05000277/LER-2004-001, Manual Scram Resulting from Low Condenser Vacuum Due to a Failed Feedwater Turbine Expansion Joint
| ML041180567 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 04/16/2004 |
| From: | Stone J Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CCN 04-1040, NEI 99-04 LER 04-001-00 | |
| Download: ML041180567 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| 2772004001R00 - NRC Website | |
text
Exelon..
Exelon Nuclear Telephone 717.456.7014 Nuclear Peach Bottom Atomic Power Station www.exeloncorp.com 1848 Lay Road Delta, PA 17314-9032 1 OCFR 50.73 April 16, 2004 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station (PBAPS) Unit 2 Facility Operating License Nos. DPR-44 NRC Docket No. 50-277
Subject:
Licensee Event Report (LER) 2-04-01 This LER reports a manual scram of Unit 2 and resultant Primary Containment Group II and IlIl isolations. In accordance with NEI 99-04, the regulatory commitment contained in this correspondence is to restore compliance with the regulations. The specific methods that are 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 us.
Sincerely, Ag
/dt J ~hn A. Stone Pfant Manager leach Bottom Atomic Power Station JAS/ajs/CR 203355 Attachment cc:
PSE&G, Financial Controls and Co-owner Affairs R. R. Janati, Commonwealth of Pennsylvania INPO Records Center H. J. Miller, US NRC, Administrator, Region I R. l. McLean, State of Maryland C. W. Smith, US NRC, Senior Resident Inspector CCN 04-14040
SUMMARY OF EXELON NUCLEAR COMMITMENTS The following table identifies commitments made in this document by Exelon Nuclear.
(Any other actions discussed in the submittal represent intended or planned actions by Exelon Nuclear. They are described to the NRC for the NRC's information and are not regulatory commitments.)
Commitment
Committed Date or "Outage" In accordance with NEI 99-04, the In accordance with the Corrective Action regulatory commitment contained in this Program correspondence is to restore compliance with the regulations. The specific methods that are planned to restore and maintain compliance are discussed in the LER.
I
Abstract
Peach Bottom Unit 2 was manually scrammed at approximately 1510 hours0.0175 days <br />0.419 hours <br />0.0025 weeks <br />5.74555e-4 months <br /> on 2/22/04 as a result of decreasing Main Condenser vacuum. Prior to the event, at 1424 hours0.0165 days <br />0.396 hours <br />0.00235 weeks <br />5.41832e-4 months <br />, an increase in the air in-leakage into the condenser occurred. This prompted entry into the Operational Transient (OT) procedure for low condenser vacuum.
Condenser vacuum was 27.1" Hg at the time the OT procedure was entered. A power reduction was performed to approximately 43% power with a resultant condenser vacuum of approximately 25.5" Hg. A briefing was conducted and the reactor was manually scrammed in accordance with the OT procedural direction since Condenser vacuum was not restored to above the procedurally required 26.2" Hg value for the current plant condition.
As a result of the manual scram, reactor water level decreased, as expected, to below the reactor water level-three (lo-level) set point resulting in Primary Containment Isolation System Group II and III isolations. The cause of the event was due to a leaking Reactor Feedpumnp Turbine Exhaust expansion joint. The expansionjoint was repaired. There were no safety consequences as a result of this event.
NRC FORM 366 (7-2001)
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
Analysis of the Event
There were no actual safety consequences as a result of this event. All control rods inserted on the reactor scram signal. Group II and Group III PCIS isolations initiated as expected when reactor water level decreased to the level-three (lo-level) reactor water level set point.
Subsequent analysis has determined that the size of the leak in the. Reactor Feed pump turbine exhaust expansion joint bellows (EIIS: XJ) was within the capacity of the steam jet air exhausters and therefore, the automatic low Condenser vacuum set point would not have been reached. Therefore, there was no concern that the normal heat sink for the plant could have been lost. Normal heat removal systems were used for plant shutdown.
The event was determined to not be risk significant.
Cause of the Event
The cause of the event was due to.a breach in the, 2A.Reactor Feed Pump Turbine Exhaust Expansion Joint bellows (46"x46", Model.83-1983-C, manufactured by Tube Turns). Subsequent to the unit shutdown, inspections were performed. for. the, source of the Condenser vacuum reduction. The inspection revealed that a small opening had developed in the expansion joint.
Corrective Actions
Temporary repairs were. made to.-the. 2A Reactor Feed Pump Turbine Exhaust expansion joint, XJ-21 70A. Post repair testing -was performed with satisfactory results. The expansionjoints for the other Reactor Feed Pump Turbines were tested for leakage and no additional problems were noted. Other pressure boundary components that could.contribute to condenser in-leakage were examined and/or tested for leakage. Additional. analysis of the expansion joint is being performed. Additional underlying causes and corrective. actions will ber-pursued.in accordance with the Corrective Action program. Long term repairs to the.expansion'joint a-re platned for the next refueling outage.
Previous Similar Occurrences There were no previous similar LERs identified involving a failure of a reactor feed pump turbine exhaust joint.