05000364/LER-2008-001

LER-2008-001,

Joseph M Farley Nuclear Plant - Unit 2
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3642008001R00 - NRC Website

Westinghouse -- Pressurized Water Reactor Energy Industry Identification Codes are identified in the text as [XX]

Description of Event

On February 11, 2008 the quarterly surveillance testing was performed on the Unit 2 Auxiliary Building B-Train Battery [EJ]. The surveillance test was signed off as satisfactory. This quarterly surveillance test was repeated on May 7, 2008 and Cell number 33 of B-Train Battery was determined to have a voltage of 2.06 V which is below the minimum allowed cell voltage of 2.08 V.

Technical Specifications (TS) Action statements were entered which required surveillance every seven days and the restoration of Cell number 33 within 31 days. Cell number 33 was replaced on June 3, 2008. On June 6, 2008 during the review of the paper work associated with this Cell replacement, SNC determined that the February 11, 2008 surveillance test was approved in error since the recorded voltage for Cell number 33 was 2.06 V which is below the minimum allowed voltage of 2.08 V. The recorded voltage was transcribed illegibly by the journeymen and subsequently misread by the journeymen and supervisor as 2.16 V. This error resulted in the B- Train battery being inoperable between February 11 and May 7, 2008 due to not completing the required TS Action Statement.

Cause of Event

The journeymen involved in taking the voltage reading failed to follow the procedure and compare the voltage to the correct acceptance criteria. Additionally, the journeymen and supervision failed to ensure the procedure was correctly completed.

Safety Assessment This event had no adverse effect on the safety and health of the public.

The Auxiliary Building 125 Volt Direct Current (VDC) system consists of two independent and redundant subsystems (A-Train and B-Train) which supply Direct Current (DC) power to various Engineered Safety Feature (ESF) systems throughout the plant. Each Auxiliary Building subsystem (train) consists of a 125 Volt battery, an associated full capacity battery charger and all associated control equipment and interconnecting cabling. During normal operation, the 125 VDC load is powered from the battery chargers with the batteries floating on the system. In case of loss of normal power to the battery charger, the DC load is automatically powered from the station batteries.

The Auxiliary Building batteries are stationary type consisting of 60 individual lead-calcium cells electrically connected in series to establish a nominal 125 VDC power supply. Under both normal and accident conditions the batteries are capable of providing the required voltage for component operation. The battery float voltage is 2.20 V per cell average and 132 V total terminal voltage.

� Although not a requirement for the mitigation of design basis events, each battery is capable of providing Loss of Off Site Power (LOSP) or LOSP plus Safety Injection (SI) loads for a period of two hours assuming the single failure loss of the battery charger aligned at the onset of the event.

Cell number 33 of the 2B Auxiliary Building battery was replaced, surveillance testing was completed satisfactorily and the battery was returned to service on June 3, 2008. A test was performed on the removed Cell number 33 that demonstrated the Cell would have provided the energy needed to meet its safety function for a period of two hours as required by the design of the system. In addition, an engineering evaluation documented that the Unit 2 Auxiliary Building B- Train Battery would have met its safety function with Cell number 33 jumpered out of the battery.

This engineering evaluation and actual test results of Cell number 33 provided reasonable assurance that the safety and health of the public was not adversely affected by this event.

Corrective Action Cell number 33 of the 2B Auxiliary Building Battery was replaced on June 3, 2008.

As an interim measure, additional supervisory personnel (Maintenance Team Leader) reviews are performed on Technical Specifications battery surveillance test packages.

Personnel involved in the event have been coached on the importance of attention to detail when using procedures and legibility of recorded data.

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