ML23155A001

Response to Request for Additional Information by the Office of Nuclear Reactor Regulation to Support Review of an Emergency License Amendment Request - One-Time Extension of the Control Room Emergency Ventilation System (C

ML23155A001
Person / Time
Site:	Calvert Cliffs
Issue date:	06/04/2023
From:	David Helker Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML23155A001 (1)

Text

200 Exelon Way Kennett Square, PA 19348 www.constellation.com 10 CFR 50.90 10 CFR 50.91(a)(5)

June 4, 2023 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318

SUBJECT:

Response to Request for Additional Information by the Office of Nuclear Reactor Regulation to support Review of an Emergency License Amendment Request - One-Time Extension of the Control Room Emergency Ventilation System (CREVS) Technical Specification REFERENCES 1. Letter from D. P. Helker (Constellation) to U.S. Nuclear Regulatory Commission, Emergency License Amendment Request - One-Time Extension of the Control Room Emergency Ventilation System (CREVS)

Technical Specification, dated June 2, 2023 (ADAMS Accession No. ML23153A098)

2. Electronic mail from S. Goetz (U.S. Nuclear Regulatory Commission) to W. Para (Constellation), Calvert Cliffs - Request for Additional Information Re: Revision to TS 3.7.8," dated June 4, 2023 (EPID: L-2023-LLA-0076)

By letter dated June 2, 2023 (Reference 1) Constellation Energy Generation, LLC (CEG),

requested a change to the Technical Specifications (TS), Appendix A of Renewed Facility Operating License Nos. DPR-53 and DPR-69 for Calvert Cliffs Nuclear Power Plant, Units 1 and 2 (CCNPP) under an emergency basis pursuant to 10 CFR 50.91(a)(5). The proposed amendment requested a one-time extension to TS 3.7.8 Control Room Emergency Ventilation System (CREVS) Action C.1 Completion Time (CT), from seven (7) days to 16 days, for one train of the control room emergency ventilation system inoperable due to the emergency power supply for the train being inoperable.

By electronic mail dated June 4, 2023 (Reference 2), the U.S. Nuclear Regulatory Commission (NRC) identified areas where additional information was necessary to complete the review.

The attachment to this letter contains the NRC's request for additional information immediately followed by CEGs response.

Response to Request for Additional Information by the Office of Nuclear Reactor Regulation to support Review of an Emergency License Amendment Request for One-Time Extension of the CREVS Technical Specification Docket Nos. 50-317 and 50-318 June 4, 2023 Page 2 CEG has reviewed the information supporting a finding of no significant hazards consideration and the environmental consideration provided to the NRC in Reference 1. The information attached to this letter does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. Furthermore, the information attached to this letter does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.

There are no regulatory commitments contained in this submittal.

Should you have any questions concerning this submittal, please contact Ms. Wendi E. Para at (267) 533-5208.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 4th day of June 2023.

Respectfully, David P. Helker Sr. Manager - Licensing Constellation Energy Generation, LLC

Attachment:

NRC Request for Additional Information and CEG Response cc: USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, Calvert Cliffs Nuclear Power Plant USNRC Project Manager, NRR - Calvert Cliffs Nuclear Power Plant S. Seaman, State of Maryland

ATTACHMENT 1 NRC Request for Additional Information and CEG Response Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318 RAI #1 The non-safety related 0C DG is credited as the onsite source of power for the 11 CREVS for the duration of the proposed AOT extension. The submittal states:

CCNPP has also evaluated the 0C DG for the same condition existing on the 1A DG, since they are both Societie' Alsacienne de Constructions Mechaniques De Mulhouse (SACM) DGs from the same manufacturer. CCNPP is confident that the 0C DG remains capable of performing its function following a loss-of-offsite power.

Over the past few years, the 1A DG, which is safety related and similar to the 0C DG, has experienced several failures requiring extended maintenance. Please discuss why CCNPP is confident that the 0C DG remains capable of supplying 11 CREVS and other loads if needed.

CEG RESPONSE:

The 1A DG piston failures have been attributed to foreign material or over-fueling. Two failures (2007 and 2022) have direct connection with FME and very specific issues that would have no commonality with the 0C DG. The third failure (2023) appears to be tied to an over-fueling event. A modification was performed on the 1A DG that had the potential to adjust the governor actuator shaft and fuel rack during the modification process that could have reinstalled the assembly outside of designated factory settings. This modification was not performed on the 0C DG and therefore does not render it susceptible to that potential non-conforming condition.

Furthermore, the 0C DG has pistons that have been in-service for greater than 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> with no failures whereas the 1A DG piston failed after approximately 330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br /> of service time. This would indicate that the overall fuel delivery system of the 0C DG is working properly. Also, the 0C DG is expected to be loaded to approximately 4.0 MW in an event which does not position the fuel rack to the maximum setting, which allows margin for a fuel injection pump with a high setting. Based on the preceding documented items, CCNPP is confident there is no common cause of failure with the 1A DG and the 0C DG remains capable of supplying 11 CREVS and other loads if needed.

RAI #2 The LAR discusses other options should 0C DG fail to operate. Specifically, the submittal states:

Additionally, in the event of failure of the 0C diesel, the 11 CREVS can be powered by tying lower level busses in accordance with site operating procedures. Loss of all power to the CREVS would require loss of the four offsite power sources and failure of the 0C DG to start.

Please discuss the capability to power 11 CREVS from other lower level busses and the ability of those busses to carry the assumed loads.

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ATTACHMENT 1 NRC Request for Additional Information and CEG Response Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318 CEG RESPONSE:

Motor Control Center (MCC) 114R supplies power to 11 CREVS, specifically 11 control room HVAC fan and 11 Post-LOCI Filter Fan. This is an A train MCC and can be powered from the 1B diesel generator thru MCC 104R if required. Motor Control Centers 104R and 114R are equipped with tie breakers which allow the busses to be re-energized from the opposite train in the event of a loss of power to the upstream load center. The tie breakers are operated manually at the MCC. The operation will be accomplished in accordance with Operating Instruction OI-27D-1. Section 6.14 TYING VITAL MCCs directs operators to open pre-determined Non-Essential loads in accordance with Attachment 1A prior to tying the MCCs to prevent overloading the supplying MCCs feeder breaker. Operating crews will be briefed on the required actions.

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