05000424/FIN-2010006-01
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Finding | |
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| Title | Control Room Fire Alternate Shutdown Evaluation (X4C2301S035) Does Not Reflect Integrated Plant Response |
| Description | The team identified an unresolved item (URI) related to the Control Room Fire Alternate Shutdown Evaluation (CRFASE), calculation number X4C2301S035. Specifically, the team found that the CRFASE does not reflect integrated automatic plant response to fire in the MCR requiring shutdown from the RSPs. Description: The CRFASE is an evaluation of the impact of a fire in the MCR on the operators ability to safely shut down the plant from outside the MCR. The evaluation addresses discreet spurious operation concerns on a system basis. The CRFASE provides time constraints and compensatory measures used to develop the operator actions, and sequencing of these actions, in procedure 18038-1, Operation from Remote Shutdown Panels. During review of procedure 18038-1 and the CRFASE, the team questioned whether certain operator actions contained in step 3 of procedure 18038-1, if unable to be performed from the MCR, would be able to be performed within established time constraints in order to prevent and/or mitigate the adverse effects of spurious actuations. These time constraints, adverse spurious actions, and the impact on the plant of these spurious actuations are described in the CRFASE. Specifically, the team questioned whether reactor coolant pumps #1 and #4 would be able to be tripped early enough from the RSP in time to prevent depressurization of the reactor coolant system to the safety injection (SI) actuation set point, in the event one pressurizer spray valve spuriously opens. The team also questioned whether main steam isolation valves (MSIVs) would be closed from the RSP in sufficient time to minimize the chances of a significant overcooling transient (as described in the CRFASE) in the event the MSIVs were not closed from the MCR in step 3. Subsequent to the on-site inspection, the licensee developed a simulator exercise guide for the purpose of validating the time necessary for an operating crew to perform the steps in procedure 18038-1, through the point of tripping reactor coolant pump (RCP) #1 and #4 from the RSP, given immediate evacuation of the MCR and subsequent spurious operation of a pressurizer spray valve. The licensee stated that the time at which the pressurizer spray valve was set to open during the simulator exercise was based on a timing analysis contained in Request for Engineering Review RER C071912101, Safe Shutdown Time Critical Operator Actions in 18038-1/2 and 17103A-C. When validating the simulator exercise guide, the licensee found that the CRFASE does not reflect integrated plant response for a control room fire as predicted through simulation. Simulated plant response was different from the response described in the CRFASE, in that an automatic SI actuation occurred approximately 6 minutes after plant trip due to decreasing RCS pressure arising from RCS cooldown caused by high auxiliary feedwater (AFW) flow. Additionally, in the simulated plant response, the SI actuation automatically isolated instrument air to containment, which caused the pressurizer spray valve to close before spurious operation of the valve was input into the simulator scenario in accordance with the timing analysis. As a result of questions raised by the team during subsequent in-office inspection of this issue, the licensee initiated Condition Report (CR) 2010112114 to revise the CRFASE to review integrated plant response for a control room fire. In a telephone call with the licensee on October 4, 2010, the team stated that additional information would be required concerning the nature and extent of differences between plant response specified or assumed in the CRFASE and simulated or actual plant response. The team discussed the nature of the additional information required in telephone calls with the licensee on October 4, 2010, January 6, 2011, and January 11, 2011. On January 26, 2011, the licensee provided information concerning integrated plant response obtained from plant-referenced simulator scenarios, relative to spurious component actuations and plant conditions described in the licensees CRFASE. During an initial review of this material, the team identified additional questions regarding the new information. During a final briefing of the inspection on February 9, 2011, the licensee informed the team that the information provided on January 26, 2011, needed to be revised for clarification, and additional information would be provided. This additional information is necessary for the team to determine whether the plant response to a control room fire as described in the CRFASE represents a performance deficiency, and to determine whether procedure 18038-1 is adequate for maintaining safe plant conditions while performing shutdown outside the MCR. A URI was opened pending receipt and review of this additional information which is identified as URI 5000424;425/2010006-01, Control Room Fire Alternate Shutdown Evaluation (X4C2301S035) Does Not Reflect Integrated Plant Response. |
| Site: | Vogtle  |
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| Report | IR 05000424/2010006 Section 4OA5 |
| Date counted | Sep 30, 2010 (2010Q3) |
| Type: | URI: Green |
| cornerstone | Emergency Prep |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | A Dahbur B Metzger F Ehrhardt G Wiseman H Barrett M Thomas P Braxton P Fillion R Neasef Ehrhardtm Bates J Hickey M Cain R Baldwin B Caballero T Chandler T Lighty |
| INPO aspect | |
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Finding - Vogtle - IR 05000424/2010006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Vogtle) @ 2010Q3
Self-Identified List (Vogtle)
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