05000454/FIN-2010007-04
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Finding | |
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| Title | Thermal Models in FSAR Design Basis Analysis May Not be Conservative |
| Description | The inspectors identified an unresolved item associated with peak cladding temperature thermal analyses during short term vacuum drying operations as described in the Holtec FSAR and the associated use of the Holtec FSAR at the Byron Station. SFST ISG-11 discusses that cladding temperature limits should not exceed 1058 oF during short term operations. During an independent review of the licensees failure to provide adequate cooling to the Byron Station ISFSI MPC during vacuum drying operations, a SFST technical reviewer assessed the Holtec FSAR Revision 5 design basis calculation for adequacy. When comparing the results of the reviewers model to the results provided by Holtecs model which were subsequently incorporated into the Holtec FSAR, Revision 5, a potential discrepancy was noted. The Holtec FSAR, Revision 5, states that during steady state vacuum drying of an MPC-32 canister with a heat load of 28.74 kilowatts and a shell temperature postulated at 125oF, fuel cladding temperatures will not exceed 1040oF. The SFST reviewers model calculated fuel cladding temperatures in excess of 1058 oF. The licensee documented this concern in its corrective action program under IR 1116408, NRC Potential URIs from ISFSI Reactive Inspection. The licensee commissioned canister specific two dimensional thermal analyses for each remaining canister in the licensees campaign. An additional safety factor was included in the licensees analyses to ensure that any discrepancies between the NRC model and the Holtec model would not result in peak cladding temperatures in excess of 1058oF. This unresolved issue will remain open pending additional SFST review of the design basis fuel cladding temperatures documented in the Holtec FSAR, Revision 5, and the use of this FSAR at the Byron Station. (URI 05000454/2010007-04; 05000455/2010007-04; 07200068/2010002-04, Thermal Models in FSAR Design Basis Analysis May Not Be Conservative.) |
| Site: | Byron  |
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| Report | IR 05000454/2010007 Section 4OA5 |
| Date counted | Sep 30, 2010 (2010Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | J Mcgee J Robbins M Holmberg M Learn B Metrow C Thompson E Duncan J Cassidyc Lipae Love J Nicholson J Robbins J Solis M Learn |
| INPO aspect | |
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Finding - Byron - IR 05000454/2010007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Byron) @ 2010Q3
Self-Identified List (Byron)
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