05000249/LER-2024-002-01, Nuclear Power Station, Unit 3, Low Pressure Coolant Injection Pump Suction Relief Valve Inoperable as a Primary Containment Isolation Valve Resulted in a Condition Prohibited by Technical Specifications
| ML25162A028 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/04/2025 |
| From: | Hardik Patel Constellation Energy Generation |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 2024-002-01 | |
| Download: ML25162A028 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2492024002R01 - NRC Website | |
text
Constellation June 4, 2025 SVPL TR 25-0036 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 3 Renewed Facility Operating License No. DPR-25 NRC Docket No. 50-249 Dresden Nuclear Power Station 6500 North Dresden Road Morris, IL 60450 10 CFR 50.73
Subject:
Licensee Event Report 249/2024-002-01, "Low Pressure Coolant Injection Pump Suction Relief Valve Inoperable as a Primary Containment Isolation Valve Resulted in a Condition Prohibited by Technical Specifications" Enclosed is Licensee Event Report 249/2024-002-01, "Low Pressure Coolant Injection Pump Suction Relief Valve Inoperable as a Primary Containment Isolation Valve Resulted in a Condition Prohibited by Technical Specifications." This report describes an event being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) for an Operation or Condition Prohibited by Technical Specifications and a Loss of Safety Function.
There are no regulatory commitments contained in this submittal.
Should you have any questions concerning this letter, please contact Mr. Daniel J. Murphy, Regulatory Assurance Manager, at (779) 231-7443.
Respectfully, Hardik Patel Acting Site Vice President Dresden Nuclear Power Station
Enclosure:
Licensee Event Report 249/2024-002-01 CC:
Regional Administrator - NRC Region Ill NRC Senior Resident Inspector-Dresden Nuclear Power Station
Abstract
On 11/20/2024 at 1407 CST, the Main Control Room was notified that the operating handle for the 3A Low Pressure Coolant Injection (LPCI) Suction Relief Valve was found positioned higher than the operating handle for the other relief valves in the system, making the valve inoperable as a Primary Containment Isolation Valve (PCIV). Technical Specification (TS) 3.6.1.3 Condition C was entered. At 1650 CST, the operating handle for the relief valve was moved to the down position in accordance with station procedure and TS 3.6.1.3 Condition C was exited. The valve had been replaced during refueling outage activities on 11/8/2024. At 0202 on 11/15/2024, Unit 3 entered Mode 2 and the 4-hour required completion time for Condition C and subsequent actions of Condition E became applicable. Therefore, the station concluded the TS was not met from 0602 CST on 11/15/2024 to 1650 CST on 11/20/2024. This event is being reported in accordance with 1 O CFR 50. 73(a)(2)(i)(B) for an Operation or Condition Prohibited by Technical Specifications. The cause of the event was determined to be a lack of instruction to verify the relief valves are in the closed position prior to return to service. Follow up corrective actions are to update relief valve planner guides and model work orders for lnservice Testing program relief valves to include a sign off step to verify the valve is in the closed position after installation. This event is being reported in accordance with 10 CFR
- 50. 73( a)(2)(i)( B).I PLANT AND SYSTEM IDENTIFICATION General Electric - Boiling Water Reactor, 2957 megawatts thermal rated core power Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
A. CONDITIONS PRIOR TO EVENT SEQUENTIAL NUMBER 002 Unit: 3 Reactor Mode: 1 Event Date:
November 20, 2024 Mode Name: Power Operation Event Time:
1407 CST Power Level: 100%
No structures, systems or components were inoperable at the time of the event that contributed to the event.
B. DESCRIPTION OF EVENT
REV NO.
01 On 11/20/2024 at 1407 CST, with Dresden Unit 3 at 100 percent power, the Main Control Room was notified that the operating handle for the 3A Low Pressure Coolant Injection (LPCI) [BO] Suction Relief Valve [RV] was found position higher than the operating handles of the other relief valves in the system.
