05000364/LER-2004-004, Unit 2 Reactor Trips Due to Unblocking of Source Range Permissive Interlock
| ML041600174 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 06/04/2004 |
| From: | Stinson L Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-04-0938 LER 04-004-00 | |
| Download: ML041600174 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iii) 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) 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3642004004R00 - NRC Website | |
text
L M. Stinson (Mike)
Vice President Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.5181 Fax 205.992.0341 June 4, 2004 Docket No.: 50-364 SOUTHERNAZM COMPANY Energy to Serve Your World' NL-04-0938 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Unit 2 Licensee Event Report 2004-004-00 Reactor Trins Due to Unblocking of Source Range Permissive Interlock Ladies and Gentlemen:
Joseph M. Parley Nuclear Plant - Licensee Event Report (LER) No. 2004-004-00 is being submitted in accordance with 10 CFR 50.73(a)(2)(iv)(A).
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely, L. M. Stinson LMS/WAS/sdl Enclosure: Licensee Event Report 2004-004-00 cc:
Southern Nuclear Operating Company Mr. J. B. Beasley, Jr., Executive Vice President Mr. D. E. Grissette, General Manager - Plant Farley RTYPE: CFAO4.054; LC# 14045 U. S. Nuclear Regulatorv Commission Dr. W. D. Travers, Regional Administrator Mr. S. E. Peters, NRR Project Manager - Farley Mr. C. A. Patterson, Senior Resident Inspector-Farley 0
g NR OM36US ULA EUAOY APPROVED BY OM B NO. 3150-0104 EXPIRES 7431-2004 NRC FORM 366 U.S. NUCLEAR REGULATORY
, the NRC may not conduct or sponsor. and a digitstcharacters for each block) person is not reqmired to respond to. the Information collection FACILITY NAME (1)
DOCKET NUMBER (2)
P E (3)
Joseph M. Farley Nuclear Plant - Unit 2 05000364 1 OF 4 mTLE(4)
Reactor Trips Due to Unblocking of Source Range Permissive Interlock EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
FACILITY NAME DOCKET NUMBER SEQUENTIAL REV MO DAY YEAR YEAR NUMBER NO MO DAY YEAR 04 11 2004 2004 004 00 06 04 2004 FACILITY NAME DOCKET NUMBER OPERATING 2
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Check all that apply) (11)
MODE (9)
=
20.2201(b)
= 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(ix)(A)
POWER 0
20.2201 (d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)
LEVEL (10) 00 20.2203(a)(1) 50.36(c)(1)(i)(A)
X 50.73(a)(2)(iv)(A) 73.71(a)(4)
=
20.2203(a)(2)(i) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(5) 20.2203(a)(2)(ii) 50.36(c)(2) 50.73(a)(2)(v)(B)
OTHER 20.2203(a)(2)(iii) 50.46(a)(3)(ii) 50.73(a)(2)(V)(C)
Specify In Abstract below or in
=
20.2203(a)(2)(iv)
= 50.73(a)(2)(i)(A)
= 50.73(a)(2)(v)(D)
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17) source confirmed that the failure came in as the card temperature increased.
A review of work order history and of card components indicated that the card (A406) had components manufactured as early as 1974 and as late as 1985. The failed card (A406), as well as other cards (A408 and A41 1) in the source range high flux trip (P-6 interlock) were replaced. The special test procedure was conducted again simulating actual cabinet temperature. No problems were observed. SSPS surveillances were conducted to confirm proper functions.
Following a thorough review of investigative results and corrective measures, Unit 2 reactor was restarted.
Cause of Event
Both reactor trip events were due to an intermittent failure of universal logic card (A406) in the B Train Solid State Protection System (SSPS). The card failure was due to an increased sensitivity to heat believed to be the result of aging. The card was found to be overly sensitive to ambient temperature changes after energization of the Source Range Trip Block (P-6 interlock).
Safety Assessment
All safeguards equipment functioned as designed following both trips.
The logic circuit failure in the B Train SSPS resulted in an inappropriate safety function actuation and did not result in the loss of a train of safety function.
The health and safety of the public were unaffected by this event.
This event does not represent a Safety System Functional Failure.
Corrective Action
The failed card (A406) was replaced as well as other applicable cards (A408 and A41 1) in the P-6 interlock circuit.
The equipment reliability plan associated with the 7300 system will be revised by November 30, 2004 to incorporate SSPS card failure and aging issues identified during this event.
LICENSEE EVENT REPORT (LER)
DOCKET (2)
FACILITY NAME (1)
NUMBER LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION IINUMBER INUMBER seph M. Farley Nuclear Plant - Unit 2 05000364 NU4 OF 4
2004 004 00 RRATIVE (If more space is required, use additional copies of NRC Form 366A) (17)
Additional Information
The following LER has been submitted in the past two years regarding aging of electronic circuits.
LER 2004-001-00 Unit 1, Reactor Trip Due to Steam Generator Feedwater Pump Speed Control Failure.