05000397/LER-2003-009

LER-2003-009,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident
3972003009R00 - NRC Website

Event Description

On August 22, 2003, at 0234 PDT, the Reactor Core Isolation Cooling (RCIC) system was isolated as a result of a battery cell in the Division 1 250 VDC battery (E-B2-1) not meeting Technical Specification (TS) battery cell parameter requirements. E-B2-1 had been declared inoperable due to failure of one battery cell to meet Technical Specification (TS) 3.8.6, Battery Cell Parameters, Table 3.8.6-1, Category C specific gravity limits.

With E-B2-1 inoperable, TS 3.8.4, DC Sources - Operating, Required Action C.1, requires the equipment supported by the inoperable battery to be immediately declared inoperable.

RCIC-V-19, the RCIC pump minimum flow bypass valve, is a primary containment isolation valve (PCIV). RCIC-V-19 is also supported by battery E-B2-1. RCIC-V-19 was declared inoperable, and was closed and deactivated to comply with TS 3.6.1.3, Primary Containment Isolation Valves, Required Action C.I. Because RCIC-V-19 was inoperable, operators closed the steam inlet valve (RCIC-V-1) to the RCIC turbine to prevent operation of the RCIC system. Isolation of RCIC-V-1 removes RCIC from service.

'Cause of Event The isolation and removal from service Of the RCIC system was a result of declaring E-B2-I and associated support features (including RCIC-V-19) inoperable, as required by the plant's Technical Specifications. To prevent operation of the RCIC system with RCIC-V-19 closed and deactivated, it was necessary to isolate the steam inlet valve (RCIC-V-1) to the RCIC turbine.

The reason-for declaring E-B2-1.inoperable was_the discovery that ,the specific.gravity of the electrolyte in E-B2-1 cell number 166 did not meet the TS Table 3.8.6-1 Category C battery cell parametr requirements. This TS table specifies that no connected battery cell electrolyte specific gravity maybe more than 0.020 below the average of all the connected cells of that battery. The root cause is thought to be less than adequate battery recharging following the 5- year modified discharge test during the most recent refueling outage.

Safety Significance

The RCIC system is designed to operate either manually or automatically following a reactor pressure vessel (RPV) isolation accompanied by a loss of coolant flow from the feedwater system to provide adequate core cooling and control of RPV water level. Under these conditions, the High Pressure Core.Spray (HPCS) and RCIC systems perform similar 26158 R2

Corrective Actions

Upon replacement of the battery cell that did not meet the TS battery cell parameter requirements, the 250 VDC battery (E-B2-1) was restored to service, and the RCIC system was declared operable at 1700 PDT on August 22, 2003.

The battery discharge and quarterly operability surveillance procedures will be revised to include directions to place the battery on equalize for two 5-day periods (separated by a 2-day period) following performance of the surveillance.

Previous Similar Events

On July 8, 2003, the RCIC system was declared inoperable after one of its steam supply containment isolation valves was inadvertently closed during the performance of a surveillance test. The surveillance test was discontinued and plant operators verified that the High Pressure Core Spray system was operable. The RCIC system was restored to its normal standby lineup and declared operable within one hour. The details concerning this event are discussed in LER 397-2003-008.

EIIS Information Text Reference � System � Component Reactor Core Isolation Cooling System �

BN

High Pressure Core Spray System � BG RCIC-V-1 � BN � V RCIC-V-19 � BN � ISV 250 VDC Battery � El 26158 R2