05000416/LER-2023-001-01, Valve Closure Test Failure Resulting in Condition Prohibited by Technical Specification

Valve Closure Test Failure Resulting in Condition Prohibited by Technical Specification

ML23334A051
Person / Time
Site:	Grand Gulf
Issue date:	11/30/2023
From:	Hardy J Entergy Operations
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
GNRO2023-00028 LER 2023-001-01
Download: ML23334A051 (1)

LER-2023-001, Valve Closure Test Failure Resulting in Condition Prohibited by Technical Specification

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4162023001R01 - NRC Website

text

} entergy GNRO2023-00028 November 30, 2023 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.

P.O. Box 756 Port Gibson, Mississippi 39150 Jeffery A. Hardy Manager Regulatory Assurance Grand Gulf Nuclear Station Tel: 802-380-5124 10 CFR 50.73

SUBJECT:

Grand Gulf Nuclear Station, Unit 1 Licensee Event Report 2023-001-01, Valve Closure Test Failure Resulting in Condition Prohibited by Technical Specification Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 Renewed License No. NPF-29 Attached is Licensee Event Report (LER) 2023-001-01, Valve Closure Test Failure Resulting in Condition Prohibited by Technical Specification. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B), any operation or condition which was prohibited by the plant's Technical Specifications. This supplement is being provided to include that this condition was also prohibited by Technical Specifications section 3.6.3.3 "Drywell Purge Systems" and add detail to the Reportability section of the LER.

This letter contains no new Regulatory Commitments. Should you have any questions concerning the content of this letter, please contact me at 802-380-5124.

Sincerely,

~

JAH/sawr'A Attachments: Licensee Event Report 2023-001-01

GNRO2023-00028 Page 2 of 3 cc:

NRG Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 U.S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

GNRO2023-00028 Page 3 of 3 Attachment Licensee Event Report 2023-001-01

Abstract

On June 13, 2023, while trending as found periodic data from motor operated valve diagnostic test on 1 E61 F003B Drywell Purge Inlet Isolation Valve, it was identified that the butterfly valve disc was traveling past the valve seat, resulting in 1 E61 F003B and Division 2 of the drywell purge and initial vacuum relief subsystem being declared inoperable. 1 E61 F003A Division 1 drywell purge and initial vacuum relief subsystem was operable during this time.

Per Grand Gulf Technical Specifications, two drywell post-Loss-of-Coolant Accident and two drywell purge vacuum relief subsystems shall be operable in MODES 1, 2 and 3. Division 2 drywell purge and vacuum relief subsystem was determined to have been inoperable since October 26, 2017.

There were no consequences to the general safety of the public, nuclear safety, industrial safety or radiological safety.

No radiological releases occurred due to this event.

This report is made pursuant to 10 CFR 50.73 (a)(2)(i)(B), any operation or condition which was prohibited by the plant's Technical Specifications.

Plant Conditions

Mode 1, 98 percent power

Description of Event

2. DOCKET NUMBER

3. LER NUMBER YEAR SEQUENTIAL REV NUMBER NO.

416 2023

- 001

- 01 On October 26, 2017, while performing surveillance for Division 2 post-Loss-of-Coolant Accident (LOCA) Drywell Vacuum Breaker operability, the operator did not observe any movements from the stem of the valve 1 E61 F003B Drywell Purge Inlet Isolation Valve upon initiation. The control room indications were indicating that the valve was opened and closed. Movements of the stem are required for Technical Specification Acceptance Criteria. Thus, the surveillance was completed unsatisfactory. The valve 1 E61 F003B and Division 2 Drywell Purge/Initial Vacuum Relief was declared inoperable.

Upon inspection, the spline adapter of valve 1 E61 F003B was found slipping down the valve stem, causing the disengagement between the valve stem and the drive sleeve. Thus, the actuator was moving and indicating opened/closed. However, the valve didn't move.

