05000440/LER-2013-004, Regarding Vulnerability. to Cause Secondary Fire Due to Unfused Control Room Ammeters
| ML13346A430 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 12/09/2013 |
| From: | Harkness E FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-13-382 LER 13-004-00 | |
| Download: ML13346A430 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 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)(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 |
| 4402013004R00 - NRC Website | |
text
FENOCT FirstEnergy Nuclear Operating Company Perry Nuclear Power Plant PO. Box 97 10 Center Road Perry, Ohio 44081 Ernest J. Harkness Vice President 440-280-5382 Fax: 440-280-8029 December 9, 2013 L-1 3-382 1 0CFR50.73(a)(2)(ii)(B)
ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
Perry Nuclear Power Plant Docket No. 50-440, License No. NPF-58 Licensee Event Report Submittal Enclosed is Licensee Event Report (LER) 2013-004, "Vulnerability to Cause Secondary Fire due to Unfused Control Room Ammeters." There are no regulatory commitments contained in this submittal.
If there are any questions or if additional information is required, please contact Mr. Thomas Veitch, Manager-Regulatory Compliance, at (440) 280-5188.
Sincerely, Ernest J. Harkness
Enclosure:
LER 2013-004 cc:
NRC Project Manager NRC Resident Inspector NRC Region III
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 10/31/2013 (10-2010)
, 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 Perry Nuclear Power Plant, Unit 1 05000-440 1 OF 4
- 4. TITLE Vulnerability. to Cause Secondary Fire due to Unfused Control Room Ammeters
- 5. EVENT DATE
- 6. LER NUMBER J 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH SEQUENTIAL REV MONT FACILITY NAME DOCKET NUMBER 10 17 2013 2013 -004 I 12 09 2013 FACILITY NAME DOCKET NUMBER
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i)
[] 50.73(a)(2)(i)(C)
E] 50.73(a)(2)(vii)
[] 20.2201(d)
E] 20.2203(a)(3)(ii)
[
50.73(a)(2)(ii)(A)
E] 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
E] 20.2203(a)(4)
[
50.73(a)(2)(ii)(B)
LI 50.73(a)(2)(viii)(B)
E] 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
E] 50.73(a)(2)(iii)
LI 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL [1 20.2203(a)(2)(ii)
[
50.36(c)(1)(ii)(A)
E] 50.73(a)(2)(iv)(A)
[L 50.73(a)(2)(x)
[j 20.2203(a)(2)(iii)
LI 50.36(c)(2)
[: 50.73(a)(2)(v)(A)
LI 73.71 (a)(4) 100 LI 20.2203(a)(2)(iv)
[
50.46(a)(3)(ii)
[j 50.73(a)(2)(v)(B)
LI 73.71 (a)(5)
LI 20.2203(a)(2)(v)
E] 50.73(a)(2)(i)(A)
LI 50.73(a)(2)(v)(C)
El OTHER Specify in Abstract below 20.2203(a)(2)(vi)
E] 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D) or in With no overcurrent protection provided for these ammeter circuits, a postulated fire in a fire area containing these ammeter cables could cause one of the ammeter wires to short to ground. At the same time, the postulated fire causes another DC wire from the opposite polarity on the same battery to short to ground. This could cause a ground loop through the unfused ammeter circuit resulting in current in excess of the cables ampacity rating.
This high current could cause heating and/or arcing effects from the ammeter cable which could result in a secondary fire along the raceway these circuits are routed in outside the original fire area, damaging adjacent cables that may be credited for safe shutdown.
The circuits for the ammeters are routed through fire areas that contain other circuits required for safe shutdown. In some instances, the ammeter circuits are routed in raceways adjacent to other safe shutdown circuits. Lack of fuse protection for these circuits and routing in areas of other safe shutdown circuits is contrary to the requirements of 10 CFR 50, Appendix R Section III.G to ensure circuits required for safe shutdown remain free of fire damage.
CAUSE OF EVENT
The original plant design contained a latent design error related to wiring and isolation that constituted a fire protection program deficiency which could adversely affect the ability to achieve and maintain safe shutdown of the plant in the unlikely event of a control room fire.
EVENT ANALYSIS
This event is being reported in accordance with 10CFR50.73(a)(2)(ii)(B) in that the overcurrent condition in the DC ammeter circuits could cause damage in other wiring in physical contact with the cable and result in the loss of the associated safe shutdown function required by 10 CFR 50 Appendix R.
There were no actual consequences for this event because a short circuit of the affected ammeter circuits has not occurred. The event investigation and extent of condition review determined that the Division 3 DC ammeter circuit does not impact safe shutdown capability as Division 3 is not a credited system for 10 CFR 50 Appendix R. The Division 3 125 VDC system provides power to the High Pressure Core Spray System [BG].
A Probabilistic Risk Assessment (PRA) evaluation was performed to assess the identified deficiency involving unfused remote DC ammeter circuits. An analysis of this condition estimates a delta core damage frequency (CDF) on the order of 6.1 E-08/yr, and a delta large early release frequency (LERF) on the order of 1.85E-09/yr. The delta CDF and delta LERF values are well below the acceptable thresholds of 1.0E-06/yr and 1.OE-07/yr, respectively, as discussed in Regulatory Guide 1.174, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis". Therefore, the risk of this event is considered small in accordance with the regulatory guidance.
CORRECTIVE ACTIONS
Interim compensatory measures (i.e., fire watches) were implemented for affected areas of the plant at 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br />, on October 17, 2013.
Lifting of leads to remove the potential ground loop in the affected DC ammeter circuits was completed at 1435 hours0.0166 days <br />0.399 hours <br />0.00237 weeks <br />5.460175e-4 months <br />, on October 18, 2013, under the temporary modification process.
A permanent plant modification will be completed to install fuses in the five affected DC ammeter circuits.
PREVIOUS SIMILAR EVENTS
A review of LERs and the corrective action database for the past three years identified one previous similar event documented in LER 2011-001 submitted August 23, 2011. LER 2011-001 identified the following condition:
On July 5, 2011, during a review for applicability of a 10 CFR 21 notification made by WorleyParsons (formerly Gilbert/Commonwealth), an original plant design wiring deficiency was identified. The deficiency is in the design of two control room ammeter circuits and results in the plant being vulnerable to a hot short in the unlikely event of a postulated control room fire. The hot short could cause a loss of the capability of the Division 1 train to achieve and maintain safe shutdown of the plant (the site Safe Shutdown Analysis credits Division 1 to shutdown the plant in the event of a control room fire).
COMMITMENTS
There are no regulatory commitments contained in this LER. Actions described in this document represent intended or planned actions, are described for the NRC information, and are not regulatory
commitments