05000445/FIN-2008006-01
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Finding | |
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Title | Inadequate POST-FIRE Safe Shutdown Procedure |
Description | The team identified an unresolved item associated with Technical Specification 5.4.1.d concerning the failure to maintain adequate written procedures covering fire protection program implementation. Specifically, Procedure ABN-803A, Response to a Fire in the Control Room or Cable Spreading Room, Revision 8, which is used to perform an alternate shutdown, may be inadequate to assure that the charging pump relied on for achieving post-fire safe shutdown would not be damaged because of a loss of suction. During an alternate shutdown, the charging pump is necessary to support the reactivity control and reactor coolant makeup functions by providing borated water from the refueling water storage tank. Description. During normal plant operations, the chemical and volume control system normally operates to allow a continuous feed (charging and seal injection) and bleed (letdown and seal leak-off) for the reactor coolant system. Normally one centrifugal charging pump is in operation. In the event of fire in the main control room or cable spreading room, inventory makeup is intended to be accomplished using the Train A centrifugal charging pump with the refueling water storage tank as a source of borated water makeup. Procedure ABN 803A included procedural steps to establish a suction path from the refueling water storage tank to the charging pumps. However, the inspection team determined that if the charging pump credited for safe shutdown was running at the time of the fire, a spurious closure of one of the two series-connected volume control tank outlet valves (1-LCV-112B or 1-LCV-112C) prior to successfully opening one of the refueling water storage tank outlet valves would result in a loss of suction and damage to the credited charging pump. The refueling water storage tank to Charging Pump Suction Valves 1-LCV-0112D and 1-LCV-0112E are motor-operated isolation valves and are connected in parallel to the suction of the charging pumps. Each valve is controlled from a switch on Panel CB-06 in the main control room. Prior to evacuating the main control room and establishing control at the remote shutdown panel, operators are directed in Section 2.3, Step 4(g), of Procedure ABN-803A, to open refueling water storage tank Suction Valves 1-LCV-112D and 1-LCV-112E. However, these actions are not credited because they were not approved by the NRC, since the time available to perform actions prior to evacuating the control room may be very limited. From a review of related wiring diagrams, the inspection team determined that the occurrence of a single short to ground for each valve could preclude the success of this step. In addition, although the procedure includes a back-up action outside the main control room to ensure refueling water storage tank Suction Valve 1-LCV-112E is open, this step was not performed for at least 20 minutes, based on the teams observations during a walk-through of the procedure. Analysis. Failure to ensure that Procedure ABN-803 contained sufficient instructions to ensure that the Train A centrifugal charging pump would be available in a control room evacuation was potentially a performance deficiency. The team determined that this finding was more than minor because it is associated with the Protection Against External Factors attribute of the Mitigating Systems cornerstone and could affect the availability, reliability, and capability of systems that respond to fire events to prevent undesirable consequences. Volume control tank outlet Valves 1-LCV-0112B and 1-LCV-0112C are motor-operated valves connected in series in the line from the volume control tank to the charging pumps. In the main control room, each valve is controlled from a switch located on the same panel (CB-06) as the refueling water storage tank suction valve switches. Should either of the volume control tank outlet valves spuriously close during the time prior to successfully opening one of the refueling water storage tank suction valves, the operating charging pump could be damaged. If the credited charging pump is in operation and is damaged, operators may not be able to achieve the reactivity control and reactor coolant makeup functions required for post-fire safe shutdown using the protected train. The team initiated an evaluation of this finding using the Significance Determination Process in Manual Chapter 0609, Appendix F, Fire Protection Significance Determination Process, because it affected fire protection defense-in-depth strategies involving post fire safe shutdown systems. However, additional analysis, to be performed by a senior reactor analyst, is needed to determine the safety significance of this issue. The licensee has entered this issue into their corrective action program as Smart Form SMF-2008-000488-00. Enforcement. Technical Specification 5.4.1.d states that written procedures shall be established, implemented, and maintained covering fire protection program implementation. Procedure ABN-803A, Response to a Fire in the Control Room or Cable Spreading Room, Revision 8, implements this requirement for fires requiring the main control room to be evacuated. The team was concerned that procedural guidance may have been inadequate to prevent damage to the protected centrifugal charging pump if it was in operation at the time of a fire requiring an evacuation of the main control room. Pending completion of additional analyses to determine if a credible fire scenario exists for this concern and to determine the safety significance of this finding, this issue is being treated as an unresolved item: URI 05000445; 446/2008006-01, Inadequate Post- Fire Safe Shutdown Procedure |
Site: | Comanche Peak |
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Report | IR 05000445/2008006 Section 1R05 |
Date counted | Jun 30, 2008 (2008Q2) |
Type: | URI: |
cornerstone | No Cornerstone |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.05 |
Inspectors (proximate) | K Sullivan R Mullikin P Qualls B Correll L Smithp Elkmannw Walker B Tindell R Hagar J Mateychick J Kramer |
INPO aspect | |
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Finding - Comanche Peak - IR 05000445/2008006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Comanche Peak) @ 2008Q2
Self-Identified List (Comanche Peak)
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