05000316/LER-2007-001

LER-2007-001, As-Found Local Leak Rate Tests Not Performed

Docket Number
Event date:	10-28-2007
Report date:	06-13-2008
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3162007001R01 - NRC Website

Conditions Prior to Event Unit 2 was in a scheduled refueling outage and was in Mode 5.

Description of Event

On October 28, 2007, Donald' C. Cook Nuclear Plant (CNP) failed to perform the required as-found local leak rate tests Containment Isolation Valves. Originally identified were 2-WCR-942, Non-Essential Service Water (NESW) to Reactor Coolant Pump (RCP) No. 2 Motor Air Coolers Train A Containment Isolation Valve and 2-WCR-946, RCP No. 2 Motor Air Coolers NESW Outlet Train A Containment Isolation Valve. An extent of condition investigation noted that additional as-found LLRTs were not performed prior to maintenance performed September 26, 2007, on 2-WCR-922 and October 7, 2007,'on 2-WCR-923; these are series Containment Isolation valves for NESW. This condition prohibitedby Technical Specifications (TS) was not recognized initially. This Licensee Event Report (LER) supplement addS these two additional valves which were not previously reported as extent of condition.

A maintenance planner was assigned to plan emergent maintenance activities for 2-WCR-942 and 2-WCR-946.

For each of the valves, the planner failed to include a task directing performance of an as-found LLRT. and did not include a prereOisite to validate as-found LLRT prior to performing maintenance. As a result, maintenance, was performed withOut having first performed the as-found LLRT.

Additionally, the- piping containing 2-WCR-922 and 2-WCR-923 valves in series was believed to haVe:beenPlugged with sediment, a condition which would preclude as-found LLRTs. As a result, maintenance was performed on October 7, 2007, that identified that the apparent blockage was actually due to an internal valve component installed incorrectly (reversed finger plate) on 2-WCR-923 which prevented the valve from passing flow. The maintenance that was performed precluded performing the required as-found LLRT.

CNP's Containment Leakage Rate Testing Program, as directed by Surveillance Requirement (SR) 3.6.1.1, requires the conduct of as-found LLRTs. This is performed to validate containment integrity through that penetration if an accident condition would have occurred during the previous cycle of power operations.

The failure to meet SR 3.6.1.1 is reportable in accordance with the requirements of 10 CFR 50.73(a)(2)(i)(B), Operation or Condition Prohibited by Technical Specifications.

Cause of Event

The cause of the 2-WCR-942 and 2-WCR-946 event can be attributed to human error due to inadequate validation of assumptions. The emergent work order tasks were created in an expeditious manner to ensure completion of the work within the known window of opportunity. The job planner understood that as-found LLRTs are required for these valves, but incorrectly assumed that the maintenance was required because the valves failed their as-found LLRTs.

Additionally, the planner identified work order tasks for performing routine, scheduled as-found LLRTs on these valves, and again incorrectly assumed that because these tasks existed, no other as-found LLRTs would need to be created.

The cause of the 2-WCR-922 and 2-WCR-923 event was that, based on results of troubleshooting, the piping for these valves appeared to be blocked or plugged. Blocked piping would preclude any LLRTs, so maintenance was initiated to clear the piping. The maintenance identified a reversed finger plate on 2-WCR-923 rather than blocked piping. The reversed finger plate prevented 2-WCR-923 from opening. For this event, it was understood that the as-found testing would not be performed on 2-WCR-922 and 2-WCR-923 due to the apparent blockage, but not performing the as-found testing was not initially recognized as being a condition prohibited by TS. This was due to a mindset that an inability to perform the required testing, in this case due to apparent blockage, would make the condition (not performing the as-found testing) acceptable under program requirements.

Analysis of Event

As-found LLRTs were not performed prior to maintenance on these NESW system containment isolation valves:

However, in the case of both the original and this LER supplement, the maintenance was not for repair of any seat leakage and not due to valve closure issues, such that the valves were able at all times to perform their containment isolation function. As such, failure to properly implement the "as-found" LLRT test requirement had no impact on plant risk in terms of an increase in Core Damage Frequency or Large Early Release Frequency, or the consequences of design basis events.

The valves of concern, which were on an extended testing interval, have been returned to the nominal testing­ interval as the missing as-found LLRTs will preclude meeting the procedure requirements for extended frequency.,,!f,-, .

Post-maintenance as-left LLRTs were completed following the maintenance on the valves.

Corrective Actions

The Work Package Planner Training Program (initial and recurring) will be modified to include focus on LLRT requirements.

Work Control planner templates have been enhanced to include verification of LLRT performed prior to any work on containment isolation valves.

Engineering procedures governing the conduct of the LLRT program will be revised to specify required actions for a missed LLRT, whether inadvertent or intentionally not performed due to system/component conditions.

2-WCR-923 was disassembled, properly repaired, and successfully tested.

Previous Similar Events

A search of the past three years identified one Licensee Event Report (LER) for a similar missed as-found LLRT surveillance:

05000316/2006-005-00F Failure to Comply with Technical Specification Surveillance Requirement 3.6.1.1 The corrective actions for the event documented in LER 05000315/2006-005-00 failed to prevent the events documented in this LER. This failure to prevent recurrence has been captured in CNP's Corrective Action Program.