05000285/LER-2010-004, For Fort Calhoun Station, Regarding Acoustic Monitor Failure Due to Inadequate Barriers for Protection of Cable
| ML102430366 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 08/30/2010 |
| From: | Reinhart J Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LlC-10-0078 LER 10-004-00 | |
| Download: ML102430366 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(8) 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 |
| 2852010004R00 - NRC Website | |
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Omaha Public Power Oistrict 444 South 16 th Street Mall Omaha, NE 68102-2247 August 30, 2010 LlC-10-0078 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Reference: Docket No. 50-285
Subject:
Licensee Event Report 2010-004, Revision 0, for the Fort Calhoun Station Please find attached Licensee Event Report 2010-004, Revision 0, dated August 30, 2010. This report is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(8).
No regulatory commitments are contained in this submittal. Ilf you should have any questions, please contact me.
effrey A. Reinhart ite Vice President JARIepm Attachment c:
E. E. Collins, NRC Regional Administrator, Region IV L. E. Wilkins, NRC Project Manager J. C. Kirkiland, NRC Senior Resident Inspector INPO Records Center Employment with Equal Opportunity
NRC FORM 366 U.S. NUCLEAR REGULATORYCOMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
(See reverse for required number of digits/characters for each block)
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME Fort Calhoun Station
- 2. DOCKET NUMBER 05000285
- 3. PAGE 1 OF 3
- 4. TITLE Acoustic Monitor Failure Due to Inadequate Barriers for Protection of Cable
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTI AL NUMBER REV NO MONT H
DAY YEAR FACILITY NAME DOCKET NUMBER 05000 4
28 2010 2010
- - 004 -
00 08 30 2010 FACILITY NAME 05000
- 9. OPERATING MODE 1
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 20.2201(b)
20.2203(a)(3)(i)
50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201(d)
20.2203(a)(3)(ii)
50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2203(a)(1)
20.2203(a)(4)
50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i)
50.36(c)(1)(i)(A)
50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 100 20.2203(a)(2)(ii)
50.36(c)(1)(ii)(A)
50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2203(a)(2)(iii)
50.36(c)(2)
50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iv)
50.46(a)(3)(ii)
50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(v)
50.73(a)(2)(i)(A)
50.73(a)(2)(v)(C)
OTHER 20.2203(a)(2)(vi)
X 50.73(a)(2)(i)(B)
50.73(a)(2)(v)(D)
Specify in Abstract below or in
EVENT DESCRIPTION
FE-142, Accelerometer for Pressurizer Safety Valve RC-142 Flow Detection, failed its monthly surveillance test, IC-ST-RC-0001, "Functional Test of Acoustic Flow Monitors," on May 26, 2010. The surveillance test failure occurred during performance of Section 7.2.1; verify response at FE-142. In this section, FE-142 showed no response as the impactor was operated. One month earlier, on April 28, 2010, FE-142 had also failed its monthly surveillance test, IC-ST -RC-0001. The surveillance test failure also occurred during performance of Section 7.2.1, in that, FE-142 showed no response as the impactor was operated. The failure of FE-142 on April 28, 2010, was identified in condition report (CR) 2010-2070. During the investigation for the May 26, 2010 failure, it was discovered that the direct cause for the earlier failure on April 28, 2010, was the same and had not been corrected.
As a result of this discovery, FE-142 was reclassified as inoperable from April 28, 2010, to June 2, 2010, and the TS action time was exceeded. On June 30, 2010, the failure of FE-142 was determined to be reportable in accordance with 10 CFR 50.73(a)(2)(i)(B). This LER is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B).
CONCLUSION A root cause analysis was completed that determined that the failure of FE-142 was caused by the failure of the center conductor of the softline cable connecting the charge converter to the hardline cable. The reason for this failure was that external stress when the hardline cable was pulled was applied to the softline cable. The exact time and circumstance this stress was applied could not be determined, but there are two possible scenarios:
The hardline cable was inadvertently snagged during a containment walkdown during the plant shutdown in April 2010, or The hardline cable had previously been snagged or pulled which weakened the center conductor of the softline cable, and finally caused the failure prior to the completion of IC-ST-RC-0001 on April 29, 2010.
In either case, the root cause of this event was that the hardline cable for the FE-142 accelerometer was allowed to have external stress applied because there were no barriers for the protection of the hardline cable during maintenance activities in the pressurizer cubicle. This allowed stress to be applied to the softline cable, which weakened the center conductor of the softline cable and caused the failure.
CORRECTIVE ACTIONS
The softline cable was replaced making FE-142 operable. Other actions will be administered by the stations corrective action program.
SAFETY SIGNIFICANCE
The acoustic monitors are only one of several methods the operators use to determine if a PORV or safety valve is open or leaking. Since there are other methods of monitoring the status of the safety valves and PORVs, this event had no impact on the health or safety of the public.
SAFETY SYSTEM FUNCTIONAL FAILURE This event does not result in a safety system functional failure in accordance with NEI-99-02.
PREVIOUS SIMILAR EVENTS
The station has not had any similar failure of the acoustic monitors in the past. PRINTED ON RECYCLED PAPER