05000278/LER-2018-002, Reactor Coolant System Pressure Boundary Leakage Resulting in Technical Specification Required Shutdown
| ML18323A186 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/19/2018 |
| From: | Herr M Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CCN: 18-116 LER 2018-002-00 | |
| Download: ML18323A186 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2782018002R00 - NRC Website | |
text
Exelon Generation CCN: 18-116 November 19, 2018 U.S. Nuclear Regulatory Commission A TIN: Document Control Desk Washington, DC 20555-0001
Subject:
Peach Bottom Atomic Power Station (PBAPS) Unit 3 Renewed Facility Operating License No. DPR-56 NRC Docket No. 50-278 Licensee Event Report (LER) 3-18-002 10CFR 50.73 Enclosed is a Licensee Event Report concerning a Technical Specifications required plant shutdown due to reactor pressure boundary leakage. In accordance with NEI 99-04, the regulatory commitment contained in this correspondence is to restore compliance with the regulations.
The specific methods that have been planned to restore and maintain compliance are discussed in the LER.
If you have any questions or require additional information, please do not hesitate to contact Matt Retzer at 717-456-4351.
Sincerely, (Y\\w:l_'J...t ).._
Matthew J. Herr Plant Manager Peach Bottom Atomic Power Station MJH/dnd/IR 4175898 Enclosure cc:
US NRC, Administrator, Region I US NRC, Senior Resident Inspector R. R. Janati, Commonwealth of Pennsylvania S. Gray, State of Maryland B. Watkins, PSE&G, Financial Controls and Co-Owner Affairs
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150*0104 EXPIRES: 03/31/2020 (04-2018)
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- 3. Page Peach Bottom Atomic Power Station Unit 3 05000278 1
OF 3
- 4. Title Reactor Coolant System Pressure Boundary Leakage Resulting in Technical Specification Required Shutdown
- 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 05000 Facility Name Docket Number 09 21 2018 2018 -
002 0
11 19 2018 05000
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 1 O CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a){3)(i)
~ 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
D 20.2201(d)
D 20.2203(a){3)(ii)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B) 1 D
D D
D 20.2203(a)(1) 20.2203(a)(4)
- 50. 73(a)(2)(iii)
- 50. 73(a)(2)(ix)(A)
D 20.2203{a){2)(i)
D 50.36(c)( 1 )(i)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2){x)
- 10. Power Level D 2D.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4)
D 2D.2203(a)(2)(iii)
D 50.36(c)(2)
D 50. 73(a)(2)(v)(B)
D 73.71 (a)(5)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v){C)
D 73.77(a){1) 100%
D 20.2203(a)(2)(v)
~ 50.73(a)(2)(i)(A)
~
50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
~ 50. 73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73. 77(a)(2)(ii)
D 50.73(a)(2)(i)(C)
D Other (Specify in Abstract below or in SEQUENTIAL NUMBER 002 0955 hours0.0111 days <br />0.265 hours <br />0.00158 weeks <br />3.633775e-4 months <br /> when leakage was identified on an instrument line associated with monitoring HPCI steam line differential pressure. The instrument line is part of the RCS pressure boundary.
REV NO.
0 1 O CFR 50.73(a)(2)(i)(B) - any condition prohibited by plant Technical Specifications. Differential pressure switches DPIS-3-23-076 and DPIS-3-23-077 were identified as reading low on 9/20/18 at approximately 1930 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.34365e-4 months <br />. Further analysis determined that they would not have been able to perform their safety function of isolating the HPCI turbine steam line in the event of a steam line break. TS 3.3.6.1 Condition B requires the isolation capability performed by these switches to be restored in one hour. If not restored within one hour, Condition F requires the penetration flow path to be isolated within one hour (two hours after discovery). Because of the additional analysis performed to determine if they could perform their safety function, the required actions were not performed until 9/21 /18 at approximately 1755 hours0.0203 days <br />0.488 hours <br />0.0029 weeks <br />6.677775e-4 months <br />, which is approximately 22-1 /2 hours after discovery.
1 O CFR 50.73(a)(2)(ii)(A) - the condition of the plant, including its principal safety barriers, being seriously degraded. Leakage was identified on an instrument line associated with monitoring HPCI steam line differential pressure. The instrument line is part of the RCS pressure boundary, which is one of the principal safety barriers.
1 O CFR 50.73(a)(2)(v)(D) - any condition that could have prevented the fulfillment of the safety function of a system needed to mitigate the consequences of an accident. HPCI is considered a single train system and was required by TS to be declared inoperable as a result of this event.
Cause of the Event
The one-inch diameter instrument line was aligned such that it was in contact with one side of a rectangular support. Vibration-induced wear (fretting) reduced the wall thickness of the pipe at the contact point until a steam leak developed. It could not be determined why the pipe was aligned such that it was in contact with the support bracket.
Corrective Actions
The section of pipe where the leak occurred was replaced. Inspections were performed on other small-bore piping in the drywell that are supported by the same style support bracket and subject to vibration. One other location was identified where fretting was significant enough to proactively have the pipe replaced.
Piping with less significant fretting was identified at nine other locations. These wear areas were wrapped with a layer of stainless steel sheet metal to protect the line until permanent repairs can be completed if needed. Additional corrective actions are documented in the corrective action program.
Previous Similar Occurrences No previous similar occurrences have been identified of RCS pressure boundary leakage due to fretting.
Unit 3 LEA 17-001 documents RCS pressure boundary leakage due to a weld failure in a one-inch diameter instrument line. Unit 3 LEA 05-003 documents RCS pressure boundary leakage due to a weld failure in a one-inch diameter equalizing line in the Residual Heat Removal System. Page _3_ of _L