ML25076A675
| ML25076A675 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/17/2025 |
| From: | Para W Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| Download: ML25076A675 (1) | |
Text
200 Energy Way Kennett Square, PA 19348 www.constellation.com 10 CFR 50.90 10 CFR 50.91(a)(5)
March 17, 2025 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317
SUBJECT:
Response to Request for Additional Information for the Emergency License Amendment Request - One-Time Extension of the Control Room Emergency Ventilation System (CREVS) Technical Specification
REFERENCE:
1.
Letter from W. Para (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 March 15, 2025 (ADAMS Accession No. ML25074A002) 2.
Electronic mail from S. Bina (U.S. Nuclear Regulatory Commission) to A. Donell (Constellation), RAIs for Calvert Cliffs Emergency LAR,"
March 16, 2025, 9:01 PM EDT By letter dated March 15, 2025 (Reference 1) Constellation Energy Generation, LLC (CEG),
requested a change to the Technical Specifications (TS) of Renewed Facility Operating License No. DPR-53 for Calvert Cliffs Nuclear Power Plant (CCNPP), Unit 1 under an emergency basis pursuant to 10 CFR 50.91(a)(5). The proposed change is 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 17 days, for one train of the CREVS inoperable.
This one-time extension is necessary to support ongoing modifications and return to service testing of the 13.8 kV Service Bus 21, which CEG is projecting will challenge the current CREVS CT of seven (7) days.
By electronic mail dated March 16, 2025 (Reference 2), the U.S. Nuclear Regulatory Commission (NRC) identified areas where additional information was necessary to complete the review. to this letter contains the NRC's request for additional information immediately followed by CEGs response. Attachment 2 provides an updated list of Protected Equipment
Response to Request for the Additional Information for Emergency License Amendment Request One-Time Extension of the CREVS Technical Specification Docket No. 50-317 March 17, 2025 Page 2 for 12 CREV OOS. Attachments 3 and 4 provide an updated markup of the affected TS page and the associated clean page, respectively. The update adds a reference to this response to document the updated list of Protected Equipment for 12 CREV OOS.
The Technical Evaluation documented in Reference 1 is supplemented by the information in this transmittal. 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.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," paragraph (b), CEG is notifying the State of Maryland of this application for license amendment by transmitting a copy of this letter and its attachments to the designated State Official.
Should you have any questions concerning this submittal, please contact Adam Donell at (267) 533-5156.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 17th day of March 2025.
Respectfully, Wendi Para Sr. Manager - Licensing Constellation Energy Generation, LLC Attachments:
1.
Request for Additional Information and CEG Response 2.
Protected Equipment for 12 CREV OOS
- 3.
Updated Proposed Technical Specification Change (Markup) 4.
Updated Proposed Technical Specification Change (Clean) 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 Request for Additional Information and CEG Response Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317 Page 1 of 3 By application dated March 15, 2025, Constellation Energy Generation, LLC requested changes to the Technical Specifications (TSs) for Calvert Cliffs Nuclear Power Plant (CCNPP), Unit 1.
The proposed changes would allow a one-time extension to the Completion Time (CT) for TS 3.7.8, Control Room Emergency Ventilation System (CREVS), Required Action C.1 from 7 days to 17 days. The licensee stated the one-time extension is necessary to support ongoing modifications and return to service testing of the 13.8 kV Service Bus 21.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the submittal and has determined that the following additional information is needed to complete its review.
Request for Additional Information (RAI) EEEB-1 The fourth paragraph of section 3.1, Safety Analysis, of the LAR states, in part:
In the current electrical line up, CCNPP has two of the four offsite power sources available (5051 and 5052). These sources are being supplied to downstream 4 kV buses through a single 13 kV Bus (11) and a single 13 kV/4 kV transformer (U-4000-12), including the 24 4 kV bus for 12 CREVS/CRETS.
