ENS 45236: Difference between revisions
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| event date = 02/16/2009 PDT | | event date = 02/16/2009 PDT | ||
| last update date = 07/29/2009 | | last update date = 07/29/2009 | ||
| title = Part 21 Report - Thermo-Hydraulic Limits Based | | title = Part 21 Report - Thermo-Hydraulic Limits Based on Incorrect Fuel Liftoff Assumptions | ||
| event text = Measurements obtained from LaSalle spent fuel indicates that the liftoff [corrosion film and coolant system crud deposit thickness] on LaSalle fuel may be greater than assumed in thermal-hydraulic calculations for MCPR (Minimum Critical Power Ratio) and LHGR (Linear Heat Generation Rate). Thickness measurements of liftoff on ATRIUM-10 fuel at LaSalle are as high as 93 micrometers whereas the maximum value observed for other facilities is less than 60 micrometers. The greater than expected liftoff present on LaSalle fuel has been attributed to the operation with zinc levels that exceeded EPRI guidelines for reactor water chemistry. AREVA thermal-hydraulic analyses for LaSalle did not account for the higher liftoff. | | event text = Measurements obtained from LaSalle spent fuel indicates that the liftoff [corrosion film and coolant system crud deposit thickness] on LaSalle fuel may be greater than assumed in thermal-hydraulic calculations for MCPR (Minimum Critical Power Ratio) and LHGR (Linear Heat Generation Rate). Thickness measurements of liftoff on ATRIUM-10 fuel at LaSalle are as high as 93 micrometers whereas the maximum value observed for other facilities is less than 60 micrometers. The greater than expected liftoff present on LaSalle fuel has been attributed to the operation with zinc levels that exceeded EPRI guidelines for reactor water chemistry. AREVA thermal-hydraulic analyses for LaSalle did not account for the higher liftoff. | ||
Following discovery of the deviation, AREVA supplied an operability assessment to Exelon that identified limitations on the operating limit MCPR and rod average exposure. Revised operating limits are being provided to Exelon based on liftoff values that are lower than used in the original operability assessments. These limits are scheduled to be provided by July 31, 2009. Actions have been identified where AREVA will obtain information from the licensees on the anticipated water chemistry environment to be implemented for the next operating cycle, in advance of AREVA core design efforts supporting that cycle. This will assure that AREVA can adequately project the impact of this chemistry environment on liftoff, and to account for it during the design activities. | Following discovery of the deviation, AREVA supplied an operability assessment to Exelon that identified limitations on the operating limit MCPR and rod average exposure. Revised operating limits are being provided to Exelon based on liftoff values that are lower than used in the original operability assessments. These limits are scheduled to be provided by July 31, 2009. Actions have been identified where AREVA will obtain information from the licensees on the anticipated water chemistry environment to be implemented for the next operating cycle, in advance of AREVA core design efforts supporting that cycle. This will assure that AREVA can adequately project the impact of this chemistry environment on liftoff, and to account for it during the design activities. | ||
Latest revision as of 22:11, 1 March 2018
| Where | |
|---|---|
| Areva Np Inc Richland, Washington (NRC Region 4) | |
| Organization: | Areva Np Inc |
| Reporting | |
| 10 CFR 21.21 | |
| Time - Person (Reporting Time:+3923.1 h163.463 days <br />23.352 weeks <br />5.374 months <br />) | |
| Opened: | Alan Meginnis 17:06 Jul 29, 2009 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Jul 29, 2009 |
| 45236 - NRC Website | |