The relief valve [RV] is normally seated closed and relieves back to the suppression pool [NH] to provide over-pressure protection of the LPCI [BO] piping when the pump [P] is isolated. The relief valve [RV] also functions as a Primary Containment Isolation Valve (PCIV) [ISV]. As a PCIV [ISV], its safety-related function is to isolate containment from the LPCI [BO] system. Technical Specification (TS) 3.6.1.3 Condition C requires lines with only one PCIV [ISV] to be isolated within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and to be verified isolated every 31 days when in Operating Modes 1, 2, and 3. If this action is not met, Condition E of TS 3.6.1.3 requires the operating unit to be placed in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. At 0202 on 11/15/2024, Dresden Unit 3 entered the applicable Mode 2. The station concluded the condition existed from this time to 1650 CST on 11/20/2024 when the operating handle for the 3A LPCI [BO] Suction Relief Valve [RV] was moved to the down position in accordance with station procedure and TS 3.6.1.3 Condition C was exited.
This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) for an Operation or Condition Prohibited by Technical Specifications.
C. CAUSE OF EVENT
The relief valve [RV] had been replaced on 11/08/2024 during a refueling outage. Prior to the replacement of the relief valve [RV], there is no record of valve failure or mispositioning.
An evaluation of the event was completed. The cause was determined to be that the relief valve [RV]
process does not provide instruction to verify relief valves [RV] are in the closed position prior to return to service.
D. SAFETY ANALYSIS
- 2. DOCKET NUMBER YEAR 00249 2024
- 3. LER NUMBER SEQUENTIAL NUMBER 002 REV NO.
01 The safety significance of the event is very low. The open relief valve [RV] piping ties back to the same suction piping upstream of the 3A LPCI [BO] pump [P] suction. The open relief valve [RV] did not create any additional flow paths that would divert LPCI [BO] pump [P] discharge flow away from the reactor vessel or suppression pool [NH] and did not negatively affect the available pump [P] suction head. As discussed in the Dresden Updated Final Safety Analysis Report (UFSAR), for closed system piping which communicates with the suppression pool [NH] and is expected to remain submerged during a Loss of Coolant Accident (LOCA), the intact piping or the water seal acts as the penetration isolation barrier and ensures that the primary containment boundary is maintained intact until another barrier can be established to isolate the penetration. The LPCI [BO] suction line is closed system piping which communicates with the suppression pool [NH] and is expected to remain submerged during a LOCA. Therefore, the water seal can be credited as an isolation barrier maintaining the safety function of the primary containment system.
E. CORRECTIVE ACTIONS
At 1650 CST on 11/20/2024, the operating handle for the 3A LPCI [BO] Suction Relief Valve [RV] was moved to the correct (down) position in accordance with station procedure.
Additional corrective actions were developed by the evaluation of the event. These include actions to update relief valve [RV] planner guides and model work orders for 1ST Program Safety Related Relief Valves [RV] to include a sign off step to verify the valve is in the closed position after installation. These actions are tracked in the station's Corrective Action Program. I
F. PREVIOUS OCCURENCES
A 5-year internal corrective action program and LER database review was performed for Dresden Nuclear Power Station (DNPS). One occurrence of a relief valve [RV] operating handle being found in the lifted position from DNPS from 2019 was identified. The cause of this event was determined to be that the work package instructions did not include direction for control of the relief valve [RV] lifting device during or upon completion of installation. The relief valve [RV] for this event was part of a different system and of a different type than the relief valve that is the subject of this report. However, the evaluation performed for the 2019 event had corrective actions which were closed without the necessary rigor to prevent recurrence; specifically, a thorough effectiveness review of the corrective actions from the 2019 event could have prevented the subject event of this report. The 2019 event did not result in a Technical Specification required system to be inoperable or unable to perform its required safety function. Therefore, the 2019 event was determined to not be reportable per 10 CFR 50. 73.
G. COMPONENT FAILURE DATA
No equipment failures are applicable. Page_3_ of _3_