Please clarify which single 13 kV Bus supplies power to the 12 CREVS/CRETS (i.e.,13 kV Bus (11) or 13 kV Bus (21).
CEG RESPONSE:
In the current alignment to support outage work, the 12 CREVS/CRETS train is being powered from the CCNPP, Unit 1 13.8 kV Service Bus 11. This electrical alignment for the 12 CREVS/CRETS train is through the U-4000-12 transformer and the 4.16 kV Engineered Safety Feature (ESF) Bus 24, and is backed up by the 2B Diesel Generator (DG).
The 12 CREVS/CRETS train is normally powered from the CCNPP, Unit 2 13.8 kV Service Bus 21, through the U-4000-22 transformer and the 4.16 kV ESF Bus 24, and is backed up by the 2B DG.
RAI EEEB-2 The fifth paragraph of section 3.1 of the LAR states, in part:
As detailed in Section 3.2, Risk Assessment Insights and Compensatory Measures, to reduce the possibility that maintenance activities could contribute to a loss-of-offsite power, the protected equipment to prevent 11 CREVS being declared INOPERABLE includes 11 CR HVAC, 1A DG, and the 2B DG which is the emergency supply to the 12 CREVS. The main control room has placed protected equipment tags on the hand switch for 13 kV Bus (11) and will continue to protect the single 13 kV / 4 kV transformer (U-4000-12), including the 4 kV Bus 11 for 11 CREVS/CRETS.
However, the seventh paragraph of Section 3.1 of the LAR further states, in part:
ATTACHMENT 1 Request for Additional Information and CEG Response Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317 Page 2 of 3 During the electrical upgrade maintenance window in which the 4 kV Bus 11 (power to 11 CREVS) is protected, some work will be required on the bus. Specifically, wiring will be required on the alternate feeder breaker for the 4 kV Bus 11. This breaker is on the bus and will be open as the normal feeder will be supplying power to the bus.
According to the above paragraphs, the licensee is protecting equipment including 13 kV Bus (11) and the single 13 kV / 4 kV transformer (U-4000-12) to reduce the possibility that maintenance activities could contribute to a loss-of-offsite power. However, it appears that the 13 kV Bus (11), the single 13 kV / 4 kV transformer (U-4000-12), and the 4 kV Bus 11 are not included in the list of protected equipment in section 3.2, Risk Assessment Insights and Compensatory Measures of the LAR.
Please explain why the 13 kV Bus (11), the single 13 kV / 4 kV transformer (U-4000-12), and the 4 kV Bus 11 are not listed as protected equipment in section 3.2 of the LAR or add this aforementioned equipment to section 3.2 of the LAR as protected equipment.
CEG RESPONSE:
The 13.8 kV Service Bus 11 feeder breaker, U-4000-11 transformer and feeder breaker, and the 4.16 kV ESF Bus 11 feeder breaker are protected in the field with physical barriers, and the control room hand switches are being protected with green protected equipment signs.
Additionally, although 12 CREV is inoperable based on not having independent power, it is available to provide cooling. Therefore, the U-4000-12 transformer and feeder breaker, and the 4.16 kV ESF Bus 24 feeder breaker, are being protected in the field with physical barriers, and the control room hand switches are being protected with green protected equipment signs.
provides an updated list of Protected Equipment for 12 CREV OOS, which includes the 13.8 kV Service Bus 11 feeder breaker, the U-4000-11 transformer and feeder breaker, the U-4000-12 transformer and feeder breaker, the 4.16 kV ESF Bus 11 feeder breaker, and the 4.16 kV ESF Bus 24 feeder breaker. The remaining Compensatory Measures, including other protected equipment, described in the March 15, 2025, letter remain unchanged.
Attachments 3 and 4 provide an updated markup of the affected TS page and the associated clean page, respectively. The update adds a reference to this response to document the updated list of Protected Equipment for 12 CREV OOS.
