05000338/LER-2011-001, For North Anna Power Station, Unit 1, Regarding Annunciator Card Failure Due to Carbon Resistor Degradation
| ML111020308 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/01/2011 |
| From: | Lane N Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 11-193 LER 11-001-00 | |
| Download: ML111020308 (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 |
| LER closed by | |
| IR 05000338/2011003 (28 July 2011) | |
| 3382011001R00 - NRC Website | |
text
1 OCFR50.73 Virginia Electric and Power Company North Anna Power Station P. 0. Box 402 Mineral, Virginia 23117 April 1, 2011 Attention: Document Control Desk Serial No.:
11-193 U. S. Nuclear Regulatory Commission NAPS:
MPW Washington, DC 20555-0001 Docket No.: 50-338 License No.: NPF-4
Dear Sirs:
Pursuant to 10CFR50.73, Virginia Electric and Power Company hereby submit the following voluntary Licensee Event Report applicable to North Anna Power Station Unit 1.
Report No. 50-338/2011-001-00 This report has been reviewed by the Facility Safety Review Committee and will be forwarded to the Management Safety Review Committee for its review.
Sincerely, N. Larry Lane Site Vice President North Anna Power Station Enclosure Commitments contained in this letter: None cc:
United States Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, Georgia 30303-1257 NRC Senior Resident Inspector North Anna Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES: 10/31/2013 (10-20 10)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE NORTH ANNA POWER STATION, UNIT 1 05000 338 1 OF 3
- 4. TITLE Annunciator Card Failure Due To Carbon Resistor Degradation
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR FACILITY NAME DOCUMENT NUMBER I
NUMBER NO.
05000 02 03 2011 2011 I "001 --
00 04 01 2011 FACILITY NAME DOCUMENT NUMBER
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
DJ 20.2201(b)
Ei 20.2203(a)(3)(i)
[
50.73(a)(2)(i)(C)
[]
50.73(a)(2)(vii)
Ej 20.2201(d)
[
20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A) 1 Ei 20.2203(a)(1)
LI 20.2203(a)(4)[L 50.73(a)(2)(ii)(B)
[] 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i)
E]
50.36(c)(1)(i)(A)
[]
50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL
[
20.2203(a)(2)(ii)
LI 50.36(c)(1)(ii)(A)
LI 50.73(a)(2)(iv)(A)
L] 50.73(a)(2)(x)
LI 20.2203(a)(2)(iii)
[]
50.36(c)(2)
[]
50.73(a)(2)(v)(A)
[Z 73.71(a)(4)
Ej 20.2203(a)(2)(iv)
EJ 50.46(a)(3)(ii)
[J 50.73(a)(2)(v)(B)
EJ 73.71(a)(5)
LI 20.2203(a)(2)(v)
EJ 50.73(a)(2)(i)(A)
LI 50.73(a)(2)(v)(C)
[X] OTHER 100%
E] 20.2203(a)(2)(vi)
[]
50.73(a)(2)(i)(B)
[]
50.73(a)(2)(v)(D)
Specify in Abstract below or in
3.0 CAUSE
The cause of the annunciator card fire was age related degradation of the carbon resistor.
As the resistors age, they can either increase or decrease in resistance. In either case, the heat dissipation of the resistors increases causing the temperature to approach the high end of the specification for these resistors. This is defined as electrical fatigue.
4.0 IMMEDIATE CORRECTIVE ACTION(S)
Fire Contingency Action procedure 0-FCA-0, Fire Protection - Operations Response was entered. The fire was promptly extinguished and a re-flash fire watch was established.
5.0
ADDITIONAL CORRECTIVE ACTIONS
Engineering performed a thermography scan of both Unit 1 and Unit 2 Hathaway cabinets to determine if any of the other resistors were at risk for combustion. All scans showed that, while temperatures on some resistors were elevated, none of the temperatures were above the resistors specification. Resistors were replaced on eight cards that had elevated temperatures.
6.0 ACTIONS TO PREVENT RECURRENCE A plan has been developed to replace the carbon resistors in the Hathaway system annunciator cards with metal film resistors. Temperature monitoring for the Hathaway cabinets to trend component temperatures and drive component replacements is being established. Appropriate Preventive Maintenance strategies for Hathaway System will include a replacement frequency for the resistors.
7.0 SIMILAR EVENTS
None
8.0 ADDITIONAL INFORMATION
Unit 2 was operating at 100 percent power, Mode 1, and was not affected by this event.
Component Manufacturer:
Hathaway Component Model Number: 744202 Component Type:
Annunciator Point Card