05000249/LER-2012-001, Regarding Unexpected Isolation of the Isolation Condenser Due to Test Switch Failure
ML12263A423 | |
Person / Time | |
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Site: | Dresden ![]() |
Issue date: | 09/10/2012 |
From: | Czufin D Exelon Generation Co |
To: | Document Control Desk, Office of Nuclear Reactor Regulation |
References | |
SVPLTR: 12-0048 LER 12-001-00 | |
Download: ML12263A423 (4) | |
Event date: | |
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Report date: | |
Reporting criterion: | 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 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)(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 |
2492012001R00 - NRC Website | |
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Dresden Nuclear Power Station A6500 North Dresden Road A
IExe!on Generation, Morris, IL 60450 815 942 2920 Telephone www.exeloncorp.com 10 CFR 50.73 September 10, 2012 SVPLTR: #12-0048 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 3 Renewed Facility Operating License No. DPR-25 NRC Docket No. 50-249
Subject:
Licensee Event Report 249/2012-001-00, Unexpected Isolation of the Isolation Condenser Due to Test Switch Failure Enclosed is Licensee Event Report 249/2012-001-00, "Unexpected Isolation of the Isolation Condenser Due to Test Switch Failure." This event is being reported in accordance with 10 CFR 50.73(a)(2)(v)(B), "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat."
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. Czufiin Site Vice Presidenitt 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 0MB: 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 Dresden Nuclear Power Station, Unit 3 05000249 1 OF 3
- 4. TITLE Unexpected Isolation of the Isolation Condenser Due to Test Switch Failure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NEUMENALREVO MONTH DAY YEAR IN/A 05000 NUMBER NO.N/05 0
FACILITY NAME DOCKET NUMBER 07 10 2012 2012 001 -
00 09 10 2012 N/A 05000
- 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)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 El 20.2201(d)
[I 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)
[I 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
[I 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)
El 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) 100 El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B)
El 73.71(a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in C.
Cause of Event
The suspect TTS was sent for failure analysis. The failure analysis indicated that the most probable cause was grease on the UTS internal stationary contacts. The TTSs were assembled by plant instrument maintenance personnel between 1998 and 2000. Even though the TTS test leads are periodically replaced, there have been no preventative maintenance activities to identify age-related degradation with regard to UTS internal operations.
D.
Safety Analysis
The safety significance of this condition is low. The High Pressure Coolant Injection system [B1J] was available to provide pressure control and makeup to the reactor vessel inventory in the event of an accident or transient. Therefore, health and safety of the public were not compromised as a result of this condition.
E.
Corrective Actions
All TTSs were replaced. A preventative maintenance activity is being generated to inspect or refurbish all TTSs assembled by the instrument maintenance personnel on a periodic basis.
F.
Previous Occurrences
A review of DNPS Licensee Event Reports (LERs) for the last three years did not reveal any reportable conditions related to Isolation Condenser isolations.
G.
Component Failure Data
Manufacturer Component Type Model N/A Toggle Switch N/A Test Toggle Switch