RAI EEEB-3 LAR section 2.1, CREVS Design and Operation states, in part, that the 12 CREVS train is normally powered from the Unit 2 4.16 kV ESF Bus 24, which is connected to the 13.8 kV Service Bus 21 offsite circuit and backed up by the 2B DG.
The third paragraph of section 3.1 of the LAR states, in part:
The 12 CREVS train will be powered from its alternate offsite power supply during this
ATTACHMENT 1 Request for Additional Information and CEG Response Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317 Page 3 of 3 period, and have its emergency onsite power supply, the 2B DG, available during this period. The non-safety related 0C DG is available as a backup emergency power source for the 12 CREVS.
LAR section 3.2 states, in part, that wiring work on the 4 kV Bus 24 normal feeder breaker will be performed.
It appears that any potential failure of the 4 kV Bus 24 as the result of work on this bus would make it not available to receive power from the 2B DG. Consequently, 0C DG becomes a backup power source for the 12 CREVS train in the event of loss of offsite power.
Please clarify whether the 0C DG should be protected (i.e. added to protected equipment list in section 3.2) during the proposed extended completion time for TS 3.7.8, Required Action C.1, given the stated wiring work to be performed.
CEG RESPONSE:
The 0C DG is being protected and will continue to be protected during the proposed extended completion time for TS 3.7.8, Required Action C.1.
A failure of the 4.16 kV Bus 24 normal feeder breaker would cause the 2B DG to start and would not prevent the 2B DG from powering the bus. This configuration meets the requirements for a response to an undervoltage event. The 0C DG is available as a backup power source for the 4.16 kV Bus 24 in the event the 2B DG is unavailable.
However, if the 4.16 kV Bus 24 is faulted due to a lockout on the Bus, it would be unable to receive power from either the 2B DG or the 0C DG.
provides an updated list of Protected Equipment for 12 CREV OOS, which includes the 0C DG. The remaining Compensatory Measures, including other protected equipment, described in the March 15, 2025, letter remain unchanged.
Attachments 3 and 4 provide an updated markup of the affected TS page and the associated clean page, respectively. The update adds a reference to this response to document the updated list of Protected Equipment for 12 CREV OOS.
ATTACHMENT 2 Protected Equipment for 12 CREV OOS Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317 Page 1 of 2 Protected Equipment for 12 CREV OOS*
11 CR HVAC o
Fan housing o
Condenser breaker o
Compressor breaker o
Fan Hand Switch 1A DG o
Control Room Console o
Diesel Generator Room 2B DG**
o Control Room Console o
Diesel Generator Room 0C DG o
Control Room Console o
Diesel Generator Room 500 kV Breakers 552-22, 552-41, 552-43, 552-21, 552-23, and control room hand switches 500 kV Switchyard Control House 13 kV Bus 11 o
Unit 1 Metal Clad Enclosure and all enclosed breakers, including feeder breaker o
Control Room Feeder Breaker Hand Switch U-4000-11 13/4 kV Transformer o
Transformer o
Feeder Breaker o
Control Room Feeder Breaker Hand Switch U-4000-12 13/4 kV Transformer o
Transformer o
Feeder Breaker o
Control Room Feeder Breaker Hand Switch 4 kV Bus 11 o
Feeder Breaker o
Control Room Feeder Breaker Hand Switch 4 kV Bus 24 o
Feeder Breaker o
Control Room Feeder Breaker Hand Switch
- Note: During the electrical upgrade maintenance window in which the 4 kV Bus 11 (power to 11 CREVS) is protected, some work will be required on the bus. Specifically, wiring will be required on the alternate feeder breaker for the 4 kV Bus 11. This breaker is on the bus and will be open as the normal feeder will be supplying power to the bus. This will be approved by the protected equipment procedure (OP-AA-108-117) and require a targeted pre-job brief, supervisor oversight in the field and periodic monitoring by an Operations Supervisor. Additionally, this work screens as Elevated Risk per the Integrated Risk Management procedure (OP-AA-107). A risk mitigation plan (RMP) will also be required to specify actions required to mitigate any potential errors. Separate from that work, wiring work on the 4 kV Bus 24 normal feeder breaker will be performed. This will not screen as elevated risk work due to Unit 2 being in mode 5. Work
ATTACHMENT 2 Protected Equipment for 12 CREV OOS Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317 Page 2 of 2 on the 4 kV Bus 24 will not be performed at the same time as the 4 kV Bus 11 work and will have supervisor oversight. Work will not be allowed on both 11 and 12 CREVS power supplies at the same time.
