05000352/LER-2018-002, Primary Containment Isolation Valve Failed to Fully Close Resulting in Condition Prohibited by Technical Specifications
| ML18155A193 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/04/2018 |
| From: | Libra R Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LG-18-067 LER 2018-002-00 | |
| Download: ML18155A193 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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)(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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 3522018002R00 - NRC Website | |
text
Exelon Generation LG-18-067 June 4, 2018 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Unit 1 Renewed Facility Operating License No. NPF-39 NRC Docket No. 50-352 10 CFR 50.73
Subject:
LER 2018-002-00, Primary Containment Isolation Valve Failed to Fully Close Resulting in a Condition Prohibited by TS Enclosed is a Licensee Event Report (LER) which addresses a Primary Containment Isolation Valve (PCIV) being inoperable, resulting in a condition prohibited by Technical Specifications
{TS) at Limerick Generating Station, Unit 1.
This LER is being submitted pursuant to the requirements of 1 O CFR 50.73(a)(2)(i)(B),
Operation or Condition Prohibited by TS.
There are no commitments contained in this letter.
If you have any questions, please contact Robert B. Dickinson at (610) 718-3400.
~lly~
.f(> tz.,.Aictiard W. Libra Vice President - Limerick Generating Station Exelon Generation Company, LLC cc: Administrator Region I, USNRC USNRC Senior Resident Inspector, Limerick Generating Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-01 04 EXPIRES: 03/31/2020 (02-2018)
Estmated b\\Jrden per response to comp!\\' with th~ mandatOI)' collect10n 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 (LEA)
Reported lessons learned are incorporated into the licensing process and fed back to i'ldustry Send comments regarding b\\Jrden estinate to lhe lnfonnat10n Services Branch
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(See Page 2 for required number of digits/characters for each block)
(T*2 F43). U S Nuclear Regula\\ory Commission Washington DC 20555-0001, or by e*mai n
to lnfocollects Resourte@nrt gov, and lo \\he Desk Offcer, Office of lnfonnation and 0
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(See NUREG-1022, R.3 for instruction and guidance for completing this form Regulalory Affairs, NEOB-10202, (3150-0104)
Ottice ol Managemenl and Budge\\.
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Washington DC 20503 If a means used to impose an nlonna\\ion conectoo does not
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d~play a currently valid OMS control number, lhe NRC may not conduct or sponsor. and a person is not required to respond lo, the ilfonnatoo collection 3.Page Limerick Generating Station, Unit 1 05000352 1
OF 4
- 4. Title Primary Containment Isolation Valve Failed to Fully Close Resulting in Condition Prohibited by Technical Specifications
- 5. Event Date
- 6. LEA 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 Facility Name Docket Number 04 03 2018 2018 - 002
- - 00 06 04 2018
- 9. Operating Mode
- 11. This Report is Submitted Pursuant to the Requirements of 10 CFR §: {Check all that apply)
D 20.2201 (bl D 20.2203(a)(3)(iJ D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
D 20.2201 (dJ D 20.2203(a)(3)(iiJ D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B) 4 D 20.2203(a)(1 i D 20.2203(aJ(4J D 50.13(a)(2)(iiiJ D 50.73(a)(2)(ix)(A)
D 20.2203(a)(2Hil 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)(iiJ D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(v)(A)
D 13.11 (a)(4J D 20.2203(a)(2)(iiiJ D 5o.36(c)(2J D 50.73(a)(2)(v)(B)
D 13.11 (a)(5J D 20.2203(a)(2)(iv)
D 5o.46(a)(3)(iiJ D 50. 73(a)(2)(v)(G)
D 73.77(a)(1J 000 D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 13_11(a)(2)(iiJ D 20.2203(a)(2)(vi)
IZ! 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 13.77(a)(2)(iiiJ D 50.73(a)(2)(i)(C)
D Other (Specify in Abstract below or in Ill.
Analysis of the Event
When the RWCU steam leak was initially identified it was believed to only affect the humidity in the room. Operations monitored the steam leak via a camera. The issue was evaluated in the Operational Decision-Making Process (ODM) to determine the correct course of action.
00 On 9/8/17, a ground occurred due to moisture penetrating the limit switch compartment on the motor operator of the A LPCI Outboard Injection Valve. The valve was declared inoperable and isolated.
Maintenance opened the motor operator and removed the water, dried the components, and inspected the motor operator. The ground alarm cleared following drying of the compartment. The power was restored and the LPCI Injection Valve was returned to operable status.
IV.
Safety Significance
The safety significance was low since the primary containment function was maintained and the injection valve was not opened until the system flushes were performed.
Primary containment was not adversely impacted by this condition because the inboard injection check valve was functional and the RHR system is a qualified closed loop system that is credited as a primary containment boundary.
The LGS long term containment analysis supports the conclusion that the same amount of energy can be removed from the suppression pool following a LOCA whether the exit flow from the RHR Heat Exchanger is injected into the reactor vessel or into the suppression pool. Since the LGS procedures allow this method of suppression pool cooling following a LOCA, this function was not lost with the failure of the A LPCI Outboard Injection Valve to close.
Suppression Pool Spray function was maintained because the B Loop of Suppression Pool Spray was maintained available during the time the A Loop LPCI valve was inoperable.
V.
Cause of the Event
The cause was determined to be water intrusion from a nearby steam leak that prevented normal control circuit operation. Corrosion to torque switch mechanical parts prevented electrical and mechanical switch makeup on a close demand signal. A contributing cause was identified in that the risk assessment was performed based on incomplete scope of potential impacts. The focus of the risk assessment was on the RWCU system and not the other systems contained in the general area which would have included the Residual Heat Removal (RHR) system injection valve.
VI.
Corrective Actions Completed/Planned SEQUENTIAL NUMBER 002 REV NO.
00 HV-051-1 F017A was repaired including a replacement of the control circuit hardware.
The station is taking actions to improve risk assessments associated with steam leaks and the potential impact to nearby equipment.
VII.
Previous Similar Occurrences There were no previous similar occurrences in the past 5 years.
VIII.
Component Data System:
Component:
Component number:
Manufacturer:
Model number:
Serial number: BO RHR/Low Pressure Coolant Injection System ISV Isolation Valve HV-051-1 F017A Flowserve Corporation 3232-3 DWG 1N292 Page _4_ of _4_