05000334/LER-2014-004, Unit Number 1 Regarding Unanalyzed Condition Resulting from Unfused Direct Current Control Circuits
| ML14183A399 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 06/27/2014 |
| From: | Emily Larson FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-14-226 LER 14-004-00 | |
| Download: ML14183A399 (4) | |
| 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 |
| 3342014004R00 - NRC Website | |
text
Beaver Valley Power Station P.O. Box 4
%Shippingport, PA 15077 FirstEnergy Nuclear Operating Company Eric A. Larson 724-682-5234 Site Vice President Fax: 724-643-8069 June 27, 2014 L-14-226 10 CFR 50.73 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
Beaver Valley Power Station, Unit Nos. 1 and 2 BV-1 Docket No. 50-334, License No. DPR-66 BV-2 Docket No. 50-412, License No. NPF-73 LER 2014-004-00 Enclosed is Licensee Event Report (LER) 2014-004-00, "Unanalyzed Condition Resulting From Unfused Direct Current Control Circuits." This event is being reported in accordance with 10 CFR 50.73(a)(2)(ii)(B).
There are no regulatory commitments contained in this submittal. Any actions discussed in this document that represent intended or planned actions are described for the NRC's information, and are not regulatory commitments.
If there are any questions or if additional information is required, please contact Mr. William C. Cothen, Manager, Regulatory Compliance at 724-682-4284.
Sincerely, Eric A. Larson Enclosure - LER 2014-004-00 cc:
Mr. W. M. Dean, NRC Region I Administrator Mr. J. A. Krafty, NRC Senior Resident Inspector Mr. J. A. Whited, NRR Project Manager INPO Records Center (via INPO Consolidated Event System)
Mr. L. E. Ryan (BRP/DEP)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 01131/2017 (02-2014) the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
_171
_OF 1, FACILITY NAME
- 2. DOCKET NUMBER
- 3. PAGE Beaver Valley Power Station Unit Number 1 05000334 1 OF 3
- 4.
TITLE Unanalyzed Condition Resulting From Unfused Direct Current Control Circuits
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DY YA AiiYNM OKTNME NUMBER DAY YEAR Beaver Valley Unit 2 05000412 04 Z I l FACITY NAME DOCKET NUMBER 04 30 2014 2014 - 004
- - 00 06 27 2014I 9, OPERATING M11.
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
ED 20.2201(b)
ED 20.2203(a)(3)(i)
EZ 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
Mode 1 [1 20.2201(d)
[] 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
E 50.73(a)(2)(ii)(B)
[: 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL [I 20.2203(a)(2)(ii)
[I 50.36(c)(1)(ii)(A)
[: 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
[] 50.73(a)(2)(v)(A)
LI 73.71(a)(4) 100 l 20.2203(a)(2)(iv)
DI 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
LI 73.71(a)(5) 1 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
EI 50.73(a)(2)(v)(C)
LI OTHER Specify in Abstract below or in NRC 20.2203(a)(2)(vi)
EL 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Form 36A
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT I TELEPHONE NUMBER (Include Area Code)
William C. Cothen, Manager, Regulatory Compliance I
724-682-4284CAUSE SYSTEM COMPONENT MANU-REPORTABLES SYSTEM C
T FACU RER OTOBE C
S FACTURER TO EPIX FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR El YES (if yes, complete 15. EXPECTED SUBMISSION DATE)
I]
NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
Based on a review of industry operating experience, it was identified that Beaver Valley Power Station (BVPS) Unit 1 and Unit 2 each have unfused direct current (DC) control circuits for DC motors which are routed from the turbine building through other fire areas. The DC breakers used to protect the motor power conductors are insufficient to protect the control conductors for these circuits. It is postulated that a fire induced short in one fire area could adversely impact safe shutdown equipment by overheating the cable and causing a secondary fire in other fire areas where the cable is routed. The postulated secondary fires or cable failures are outside the assumptions of each unit's fire protection analysis.
This condition is reportable under 10 CFR 50.72(b)(3)(ii)(B) / 10 CFR 50.73(a)(2)(ii)(B) as an unanalyzed condition that significantly degraded plant safety. The 10 CFR 50.72(b)(3)(ii)(B) notification was made on April 30, 2014.
The apparent cause was determined to be a latent error in original plant design. Compensatory fire watches have been implemented for affected fire areas. Planned corrective actions include plant modifications to the affected DC control circuits to protect against a postulated fire induced short that could overheat the cable causing a secondary fire in separate fire areas. Alternatively, other actions may be taken through an analytical resolution, if appropriate.
NRC FORM 366 (02-2014)
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
CONDITIONS PRIOR TO OCCURRENCE The events described in this LER are a result of a legacy issue that was discovered on April 30, 2014, during a review of external operating experience. When the issue was identified, Beaver Valley Power Station (BVPS) Unit 1 was operating in Mode 1 at 100 percent power and BVPS Unit 2 was in an undefined Mode with no fuel in the reactor vessel.
