05000261/FIN-2010009-01
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Finding | |
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| Title | Monitoring of Plant Parameters and Alarms |
| Description | The team conducted an independent review of control room activities to determine if licensee staff responded properly during the events. With respect to operator awareness and decision making, the team was specifically focused on the effectiveness of control board monitoring, communications, technical decision making, and work practices of the operating crew. With respect to command and control, the team was specifically focused on actions taken by the control room leadership in managing the operating crews response to the event. The team performed the following activities in order to understand and/or confirm the control room operating teams actions to diagnose the event and implement corrective actions: Conducted interviews with control room operations personnel on shift during the event. Reviewed procedures, narrative logs, event recorder data, system drawings, and plant computer data. Observed a simulated plant response to this event as demonstrated on the plant reference simulator. Reviewed the crews implementation of emergency, abnormal, and alarm procedures as well as Technical Specifications. Reviewed Operations administrative procedures concerning shift manning and procedure use and coordination. Reviewed Operations procedures in use at the time of the second fire. The team determined that operators exhibited weaknesses in fundamental operator competencies when responding to the event. Specifically, the team determined that the operating crew did not identify important off-normal parameters and alarms in a timely manner, resulting in a failure to recognize an uncontrolled RCS cooldown and a potential challenge to RCP seal cooling. Additionally, the team determined that crew supervision did not exercise effective oversight of plant status, crew performance, or site resources. Through a review of plant data, the team determined that the crews response to the first event was not effective in stabilizing the plant. Through interviews and review of plant data, the team determined that the crew did not recognize the magnitude of the RCS cool down caused by an on-going steam demand. The RCS cool down rate exceeded the limit of 100o/hr in any one hour period as specified in Technical Specification (TS) 3.4.3, RCS Pressure and Temperature (P/T) Limits. The fact that the RCS cooldown rate exceeded the limiting value specified in TS 3.4.3, and the requirement to evaluate the actions contained in TS 3.4.3, was not recognized by the crew at any time during or after the cooldown. Based on interviews, the Reactor Operator (RO) and Control Room Supervisor (CRS) assessed the cool down rate as being consistent with what was experienced during simulator training for an RCP trip followed by a reactor trip. The RCS cool down continued until Instrument Bus 3 was inadvertently de-energized (approximately 33 minutes after the start of the first event), which caused the MSIVs to close, isolating the steam generators from the steam header. Based on the sequence of events, a review of plant data, and operator interviews, the team concluded that the crew did not recognize that VCT level was decreasing, a low VCT level alarm had annunciated, and automatic swapover of the charging pump suction from the VCT to the RWST failed to occur, until indicated level in the VCT had decreased to approximately 2-3 inches and charging flow had degraded. Once the crew identified this condition, the RO attempted to manually align the suction of the charging pumps to the RWST but made an error when performing the alignment. The error left the suction of the charging pumps aligned to the VCT. The Shift Technical Advisor (STA) determined the alignment was incorrect and the RO corrected the error. The crew did not reference APP-003-E3, VCT HI/LO LVL, which provided direction to manually transfer the charging pump suction to the RWST. RCP seal cooling was maintained because the crew reopened FCV-626 to restore CCW cooling to the RCP thermal barrier heat exchanger approximately 6 minutes before depletion of the VCT. However, high pump bearing temperature alarms were received on all three RCPs. The high temperature alarms subsequently cleared after operators reopened FCV-626. Based on operator interviews, the team concluded that, following implementation of Emergency Operating Procedures (EOPs), the operators did not complete a satisfactory review and evaluation of alarm conditions prior to the second event. Instead, the operating crew entered GP-004, Post Trip Stabilization, and attempted to reset the generator lockout relay without using the information in the Annunciator Panel Procedures (APPs) to completely and accurately assess abnormal electric plant status. GP-004 is a normal operating procedure and is written with the assumption that the plant is in a normal (undamaged) configuration. The crew was not aware that a sudden pressure fault signal from the UAT was still applied to the generator lockout circuit logic, as indicated by a locked in UAT fault trip alarm (APP-009-B6, AUX TRANSF FAULT TRIP). The attempted reset reenergized Bus 4 and caused a fault at breaker 52/24, initiating the sequence for the second fire. The team concluded that if the crew had performed a thorough control board walkdown, additional electric plant APPs and/or AOPs could have been identified and implemented before exiting to a normal operating procedure (GP-004). Additional review by the NRC will be required to determine if the licensees programs resulted in untimely identification and investigation of abnormal plant parameters and unexpected main control room alarms. This review will also determine whether the crews monitoring of plant parameters and alarms, and use of associated procedures, represents a performance deficiency. An Unresolved Item will be opened pending completion of this review. The URI is identified as05000261/2010009-01, Monitoring of Plant Parameters and Alarms. Additionally, further review by the NRC will be required to determine if the RCS cooldown rate exceeding the limiting value specified in TS 3.4.3 represents a performance deficiency. An Unresolved Item will be opened pending completion of this review. The URI is identified as05000261/2010009-02, RCS Cooldown Rate Exceeds Technical Specification 3.4.3 Limit. |
| Site: | Robinson  |
|---|---|
| Report | IR 05000261/2010009 Section 4OA5 |
| Date counted | Jun 30, 2010 (2010Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 93800 |
| Inspectors (proximate) | J Hanna J Hickey L Miller L Wert P Fillion P Pieringer R Monk S Currie F Ehrhardtc Kontzg Laska L Wert M Bates W Rogersa Nielsenc Kontz D Bollock D Mills G Laska G Skinner J Beavers J Brady J Hickey J Worosilo M Bates P Braxton R Musserr Monkf Ehrhardt J Hanna L Miller J Hickey P Fillion L Wert P Pieringer S Currie |
| INPO aspect | |
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Finding - Robinson - IR 05000261/2010009 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Robinson) @ 2010Q2
Self-Identified List (Robinson)
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