On October 27, 2017, the spline adapter was reinstalled per a work order and surveillance was re-performed satisfactorily. This included a current and switches only diagnostic test which was the current test standard for limit controlled soft seated butterfly valves.

On January 24, 2019, it was identified that the diagnostic testing on motor operated valve (MOV) butterfly valves did not currently meet the requirements of GL 96-05/JOG program. This was due to not using a strain gauge to measure valve stem torque. The preventative maintenance requirements (PMRQs) and model work orders (MWOs) were updated for all applicable butterfly valves to reflect that the diagnostic testing required measuring the valve stem torque.

On June 6, 2023, the periodic 1 E61 F003B MOV diagnostic test was performed with strain gauge on the stem per work order. The test data was within the criteria in the motor operator valve data record.

On June 13, 2023, while trending as found periodic data from the MOV diagnostic test on 1 E61 F003B, it was identified that the butterfly valve's disc is traveling past the valve seat, resulting in valve 1 E61 F003B and Division 2 Drywell Purge/Initial Vacuum Relief being declared inoperable. The test data indicates that the valve is contacting the seat at 40 secs of the full 60 sec stroke time. After contacting the seat, the seating torque decreases (relaxes) and the valve continues to travel for 20 secs past the seat. This MOV design has a full travel of 90 degrees. With the actuator in the full open position, the valve disk is 60 degrees open. Conversely with the actuator in the full closed position, the valve disk is 30 degrees open. This valve has no torque switch in the circuit and is seated using the limit switches.

On June 16, 2023, the actuator/valve assembly was adjusted to the proper required position per work order. This was followed by a satisfactory as left diagnostic test using strain gauge to measure valve stem torque. The diagnostic test indicated that the valve disk is now going to full closed position when the actuator is stroked to the full close position.

Reportability

2. DOCKET NUMBER

3. LER MJMBER YEAR SEQUENTIAL REV NUMBER NO.

416 2023

- 001

- 01 This was a condition that is prohibited by technical specifications and is reportable per 10 CFR 50.73 (a)(2)(i)(B). Per Grand Gulf Technical Specifications section 3.6.5.6, two drywall post-Loss-of-Coolant Accident (LOCA) and two drywall purge vacuum relief subsystems shall be operable in MODES 1, 2 and 3. This condition was also prohibited by Technical Specifications section 3.6.3.3 "Drywall Purge Systems." Two drywall purge subsystems shall be operable in MODES 1 and 2. Division 2 drywall purge and vacuum relief subsystem was determined to have been inoperable since October 26, 2017.

Cause(s)

Direct Cause: 1 E61 F003B valve disc traveling past the valve seat was caused by the splined adapter not being properly installed in the past per work order on October 27, 2017. The issue was corrected by adjusting actuator/valve assembly to the proper required position in a later work order.

Corrective Actions

1.

Update procedure to include confirmation of valve stem orientation in relation to the disc orientation.

2.

The PMRQs and MWOs were updated for all applicable butterfly valves to reflect that the diagnostic testing required measuring the valve stem torque as part of the corrective actions.

Safety Significance

The drywall purge system consists of two 100 percent subsystems that serve to purge the hydrogen produced after a LOCA into the larger containment volume for dilution. It also provides a means to relieve drywall vacuum following a LOCA. The 1 E61 F003B is a Division 2 drywall purge compressor system isolation valve. If the 1 E61 F003B is open, the drywell purge compressor will be able to pressurize the drywell with Division 1 unavailable. If the 1 E61 F003B is open and Division 2 is failed, the check valve 1 E61 F002B will prevent reverse flow.

The safety significance of this event was minimal. Since operation of only one of the two subsystems are required, a single failure will not prevent the system from fulfilling its design function. Therefore, the consequences of this event had minimal impact on the health and safety of the public and reactor safety.

Previous Similar Events

A review of the corrective action program for the past three years did not identify any similar events. Page _3_ of _3_