05000366/LER-2024-002, Incorrectly Installed Temporary Modification Results in a Condition Prohibited by Plant Technical Specifications

Incorrectly Installed Temporary Modification Results in a Condition Prohibited by Plant Technical Specifications

ML24115A241
Person / Time
Site:	Hatch
Issue date:	04/24/2024
From:	Busch M Southern Nuclear Operating Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
NL-24-0157 LER 2024-002-00
Download: ML24115A241 (1)

LER-2024-002, Incorrectly Installed Temporary Modification Results in a Condition Prohibited by Plant Technical Specifications

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3662024002R00 - NRC Website

text

Matt Busch llalch 'iuclear Plan!

-~ Southern Nuclear Vice President - Plant Hatch I I 028 I latch Parkway Nonh Baxley. GA 31513 Agril 24, 2024 Docket Nos.: 50-366 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant-Unit 2 Licensee Event Report 2024-002-00 912 537 5859 tel 912 366 2077 fax NL-24-0157 Incorrectly Installed Temporary Modification Results in a Condition Prohibited by Plant Technical Specifications Ladies and Gentlemen:

In accordance with the requirements of 10 CFR 50.73 (a)(2)(i)(B), Southern Nuclear 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, Matt Busch Vice President - Hatch MSB/JMH Enclosure: LER 2024-002-00 Cc:

NRC Regional Administrator, Region II NRR Project Manager - Hatch Senior Resident Inspector - Hatch RTYPE: CHA02.004

Enclosure to NL-24-0157 LER 2024-002-00 Edwin I. Hatch Nuclear Plant Unit 2 Licensee Event Report 2024-002-00 Incorrectly Installed Temporary Modification Results in a Condition Prohibited by Plant Technical Specifications Enclosure LER 2024-002-00

Abstract

At 13:01 EST on 2/27/2024 while Unit 2 was at 100% power in Mode 1, it was discovered that a temporary Plant Service Water (PSW) modification was incorrectly installed on the Main Control Room Air Conditioning (MCRAC) subsystem. This inadvertently and administratively rendered one Main Control Room Environmental Control (MCREC) subsystem inoperable for Unit 2 for a period of sixteen days which exceeds the allowable Technical Specification (TS) Limited Condition of Operability (LCO) time of seven days.

Although Unit 1 and Unit 2 share the same MCREC subsystems, during the period that the temporary PSW modification was installed, Unit 1 was in modes 4 and 5 for a refueling outage (RFO), and no fuel movement or core alterations took place for a continuous period of seven days. Therefore, during the period that one MCREC subsystem was inoperable for Unit 2, Unit 1 was not in the mode of applicability for the system for longer than allowed by TS. With the removal of the temporary PSW modification on 2/28/2024 the operability of the MCREC subsystem was restored.

EVENT DESCRIPTION 050 052 I

2. DOCKET NUMBER

3. LER NUMBER 00366 I

YEAR SEQUENTIAL REV NUMBER NO.

~-I 002 1-G At 13:01 EST on 2/27/2024 while Unit 2 was at 100% power in Mode 1, it was discovered that a temporary Plant Service Water (PSW) (EIIS Code: Bl) modification was possibly installed incorrectly on the Bravo condensing unit (CDU) of the Main Control Room Air Conditioning (MCRAC) subsystem (EIIS Code: VI).

For the period that the temporary PSW modification was in place (1/30/2024 - 2/28/2024), a past operability review (POR) was performed. The POR confirmed that the temporary PSW modification was indeed installed incorrectly rendering the MCRAC Bravo subsystem inoperable for a period of 29 days. This did not exceed the TS LCO 3.7.5 time of 30 days for the MCRAC subsystem. Additionally, during this time the MCRAC Alpha subsystem was running, therefore the habitability of the Control Room Envelope (CRE) was maintained, as only one MCREC and one MCRAC subsystem are credited per the accident analysis. MCRAC Charlie subsystem was operable but not in-service during this time.

However, regarding operability of the MCRAC subsystem (TS 3.7.5) as it relates to the operability of the Main Control Room Environmental Control (MCREC) subsystem (TS 3.7.4), per the Technical Requirements Manual (TRM), with the MCRAC Bravo subsystem inoperable, the other two subsystems (Alpha and Charlie) have to be in-service to meet the requirements of LCO 3. 7.4. The POR revealed that this condition was not continuously met for the duration of the time when the MCRAC Bravo subsystem was inoperable. From 2/12/2024 until the temporary PSW modification was removed and the MCRAC Bravo subsystem restored on 2/28/24, only the MCRAC Alpha subsystem was in-service. MCRAC Charlie subsystem was operable and in standby, but not in-service or capable of auto-starting. Therefore, this resulted in administratively rendering one Main Control Room Environmental Control (MCREC) subsystems inoperable for Unit 2 for a period of sixteen days which exceeds its allowable TS 3.7.4 LCO time of seven days.

Although Unit 1 and Unit 2 share the same MCREC subsystem, during the period that the temporary PSW modification was installed, Unit 1 was in modes 4 and 5 for a refueling outage (RFO), and no fuel movement or core alterations took place for a continuous period of seven days. Therefore, during the period that one MCREC subsystem was inoperable for Unit 2, Unit 1 was not in the mode of applicability for the system for longer than allowed by TS. With the removal of the temporary PSW modification on 2/28/2024 the operability of the MCREC subsystem was restored.

FAILED COMPONENTS INFORMATION Master Parts List Number: 1 Z41 D004A/B Manufacturer: FARR Model Number: N-131 Type: Control Room Filter Train EVENT CAUSE ANALYSIS One MCREC subsystem was inoperable in exceedence of its TS LCO time due to the incorrect installation of a temporary PSW modification. The direct cause of the incorrect installation of the temporary PSW modification was a failure of non-licensed, contract maintenance personnel to properly use Human Performance (HU) tools to ensure the temporary PSW modification was properly installed per the procedure. Contributing to this, the procedure did not contain adequate steps or guidance for certain aspects of the installation of the temporary PSW modification.

SAFETY ASSESSMENT There were no actual safety consequences as a result of this event. One of two MCREC subsystems remained operable during the event, therefore there was no loss of safety function. This event is reportable per 10 CFR 50.73 (a)(2)(i)(B) as a condition prohibited by TS due to one MCREC subsystem being inoperable for Unit 2 in excess of the allotted TS 3.7.4 LCO timeframe.

CORRECTIVE ACTIONS I

2. DOCKET NUMBER

3. LER NUMBER I

YEAR SEQUENTIAL REV 00366 I 2024 I NUMBER NO.

- I 002 I -G With the removal of the temporary PSW modification on 2/28/24 the operability of the MCREC system was restored.

Although the temporary PSW modification was installed on the other two MCRAC trains ('A' and 'C'), a walkdown of the other trains was performed and no issues were identified. Additionally, corrective actions are in progress to: (1) add this scenario to the Craft On-Boarding Ranking Assessment (COBRA) proficiency assessment, (2) add a SNC Cognizant Person Hold Point/ Sign Off in the job plan for this work evolution to validate proper implementation, and (3) update the procedure with better detailed instructions for installing the temporary PSW modification.

PREVIOUS SIMILAR EVENTS None. Page 3

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