05000293/LER-2009-002, Failure to Meet Technical Specification Requirements for Secondary Containment
| ML100540085 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 02/16/2010 |
| From: | Bronson K Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 2.10.013 LER 09-002-00 | |
| Download: ML100540085 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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)(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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2932009002R00 - NRC Website | |
text
"'Entergy Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360 Kevin H. Bronson Site Vice President February 16, 2010 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555
SUBJECT:
Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station Docket No.: 50-293 License No.: DPR-35 Licensee Event Report 2009-002-00 LETTER NUMBER: 2.10.013
Dear Sir or Madam:
The enclosed Licensee Event Report (LER) 2009-002-00, "Failure to Meet Technical Specification Requirements for Secondary Containment" is submitted in accordance with 10 CFR 50.73.
This letter contains no commitments.
Please do not hesitate to contact Mr. Joseph R. Lynch, (508) 830-8403, if there are any questions regarding this submittal.
Kevin H. Bronson RMB Enclosure cc:
Mr. James S. Kim, Project Manager Plant Licensing Branch I-1 Division of Operator Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission One White Flint North O-8C2 11555 Rockville Pike Rockville, MD 20852 INPO Records 700 Galleria Parkway Atlanta, GA 30399-5957 Mr. Samuel J. Collins Regional Administrator, Region 1 U.S. Nuclear Regulator Commission 475 Allendale Road King of Prussia, PA 19406 Senior Resident Inspector Pilgrim Nuclear Power Station
Enclosure to Letter Number 2.10.013 (5 pages)
NRC Form 366 U.S. NUCLEAR REGULATORY COMMISSION Approved by OMB: No. 3150-0104 Expires: 08/31/2010 (9-2007)
Estimated burden per response to comply with this mandatory information collection request: 80 hrs. Reported lessons learned are incorporated into the LICENSEE EVENT REPORT (LER) licensing process and fed back to industry. Send comments regarding burden estimate to the Records and FOIA/Privacy Service Branch (T-5 F52). U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503.
If a means used to impose and information collection does not display a currently valid control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE PILGRIM NUCLEAR POWER STATION 05000-293
- 1 of 5
- 4. TITLE Failure to Meet Technical Specification Requirements for Secondary Containment
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE)
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL NUMBER REVISION FACILITY NAME DOCKET MONTH DAY YEAR YEAR NUMBER MONTH DAY YEAR N/A NUMBER 05000 FACILITY NAME DOCKET 12 22 2009 2009 002 00 02 16 2010 N/A NUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR: (Check one or more) 20.2201 (b) 22.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)
N 22.2202(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2203(a)(1) 20.2203(a)(4).
50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(3)(1 )(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(ii) 50.36(3)(1 )(ii)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)
- 10. Power Level 20.2203(a)(2)(iii) 50.36(0)(2) 50.73(a)(2)(v)(A) 73.71 (a)(4) 20.2203(a)(2)(iv) "_
50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71 (a)(5) 100 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)
OTHER 20.2203(a)(2)(vi)
X 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in
EVENT DESCRIPTION
On December 22, 2009, at approximately 0845 hours0.00978 days <br />0.235 hours <br />0.0014 weeks <br />3.215225e-4 months <br /> a design engineer performing a walk down of the torus room notified the main control room (MCR) that the torus trough (bay #15) for auxiliary bay 'A' was dry. The engineer also indicated that the torus trough (bay #13) for auxiliary bay 'B' appeared to be at a lower level than normally observed. The Shift Manager immediately took actions to verify the engineer's observations.
Main Control Room (MCR) alarm, C904L-A7, Torus Trough Hi/Lo, which was not in alarm status, was verified to be enabled. The Operations Field Shift Supervisor was dispatched to the torus room to verify the engineer's observations.
Secondary containment integrity is ensured by maintaining a controlled water level above the drain pipe openings in each trough such that a water seal ensures the ability to establish and maintain 0.25 inches of negative water pressure within secondary containment. Active LCO, LCO ACT-I 0219, was entered at 0845 hours0.00978 days <br />0.235 hours <br />0.0014 weeks <br />3.215225e-4 months <br /> because secondary containment integrity could not be ensured with one trough dry. The trough was filled and the LCO was exited one hour later at 0945 hours0.0109 days <br />0.263 hours <br />0.00156 weeks <br />3.595725e-4 months <br />.
