05000461/LER-2012-003, Regarding Breaker Failure Leads to Loss of Safety Function and System Start
| ML13031A006 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 01/17/2013 |
| From: | Noll W Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| U-604104 LER 12-003-00 | |
| Download: ML13031A006 (5) | |
| 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 |
| 4612012003R00 - NRC Website | |
text
Exelon Generation.
Clinton Power Station 8401 Power Road Clinton, IL 61727 U-604104 10 CFR 50.73 January 17, 2013 SRRS 5A.108 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461
Subject:
Licensee Event Report 2012-003-00 Enclosed is Licensee Event Report (LER) No. 2012-003-00: Breaker Failure Leads to Loss of Safety Function and System Start. This report is being submitted in accordance with the requirements of 10 CFR 50.73.
There are no regulatory commitments contained in this report.
Should you have any questions concerning this report, please contact Ms. Kathy Ann Baker, Regulatory Assurance Manager, at (217)-937-2800.
Re p Wlilim.Noll~
Site Vice President Clinton Power Station RSF/blf
Enclosures:
Licensee Event Report 2012-003-00 cc:
Regional Administrator - NRC Region III NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - IEMA Division of Nuclear Safety
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)
, the NRC may
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,ock) not conduct or sponsor, and a person is not required to respond to, the digits/characters finformation collection.
- 3. PAGE Clinton Power Station, Unit 1 05000461 1 OF 4
- 4. TITLE Breaker Failure Leads to Loss of Safety Function and System Start
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED S
NFACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NSEUENTIAL REV MONTH DAY YEAR 05000 INUMBER NO.
FACILITY NAME DOCKET NUMBER 11 23 2012 2012 003 00 01 17 2013 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
[1 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 El 20.2201(d)
El 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)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
E] 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 El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4) 097 El 20.2203(a)(2)(iv)
[I 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
Z 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify in Abstract below or in declared Secondary Containment inoperable, and entered the applicable TS actions for Secondary Containment.
At 2009 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.644245e-4 months <br />, after evaluating plant conditions, operators reenergized the Unit Sub B to support restoration of plant systems, declared VC B train operable, and exited the applicable TS actions for VC ventilation train (chiller remained inoperable). The HPCS system was restored to operable status when the Unit Sub B was restored and operators exited the applicable TS actions for HPCS. Operators re-opened the IA containment isolation valve. Reenergizing the Unit Sub B resulted in an invalid automatic actuation of the Division 2 Shutdown Service Water System (SX) [BI] system pump [P] 1 SX01 PB as power was restored to the low pressure trip unit [94].
At 2011 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.651855e-4 months <br /> operators manually initiated the Division 1 Standby Gas Treatment system (VG) [BH] to restore Secondary Containment negative differential pressure, and Secondary Containment differential pressure was restored by 2013 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.659465e-4 months <br />, and operators exited the applicable TS actions for Secondary Containment. The Division 2 SX pump was shut down by 2222 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.45471e-4 months <br />.
Operators secured the VG A train and restarted the VF system to maintain Secondary Containment differential pressure by 2248 hours0.026 days <br />0.624 hours <br />0.00372 weeks <br />8.55364e-4 months <br /> and exited EOP-8 at 0025 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> on 11/24/12. Following other system restorations ISV 1 SA030 was reopened.
This event is reportable under the provisions of 10 CFR 50.73(a)(2)(v)(C) for the loss of Secondary Containment differential pressure as a condition that could have prevented the fulfillment of a safety function needed to control the release of radioactive material, 10 CFR 50.73(a)(2)(v)(D) for the unplanned inoperability of High Pressure Core Spray system as a condition that could have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident, and 10 CFR 50.73(a)(2)(iv)(A) for the invalid actuation of the SX system and isolation of the IA and SA containment isolation valves.
Issue Report 1443700 was initiated to investigate this event.
C. CAUSE OF EVENT
The VC B chiller breaker closing spring charging mechanism failed to operate as designed. Based on breaker testing performed following the event, the latching mechanism for the closing spring of the VC B chiller breaker appears to have failed after the chiller was started, causing the breaker charging motor to run continuously and trying to close the breaker every time it finished charging, thus cycling the breaker open and closed. The reason for the latching mechanism failure is unknown at this time. The breaker has been sent to an offsite laboratory for failure analysis.
D. SAFETY CONSEQUENCES
There were no actual safety consequences of this event. This event resulted in the loss of secondary containment for approximately five minutes, from 2008 to 2013 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.659465e-4 months <br /> due to the trip of the fuel building ventilation system following loss of power to the VF Division 2 isolation dampers. The Division 1 VG system was operable during this event and was manually started by operators to restore secondary containment negative pressure. The VC B train ventilation system was inoperable for four minutes from 2005 to 2009 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.644245e-4 months <br /> during this event but the VC A train was operable and available for control room ventilation if needed.
Containment isolation valves 1 IA006 and 1SA030 automatically closed at 2005 hours0.0232 days <br />0.557 hours <br />0.00332 weeks <br />7.629025e-4 months <br />; 1 IA006 was restored to open at 2009 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.644245e-4 months <br />, and 1SA030 was restored following the Unit Sub B restoration. The HPCS was
inoperable from 2005 hours0.0232 days <br />0.557 hours <br />0.00332 weeks <br />7.629025e-4 months <br /> to 2009 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.644245e-4 months <br /> due to the loss of room cooling to the Division 4 inverter and charger. Although inoperable, the HPCS continued to be available during this period of inoperability.
Additionally the Reactor Core Isolation Cooling [BN] system and the Low Pressure Core Spray [BM] system were operable and available during this event for accident mitigation if needed. There were no operability concerns with the invalid automatic start of the Division 2 SX pump.
E.
CORRECTIVE ACTIONS
The VC B chiller breaker that failed has been replaced with a newly refurbished breaker.
The breaker has been sent to an offsite laboratory for failure analysis.
F.
PREVIOUS OCCURRENCES
A review for previous occurrences did not identify similar events at CPS.
G. COMPONENT FAILURE DATA
Manufacturer Nomenclature 480 volts Breaker Manufacturer Model Number ABB Model K600S