05000454/LER-2005-004

LER-2005-004, ethnical Specification Required Action Not Satisfied Due to Ambiguous Implementing Procedure.

Docket Number
Event date:
Report date:
4542005004R00 - NRC Website

A. Plant Condition Prior to Event:

Event Date/Time: May 24, 2005/1505 hours CST Unit 1 and Unit 2 - Mode 1 — Power Operations, Reactor Power 100% Reactor Coolant System [AB): Normal operating temperature and pressure.

No structures, systems or components were inoperable at the start of the event that contributed to the event.

Background

The 125 Volts Direct Current (VDC) electrical power system (DC) [EJ] for each unit consists of two and Division 21 and 22 for Unit 2.) Each subsystem consists of one 125 VDC battery, the associated battery charger and all the associated control equipment and interconnecting cabling. A capability exists to interconnect the Unit 1 and Unit 2 DC electrical power subsystems via a cross-tie breaker when a DC source must be taken out of service for maintenance/testing or in the event of a DC source failure. TS 3.8.4, "DC Sources — Operating" Limiting Condition for Operations (LCO) requires both divisions for each Unit to be OPERABLE and not crosstied to the opposite unit.

Condition "A" of TS 3.8.4 require the following actions when one battery charger is inoperable:

1. Crosstie the opposite-unit bus with associated OPERABLE battery charger to the affected division within two hours. AND 2. Restore battery terminal voltage to greater than or equal to the minimum established voltage within two hours, AND 3. Verify battery float current is 3 amps once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, AND 4. Restore the battery charger to OPERABLE status within 7 days.

Byron Station Unit 1 Operating Procedure 1BOL 8.4, "LCOAR DC Sources — Operating Tech Spec LCO # 3.8.4" is used to aid in implementing these action requirements. The operating expectation is that these types of procedures are intended to be used in conjunction with the TSs and not to be used as a stand­ alone document.

B. Description of Event:

On May 23, 2005, at approximately 2105 hours0.0244 days <br />0.585 hours <br />0.00348 weeks <br />8.009525e-4 months <br />, the Unit 1 Control Room Supervisor (CRS) (licensed) entered Action Condition A of TS 3.8.4 due to planned work on the Division 11 Battery Charger. In CRS incorrectly determined that the procedure that needed to be performed to obtain battery float current for Required Action 3 should be the Unit 2 Byron Station Operating Surveillance Requirement procedure 2BOSR 8.6.1-1, "Unit 2 125V DC ESF Battery Bank and Charger 211 Operability Weekly Surveillance.

The Unit 1 CRS arrived at this determination using the rationale that the battery charger for Division 11 was de-energized so the battery float current would not be able to be obtained from this Unit and since the battery charger for Division 21 was supplying both Division 11 and 21 batteries then Division 21 is where the reading would need to be taken. However, 1BOL 8.4 listed four procedures that should be used to satisfy this condition depending on the Mode Unit 1 was in, and 2BOSR 8.6.1-1 was not one of them. The correct Unit 1 equivalent procedure, 1BOSR 8.6.1-1, "125V DC ESF Battery Bank and Charger 111 Operability Weekly Surveillance," was in fact listed.

The Unit 1 CRS received a verbal independent peer check from the Unit 2 CRS (licensed) that the appropriate surveillance procedure to meet the current reading for 1BOL 8.4 Condition A.3 should be 2BOSR 8.6.1-1. No electrical prints were reviewed or other members of the operating crew consulted.

The first verification of adequate battery float current was due by 0905 hours0.0105 days <br />0.251 hours <br />0.0015 weeks <br />3.443525e-4 months <br /> on May 24, 2005, however the Shift Manager (licensed) directed that the float current measurements be taken before shift turnover at 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br />.

At 0452 hours0.00523 days <br />0.126 hours <br />7.473545e-4 weeks <br />1.71986e-4 months <br />, 2BOSR 8.6.1-1 was completed to satisfy Action Condition A.3 and 1BOL 8.4 annotated completion of the first verification. No procedure revision was initiated to 1BOL 8.4 by Unit 1 CRS to correct what he believed was a typographical error.

