05000388/LER-2002-005, Operations Prohibited by TS Due to Inoperable Main Steam Isolation Valve
| ML023440246 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 11/27/2002 |
| From: | Richard Anderson Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-5557 LER 02-005-00 | |
| Download: ML023440246 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3882002005R00 - NRC Website | |
text
R. L. Anderson Vice President - Nuclear Operations PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3883 Fax 570.542-1504 rlanderson @ pplweb.com 0*0 4,4,,
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pp 1 k NOV 2 7 2O U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station OPI-17 Washington, DC 20555 SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-388/2002-005-00 PLA-5557 Docket 50-388 License No. NPF-22 Attached is Licensee Event Report (LER) 50-388/2002-005-00. This event is reportable per 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications in that the Unit 2 'B' Inboard Main Steam Isolation Valve was determined to be inoperable for a period of time that exceeded Technical Specification specified completion times.
Cold shutdown surveillance testing showed that the valve's stroke time did not meet Technical Specification mandated acceptance criteria. Analysis of the test results has concluded that the peak reactor vessel pressure following a postulated Main Steam Line Isolation would have remained within reactor pressure vessel limits. There were no actual consequences to the health and safety of the public as a result of this event.
Richard L. An erson Vice President - Nuclear Operations Attachment cc: Mr. H. J. Miller Regional Administrator U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 cc: Mr. S. L. Hansell Sr. Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 35 Berwick, PA 18603-0035 e<,,eaD
Abstract
On October 7, 2002 with Unit 2 in Mode 4 (Cold Shutdown) at 0% power, the '2B' Inboard Main Steam Isolation Valve (MSIV: HV241 F022B) was declared inoperable when the valve stroked greater than a second faster than allowed by Technical Specifications (1.92 sec. Actual vs. 3-5 sec. Target). A review of test history concluded that the valve may have been inoperable for as many as 360 days prior to the time of discovery. This period exceeds Technical Specification required completion times developed for Primary Containment Isolation Valves (PCIV). Calculations were performed following this event, using more restrictive closure stroke times than those actually experienced, to determine reactor pressures following a postulated Main Steam isolation. These calculations confirm that the peak reactor vessel pressure would not have exceeded established limits. Primary containment entry and inspection revealed that an oil leak on the oil dashpot hydraulic piping was responsible for the failed stroke test.
The leak was repaired on October 7, 2002 and the MSIV is now fully operable. Maintenance procedures, preventative maintenance activities, modification solutions and industry best practices will all be explored for changes to enhance MSIV oil piping leak performance. At no time was the valve's ability to provide containment isolation adversely affected by the fast closure time. This event is reportable for Unit 2 as a condition prohibited byTechnical Specification 3.6.1.3 per 10 CFR 50.73(a)(2)(i)(B). There were no actual adverse consequences to plant equipment or to the health and safety of the public as a result of this event.
NRC FORM 366 (7-2001)
(if more space Is required, use additional copies of (If more space is required, use addtional copies of NRC Form 366A)
ANALYSIS/SAFETY SIGNIFICANCE
This event is reportable as a condition prohibited by Technical Specifications per 10 CFR 50.73(a)(2)(i)(B) for Unit 2 in that the 'B' Inboard MSIV may have been inoperable for as long as 360 days. This period exceeds the action completion times allowed in Technical Specification 3.6.1.3. The valve was determined to be inoperable when the 3-second fast closure criteria, used to limit peak pressures in the reactor vessel, was exceeded. The current model used to determine peak vessel pressures following MSIV closure assumes closure of all MSIVs at the same time. This scenario is much more limiting than that which would have been encountered with a single MSIV closing faster than desired. Calculations performed to simulate closure of all MSIVs in 1.5 seconds (below the actual time of 1.92 seconds experienced on the 'B' Main Steam line) confirm peak pressures experienced during this bounding transient would not exceed the established vessel pressure limits. Hence, peak pressures resulting from the fast closure of one MSIV would also remain within established limits. At no time was the valve's ability to provide containment isolation adversely affected by the fast closure time. There were no actual adverse consequences to the health and safety of the public as a result of this event.
In accordance with guidance in NUREG-1 022, Revision 2, the due date for this report is December 6, 2002.
CORRECTIVE ACTIONS
Corrective actions that have been completed:
The Unit 2 'B' Inboard MSIV (HV241 F022B) dashpot was refilled with oil after the oil piping was satisfactorily repaired.
Stroke time surveillance testing was successfully performed for HV241 F022B following repair of the dashpot oil piping.
Calculations used to determine peak reactor pressures following a postulated MSIV closure have been updated to incorporate results using the 1.5 second closure time (previous assumption had been 2 seconds).
Corrective actions to be completed:
- Review modification solutions, maintenance procedures, PM activities, industry best practices and vendor recommendations pertaining to MSIV dashpot oil piping in an effort to enhance leak performance. Implement improvements as required.
ADDITIONAL INFORMATION
Past Similar Events:
None Failed Component:
'B' Inboard MSIV HV241 F022B Manufacturer:
Atwood & Morrill Co.
Model Number:
21190-H