05000277/LER-2002-001, From Peach Bottom, Unit 2 Regarding Circuit Card Failure Results in a Primary Containment Group Isolation & Plant Scram
| ML030520318 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 02/07/2003 |
| From: | Johnston G Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 02-001-00 | |
| Download: ML030520318 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2772002001R00 - NRC Website | |
text
ExelenSM Exelon Nuclear Peach Bottom Atomic Power Station 1848 Lay Road Delta, PA 17314-9032 Telephone 717 456 7014 www exeloncorp coM Nuclear February 7, 2003 Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555 Docket No.
SUBJECT:
50-277 Licensee Event Report, Peach Bottom Atomic Power Station Unit 2 This LER reports an automatic scram of Unit 2 as a result of a failed circuit card in the Electro-Hydraulic Control (EHC) system. Also, this LER reports a condition involving the Reactor Core Isolation Cooling (RCIC) system not being fully operable as required by Technical Specifications.
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.
Reference:
Report Number:
Revision Number.
Event Date:
Report Date:
Facility:
Docket No.
2-02-001 00 12/21/02 02/7103 50-277 Peach Bottom Atomic Power Station Unit 2 1848 Lay Road, Delta, PA 17314-9032 Enclosure 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 A C. McMurtray, US NRC, Senior Resident Inspector CCN 03-14013
bcc:
C. G. Pardee - KSA 3-N Jeff Benjamin - Cantera G. L. Johnston - PB, A4-1 S B. C. Hanson - PB, A4-1S E. J. Eilola - PB, A4-1 S Garey Stathes, PB, SMB 3-7 P. J. Davison - PB, A2-1 S J. P. Grimes - KSA 2-N J. P. Armstrong - KSA 3-N R. A. Kankus - KSB 3-S A. J. Sherwood - PB, TC S. C. Beck - PB, A4-5S M. P. Gallagher-KSA 3-E D. P. Helker - KSA 3-E W.M. Eckman - PB, SMB4-6 Commitment Coordinator - KSA 3-E Site Commitment Coordinator - A4-5S Correspondence Control Desk - KSA 1-N-1 DAC - KSA 1 -N-1
NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 2001 (1-2001)
COMMISSION Estimated burden per response to comply with this mandatory information collection request 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records Management Branch rT.6E6),
US Nuclear RegulatoryCommission, Washington, DC20555-000 orbyintemet LIC E EVEN-malto bjsPnrOcgov andtotheDeskOfficer, Officeo Information and ReulatoryAffairs, NEOB-10202(3150104), OfficeofManagementandBudget, Washington aC20503.
f a (See reverse for required number of means used to impose iformaton collection does not display a currently valid OMB control digits/characters for each block) number the NRC may not conduct or sponsor, and a person is not required to respond to, the FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
Peach Bottom Atomic Power Station, Unit 2 05000 277 1 OF 5
TITLE (4)
Circuit Card Failure Results in a Primary Containment Group I Isolation and Plant Scram EVENT DATE (5)
LER NUMBER (6)
J REPORT DATE (7)
OTHER FACILITIES INVOLVED (8) l FACILITY NAME DOCKET NUMBER SEQUENTIAL REV Ij_
MO DAY YEAR YEAR NUMBER NOR MO DAY YEAR IFACILITY NAME IDOCKET NUMBER 12 21 02 02 0 01 00 02 07 03 A
OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR aCheck all that apply) (11)
MODE (9) 20 2201 (b)
_ 20 2203(a)(3)(ii) 50 73(a)(2)(ii )(B) 50 73(a)(2)(Nx)(A)
POWER 20 2201 (d) 20 2203(a)(4)
_ 50 73(a)(2)Cii) 50 73(a)(2)(x)
LEVEL (10) 100 20 2203(a)(1)
So36(c)(1)(i)(A)
X 50.73(a)(2)(iv)(A) 73 71 (a)(4) 20 2203(a)(2)(i) 50 36(c)(1)(11)(A) 50 73(a)(2)(v)(A) 73 71 (a)(5) 20 2203(a)(2)(i.)
50 36(c)(2) 50 73(a)(2)(l)(B)
OTHER Speify in Abstract below or in 20 2203(a)(2)(mi)
__50 46(a)(3)(ii) 50 73(a)(2)(v)(C)
NR (if more space is required, use additonal copies of (If more space is required, use addibonal copies of (If more space is required, use addtonal copies of NRC Form 366A) (17)
Cause of the Event, cont.
The cause of exceeding the cool down rate on the reactor bottom head was due to thermal stratification, which occurred when both reactor recirculation pumps tripped, combined with cool water being introduced into the bottom head from the Control Rod Drive system. Human performance errors in evaluating recorded temperatures during cool down trending contributed to this concern.
The cause of three BPVs remaining open when the EHC system was secured is due to less than adequate maintenance on the BPVs. Without EHC fluid pressure, springs exist to close the BPVs.
The spring closure feature of the BPVs was not able to close the valves upon loss of fluid pressure due to friction within the valve, actuator and / or hydraulic binding without the EHC fluid as the primary driver.
Corrective Actions
The failed EHC card was replaced. The replacement card was tested satisfactorily and placed into service. Other similar cards that were replaced during the recent refueling outage were reviewed for similar defective components. No similar defects were determined to exist. A formal root cause analysis is in progress to determine underlying reasons for allowing a card with a defective component to be placed in service. Additional corrective actions will be generated as appropriate based on the results of the root cause analysis.
The RCIC controller was readjusted and tested satisfactorily. The Unit 3 RCIC controller was reviewed for similar concerns and it was determined that the controller was operable. Although considered operable, the Unit 3 RCIC controller gain was adjusted to further improve system performance. Other similar controllers in the HPCI systems for Units 2 and 3 were reviewed and they were determined to be properly adjusted.
The affected Secondary Containment damper solenoid valve was replaced and the damper was satisfactorily tested. A program has been initiated to replace solenoid valves on similar dampers and to routinely perform preventive maintenance on similar equipment.
A thermal cycles analysis of the reactor pressure vessel was completed with satisfactory results. The procedure used for recording temperature data during plant cool downs will be reinforced through training to operations personnel.
The procedure used for monitoring cool down rates will also be reviewed and revised as necessary for usability enhancements.
The BPVs were lubricated and verified to operate properly with EHC fluid pressure. The maintenance program is being upgraded for the BPVs.
Previous Similar Occurrences There were no previous events identified involving a failed EHC card due to a manufacturing defect that resulted in a Group I isolation and full reactor scram.