05000237/LER-2011-005-01, For Dresden, Unit 2, Regarding Standby Liquid Control Explosive Valve Failure
| ML12363A044 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/18/2012 |
| From: | Czufin D Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVPLTR # 12-0060 LER 11-005-01 | |
| Download: ML12363A044 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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 |
| 2372011005R01 - NRC Website | |
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I*lll*l=*r Pnw*r _*f*finn 16500 North DresJen Road Exe!on Generation Morris. IL 60450
.o 815 942 2920 Telephone www exeloncorp,:oin SVPLTR # 12-0060 10 CFR 50.73 December 18, 2012 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 2 Renewed Facility Operating License No. DPR-1 9 NRC Docket No. 50-237
Subject:
Supplemental Licensee Event Report 237/2011-005-01, Standby Liquid Control Explosive Valve Failure Enclosed is Licensee Event Report 237/2011-005-01, "Standby Liquid Control Explosive Valve Failure." This is a final report. This condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications."
There are no regulatory commitments contained in this submittal.
Should you have any questions concerning this letter, please contact Mr. Hal Dodd at (815) 416-2800.
Respectfully, David M. Czufin Site Vice President Dresden Nuclear Power Station Enclosure cc:
Regional Administrator - NRC Region III NRC Senior Resident Inspector - Dresden Nuclear Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/201 Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA/Privacy Section (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects.resource@nrc.gov, and to the Desk Officer, Office of LICENSEE EVENT REPORT (LER)
Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to (See reverse for required number of impose an information collection does not display a currently valid 0MB digits/characters for each block) control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Dresden Nuclear Power Station, Unit 2 05000237 1 OF 5
- 4. TITLE Standby Liquid Control Explosive Valve Failure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR N/A 05000 FACILITY NAME DOCKET NUMBER 10 28 2011 2011 005 01 12 18 2012 N/A 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)
E] 50.73(a)(2)(vii) 5 [1 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
[I 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
.[
50.73(a)(2)(viii)(B)
E_ 20.2203(a)(2)(i)
[I 50.36(c)(1)(i)(A)
[I 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
[I 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
E-50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4) 000 El 20.2203(a)(2)(iv)
[E 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71 (a)(5)
El 20.2203(a)(2)(v)
[I 50.73(a)(2)(i)(A)
[I 50.73(a)(2)(v)(C)
El OTHER
[] 20.2203(a)(2)(vi)
ED 50.73(a)(2)(i)(B)
[I 50.73(a)(2)(v)(D)
Specify in Abstract below or in PdMerExpWosie I Ih Lifaxe E
maquey (ODWWTgoeWevaowe.TiMe Cmi) 180 S..
10 W6 730 Is25 MW0 10000 Flgu" 1: Primer Explosive Material Life Expectancy (DDNP Temperature vs. Time Curve)
The failed "A" squib valve was Installed in November 2007. The "B" squib vlv was replaced in 2009 and did not show any signs of degradation when tested in the plant.
In 2007, heat tracing on Unit 2 SLC system failed and as a conmpensatory action a temporary change was implemented during portlons of the winter to install a Wmpry heater in front of the SIC pumps to provide the necessary heat to maintain the SLC suction piping above the Technical Specification temperature ltmit. This temporary change was In place for eproximately one year (i.e., October 2008 to September 2009). In August 2009, a heat trace modification was irmtalled to correct the failed heat trace system. The repairs removed the need for the temporary heater.
Even though temperatures In the area of the explosive valve during this time could not be determined while th themtoa heater was In use, it is believed that the temporary heater may have contributed to higher than normal temperatures near the explosive valve trigger asse y.
Upon further Investigation, it was revealed that the heat trace modification done in 2009 was not installed in accordance with the modifict"'s I
s. The incorrect Installation placed the heat trace around the "A" explosive valve trigger assembly which resulted In higher than normal temperatures and resulted In thermal degradation of the explosive material. Subsequently, the heat trace on Unit 3 was checked and was found to be installed correctly.
NAC FORM 30A (10-2010)
D.
Safety Allaly.s:
The safety significance of this condition is low. Disabling the WA" explosive valve would not prevent the SLC system from performing its designated function. The "B" SLC loop functional test was completed with satisfactory results subsequent to the actuation failure of the "A" explosive valve. It should be noted that system design provides for delivery of the sodium pentaborate solution from either SLC pump through either explosive valve. Hence, had system actuation 'been required.-the nA" pump could have been used in the event of failure of the 'W Pump. Therefore," hee and safety of the public were not compromised as a result of this condition.
1 E.
Cgrety-eActions:
The failed assembly was replaced and the functional testing was subsequently completed satisfactorily. Following successful testing of the 2A system, a new explosive valve was installed.
A work order was completed to rearrange the heat trace for the'Unit 2 SLC system so that it is installed in accordance with the modification instruction.
F.
Previous Occurrnces:
A review of DNPS history of similar events did not reveal any conditions associated with failures of SLC explosive valves.
J..
".1t
G.
Component Failure Data
Manufacturer IST - CONAX NUCLEAR, INC.
comvno v
mo" dSiW Ntbe)
CON-O-CAP TYPE -(131/142)
'As found' condition ofthe inlet fitting New unfired exp"kave (left) and the after removing failed explosive I
I failed expive (right) iSUCM.LI fired exlivi I
NRC FORM SSA (10-2010)