05000237/FIN-2008002-02
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Finding | |
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| Title | LPCI Room Cooler Calculation Deficiencies and Discrepancies |
| Description | The inspectors identified an unresolved item regarding the calculation of the post-LOCA, post-EPU temperatures in the LPCI Room after a DBA-LOCA without LPCI room cooling. The inspectors requested documentation with respect to LPCI room heat-up calculations. The inspectors noted that UFSAR (revision 7, dated June 2007) section 3.11.4, Loss of Ventilation, stated, The LPCI/CS (core spray) room coolers are not required to support the operation of the LPCI/CS systems. All safety-related electrical equipment located in the LPCI/CS rooms that is subject to 10 CFR 50.49 has been environmentally qualified for the elevated temperatures resulting from a LOCA concurrent with a loss of the room coolers (LORC). The inspectors were provided Calculation DRE 00-0075, Evaluation of Dresden binders for EPU environmental conditions, Revision 2, dated December 18, 2005, to support the determination that the room coolers were not needed and therefore, were not safety-related. The calculation concluded that safety-related equipment throughout the reactor building was adequately environmentally qualified for post-EPU post-LOCA conditions without the LPCI room coolers and the associated fans. The inspectors had the following concerns: FnAs discussed in the previous URI, the inspectors were concerned that the associated increase in containment temperature resulting from the increased containment pressure post-EPU may also not have been considered by the licensee in determining the post-EPU maximum reactor building room temperatures post-LOCA. Failure to do so may have underestimated the maximum reactor building (including the LPCI room) temperatures post-LOCA and the impact on the environmental qualification of equipment throughout the reactor building. The licensee initiated AR 763663763663to address the increased containment pressure post-EPU. FnThe inspectors noted that Calculation DRE 00-0075, Evaluation of Dresden Environmentally Qualified (EQ) binders for EPU environmental conditions, Rev 2, dated 12-18-05, stated that safety-related equipment throughout the reactor building was adequately environmentally qualified for post-EPU post-LOCA conditions without the LPCI/CS room coolers. However, Calculation DRE 01-0041, Revision 0, dated February 21, 2007 changed the LPCI rooms post-DBA conditions. Specifically, the post-LOCA LPCI room temperature changed from 168 to 190 degrees Fahrenheit. In addition, this revision changed the reactor building post-DBA conditions and the relevant EQ binders had not been updated. FnCalculation DRE 00-0075 assumed by engineering judgment that for zone 4 & 5 (LPCI corner rooms), the post LOCA area temperatures would be 22 degrees Fahrenheit higher based on the difference in suppression pool temperature profiles between pre-EPU and post-EPU post-LOCA conditions as shown in the Reference 5.1.2. The inspectors noted that Reference 5.1.2 did not indicate where the torus temperature profiles were calculated but rather referred back to DRE 00-0075 as the source. The licensee initiated an Issue Report (IR) indicating that calculation BSA-D-97-02, revision 1, Calculation of Long Term Suppression Pool Temperature Response for Dresden Station, was the source of the pre-EPU post-LOCA torus temperature profile and that DRE 00-0075 was a historical calculation and would not be updated. FnThe inspectors noted that Calculation DRE 01-0041, revision 2 stated in Section 6.4 that the turbine building ventilation system was assumed to run after a design basis LOCA. Likewise, Assumption 3 in RSA-D-92-07, LPCI Room Temperature response due to Loss of Room Cooler at Dresden Station, stated that the turbine building remained at 104 degrees Fahrenheit throughout the post-LOCA period which also indicated the turbine building ventilation system was assumed to be operating during and after the DBA-LOCA. The inspectors questioned whether turbine building ventilation system would be running since it was not safety-related and would not be powered by the emergency diesel generators. FnThe inspectors questioned the assumed heat load from one core spray and one LCPI pump. In Calculation BSA-D-00-01, DRES ECCS room temperature response with Loss of LPCI Room Cooling, Revision 0, dated February 9, 2000, Design Input 1 indicated that the heat load in the LPCI room 10 minutes after a LOCA was assumed to be 302,050 BTU/hr. This is equal to about 84 Btu/sec or 118 horsepower (HP). However, the inspector estimated that the heat load due to the two pumps would be at least 130 HP. In addition, the calculation did not consider the increased heat due to the increased current in the motor due to the reduced voltage in the induction motor due to the increased room temperature (190 vs 168 degree Fahrenheit). In addition, the previous EQ qualification calculation did not consider the increased heat due to the increased current in the motor due to the reduced voltage in the induction motor due to due to the assumption of an increased room temperature due to assumption that LPCI room coolers were not needed (168 vs 104 degree Fahrenheit). The licensee stated that a new calculation would be completed to address the predicted post-EPU and post-DBA-LOCA temperatures in the reactor building. This issue is considered unresolved (URI 05000237/2008002-02 (DRS) URI 05000249/2008002-02) pending review of the final calculation |
| Site: | Dresden  |
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| Report | IR 05000237/2008002 Section 1R07 |
| Date counted | Mar 31, 2008 (2008Q1) |
| Type: | URI: |
| cornerstone | No Cornerstone |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.07 |
| Inspectors (proximate) | A Dunlop D Melendez-Colon W Slawinski C Phillips D Reeser B Palagi J Neurauter M Ring J Draper M Learn D Sand R Edwards R Jickling R Schulz J Tapp R Russellr Jicklingd Melendez-Colon W Slawinski C Phillips M Ring R Schulz J Tapp R Russell |
| INPO aspect | |
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Finding - Dresden - IR 05000237/2008002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Dresden) @ 2008Q1
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