Additionally, an 8-hour 50.72 notification was made to the USNRC.
CAUSE
The apparent cause of this event is due to a small leak of water from the torus bay 'A' trough. This leakage caused the trough level to slowly lower over time which ultimately challenged the failed low level alarm level switch, LS-9038B. Plans for repair of the torus trough are ongoing and are being tracked in PNPS's Corrective Action Program via CR-PNP-2009-5309.
The second apparent cause of this event was the failure of level switch LS-9038B which provides the torus trough low level alarm signal. The level switch actuating plate was found misaligned which had required compensation with the adjustment screws during functional calibrations and eventually over time, failed to provide the trough low water level condition to the control room. This alarm is designed to alert the main control room of a high or low level in the torus trough condition and to initiate appropriate corrective actions.
The lack of a specific trough level acceptance criteria in the operator rounds contributed to this event. While operators performed the weekly torus room check/ tour, there were no inspections of the troughs or criteria for acceptable level bands.
NU.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REVISION YEAR NUMBER NUMBER PILGRIM NUCLEAR POWER STATION 05000-293 2009 002 00 4 of 5 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
CORRECTIVE ACTION
Immediate corrective actions taken were to refill the trough to the correct level, repair the level switch which was found to'be defective, ensured other the trough had adequate water level and it's level switches were working properly, and enhanced the weekly tour requirement of the Torus Compartment performed by plant operations.
Corrective actions planned include leak repair of the torus trough, level switch surveillance test enhancements, and level switch preventative maintenance (PM) basis document revision.
These above actions are being tracked in the Pilgrim Station Corrective Action Program (CR-PNP-2009-5295 and CR-PNP-2009-5309).
SAFETY CONSEQUENCES
The event posed no threat to public health and safety.
The plant was operating at 100% power prior to and during the time period when the torus trough was found without a water seal and required repair. All other secondary containment sub-systems were operable during this time period.
Secondary containment integrity is ensured by maintaining a given water level in each of the two torus troughs.
The lack of a water seal in a torus trough creates a scenario in which the auxiliary bay atmosphere would communicate directly with the secondary containment atmosphere. This would cause the effective volume upon which the standby gas system would attempt to maintain at 0.25 inches of water negative pressure to be larger.
This presents the potential for secondary containment air pressure to approach, equal or be greater than the air pressure in ambient building or atmospheric pressures. If this occurred and remained undetected the design principle of leakage into secondary containment, filtration by standby gas and release from the main stack would be reduced or neutralized. Ultimately the potential for an unmonitored ground level release would increase.
Technical Specification 3.7.C requires that the secondary containment be operable in the RUN mode. The Secondary Containment integrity definition was not satisfied during this time period.
Technical Specification definition for Secondary Containment Integrity means that the reactor building is intact and the following conditions are met:
- 1.
At least one door in each access opening is closed,
- 2.
The standby gas treatment system is operable,
- 3.
All automatic ventilation system isolation valves are operable or secured in the isolated position.
Since the Secondary Containment System was able to be restored to an operable status following the re-filling of the torus troughs to a proper level, there was no long term safety significance associated with this event.U.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REVISION YEAR NUMBER NUMBER PILGRIM NUCLEAR POWER STATION 05000-293 2009 002 00 5 of 5 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
REPORTABILITY
This report was submitted in accordance with 10 CFR 50.73(a)(2)(i)(B).
SIMILARITY TO PREVIOUS EVENTS A review was conducted of Pilgrim Station LERs since 1974. There were no LERs related to the torus troughs with the failure to maintain secondary containment.
The review identified Secondary Containment events that occurred in 1985 and 2008.
LER 1985-18 addressed an event where a Secondary Containment damper (AO-N-90) would not fully close.
LER 2008-001 addressed on-line testing of the Reactor Building Isolation Control System (RBICS) ventilation dampers. This testing identified that in the closed position, damper AO-N-78 did not fully close. The damper was reported to have a one-half inch gap opening across two of the four damper blades and did not meet Technical Specification requirements for full damper closure.
These events were reported as events where Technical Specifications were not satisfied.
ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) CODES The EIIS codes for this report are as follows:
SYSTEMS CODES Containment Leak System BD