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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 45236 | 16 February 2009 07:00:00 | 10 CFR 21.21 | Part 21 Report - Thermo-Hydraulic Limits Based on Incorrect Fuel Liftoff Assumptions | 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. AREVA states that this defect affects only LaSalle Units 1 and 2. Data from other plants currently operating with fuel licensed using AREVA methods indicate that the liftoff is low and within historical levels. | ||
| ENS 44026 | 3 March 2008 16:26:00 | 10 CFR 20.1906(d)(2) | External Contact Radiation Reading Exceeded Allowable Limits | On March 3, 2008 at approximately 1126 EST, the Radiation Protection organization at AREVA NP Inc. Lynchburg, determined that a shipment of fuel services equipment (Box 0454) exceeded the 200 mrem/hour dose rate specified in 10 CFR 71.47 (b)(1). The equipment was being returned after use during a refueling outage. Radiation Protection surveyed the shipping container and obtained a reading of approximately 340 mrem/hour. In accordance with 10 CFR 20.1906(d)(2) the final delivery carrier has also been notified. This immediate notification is being made in accordance with the requirements of 10 CFR 20.1906(d)(2) and 10CFR 71.47(b)(1). The fuel cleaning equipment had been recently used during a refueling outage at Watts Bar.
Mr. Wertz reported that area around the hot spot on the container was smeared, and no evidence of loose surface contamination exists. Notified R1DO(Caruso), FSME(Morell), and NMSS(Giitter) |