At approximately 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br />, 1BOL 8.4 was given to the Unit 2 CRS to review for accuracy. The U2 CRS indicated that the U-2 surveillance procedure that was used would need to be listed; however no further discussion occurred regarding required procedure revisions, or the discrepancy that the BOL did not have the specific U2 surveillance procedure that was actually performed.

The U-1 CRS revised 1BOL 8.4 to indicate what was believed to be a typographical error to incorrectly change 1BOSR 8.6.1-1 to 2BOSR 8.6.1-1. However, the procedure revision review process for this type of procedure revision was not followed properly.

At 0615 hours0.00712 days <br />0.171 hours <br />0.00102 weeks <br />2.340075e-4 months <br />, turnover between off-going Unit 1 CRS and the on-coming Unit 1 CRS occurred. LCO action requirements were discussed and the off-going CRS mentioned that the U-2 surveillance procedure was being performed to meet the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Required Action A.3 and that the Unit 1 surveillance procedure was identified as a typographical error in 1BOL8.4.

After turnover, the on-coming Unit 1 CRS questioned whether this was this indeed was the correct procedure to use and evaluated it further with other licensed on-shift personnel and engineering personnel.

As a result, at 1548 hours0.0179 days <br />0.43 hours <br />0.00256 weeks <br />5.89014e-4 months <br /> it was confirmed that 1BOSR 8.6.1-1 was in fact the correct procedure to use and that 1BOL 8.4 was correct as originally written. The appropriate battery float current reading was taken immediately.

The Shift Manager concluded that Required Action A.3 was not completed within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. With Required Action A.3 not met within the required Completion time, this would have required entering Condition E of TS 3.8.4 at 0905 hours0.0105 days <br />0.251 hours <br />0.0015 weeks <br />3.443525e-4 months <br />. Condition E requires Unit 1 to be in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> AND Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Consequently, with Unit 1 not in Mode 3 by 1505 hrs on May 24, 2005, Unit 1 was in a condition prohibited by TS and therefore reportable to the NRC in accordance with 10 CFR 50.73 (a)(2)(i)(b).

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C. Cause of Event:

The root cause of this event was determined to be ambiguous instructions in 1BOL 8.4. The Unit 1 CRS was given a list of surveillance procedures in 1BOL 8.4 to choose from to verify battery float current. A direct procedural link did not exist which identified specifically which surveillance was appropriate in order to correctly perform verification of battery float current for battery 111. It is believed that this menu style selection of fulfilling TS Action Requirements has posed an unnecessary decision point on the operating crew. It could not be determined why the procedure was written in this manner.

A contributing cause include less than adequate individual performance exhibited by the Unit 1 and 2 CRSs in the area of technical human performance and procedural adherence.

D. Safety Analysis:

The intent of Required Action A.3 of TS 3.8.4 is to ensure that if the battery has been discharged as a result of an inoperable battery charger, that it has been fully recharged within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The delay in conducting this verification was approximately 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />. This delay had minimal safety significance. The Division 11 battery was believed to be operable in this delay period. In addition, no equipment was made unavailable or inoperable by the performance of the incorrect surveillance procedure.

E. Corrective Actions:

The correct surveillance procedure (1BOSR 8.6.1-1) was performed satisfactorily in order to comply with TS Spec 3.8.4 Action Requirement A.3.

Unit 1 and Unit 2 BOL 8.4 have been revised to clearly identify which battery float current should be obtained based on which battery charger is inoperable.

Appropriate management actions were taken to address the less than adequate individual performance issues with the Unit 1 and Unit 2 CRSs.

Training will be provided to operators cornering the human performance issues involved in this event.

F. Previous Occurrence:

Allowed by Technical Specifications Due to Inadequate Procedure," dated April 15, 2005