- The 2B DG is duplicated from the March 15, 2025, Protect Equipment list, and is added here for completeness. The Protect Fire Areas and Protect Equipment lists from the March 15, 2025, letter, Section 3.2 remain unchanged.
ATTACHMENT 3 Emergency License Amendment Request Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317 Updated Proposed Technical Specification Change (Markup)
TS Page 3.7.8-2
CREVS 3.7.8 CALVERT CLIFFS - UNIT 1 3.7.8-2 Amendment No. 321 CALVERT CLIFFS - UNIT 2 Amendment No. 299 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME B.
One or more CREVS trains inoperable due to inoperable CRE boundary in MODE 1, 2, 3, or 4.
B.1 Initiate action to implement mitigating actions.
AND B.2 Verify mitigating actions ensure CRE occupant exposures to radiological, chemical, and smoke hazards will not exceed limits.
AND B.3 Restore CRE boundary to OPERABLE status.
Immediately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 90 days C.
One CREVS train inoperable for reasons other than Condition A or B in MODE 1, 2, 3, or 4.
C.1 Restore CREVS train to OPERABLE status.
7 days
- This Action is extended for Unit 1 from 7 days to 17 days during electrical modifications and restoration work associated with the 13.8 kV Bus 21. The one-time extension will remain in effect until March 29, 2025 at 06:16 EDT or until the 12 CREVS train is returned to OPERABLE status, whichever occurs sooner. Compensatory measures detailed within Constellation Energy Generation, LLC letter dated March 15, 2025, including the updated "Protected Equipment for 12 CREV OOS" detailed within Constellation Energy Generation, LLC letter dated March 17, 2025, shall be implemented and shall remain in effect during the extended Completion Time period.
ATTACHMENT 4 Emergency License Amendment Request Calvert Cliffs Nuclear Power Plant, Unit 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317 Updated Proposed Technical Specification Change (Clean)
TS Page 3.7.8-2
CREVS 3.7.8 CALVERT CLIFFS - UNIT 1 3.7.8-2 CALVERT CLIFFS - UNIT 2 Amendment No.
Amendment No. 299 ACTIONS (continued)
CONDITION REQUIRED ACTION COMPLETION TIME B.
One or more CREVS trains inoperable due to inoperable CRE boundary in MODE 1, 2, 3, or 4.
B.1 Initiate action to implement mitigating actions.
AND B.2 Verify mitigating actions ensure CRE occupant exposures to radiological, chemical, and smoke hazards will not exceed limits.
AND B.3 Restore CRE boundary to OPERABLE status.
Immediately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 90 days C.
One CREVS train inoperable for reasons other than Condition A or B in MODE 1, 2, 3, or 4.
C.1 Restore CREVS train to OPERABLE status.
7 days
- This Action is extended for Unit 1 from 7 days to 17 days during electrical modifications and restoration work associated with the 13.8 kV Bus 21. The one-time extension will remain in effect until March 29, 2025 at 06:16 EDT or until the 12 CREVS train is returned to OPERABLE status, whichever occurs sooner. Compensatory measures detailed within Constellation Energy Generation, LLC letter dated March 15, 2025, including the updated "Protected Equipment for 12 CREV OOS" detailed within Constellation Energy Generation, LLC letter dated March 17, 2025, shall be implemented and shall remain in effect during the extended Completion Time period.