05000529/LER-2002-001, Re Main Steam Safety Valve As-Found Lift Pressures Outside of Technical Specification Limits
| ML021350239 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/01/2002 |
| From: | Ide W Arizona Public Service Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 192-01105-WEI/SAB/DJS LER-02-001-00 | |
| Download: ML021350239 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 5292002001R00 - NRC Website | |
text
1 OCFR50.73 William E. ide Mail Station 7602 Palo Verde Nuclear Vice President TEL (623) 393-6116 P.O. Box 52034 Generating Station Nuclear Production FAX (623) 393-6077 Phoenix, AZ 85072-2034 192-01105-WEI/SAB/DJS May 1, 2002 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555-0001
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 2 Docket No. STN 50-529 License No. NPF-51 Licensee Event Report 2002-001-00 Attached please find Licensee Event Report (LER) 50-529/2002-001-00 that has been prepared and submitted pursuant to I OCFR50.73. This LER provides the findings relating to out-of-tolerance main steam safety valves (MSSVs) which were discovered during pre-outage testing in Unit 2.
In accordance with IOCFR50.4, a copy of this LER is being forwarded to the NRC Regional Office, NRC Region IV and the Senior Resident Inspector. If you have questions regarding this submittal, please contact Daniel G. Marks, Section Leader, Regulatory Affairs, at (623) 393-6492.
Arizona Public Service Company makes no commitments in this letter. The corrective actions described in this LER are not necessary to maintain compliance with regulations.
Sincerely, WEI/SAB/DJS/kg Attachment cc:
E. W. Merschoff (all with attachment)
J. H. Moorman J. N. Donohew A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway 0 Comanche Peak 0 Diablo Canyon 0 Palo Verde 0 South Texas Project
- Wolf Creek
APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004
Abstract
On March 5, 2002, Unit 2 was in MODE 1, operating at approximately 100 percent power when augmented testing revealed that two main steam safety valves (MSSV) had an as-found lift pressure above the Technical Specification limit of +/- 3 percent of design lift pressure. These MSSVs are believed to have experienced setpoint drift.
The valves were reset to +/- 3% of setpoint to maintain plant operability for the duration of the surveillance test clock. No attempt was made to reset the valves to
+/-1 % of the required setpoint since both valves were scheduled for replacement.
Previous similar events were reported in LER 50-529/2000-002.
NRC FORM 366 (7-2001)
NRC F6RM 366A U.S. NUCLEAR REGULATORY COMMISSION (7-2001)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTAL I REVISION Palo Verde Nuclear Generating Station 05000529 NUMBER NUMBER 2 OF 5 Unit 2 2001 001 00 I
I I
- 17. NARRATIVE (If more space is required, use additional copies of (if more space is required, use additional copies of (if more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A)
Based on previous experience, APS anticipates the condition would not have prevented the fulfillment of the safety function and did not result in a safety system functional failure as defined by 10CFR50.73(a)(2)(v).
6. CAUSE OF THE EVENT
It is APS' position the out of tolerance as-found MSSV setpoints are the result of setpoint drift. The valves did not exhibit the characteristics of sticking, therefore valve seat sticking is not considered to be the cause of this event.
No unusual characteristics of the work location (e.g., noise, heat, poor lighting) directly contributed to this event. No personnel or procedural errors contributed to this event.
The out of tolerance setpoint (greater than +/- 3%) was determined to be a Maintenance Rule Functional Failure (MRFF). The intended function of the MSSVs is to lift and relieve steam pressure when pressure within the steam line is within 3% of setpoint. Each of these valves did not respond until steam line pressure was simulated to exceed +3%
(3.1% and 3.4%) Although, the second lifts fell within setpoint limits and the departure from setpoint was relatively minor, these two failures should each be counted as a Maintenance Rule Functional Failures.
- 7.
CORRECTIVE ACTIONS
Unit 2 MSSVs PSV0554 and PSV0561, discovered to have high as-found lift pressures outside of the technical specification limit during the surveillance testing, were re-tested in accordance with the approved site procedure and returned to service. The valves were replaced during the refueling outage with ones certified to be within +/-1 %
- 8.
PREVIOUS SIMILAR EVENTS
Previous similar events were reported in LER 50-529/2000-002.