05000458/LER-2019-002-01, Reactor Coolant Pressure Boundary Leakage Due to Contaminates Deposited on External Pipe Surface After Legacy Adhesive Spill
| ML19241A502 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 08/29/2019 |
| From: | Vercelli S Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RBG-47967 LER 2019-002-01 | |
| Download: ML19241A502 (3) | |
| Event date: | |
|---|---|
| Report date: | |
| 4582019002R01 - NRC Website | |
text
- -=-* Entergy.
Entergy Operations, Inc.
River Bend Station 5485 U.S. Highway 61 N St. Francisville, LA 70775 Tel 225-635-5000 RBG-47967 Steven P. Vercelli Site Vice President River Bend Station 10 CFR 50.73 August 29, 2019 Attn: Document Control Desk U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852-2738
Subject:
Licensee Event Report 50-458 I 2019-002-01, "Reactor Coolant Pressure Boundary Leakage Due to Contaminates Deposited on External Pipe Surface After Legacy Adhesive Spill".
River Bend Station, Unit 1 NRC 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.
Sine~~~
SPV/twf
Enclosure:
cc:
Licensee Event Report 50-458 I 2019-002-01, "Reactor Coolant Pressure Boundary Leakage Due to Contaminates Deposited on External Pipe Surface After Legacy Adhesive Spill".
NRC Region IV Regional Administrator, w/o Enclosure NRC 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 NRC Project Manager
NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRG 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 Reactor Coolant Pressure Boundary Leakage Due to Contaminates Deposited on External Pipe Surface After Legacy Adhesive Spill.
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved I
Sequential I Rev Facility Name Docket Number Month Day Year Year Number No.
Month Day Year NA 05000 NA Facility Name Docket Number 04 26 2019 2019 -
002 -
01 08 29 2019 NA 05000 NA
- 9. Operating Mode
)
No NA NA NA Abstract (Limit to 1400 spaces, i.e., approximately 14 single-spaced typewritten lines)
Through-wall leakage in the Safety Related Standby Liquid Control (SLC) system piping segment was identified and confirmed by Non-Destructive Evaluation personnel during a system leakage examination. 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, the station was conducting refueling activities in Mode 5.
The section of piping affected was cut out and replaced in accordance with ASME Section XI IWA-4000. 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, the pipe was returned to service. The leak was caused by Transgranular Stress Corrosion Cracking due to the presence of aggressive chemical species and crack morphology. A visual external surface inspection was performed which found no evidence of contaminants on any additional SLC system piping.
NRG FORM 366 (04-2018)
BACKGROUND The Standby Liquid Control (SLC) system [BR] is manually initiated from the main control room as directed by Emergency Operating Procedures. 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.
Through wall leakage was confirmed by Operations and Non-Destructive Evaluation (NOE) personnel during test conditions established in accordance with River Bend Station (RBS) pressure testing requirements. The SLC system was declared Inoperable and RBS issued an 8-hour report under 10 CFR 50.72(b)(3)(ii)(A).
REPORTED CONDITION This event is being reported as a Degraded Condition under 10 CFR 50. 73(a)(2)(ii)(A) due to the material defect found in the SLC system piping.
FAILURE ANALYSIS The affected segment of the pipe was sent to a materials laboratory for analysis. Pits on the outside diameter surface served as the initiation points for cracks which traversed the pipe wall to the inside diameter surface, forming a contiguous leak path. Chloride and sulfur species were identified in the deposits at the leak site origin and sulfur was identified in deposits along the length of the crack. The presence of aggressive chemical species and crack morphology indicates that Chloride-Induced Transgranular Stress Corrosion Cracking was the active cracking mechanism.
A review of station records found instances of similar chloride surface contamination on system piping in the same general area in 1994. The contamination was determined to be due to an insulation adhesive spill. The contaminates identified by the SLC pipe failure analysis were likely introduced by the adhesive spill in 1994.
CORRECTIVE ACTION TO PREVENT REOCCURRENCE The SLC system was walked down visually by Engineering personnel to ascertain if any potential contaminants were present on the external surfaces. None were identified.
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 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. There were no actual nuclear or radiological safety consequences due to this event. This event was of minimal significance to the health and safety of the public.
(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
of 2