There were no systems, structures, or components that were inoperable at the start of the event that contributed to the event.
DESCRIPTION OF EVENT
Based on a review of industry operating experience, it was identified that BVPS Unit 1 and Unit 2 each have unfused direct current (DC) control circuits [IC] for DC motors [MO] which are routed from the turbine building through other fire areas. The DC breakers [72] used to protect the motor power conductors are insufficient to protect the control conductors for these circuits. It is postulated that a fire induced short in one fire area could adversely impact safe shutdown equipment by overheating the cable [CBL] and causing a secondary fire in other fire areas where the cable is routed. The postulated secondary fires or cable failures are outside the assumptions of each unit's fire protection analysis.
At BVPS Unit 1, two pumps have DC control circuits which have been identified as vulnerable, the Air Side Seal Oil Backup Pump (BV-1LO-M-14) [TC] [P] and the Main Turbine Emergency Bearing Oil Pump (BV-1LO-M-15) [TD] [P].
Cables for the affected motor circuits are routed through fire areas TB-1 (Turbine Building), CS-1 (Cable Spreading Area), and CR-i (Control Room).
At BVPS Unit 2, two pumps have DC control circuits which have been identified as vulnerable, the Air Side Seal Oil Backup Pump (BV-2GMO-P214) [TC] [P] and the Emergency DC Bearing Oil Pump (BV-2TML-P215) [TD] [P].
Cables for the affected motor circuits are routed through fire areas CB-3 (Control Room), CB-2 (Control Building Cable Spreading), CB-6 (Control Building West Communication Room), CB-1 (Instrument Relay Room), CT-1 (Cable Tunnel), CV-1 (Cable Vault and Rod Control, El. 735 West), SB-3 (Service Building Cable Tray Area, SB-4 (Normal Switchgear), and TB-I (Turbine Building).
CAUSE OF EVENT
The apparent cause of the event was determined to be a latent error in original plant design. The control circuit wiring for the affected pumps was not provided with adequate electrical protection to protect against a postulated fire induced short that could overheat the cable causing a secondary fire in other fire areas where the cable is routed.
ANALYSIS OF EVENT
At BVPS Unit 1, two pumps have circuits which have been identified as vulnerable, BV-1LO-M-14 and BV-1LO-M-15.
The control circuit for BV-1LO-M-14 includes three 12 AWG control cables which have no overcurrent protection other than the 250 amp DC breaker which is designed to protect the power cable for the seal oil pump. The control circuit for BV-1LO-M-15 includes three 12 AWG control cables which have no overcurrent protection other than the 500 amp DC breaker which is designed to protect the power cable for the lube oil pump.
At BVPS Unit 2, two pumps have circuits which have been identified as vulnerable, BV-2GMO-P214 and BV-2TML-P215. The control circuit for BV-2GMO-P214 includes two 12 AWG control cables and a 6 AWG cable which have no overcurrent protection other than the 400 amp DC breaker which is designed to protect the power cable for the seal oil pump. The control circuit for BV-2TML-P215 includes three 12 AWG control cables which have no overcurrent protection other than the 800 amp DC breaker which is designed to protect the power cable for the lube oil pump.
It is postulated that a fire induced short in one fire area could adversely impact safe shutdown equipment by overheating the cable and causing a secondary fire in other fire areas where the cable is routed. The postulated secondary fires or cable failures are outside the assumptions of each unit's fire protection analysis. This condition is reportable under 10 CFR 50.72(b)(3)(ii)(B) / 10 CFR 50.73(a)(2)(ii)(B) as an unanalyzed condition that significantly degraded plant safety. This condition was reported to the Nuclear Regulatory Commission (NRC) per 10 CFR 50.72 on April 30, 2014 (EN 50075).
Past functionality evaluations were performed for each unit. A review of fire protection safe shutdown procedures determined that there is reasonable assurance that post-fire safe shutdown would be achieved and maintained for postulated fire events. In addition, each affected fire area has either fire detection and suppression systems or is continuously manned (Control Room), and the noted DC control cables were confirmed by cable specification to be of thermoset type which are highly unlikely to initiate a flaming secondary fire. Each functionality evaluation concluded that there is reasonable assurance that post-fire safe shutdown could have been achieved and maintained, given the nonconforming condition.
CORRECTIVE ACTIONS
- 1.
Compensatory fire watches have been implemented for affected fire areas.
- 2.
The affected control circuits will be modified to preclude the possibility of overheating the cables and causing a secondary fire in separate fire areas. Alternatively, other actions may be taken through an analytical resolution, if appropriate. Completion of this corrective action is being tracked in the BVPS corrective action program.
PREVIOUS SIMILAR EVENTS
A review of BVPS LERs in the past three years for issues related to fire protection identified the following:
LER 2011-001-00, "Use of Liquid Tight Flexible Conduits Installed In Fire Barrier Penetrations Results in Unanalyzed Configurations."
CR-2014-07961, CR-2014-07964