05000321/LER-2024-003, Reactor Core Isolation Cooling (RCIC) System Inoperable Due to Mispositioned Link
| ML24185A269 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 07/03/2024 |
| From: | Busch M Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-24-0240 LER 2024-003-00 | |
| Download: ML24185A269 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3212024003R00 - NRC Website | |
text
A Southern Nuclear Matt Busch Vice President - Plant Hatch July 3, 2024 Hat~b Nuclear Plant 11028 Hatch Parkway North Baxley,GA 31513 912 537 5859 tel 91 2 366 2077 fax Docket Nos.: 50-321 NL-24-0240 U.S. Nudear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 1 Licensee Event Report 2024-003-00 Unit 1 Reactor Core Isolation Cooling (RCIC) System Inoperable Due to Mispositioned Link Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73 (a)(2)(i)(B), Southern Nudear Operating Company hereby submits the enclosed Licensee Event Report.
This letter contains no NRC commitments. If you have any questions, please contact the Hatch Licensing Manager, Jimmy Collins, at 912.453.2342.
Respectfully submitted,
~//4~
Matt Busch Vice President - Hatch MSB/JMH Enclosure: LER 2024-003-00 Cc:
Regional Administrator, Region II NRR Project Manager - Hatch Senior Resident Inspector - Hatch RTYPE: CHA02.004
Enclosure to NL-24-0240 LER 2024-003-00 Edwin I. Hatch Nuclear Plant - Unit 1 Licensee Event Report 2024-003-00 Unit 1 Reactor Core Isolation Cooling (RCIC) System Inoperable Due to Mispositioned Link Enclosure LER 2024-003-00
Abstract
At 1133 EDT on 5/8/2024, with Unit 1 operating at 99. 7% power in MODE 1, maintenance was performing a surveillance on Reactor Core Isolation Cooling (RCIC) and identified an open electrical link that should have been in the closed position. This link being open defeated the RCIC High Reactor Water Level trip function. The High Reactor Water Level trip is a Technical Specification (TS) required function, without which RCIC is inoperable. At 1725 on 5/8/2024 the link was closed, restoring the High Reactor Water Level trip function and RCIC operability.
Causal analysis determined that, due to a gap in the usage of human performance (HU) tools, the link was inadvertantly left open after restoration of a tagout on 3/8/2024 during the refueling outage. Corrective actions for this event focused on management reinforcement of HU Tool usage.
EVENT DESCRIPTION
I
- 2. DOCKET NUMBER
- 3. LER NUMBER 00321 I
YEAR SEQUENTIAL REV NUMBER NO.
~-I 003 1-G At 1133 EDT on 5/8/2024, with Unit 1 operating at 99. 7% power in MODE 1, maintenance was performing a surveillance on Reactor Core Isolation Cooling (RCIC)(EIIS: BN) and identified an open electrical link that should have been in the closed position. This link being open defeats the RCIC High Reactor Water Level trip function. The High Reactor Water Level trip is a Technical Specification required function, without which RCIC is inoperable.
EVENT CAUSE ANALYSIS
The link being inadvertently left open was due to a gap in the usage of HU tools such as task preview, validating assumptions, and having a questioning attitude when manipulating plant equipment.
SAFETY ASSESSMENT
There were no actual safety consequences as a result of this event. At any time while the link was open, RCIC would have started at its low reactor water level setpoint and injected as required. If vessel level continued to rise during RCIC injection moisture carryover into the main steam lines could, over the course of time, lead to RCIC turbine damage. However, the RCIC mission time is only 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and RCIC can be manually secured at any time if needed. Furthermore, RCIC is not credited in the safety analysis.
This event is reportable per 10 CFR 50.73 (a)(2)(i)(B) as a condition prohibited by TS. The RCIC system was inoperable between 3/8/2024 until the link was closed on 5/8/2024. During this time, Unit 1 entered the mode of applicability on 3/10/2024 @ 1150 and then exited the mode of applicability due to cooling down from a reactor scram on 3/11/2024 @
1903. Then Unit 1 entered the mode of applicability again after the subsequent startup on 3/17/2024 @ 1928. The allowable TS 3.5.3.A (RCIC inoperable) completion time of 14 days plus the TS 3.5.3.B completion time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to be in MODE 3 was exceeded on 4/1/2024 @ 0728.
Addtionally, the High Pressure Coolant Injection (HPCl)(EIIS: BJ) pump was operable when RCIC was inoperable except from 3/10/2024@ 2331 until 3/11/2024@ 0027 for performance of a surveillance test. This overlapping time of RCIC and HPCI inoperabilities did not exceed the TS 3.5.1.G completion time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to bring the unit to MODE 3 when both RCIC and HPCI are inoperable.
All low pressure ECCS systems were operable during the time RCIC was inoperable.
CORRECTIVE ACTIONS
At 1725 on 5/8/2024 the link was closed, restoring the High Reactor Water Level trip function and RCIC operability.
Immediate corrective actions for this event focused on management reinforcement of HU Tool usage. Additionally, actions are in progress to conduct oral boards to reinforce the use of HU Tools.
PREVIOUS SIMILAR EVENTS
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