05000277/LER-2018-001, Fire Safe Shutdown Requirements Not Met for Spurious Operation of Valves at a High-Low Pressure Interface
| ML18131A272 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 05/11/2018 |
| From: | Pat Navin Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CCN: 18-45 LER 2018-001-00 | |
| Download: ML18131A272 (5) | |
| 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)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 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)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 2772018001R00 - NRC Website | |
text
Exelon Generation.
CCN: 18-45 May 11, 2018 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 10CFR 50.73 Peach Bottom Atomic Power Station (PBAPS} Unit 2 and Unit 3 Renewed Facility Operating License No. DPR-44 and DPR-56 NRC Docket No. 50-278 and 50-278
Subject:
Licensee Event Report (LEA} 2-18-001 Enclosed is a Licensee Event Report concerning an unanalyzed condition regarding implementation of fire safe shutdown requirements.
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 LEA.
If you have any questions or require additional information, please do not hesitate to contact Jim Kovalchick at 717-456-3351.
Patrick D. Navin Site Vice President Peach Bottom Atomic Power Station PDN/dnd/I R 4115309 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)
Estinated burden per response to compfy with 1115 rraida1ory a>ltection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
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LICENSEE EVENT REPORT (LER)
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~ ***** iL person 5 not required to respond to, the iiformatiln colection 3.Page Peach Bottom Atomic Power Station Unit 2 05000277 1
OF 4
- 4. Title Fire Safe Shutdown Requirements Not Met for Spurious Operation of Valves at a High-Low Pressure Interface
- 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 Dey Year Peach Bottom Atomic Power Sta. Unit 3 05000278 Facility Name Docket Number 03 14 2018 2018 -
001 0
05 11 2018 05000
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 1 o CFR §: (Check all that apply)
I D 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
D 20.2201(d)
D 20.2203(a)(3)(ii)
[8l 50. 73(a)(2)(ii)(B)
D 50. 73(a)(2)(viii)(B) 1 D 20.2203(a)(1)
D 20.2203(a)(4)
D 50.73(a)(2)(iii)
D 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) 1 O. Power Level D 20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71 (a)(4)
D 20.2203(a)(2)(iiil 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)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(iiJ D 50.73(a)(2)(i)(C)
D Other (Specify in Abstract below or in M0-2/3-12-015 M0-2/3-12-018 M0-2/3-12-068 RWCU Inlet Inboard Isolation Valve RWCU Inlet Outboard Isolation Valve RWCU Outlet Isolation Valve YEAR 2018 -
Note: the same valves exist in both units as indicated by "2/3" in the valve number.
- 3. LEA NUMBER SEQUENTIAL NUMBER 001 REV NO.
0 Once this issue was identified, it was entered into the corrective action program. Because the valves had not been properly evaluated as high/low interface valves, compensatory measures were established in fire areas 6N for Unit 2 and 13N for Unit 3.
Further review determined the issue is also considered an unanalyzed condition and is reportable as required by 10 CFR 50.72(b)(3)(ii). See ENS event number 53265.
Analysis of Event
10 CFR 50, Appendix R, Section 111.G requires at least one train of cables and equipment necessary for achieving and maintaining hot shutdown to be protected against fire damage. This includes damage from hot shorts, open circuits, or shorts to ground that could prevent operation or cause maloperation of such equipment. These requirements are further clarified in NRC guidance in Generic Letters 81-12 and 86-10.
GL 86-10, Section 5.3.1 states:
For three-phase AC circuits, the probability of getting a hot short on all three phases in the proper sequence to cause spurious operation of a motor is considered sufficiently low as to not require evaluation except for any cases involving Hi/Lo pressure interfaces.
The exception for high/low pressure interfaces is due to the potential severity of a loss of reactor coolant event concurrent with a fire.
Section 6.2 of the site's FPP provides an analysis of high/low pressure interfaces that address the above Appendix R requirements. Fire Safe Shutdown Program Specification NE-00296, Section 6.1, provides program and design requirements for high/low pressure interfaces.
Cause of the Event
The flow path from the RWCU system to the feedwater return to condenser line was not identified as a high/low pressure interface during original Appendix R analysis in the 1980's. The exact cause is unknown, although it was likely due to lack of technical rigor in the system analysis performed when implementing Appendix R requirements.
Corrective Actions
SEQUENTIAL NUMBER 001 REV NO.
0 Since unprotected cables existed in fire areas 6N for Unit 2 and 13N for Unit 3, compensatory measures were conservatively established in accordance with Technical Requirements Manual (TAM) Section 3.14.8 Condition A. A design change has been developed to add a disconnect switch to the power cable for the 2663/3663 valve such that a 3-phase hot short could not occur. Additional corrective actions are documented in the corrective action program.
Previous Similar Occurrences No previous similar occurrences have been identified. Page _4_ of....!.__