05000277/LER-2004-003, Regarding Automatic Scram Due to an Electro-Hydraulic Control System Malfunction
| ML050330127 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 01/20/2005 |
| From: | Grimes J Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CCN 05-14003 LER 04-003-00 | |
| Download: ML050330127 (4) | |
| 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 |
| 2772004003R00 - NRC Website | |
text
Pec ExeIon.M Exelon Nuclear Telephone 717.456.7014 Nuclear Peach Bottom Atomic Powver Station w wwexeloncorp.com 1848 Lay Road Delta, PA 17314-9032 1 OCFR 50.73 January 20, 2005 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station (PBAPS) Unit 2 Facility Operating License No. DPR-44 NRC Docket No. 50-277
Subject:
Licensee Event Report (LER) 2-04-03 This LER reports an automatic scram as a result of a Primary Containment Group I isolation on low Reactor steam pressure. 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, Joseph P. Grimes Plant Manager Peach Bottom Atomic Power Station JPGjrd/CR 285024 Attachment cc:
PSE&G, Financial Controls and Co-owner Affairs R. R. Janati, Commonwealth of Pennsylvania INPO Records Center S. J. Collins, US NRC, Administrator, Region I R. I. McLean, State of Maryland F. L. Bower, USNRC Senior Resident Inspector CCN 05-14003
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 (6-204)
, the NRC maynot conduct or sponsor, and a person Is not required to respond to, the Inlormation digits/characters for each block) collection.
- 3. PAGE Peach Bottom Atomic Power Station (PBAPS).
05000 277 1 OF 3
- 4. TITLE Automatic Scram due to an Electro-Hydraulic Control System Malfunction
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILMES INVOLVED 1
REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 12 22 2004 4
03 -
0 1
20 2005 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) o 20.2201(b) a 20.2203(a)(3)(i)
E 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii) 1 0 20.2201(d) 0 20.2203(a)(3)(ii)
[I 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) o 20.2203(a)(1)
El 20.2203(a)(4) 0 50.73(a)(2)(ii)(B) a 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A)
- 0. POWER LEVEL 0
20.2203(a)(2)(ii) 0 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x) o 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) o 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B) 0 73.71(a)(5) 100 0 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C) 0 OTHER o 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify In Abstract below or In (If more space Is required, use additional copies of NRC Form 366A) (17)
Cause of the Event
The cause of the EHC system malfunction is due to a failed 'A' Pressure Regulator circuit card (EIIS: IT). This circuit card is supplied by Mechanical Dynamics & Analysis (formerly Nova-Tech Corporation), Part No.
99041 P1.
Initial troubleshooting was performed on the failed circuit card. The card was found to have low voltage at the
'decrease' input pin. The voltage observed at this pin would cause the control system malfunction symptoms observed and would also adversely affect the 'B' Pressure Regulator from being able to control Reactor pressure.
Detailed failure analyses were performed on the failed circuit card. The card was found to have a manufacturing defect involving excess solder. The excess solder on the circuit card created a short across two traces on the card, causing a voltage drop on the card. Removal of the excess solder resulted in proper card operation.
This card was installed in the EHC system on 9/18/04 during the recent Unit 2 refueling outage. The previously installed card could not be properly calibrated while performing preventive maintenance on the EHC system during the refueling outage. The previous that could not be calibrated had failed in a different manner (i.e. the set point was not able to be raised above 150 psig).
Corrective Actions
The defective card was replaced and the EHC system tested to verify proper operation. The EHC system was placed in service and has been appropriately controlling Reactor pressure since this event.
Similar installed circuit cards on Unit 2 were inspected and no similar solder deficiencies were observed.
Additional evaluations and corrective actions are being performed in accordance with the corrective action program.
Previous Similar Occurrences There was a previous Unit 2 scram on 12/21/02 caused by an EHC circuit card malfunction reported in LER 2-02-01. The failed circuit card was supplied by a different manufacturer and involved failure of a different type of sub-component (i.e. Operational Amplifier). Corrective actions resulting from the event reported in LER 2-02-01 included assessments of circuit cards potentially involving similar Operational Amplifier components.