05000338/LER-2003-005
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FACILITY NAME (1) � DOCKET � LER NUMBER 16) � PAGE (3) 1.0 DESCRIPTION OF THE EVENT On November 10, 2003, at approximately 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br />, with Units 1 and 2 operating at 100 percent power, testing of the hydrogen recombiner, 2-HC-HC-1 (EIIS System BB, Component RCB) was being conducted in accordance with periodic test 0-PT-213.37, Hydrogen Recombiner 2-HC-HC-1 Flow Test. Within 60 seconds of the start of the test, the hydrogen recombiner tripped due to a low flow condition. Operations verified the valve line up (as listed in O-PT-213.37) and a second attempt to start 2-HC-HC-1 was made with the same result; the hydrogen recombiner tripped after a brief period (approximately 60 seconds). The control circuit logic is such that the hydrogen recombiner will trip after 60 seconds of low flow. During this second attempt, Operations verified hydrogen recombiner flow indication never moved from zero.
While investigating why 2-HC-HC-1 was not indicating flow, Operations determined that the high and low side isolation valves 2-HC-94 and 2-HC-95 (EIIS Component ISV) were closed. The closure of these two valves prevented the hydrogen recombiner flow transmitter, 2-HC-FT-200 (EIIS Component FT), from sensing flow through the hydrogen recombiner. This caused the hydrogen recombiner to trip from an indicated low flow condition.
Operations reviewed procedure 0-OP-63A, Valve Checkoff-Containment Atmosphere Cleanup and drawing 11715-FM-106A-Sheet 4 and determined valves 2-HC-94 and 2- HC-95 were required to be open. Operations opened valves 2-HC-94 and 2-HC-95 and the hydrogen recombiner was placed in service. Periodic test O-PT-213.37 was completed satisfactorily at 1746 hours0.0202 days <br />0.485 hours <br />0.00289 weeks <br />6.64353e-4 months <br />.
A subsequent review determined, through the use of computer narrative logs, tagging records for the Containment Atmospheric Clean-up System (HC), and work history, that the last verifiable time that valves 2-HC-94 and 2-HC-95 were open was August 21, 2003 (during the previous performance of 0-PT-213.37). With this established timeline, all events (maintenance, testing, Operations actions, etc.) for both Unit 1 and 2 hydrogen recombiners (so as to eliminate unit transposition errors) were developed. Each event was reviewed and technical information used to eliminate the event as a possible cause for the valve misposition. It was determined that the most likely event that mispositioned valves 2-HC-94 and 2-HC-95 was the performance of O-PT-213.37 on August 21, 2003.
Technical Specification 3.6.9 requires two operable hydrogen recombiners. An inoperable hydrogen recombiner must be restored to operable within 30 days or the affected Unit must 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 />. The valve misposition existed for greater than the 30- day completion time. As described above, Operations opened valves 2-HC-94 and 2-HC- 95 and the hydrogen recombiner was placed in service. Testing was completed satisfactorily. This event is reportable pursuant to 10 CFR 50.73 (a)(2)(i)(B) for a condition prohibited by Technical Specifications.
FACILITY NAME (1) � DOCKET NORTH ANNA POWER STATION UNIT 1 � 05000 - 338 LER NUMBER (6) In addition, there were two occasions when the Unit 1 hydrogen recombiner was inoperable while undergoing maintenance or testing during the time the Unit 2 hydrogen recombiner was inoperable. The Unit 1 hydrogen recombiner was returned to operable within a short timeframe. The 7-day Technical Specification allowed outage time was not exceeded during the time there were two inoperable hydrogen recombiners.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS The Containment Atmosphere Cleanup System and its components are common to both reactor units. The two skid-mounted hydrogen recombiners are connected to the reactor containments, and the system is designed to allow either hydrogen recombiner to be operational on either containment structure to maintain the hydrogen concentration below four volume percent following a design basis accident (DBA). To ensure operability of the hydrogen recombiner system in the event of a single failure of any component, the system is arranged in two redundant trains. Each hydrogen recombiner is capable of being powered from either unit's emergency buses. ' This event posed no significant safety implications because no conditions requiring the use of the hydrogen recombiner were experienced during the time the hydrogen containment hydrogen concentration was required, the Unit 1 hydrogen recombiner could have been aligned to the Unit 2 containment or the Unit 2 containment could have been vented to the process vent system (ENS System WE). Therefore, the health and safety of the public were not affected by this event.
