05000400/LER-2012-001, Regarding Delayed Closure of Main Steam Isolation Valves Due to Corrosion
| ML12172A382 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 06/20/2012 |
| From: | Kapopoulos E Progress Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| HNP-12-066 LER 12-001-00 | |
| Download: ML12172A382 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 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)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) |
| 4002012001R00 - NRC Website | |
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Progress Energy June 20,2012 Serial: HNP-12-066 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Shearon Harris Nuclear Power Plant, Unit 1 Docket No. 50-400/ Renewed Facility Operating License No. NPF-63
Subject:
Licensee Event Report 2012-001-00 Ladies and Gentlemen:
Ernest J. Kapopoulos, Jr.
Plant General Manager Harris Nuclear Plant Progress Energy Carolinas, Inc.
10 CFR 50.73 Carolina Power & Light Company, doing business as Progress Energy Carolinas, Inc., submits the enclosed Licensee Event Report (LER) 2012-001-00 in accordance with 10 CFR 50.73. This report describes a condition where unexpected long-term corrosion of valve piston rings caused delayed closing of Main Steam Isolation Valves. This LER is submitted within 60 days following discovery of the condition in accordance with 10 CFR 50.73(a).
This document contains no regulatory commitments. Please refer any questions regarding this submittal to Dave Corlett at (919) 362-3137.
Sincerely, Enclosure: LER 2012-001-00 cc:
Mr. 1. D. Austin, NRC Sr. Resident Inspector, HNP Ms. A. T. Billoch Colon, NRC Project Manager, HNP Mr. V. M. McCree, NRC Regional Administrator, Region II P.O. Box 165 New Hill, NC 27562 T> 919.362.2000
NRC FORM 366 (10-2010)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 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 Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
LICENSEE EVENT REPORT (LER)
(See reverse for required number of digits/characters for each block)
- 1. FACILITY NAME Shearon Harris Nuclear Power Plant, Unit 1
- 2. DOCKET NUMBER 05000400
- 3. PAGE 1 of 4
- 4. TITLE Delayed Closure of Main Steam Isolation Valves Due To Corrosion
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.
MONTH DAY YEAR FACILITY NAME None DOCKET NUMBER 04 21 2012 2012 - 001 - 00 06 20 2012 FACILITY NAME None DOCKET NUMBER
- 9. OPERATING MODE 4
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 20.2201(b) 20.2201(d) 20.2203(a)(1) 20.2203(a)(2)(i) 20.2203(a)(2)(ii) 20.2203(a)(2)(iii) 20.2203(a)(2)(iv) 20.2203(a)(2)(v) 20.2203(a)(2)(vi) 20.2203(a)(3)(i) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.36(c)(1)(i)(A) 50.36(c)(1)(ii)(A) 50.36(c)(2) 50.46(a)(3)(ii) 50.73(a)(2)(i)(A) 50.73(a)(2)(i)(B) 50.73(a)(2)(i)(C) 50.73(a)(2)(ii)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(iii) 50.73(a)(2)(iv)(A) 50.73(a)(2)(v)(A) 50.73(a)(2)(v)(B) 50.73(a)(2)(v)(C) 50.73(a)(2)(v)(D) 50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(ix)(A) 50.73(a)(2)(x) 73.71(a)(4) 73.71(a)(5)
OTHER Specify in Abstract below or in
Safety Consequences
The actual safety consequence at the time of the delayed closure of the two MSIVs was negligible. The reactor was in Mode 4 with all control rods fully inserted. No other conditions significantly affected the event, so there was no safety consequence at the time of the delayed closure of the MSIVs. Had an accident occurred in Mode 4 (the as-found condition), the impact of delayed closing of the MSIVs would have been less than full power operation due to reduced radiological release, lower risk of excessive cooldown rate, and lower motive force for any thermal-hydraulic transient. Other systems needed to shutdown the reactor, maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident were not affected by the condition and remained available.
The two events that would be most significantly affected by the MSIV delayed closure are Main Steam Line Break (MSLB) and Steam Generator Tube Rupture (SGTR). Major MSLBs and SGTRs are considered American Nuclear Society (ANS) Condition IV events. Condition IV events are limiting faults which are not expected to occur, but could result in offsite dose approaching regulatory limits. MSIVs are intended to mitigate the impact of a MSLB by limiting the number of affected steam generators which reduces excess cooldown. Delayed closure of the three MSIVs during a SGTR could increase the radiological inventory release, and potentially increase challenges with steam generator overfill. The consequences of design basis accidents can be more significant than described in the Final Safety Analysis Report if the conservative assumptions of the event analysis are coupled with equipment challenges such as delayed closing of multiple MSIVs.
Corrective Actions
Completed Corrective Actions Replaced the valve piston rings with upgraded rings made of a material less susceptible to corrosion.
Reviewed HNP AOV Program Category 1 and Category 2 valves to determine if others contain cast iron piston rings. (Extent of Cause).
Reviewed other AOV Category 2 Valves to determine required actions. (Extent of Condition).
Planned Corrective Actions
Implement diagnostic testing program on the MSIVs, including post maintenance testing.
Reclassify the MSIVs to be Category 1 in the Air Operated Valve Program.
Previous Similar Events
The B MSIV did not shut within the IST stroke time limits on October 1, 2009. The condition report associated with that event investigated the lack of intervention after low stroke-time margin was discovered in a previous outage, but the cause of the degradation in stroke time was not addressed in the investigation. This may be a missed opportunity for taking actions that could have prevented the most recent condition.
The B MSIV did not shut within the IST stroke time limits on Nov. 15, 2009, as reported in LER 2010-002-01.
The condition in 2009 was due to two solenoid operated shuttle valves (SOVs) not fully realigning to vent air after deenergizing. Because the delayed closing of the two MSIVs in 2012 was caused by a different mechanism, the corrective actions from the November 2009 event would not be expected to have prevented this recurrence.
Commitments
This report contains no regulatory commitments.