05000458/LER-2019-002, Standby Liquid Control System (SLC) Pipe through-wall Leak
| ML19176A031 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 06/25/2019 |
| From: | Vercelli S Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RBG-47959 LER 2019-002-00 | |
| Download: ML19176A031 (3) | |
| Event date: | |
|---|---|
| Report date: | |
| 4582019002R00 - NRC Website | |
text
-...::-- EntergYs RBG-47959 June 25, 2019 Attn: Document Control Desk U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2738 Entergy Operations, Inc.
River Bend Station 5485 U.S. Highway 61N St. Francisville, LA 70775 Tel 225-635-5000 Steven P. Vercelli Site Vice President River Bend Station 10 CFR 50.73
Subject:
Licensee Event Report 50-458 I 2019-002-00, "Standby Liquid Control System (SLC) pipe through-wall leak".
River Bend Station, Unit 1 NRG Docket No. 50-458 Renewed License No. NPF-47 In accordance with 10 CFR 50.73, enclosed is the subject Licensee Event Report. This document contains no commitments. If you have any questions, please contact Mr. Tim Schenk at 225-381-4177.
Since~J.
SPV/djp
Enclosure:
cc:
Licensee Event Report 50-458 I 2019-002-00, "Standby Liquid Control System (SLC) pipe through-wall leak".
NRG Region IV Regional Administrator, w/o Enclosure NRG Senior Resident Inspector - River Bend Station, Unit 1 Ji Young Wiley, Department of Environmental Quality, Office of Environmental Compliance, Radiological Emergency Planning and Response Section Public Utility Commission of Texas, Attn: PUC Filing Clerk N RC Project Manager
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
3.Page River Bend Station - Unit 1 05000 458 1
OF 2
- 4. Title Standby Liquid Control System (SLC) pipe through-wall leak
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Faclllty Name Docket Number Month Day Year Year Number No.
Month Day Year NA 05000 NA Facility Name Docket Number 04 26 2019 2019 -
002 -
00 06 25 2019 NA 05000 NA
- 9. Operating Mode
)
No 08 31 2019 Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
Through-wall leakage in the Safety Related Standby Liquid Control System (SLC) (**BR**) piping segment (SLS-150-037-1) was identified and confirmed by the NOE Examiners during a system leakage examination (VT-2). The identified leakage from this section of piping was at a rate of 1 drop every 1 to 2 minutes. The leak was discovered while conducting pressure test activities.
At the time of discovery RBS was in its 20th refueling outage.
The section of piping spool [PSP] affected was cut out and replaced in accordance with ASME Section XI IWA-4000 (Work Order 00523751 ). The required elements for examination/material as required in the ASME Code were followed during the replacement of the affected segment of piping. After the required examinations, line (SLS-150-037-1) was returned to service. Additional analysis of the original piping section that was removed will be tracked under the RBS corrective action program to help validate assumptions as to the cause of the piping through wall indication. No direct cause can be ascertained at this time. The affected segment of the pipe has been sent to a materials laboratory for an analysis of the location in the piping where the through wall leakage occurred. The results of that off-site analysis will be provided in a supplement to this report.
NRC FORM 366 (04-2018)
BACKGROUND The SLC system (TS 3.1.7) is manually initiated from the main control room as directed by the Emergency Operating Procedures (EOP-1, EOP-4 and EOP-5). This is an alternate method to shut down the Reactor [RCT] should the Control Rod Drive System (**AA**) fail to provide this function. The SLC system provides a backup capability for reactivity control and is independent of normal reactivity control provisions in the nuclear reactor.
Through wall leakage was confirmed by operations and NDE personnel near a 7D bend outside of the bend radius in a straight section of piping during test conditions established in accordance with RBS Pressure Testing requirements.
Because of this, the SLC system was deemed inoperable and River Bend Station (RBS) issued a required 8-hour report under 10 CFR 50.72(b)(3).
REPORTED CONDITION On April 26, 2019, while at 0% power/Mode 5, a through-wall leak was identified and confirmed by operations and non-destructive evaluation personnel (NDE) on line SLS-150-037-1 during test conditions established in accordance with River Bend pressure testing requirements. Line SLS-150-037-1 is within the boundary for ASME Section XI pressure test SLS.001 and is an ASME Section Ill, Class 1 line.
FAILURE ANALYSIS A visual examination of the non-conforming material (SLS-150-037-1) after removal did not identify any known degradation mechanisms that could be assessed visually (e.g., erosion, corrosion). The remaining (accessible) piping was visually examined and no issues similar to line SLS-150-037-1 were noted.
No direct cause can be ascertained at this time. The affected segment of the pipe has been sent to a materials laboratory for an analysis of the location in the piping where the through wall leakage occurred.
CORRECTIVE ACTION TO PREVENT RECCCURRENCE CR-RBS-2019-2883 CA08 (due date 07/17/2019) has been issued to track the off-site material analysis results of the SLC Piping with through wall leakage indication. Further actions will be developed as need based on the results of this analysis.
PREVIOUS OCCURRENCE EVALUATION There have been no similar events reported by RBS in the past three years.
SAFETY SIGNIFICANCE
Both the Reactor Coolant Pressure Boundary (RCPB) (**AD**) and SLC systems remained functional based on the amount of leakage identified during pressure test conditions. The piping has been replaced and the system pressure boundary has been tested, and will continue to be tested in accordance with ASME Section XI requirements, as applicable. Based on current data available taken from the analysis performed on-site, the SLC system was determined to be functional with the identified through wall leak.
(NOTE: Energy Industry Identification System component function identifier and system name of each component or system referred to in the LER are annotated as (**XX**) and [XX], respectively.) Page 2
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