3.0 CAUSE A root cause evaluation of the event was performed. The cause of the valve misposition was inadequate work practices, in that, documents were not followed correctly.
O-PT-213.37 requires l&C technicians install test equipment (in parallel with a permanently installed flow transmitter 2-HC-FT-200) to support the test. The steps to instalVremove the test equipment do not state that 2-HC-94 and 95 are to be manipulated. Since the system is isolated, manipulation of these valves is not required to install test equipment.
The l&C technicians involved do not recall operating these valves for this evolution. The expectation is that l&C only operate instrument valves when the procedure specifically states to operate the valve. The technicians may have had a mindset to close these valves because:
- The calibration procedure (ICP-HC-2-HC-1) for the installed flow transmitter (2-HC-FT- 200) has steps to shut/open the isolation valves (2-HC-94 and 95).
- When performing instrument calibration maintenance on any instrument, isolation of the instrument is essential to ensure correct calibration.
FACILITY NAME (1) NORTH ANNA POWER STATION UNIT 1 DOCKET LER NUMBER (6) PAGE (3) A contributing cause of the event was managerial methods due to policies not being adequately defined. Virginia Power Administrative Procedure (VPAP) 1401, Conduct of Operations states that instrument valves may be operated by qualified instrument technicians but does not provide any specific guidance. The expectation is that valves will only be operated by l&C technicians in accordance with an approved procedure.
However, there is no written guidelines or a department administrative procedure that defines valve operation. l&C may be most vulnerable when supporting other departments. l&C procedures are written such that the instrument is removed and returned to service including verifications. However, when working in support of other departments, the procedure being used by the l&C technicians may not include this level of instruction which may place the technician into a knowledge based situation to determine what is allowed.
4.0 IMMEDIATE CORRECTIVE ACTION(S) Operations personnel reviewed procedure 0-0P-63A, Valve Checkoff-Containment Atmosphere Cleanup and drawing 11715-FM-106A-Sheet 4 and determined valves 2-HC- 94 and 2-HC-95 were required to be open. Operations opened valves 2-HC-94 and 2- HC-95 and the hydrogen recombiner was placed in service. Periodic test O-PT-213.37 was completed satisfactorily at 1746 hours0.0202 days <br />0.485 hours <br />0.00289 weeks <br />6.64353e-4 months <br />.
5.0 ADDITIONAL CORRECTIVE ACTIONS A root cause evaluation was performed. The following corrective actions from the root cause evaluation were implemented.
Operations verified that 1-HC-89 and 1-HC-90 (low side and high side isolation valves, for 1-HC-FE-100, Unit 1 Hydrogen Recombiner) were open.
Immediate temporary administrative controls for l&C technicians operating instrument valves were implemented.
6.0 ACTIONS TO PREVENT RECURRENCE Management approved corrective actions to address the root cause of the event are being tracked in the Corrective Action System and are described below.
Review the RC development program to ensure recently developed departmental administrative guidance for l&C technicians operating instrument valves is incorporated. Revise lesson plans as appropriate.
Develop (or add to existing) scenario training that re-enforces recently developed departmental administrative guidance for l&C technicians operating instrument valves.
DOCKET
05000 - 338 FACILITY NAME (1) LER NUMBER 16) � PAGE (3) Develop departmental administrative guidance for I&C technicians operating instrument valves. Guideline shall address procedure usage, required documentation, and verification. Communicate this guideline to all l&C personnel.
Additional corrective actions beyond the root cause of the event are also being tracked in the Corrective Action System.
7.0 SIMILAR EVENTS that rendered the containment personnel air lock outer door inoperable.
8.0 ADDITIONAL INFORMATION None