05000305/FIN-2008003-02
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Finding | |
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| Title | Lack of Calculation to Show That the Auxiliary Building Floor Fan Coil Units CAN Perform Their SAFETY-RELATED Function at the Maximum Design Service Water Temperature |
| Description | The inspectors identified an unresolved item (URI) due to lack of a calculation to demonstrate that the auxiliary building fan floor FCUs can perform their safety-related function at the maximum design service water temperature of 80XF (degrees Fahrenheit) . Specifically, the inspectors questioned the adequacy of the licensees corrective actions in resolving this issue. This issue is unresolved pending NRC review of the results of the new calculation. The auxiliary building floor contains two FCUs whose safety-related function is to maintain the temperature in the area at 120XF or less. This is the environment qualification temperature for the equipment that is located in this area, categorized as mild environment. These FCUs are cooled by the service water system which has a maximum design inlet temperature of 80XF. Last summer, the licensee commenced a reconstitution of its heating, ventilation and air conditioning calculations. During this effort, the licensee became aware that the calculation used to determine the amount of heat generated in the auxiliary building floor FCU area had several non-conservative assumptions. As an example of these non-conservatisms, the licensee assumed: FnA loss of off-site power (LOOP) during the postulated loss of coolant accident (LOCA) is the most limiting design basis accident for this case. This is a nonconservative assumption as there is additional heat loads generated from nonsafety-related components involved in a non-LOOP LOCA, such as lighting. FnThat the refueling water storage tank (RWST) was full of water; therefore, some heat was exchanged with the tank during this scenario. This might not be the case since during a LOCA, the RWST would empty as the transient develops. FnThat there is some leakage of hot air from the Zone SV [special ventilation] charcoal filters to the environment. The exhaust for this hot air is on the fan floor. The licensee assumed that some of this hot air leaked to the environment but no design basis was found for the number. The licensee performed a test and determined that the actual leakage was much less than what the calculation assumed; therefore, this is a non-conservative assumption. Additionally, the calculation did not take into account the heat generated by the FCU pump motors. All these non-conservatisms questioned the operability of the auxiliary building fan FCUs as well as the other equipment in the area, which is supported by the system including the shield building and special ventilation zone air handling systems. The licensee performed an operability evaluation and included all the non-conservatisms from the previous calculation. The result of this operability evaluation was the FCUs were operable up to a service water inlet temperature of 71XF, but nonconforming with their design requirement of 80XF. Through this inspection cycle, the FCUs and supported systems have remained operable. The licensee is currently performing a more thorough calculation. The inspectors have the following concerns: FnThe service water temperatures may rise to 71XF in approximately the June and July time frame (last year, service water inlet temperature of 77XF was recorded during July). If the licensee fails to prove operability of the FCUs by then, the plant would have to shutdown per TS 3.0.3. FnThe inspectors believe that there is not enough conservatism in the design assumptions to prove operability above 71XF. Currently, the licensee is taking the corrective actions necessary to resolve this issue. This issue is unresolved pending NRC review of the results of the calculation (URI 05000305/2008003-02) |
| Site: | Kewaunee  |
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| Report | IR 05000305/2008003 Section 1R07 |
| Date counted | Jun 30, 2008 (2008Q2) |
| Type: | URI: |
| cornerstone | No Cornerstone |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.07 |
| Inspectors (proximate) | R Jickling R Langstaff R Winter C Acosta J Cassidy T Bilik M Kunowski P Higgins S Burton K Barclayc Zoian Valos S Sheldon C Brown H Campbell F Baxter M Jones A Stone |
| INPO aspect | |
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Finding - Kewaunee - IR 05000305/2008003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Kewaunee) @ 2008Q2
Self-Identified List (Kewaunee)
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