05000354/LER-2004-005

LER-2004-005, Hope Creek Generating Station 05000354 1 OF 3

Docket Number
Event date:	5-17-2004
Report date:	7-16-2004
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3542004005R00 - NRC Website

DOCKET

FACILITY NAME (1) NUMBER (2) LER NUMBER (6) PAGE (3)

PLANT AND SYSTEM IDENTIFICATION

General Electric — Boiling Water Reactor (BWR/4) Chilled Water System {KM}* Control Room Emergency Filtration System {VI} * Energy Industry Identification System (EllS) codes and component function identifier codes appear as (SS/CCC)

IDENTIFICATION OF OCCURRENCE

Event Date: May 17, 2004 Discovery Date: May 20, 2004

CONDITIONS PRIOR TO OCCURRENCE

Hope Creek was in Operating Condition 1 (Power Operation), at the time of discovery. No other required structures, systems or components were inoperable at the start of this event that contributed to the event.

DESCRIPTION OF OCCURRENCE

Hope Creek Technical Specification (TS) 3.7.2, requires two (2) independent Control Room Emergency Filtration (CREF) {VI} subsystems to be operable. Included in each subsystem is a chilled water system to maintain the control room envelope within specified environmental limits. The BK400 chiller is a support component of the B CREF train.

With the chiller inoperable, the B CREF train is therefore inoperable. TS 3.7.2, Action a., requires that the inoperable subsystem be made operable within 7 days or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

On May 20, 2004, at approximately 0715, a report was made to Hope Creek Operations that the BK400 chiller evaporator pressure was 61 PSIG. Procedurally, the chiller evaporator pressure is to be maintained between 35 and 50 PSIG. An investigation was performed and Technical Specification Action Statement (TSAS)04-259 was entered declaring the B CREF train inoperable in accordance with Technical Specification (TS) 3.7.2 Action a. Corrective maintenance was performed and the system was returned to operable status at 1920, on May 20, 2004.

Prior to May 20, 2004, the BK400 chiller had been out of service between May 9 and May 15 for maintenance. A portion of the maintenance activity was the replacement of the guide vane pivot arm. While trouble shooting the problem on May 20, 2004, it was discovered that the chiller guide vane pivot arm was slipping on the drive shaft.

Based on this information, the BK400 chiller was determined to not have been capable of performing its design function when it was returned to service on May 15, 2004. Therefore, the BK400 chiller was inoperable from May 9 to May 20 which exceeds the 7 day allowed outage time of TS 3.7.2 Action a. Therefore, May 17, 2004 was the date that exceeded the 7 day TSAS.

The event is being reported in accordance with 10CFR50.73(a)(2)(i)(B), Any operation or condition that was prohibited by the plant's Technical Specifications.

CAUSE OF OCCURRENCE

The cause of occurrence was inadequate procedure guidance on pivot arm replacement.

During the maintenance outage which commenced on May 9, 2004, the pivot arm was replaced. The cause for the high evaporator pressure was determined to be the inability of the guide vane to properly modulate. This was due to the pivot arm set screws that were not engaged firmly enough to prevent slipping on the shaft. This in turn prevented the chiller from operating as designed. A contributing cause to the LCO being exceeded was an insufficient retest to ensure operability of the chiller.

PREVIOUS OCCURRENCES

A review of related TS noncompliance LERs was performed for the past 3 years. LER 354103-002-00, entitled "Inoperability of Control Room Emergency Filter (CREF) subsystems due to Control Room (CR) envelope breach", dated January 12, 2003 was reviewed for applicability to operability of the BK400 chiller. That event was attributed to a ductwork access hatch opening and no correlation was found to a chiller equipment issue or operability assessments. Based on this review actions associated with that LER would not have prevented this occurrence. LER 354/04-002-00, entitled "Control Room Emergency Filtration System Train Inoperable For Greater 7 Days", involved the same CREF train. The failure mechanism related to that LER was a float which became disengaged from the float arm. Corrective actions related to that event would not have prevented the current event.

SAFETY CONSEQUENCES AND IMPLICATIONS

There were no safety consequences associated with this event since the "A" CREF train was operable during the period the "B" CREF was inoperable. Additionally, there were no design basis radiological releases during the period that the "B" CREF train was inoperable. Only one train of CREF is required to mitigate design basis radiological events that impact the control room envelope.

This event does not constitute a Safety System Functional Failure (SSFF) as defined in NEI 99-02.

CORRECTIVE ACTION

The corrective actions to address the identified problem are as follows:

1. The BK400 chiller was repaired and returned to operable status on May 20, 2004.

2. Maintenance procedure HC.MD-CM.GJ-001 will be revised to add guidance for dimpling the guide vane shaft to properly engage setscrews to prevent slipping.

3. Chiller guide vane maintenance plans will be revised to ensure retests demonstrate that the chillers are fully operable.

COMMITMENTS

The corrective actions cited in this LER do not constitute commitments.