05000282/FIN-2009003-01
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Finding | |
|---|---|
| Title | Potential Turbine Building Flooding Issue |
| Description | One unresolved item was identified due to the potential that internal flooding following a random pipe break or high energy line break (HELB) event in the turbine building could result in the loss of safety-related mitigating systems equipment. As part of the ongoing review of the potential interaction between high energy lines and the component cooling water system (discussed in NRC IR 05000282/2008005; 05000306/2008005 and 05000282/2009010; 05000306/2009010), a potential internal flooding issue was identified. Specifically, the licensee postulated that a turbine building HELB could result in the subsequent failure of cooling water piping and actuation of the fire protection sprinklers such that an unlimited supply of water could be introduced into the turbine building. This unlimited supply of water could potentially result in an internal flooding event that impacted the availability of redundant safety-related equipment that was required to respond to an event. The inspectors discussed the internal flooding licensing basis with regulatory assurance and engineering personnel. The licensing basis stated that a rupture of a high energy pipe cannot directly or indirectly result in a loss of redundant safety equipment required to mitigate the event. The licensing basis also stated that the potential for flooding safety-related equipment due to a HELB event must be evaluated. Lastly, NRC design requirements state that failures of non-safety related systems must not result in the complete failure of safety-related equipment. The licensee conducted a review and determined that flooding effects due to a HELB or random pipe break had not been analyzed. As a result, it was not clear whether a postulated HELB or random pipe break event could result in internal flooding of the turbine building that would impact the availability of safety-related/mitigating systems equipment. The licensee was conducting several evaluations at the conclusion of the inspection period. As discussed in Section 1R15 of this inspection report, the licensee performed an operability evaluation of this potential flooding concern and determined that compensatory measures were needed to ensure that the water resulting from the potential internal flooding event would not accumulate in the turbine building and result in the unavailability of mitigating systems equipment. However, the potential for safety-related equipment to be impacted by internal flooding following a HELB or a random pipe break was considered unresolved pending a review of the licensees analyses (URI 05000282/2009003-01; 05000306/2009003-01) |
| Site: | Prairie Island  |
|---|---|
| Report | IR 05000282/2009003 Section 1R06 |
| Date counted | Jun 30, 2009 (2009Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.06 |
| Inspectors (proximate) | D Betancourt J Giessner J Neurauter K Stoedter M Phalen P Zurawski R Jonesr Jicklingm Phalen K Stoedter L Haeg P Zurawski D Betancourt F Tran C Tiltonj Giessnerk Stoedter L Kozak P Zurawski |
| INPO aspect | |
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Finding - Prairie Island - IR 05000282/2009003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Prairie Island) @ 2009Q2
Self-Identified List (Prairie Island)
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