucie Plant, Units 1 and 2 (St. Lucie).

GL 2004-02 requested that licensees provide information confirming that their plants are in compliance with Section 50.46 of Title 10 of the Code of Federal Regulations (10 CFR) that requires plants to be able maintain adequate long-term core cooling to ensure that the fuel in the core can be cooled and maintained in a safe and stable configuration following a postulated accident. In accordance with 10 CFR 50.54(f),

addressees for GL 2004-02 are required to submit written responses to the generic letter.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided in FPLs final response to GL 2004-02 for St. Lucie and has determined that additional information is needed to complete the NRC staffs review. The [Draft]

request for additional information (RAIs) are below.

RAI 1

The methods for calculation of void fraction and NPSH required calculations provided in the St. Lucie, December 4, 2020, submittal did not adequately address the issues identified below.

The use of the Rayleigh-Plesset equation is not applicable to degasification because it is focused on bubbles formed by water vapor and not non-condensable gasses.

While the 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 staff also noted that the pressure changes during cavitation can be significantly more abrupt than those being evaluated for the strainer. Reference 3 of found in FPLs December 4, 2020, submittal 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. The "acceptance limit" in RG 1.82 is only part of the guidance.

Demonstration that the void fraction is less than 2 percent is also 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. 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. Conditions other than this may lead to

significantly inaccurate calculation of void fraction.

Verify that using the mid-height of the strainer provides an accurate estimate of degasification or revise the assumption. In addition, provide a degasification evaluation that addresses the issues noted above.

RAI 2

The St. Lucie submittal of December 4, 2020, states that the minimum flow rate per fuel assembly credited for Unit 1 is based on two HPSI pumps operating at a total flow rate of 1280 gpm to attain a fuel assembly flow rate of 5.9 gpm/FA. For Unit 2 it is assumed that 2 HPSI pumps provide 1400 gpm (700 gpm per pump) resulting in a flow rate of 6.5 gpm/FA. It appears that a single failure of a HPSI pump would result in a fuel assembly flow rate below the range evaluated in WCAP-17788.

Provide the basis for crediting the flow rate of 5.9 gpm for Unit 1 and 6.5 gpm for Unit

2. If the minimum flow rate could be below the analyzed range, provide an evaluation of the applicability of the analysis to the plant specific conditions, including the limiting single failure.

Please let me know if you would like to request a clarification call to discuss the proposed RAIs further.

Thanks,

-Nate

Natreon (Nate) Jordan Nuclear Engineer (Project Manager)

Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop O-8B1A Washington, DC 20555 301-415-7410 natreon.jordan@nrc.gov