05000333/LER-2018-001, Secondary Containment Differential Pressure Exceeded the Technical Specification Surveillance Requirement
| ML19032A633 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 02/01/2019 |
| From: | Timothy Peter Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| JAFP-19-0015 LER 2018-001-00 | |
| Download: ML19032A633 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3332018001R00 - NRC Website | |
text
Exelon Generation.
JAFP-19-0015 February 1, 2019 United States Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 James A. FitzPatrick NPP P.O. Box 110 Lycoming, NY 13093 Tel 315-349-6024 Fax 315-349-6480 Timothy C. Peter Plant Manager - JAF James A. FitzPatrick Nuclear Power Plant Renewed Facility Operating License No. DPR-059 NRC Docket No. 50-333
Subject:
Dear Sir or Madam:
LER: 2018-001, Secondary Containment Differential Pressure Exceeded the Technical Specification Surveillance Requirement This report is being submitted pursuant to 1 O CFR 50.73(a)(2)(v)(D) as an "Event or Condition that Could Have Prevented Fulfillment of a Safety Function."
There are no new regulatory commitments contained in this report.
Questions concerning this report may be addressed to Mr. William Drews, Regulatory Assurance Manager, at (315) 349-6562.
Sincere!~
it~ter Plant Manager TCP/WD/hm
Enclosure:
LER: 2018-001, Secondary Containment Differential Pressure Exceeded the Technical Specification Surveillance Requirement cc:
USNRC, Region I Administrator USNRC, Project Manager USNRC, Resident Inspector INPO Records Center (ICES)
NRC FORM 366 (04-2018)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (04-2018)
LICENSEE EVENT REPORT (LER)
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. Facility Name James A. FitzPatrick Nuclear Power Plant
- 2. Docket Number 05000333
- 3. Page 1 OF 4
- 4. Title Secondary Containment Differential Pressure Exceeded the Technical Specification Surveillance Requirement
- 5. Event Date
- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved
Month
Day
Year
Year Sequential Number Rev No.
Month Day Year Facility Name N/A Docket Number N/A 12 05 2018 2018 - 001 - 00 02 04 2019 Facility Name N/A Docket Number N/A
- 9. Operating Mode Month Day Year Yes (If yes, complete 15. Expected Submission date) No Abstract (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
At 1010 on December 5, 2018, Secondary Containment differential pressure exceeded the Technical Specification Surveillance Requirement of greater than or equal to 0.25 inches of vacuum water column. The highest Secondary Containment differential pressure was measured at a positive value of 0.06 inches water column. This condition existed for approximately 3 minutes before the differential pressure was restored to normal when the Standby Gas Treatment system was manually initiated.
This event was caused by a trip of the service air compressor 39AC-2A. The loss of instrument air pressure caused Reactor Building ventilation to isolate and raise Secondary Containment differential pressure. The instrument air pressure was restored when 39AC-2A was isolated and the two backup air compressors started.
This condition did not impact the ability of the Standby Gas Treatment system to establish and maintain the required negative pressure in the containment structure. When Secondary Containment did not meet the Technical Specification Surveillance Requirement 3.6.4.1.1 for differential pressure, the Limiting Condition of Operation (LCO) was not met.
Therefore, Secondary Containment was inoperable. This event was being reported under 10 CFR 50.72(b)(3)(v)(C).
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
(See Page 2 for required number of digits/characters for each block)
=
Background===
The Secondary Containment [EIIS identifier: NG] is a structure comprised of the Reactor Building that surrounds the primary containment and refuel equipment. Its safety function is designed to provide containment for postulated accident scenarios: loss-of-coolant accident and refueling accident. This structure forms a control volume that serves to hold up and dilute fission products in the event of an accident. Since pressure may increase in Secondary Containment relative to the environmental pressure, the system was designed to include a differential pressure vacuum such that external atmosphere would leak into containment rather than fission products leak out.
The systems which maintain a differential pressure vacuum inside Secondary Containment are the normal Reactor Building Ventilation (RBV) system [VA] and the safety-related Standby Gas Treatment (SBGT) system [BH]. During a postulated accident scenario, the normal RBV isolates and the SBGT initiates in order to filter gas from Secondary Containment to the environment. SBGT has the capacity to maintain the differential pressure vacuum.
Event Description
At 1010 on December 5, 2018, Secondary Containment differential pressure exceeded the Technical Specification Surveillance Requirement of greater than or equal to 0.25 inches of vacuum water gauge. The highest Secondary Containment differential pressure was measured at a positive value of 0.06 inches water column. This condition existed for approximately 3 minutes before the differential pressure was restored to normal when the Standby Gas Treatment system was manually initiated.
This event was caused by a trip of the service air compressor 39AC-2A. The loss of instrument air pressure caused Reactor Building ventilation to isolate and raise Secondary Containment differential pressure. The instrument air pressure was restored when 39AC-2A was isolated and the two backup air compressors started.
Event Analysis
Loss of instrument air pressure to the Reactor Building Ventilation systems air operated dampers caused the dampers to move to the closed position. Once air pressure is removed, spring pressure will force the air operator in the closed direction and thus close the damper. The result is the system not maintaining a negative pressure in the Reactor Building as compared to the outside environment.
Cause
The cause of this event was a loss of instrument air pressure when the 39AC-2A Service Air Compressor tripping off-line due to high inter-stage pressure and failure of the discharge check valve to close, allowing system pressure to be lost.
External Events Hatch, Unit 1, Condition Prohibited by Tech Specs due to Secondary Containment Inoperability, caused by in-leakage through degraded secondary containment door seals. (ML18080A054)
Fermi, Unit 2, Secondary Containment Pressure Exceeded Technical Specification due to Reactor Building HVAC System Manipulation - This event was cause by a degraded bolt and pivot linkage on a modulating damper. (ML18054A752) U.S. NUCLEAR REGULATORY COMMISSION (04-2018)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER James A. FitzPatrick Nuclear Power Plant 05000 - 333 YEAR SEQUENTIAL NUMBER REV N0.
2018
- - 001
- - 00 Page 3 of 3 (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
Corrective Actions
Future Corrective Actions Engineering Evaluation of installation of an external check valve on discharge of service air compressors (in addition to the compressor internal check valve).
Procure a spare station air compressor to be stored on site
Completed Corrective Actions
Service Air compressor 39AC-2A was replaced; including internal check valve (JAF Work Order #04662559)
Safety Significance
Nuclear safety - This event did not have any actual or potential impact on nuclear safety.
Radiological safety - There was no radiological consequence during this event.
The potential for a radiological consequence is only applicable during the time that Secondary Containment was below 0.25 inches water vacuum differential pressure. When this condition had occurred at JAF it was momentary excursions.
Secondary Containment maintains a differential pressure vacuum by two of four RBV exhaust fans or one of two SBGT trains. During a postulated accident scenario RBV is placed in isolation and the SBGT is used to maintain differential pressure. The condition does not adversely impact that ability of RBV to isolate or SBGT to initiate. Therefore, the capability of Secondary Containment to mitigate the consequence of an accident is unaffected by this deficiency.
Industrial safety - This event did not have any actual or potential impact on industrial safety.
References JAF Issue Report - IR 04200410 - Equipment Corrective Action Evaluation