05000528/LER-2004-011
| Docket Numbersequential Revmonth Day Year Year Month Day Yearnumber No. Pvngs Unit 2 05000 529 | |
| Event date: | 11-10-2004 |
|---|---|
| Report date: | 01-06-2005 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 5282004001R00 - NRC Website | |
1. REPORTING REQUIREMENT(S):
This LER 528/2004-011-00 is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(B), to report a missed surveillance requirement in Units 1, 2, and 3. Specifically, Technical Specification (TS) 3.6.3, Containment Isolation Valves, Surveillance Requirement (SR) 3.6.3.3 requires verification of each containment isolation manual valve and blind flange (EIIS Code: ISV) that is located outside containment (EIIS Code: BD) and not locked, sealed or otherwise secured and is required to be closed during accident conditions is closed was not performed within the required frequency.
2. DESCRIPTION OF STRUCTURE(S), SYSTEM(S) AND COMPONENT(S):
The valves are drain and test connections located on the Auxiliary Building side of the Primary Containment penetrations for the High Pressure Safety Injection System (HPSI) (EIIS Code: BQ) and the Low Pressure Safety Injection System (LIDS!) (EIIS Code: BP).
All valves are located between the containment penetration and the first isolation valve located outside containment.
3. INITIAL PLANT CONDITIONS:
On November 10, 2004 at approximately 12:00 Mountain Standard Time (MST), Palo Verde Units 1 and 2 were in Mode 1 (POWER OPERATION), operating at approximately 100 percent power. Unit 3 was defueled (Mode 6) and conducting refueling outage activities.
There were no major structures, systems, or components that were inoperable at the start of the event that contributed to the event. There were no failures that rendered a train of a safety system inoperable and no failures of components with multiple functions were involved.
4. EVENT DESCRIPTION:
On November 10, 2004 at approximately 12:00 MST, during systems review, the Operations Standards Group (Procedure authors for PVNGS) determined that Containment penetrations 13 through 20 have test connection or drain valves located between the containment isolation valves (CIVs). Compliance with TS LCO 3.6.3 would require the test and drain valves located between the containment isolation valves be locked closed, or verified closed every 31 days. These valves are not included in station procedure 40DP-90P19, (Locked Valve, Breaker and Component Tracking).
Nor were those valves included in surveillance test 40ST-9ZZ13, (Containment Isolation Valyes).
The valves/connections were controlled via 400P-9S102 (Recovery from Shutdown Cooling to Normal Operating Lineup) and were required to be placed in a closed and�
- capped configuration. This action required an Independent Verification and documentation by procedure. The frequency of performance of this procedure is normally once per normal operating cycle, that is approximately every eighteen (18) months. Procedure 40ST-9S109 (ECCS Systems Leak Test) requires a visual check for leaks every 18 months. These frequencies of approximately 18 months do not meet the TS SR 3.6.3.3 frequency that the valves be verified closed every 31 days.
5. ASSESSMENT OF SAFETY CONSEQUENCES:
The valves were controlled under procedure 400P-9S102 which requires the valves to be closed, capped and independently verified. The results of performing the TS SR 40ST-9ZZ13 (Containment Isolation Valves) in Units 1 and 2 on November 10, 2004 showed that the valves were indeed closed and the caps installed. Performing the SR in Unit 3 prior to reaching Mode 4 also ensured that the valves were closed, capped and verified under the surveillance test. Although the valves were verified closed on an 18 month frequency, versus the TS SR 3.6.3.3 frequency that the valves be verified closed every 31 days, there is reasonable assurance that the valves were indeed closed and capped meeting the intent of TS 3.6.3 - Containment Isolation Valves. There is no evidence that indicates that these valves were ever found open during Modes 1, 2, 3 or 4 in any of the three Units, therefore the impact to safety consequences is minimal.
Mitigative Considerations:
- UFSAR Section 6.2.6.3 states that ".. . Inservice testing and inspection of these isolation valves, and also the associated piping system outside the containment, will be performed periodically under the ISI requirements of ASME XI. During normal operation, the systems are water filled and degradation of valves or piping would be readily detected.. ..
- Procedure 400P-9S102, "Recovery from Shutdown Cooling to Normal Operating Lineup," notes that the drain/test connection valves may be utilized to conduct MOV diagnostic tests, but are then closed and capped. This procedure also includes all eight valves in valve verification lists, so that plant operators will verify the valves are closed when restoring SI to a normal lineup.
- 40ST-9S109, "ECCS Systems Leak Test." The purpose of this test is to conduct an inspection of the ECCS piping outside containment that is in contact with the recirculation sump inventory during LOCA conditions, to verify that total leakage from piping and components is less than 1500 ml/hr when pressurized to at least 40 psig.
Testing frequency is 18 months during shutdown. Testing is required for operation in Modes 1, 2, 3 and 4. This procedure satisfies the requirement of LCO 5.5.2 and T5.0.500.2 to perform a periodic visual inspection of the recirculation portion of the high pressure safety injection system, the shutdown cooling portion of the low pressure Safety Injection System, and the Containment Spray System. 400P-9ZZ23, "Outage GOP", requires completion of the Mode 5 to Mode 4 mode change checklist. 400P 9ZZ11, "Mode Change Checklist," invokes 40ST-9S109 in the Mode 5 to Mode 4 checklist.
- Had one of the valves not been fully closed during normal plant operation, it is likely that the condition would not have gone unnoticed for long (e.g., auxiliary operator rounds, plant drains, auxiliary building sump, recognition of water management problem, etc.).
Based on the fact that the valves were controlled under procedure 400P-9S102 which requires the valves to be closed, capped and independently verified would have ensured 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:
The direct cause of the event was an inadequate procedure. Due to human error, these containment penetration test and drain valves, from initial plant operations until November 2004, were not included in the surveillance test for Containment Isolation Valves.
No unusual characteristics of the work location (e.g., noise, heat, poor lighting) directly contributed to this event.
7. CORRECTIVE ACTIONS:
These eight ECCS injection containment penetration test and drain valves were added to Surveillance Test procedure 40ST-9ZZ13 (Containment Isolation Valves).
The surveillance test procedure was revised to include these test and drain valves and successfully completed the ST prior to entering MODE 4 from its refueling outage.
Any additional corrective actions taken as a result of the investigation of this event, including an evaluation of the extent of condition will be implemented in accordance with the APS corrective action program. If information is subsequently developed that would significantly affect a reader's understanding or perception of this event, a supplement to this LER will be submitted.
8. PREVIOUS SIMILAR EVENTS:
Previous similar events were reported in LER 50-528/2001-005 and