05000424/FIN-2007007-02
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Finding | |
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| Title | Fire Alarm Computer Replacement Design Change |
| Description | The team identified an unresolved item (URI) related to implementation of DCP C052267801, Version 3.0, for the fire alarm computer in the MCR. This design change introduced a potential time delay of up to one minute and 59 seconds for a fire alarm signal notification to the MCR. The team noted that this potential time delay was not evaluated in the DCP to determine if the delay would adversely affect the ability to achieve and maintain SSD conditions. DCP C052267801 was implemented in December 2006 and replaced the existing Excel Building Supervisor (XBS) fire alarm computer system with an Enterprise Building Integrator (EBI) fire alarm computer system. The main reason stated for replacing the existing XBS system was that operations personnel had to take multiple actions to acknowledge and silence the fire alarm signals. In the pre-modified configuration, a plant fire alarm notification signal was received and annunciated by the 10 fire alarm computer in the MCR which is continuously manned. With the change implemented by the DCP, a work station was added in the Clearance and Tagging (C&T) office and that work station became the primary fire alarm computer station which received and annunciated all plant fire alarm signals. The C&T office was manned by a licensed senior reactor operator (SRO) who was normally assigned as the fire brigade chief. Licensee personnel stated that, unlike the MCR, the C&T office was not manned continuously because the duties and responsibilities of the C&T SRO or other personnel assigned to C&T included activities that could temporarily take them away from the C&T office. Per the DCP, the new EBI fire alarm system was set up to page the assigned personnel if a fire alarm condition was not acknowledged in 60 seconds at the C&T work station. In addition, the server was designed to poll the EBI system every 60 seconds to determine if a condition was not acknowledged at the C&T work station. If the condition was not acknowledged by the second polling of the EBI system, the system would then automatically notify the MCR server of the un-acknowledged condition. This had the potential to cause a delay of up to one minute and 59 seconds from the time a fire alarm signal was actuated until the time the MCR was notified. The team noted that the licensees FPP (Section C.6.a(4) of UFSAR Appendix 9B) stated that fire detection systems should give audible and visible alarm and annunciation in the control room. Appendix 9B further stated that the Vogtle FPP was in conformance with Section C.6.a(4). Implementation of this DCP introduced a potential one minute and 59 second delay to the annunciation of a fire alarm signal in the MCR and resulted in the licensees FPP not being in conformance with Section C.6.a(4) of Appendix 9B. The team noted that DCP C052267801 included a 10 CFR 50.59 screening evaluation which assessed the impact of this design change on the FPP and SSD. The 10 CFR 50.59 screening evaluation concluded that this design change did not adversely affect the ability to achieve and maintain SSD in the event of a fire. The team questioned this conclusion because the potential time delay was not addressed in the 10 CFR 50.59 screening evaluation. Additionally, there was no evaluation of the impact this design change had on the conformance to Section C.6.a(4) in Appendix 9B regarding audible and visible alarms in the MCR. Specifically, the team questioned if implementation of this DCP complied with the licensees commitment to NFPA Code 72D - 1979 Edition, as described in UFSAR Table 9.5.1-9 of the FPP. As a result of questions raised by the team during the inspection, the licensee initiated CR 2007110797 and changed the fire alarm computer system configuration such that any fire alarm signal generated in the plant would alarm and annunciate in the MCR without any time delay. Subsequent to the onsite inspection, the licensee provided additional information to the team to support the conclusion that the design change did not adversely affect the ability to achieve and maintain SSD in the event of a fire. This information is still under review. Pending further inspector review of the additional information provided by the licensee, this issue will be identified as URI 05000424,425/2007007-02, Fire Alarm Computer Replacement Design Change. |
| Site: | Vogtle  |
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| Report | IR 05000424/2007007 Section 1R05 |
| Date counted | Dec 31, 2007 (2007Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.05 |
| Inspectors (proximate) | E Crowe S Shaeffer A Nielsen J Hanna A Vargas-Mendez M Thomas G Wiseman B Caballero L Cain M Coursey T Chandlerj Quinonesm Thomas F Mccreesh P Fillion R Lewis D Payne |
| INPO aspect | |
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Finding - Vogtle - IR 05000424/2007007 | |||||||||||||||||||||
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Finding List (Vogtle) @ 2007Q4
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