05000416/LER-2023-001, Valve Closure Test Failure Resulting in Condition Prohibited by Technical Specification
| ML23215A204 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 08/03/2023 |
| From: | Hardy J Entergy Operations |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| GNRO2023-00019 LER 2023-001-00 | |
| Download: ML23215A204 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4162023001R00 - NRC Website | |
text
- ) entergy GNRO2023-00019 August3,2023 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 2023-001-00, 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 2023-001-00, 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 letter contains no new Regulatory Commitments. Should you have any questions concerning the content of this letter, please contact me at 802-380-5124.
Sinc9 A t-\\1/
JAH/saw Attachments: Licensee Event Report 2023-001-00
GNRO2023-00019 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
GNRO2023-00019 Page 3 of 3 Attachment Licensee Event Report 2023-001-00
Abstract
On June 13, 2023, while trending as found periodic data from motor operated valve diagnostic test on 1 E61 F0038 Drywell Purge Inlet Isolation Valve, it was identified that the butterfly valve disc was traveling past the valve seat, resulting in 1 E61 F0038 and Division 2 of the drywell purge and initial vacuum relief subsystem being declared inoperable. 1 E61 F003A Division 1 drywall 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 drywall purge vacuum relief subsystems shall be operable in MODES 1, 2 and 3. Division 2 drywall 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 YEAR 416 2023 3, LEA NUMBER SEQUENTIAL NUMBER
- - 001 REV NO.
- - 00 On October 26, 2017, while performing surveillance for Division 2 post-Loss-of-Coolant Accident (LOCA) Drywall Vacuum Breaker operability, the operator did not observe any movements from the stem of the valve 1 E61 F003B Drywall 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 F0038 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 Drywall 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. Page 2 of 3 (03-14-2023)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-01 04 EXPIRES: 0 8 / 3 1 /2023 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/l
- 1. FACILITY NAME Grand Gulf Nuclear Station, Unit 1 181 050 0
052
Reportability
- 2. DOCKET NUMBER YEAR 416 2023
- 3. LER NUMBER SEQUENTIAL NUMBER
- - 001 REV NO.
- - 00 This was a condition that is prohibited by technical specifications and is reportable per 10 CFR 50.73 (a)(2)(i)(B) Any operation or condition which was prohibited by the plant's Technical Specifications. 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. 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 drywell 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