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| Entered date | Event description | |
|---|---|---|
| ENS 40873 | 14 July 2004 23:45:00 | At 1300 (CDT) on 7/14/04, the Plant Shift Superintendent (PSS) was notified that a cylinder, which was to be washed, was determined to contain heel material. The cylinder had been filled a single time with natural material at Honeywell (2/2001) since its last wash in 8/1999. An examination of the associated Nuclear Material Control and Accountability (NCM&A) data and cylinder card indicated that the only other filling was in 9/1982 with depleted material at C-315. The cylinder was fed to the cascade in 9/2003 at C-337-A. A total of 4 gas over solid samples were taken of the cylinder and all indicated that the cylinder contains material. Nuclear Criticality Safety Evaluation 085 and Nuclear Criticality Safety Analysis 400-012 establish double contingency to ensure that a fissile cylinder is not washed in the non-fissile cylinder wash facility. The NRC Resident Inspector has been notified of this event. PGDP Assessment and Tracking Report No. ATR 04-2756; PGDP Event Report No. PAD 2004-019; Responsible Division: Operations. SAFETY SIGNIFICANCE OF EVENTS: NMC&A showed this cylinder contained a heel of around 8 lbs. Gas over solid sampling determined this non-fissile cylinder contained fissile material and could not be washed. Although the cylinder was not washed, an unlikely failure occurred that allowed fissile material to enter a cylinder controlled as non-fissile. CONTROLLED PARAMETERS: The process condition relied upon for double contingency for this scenario is enrichment. NUCLEAR CRITICALITY SAFETY CONTROL OR CONTROL SYSTEMS AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency relies on a gas over solid sample of the cylinder to demonstrate that the cylinder contains non-fissile material prior to washing. The second leg of double contingency relies on an argument that back- or cross-feeding at C-337A is unlikely to result in a significant amount of fissile material to be transferred to the cylinder. Since fissile material was found in the cylinder after it was fed at C-337A, this unlikely argument appears to have failed. However, the cylinder was not washed, maintaining this parameter. Although the parameter was maintained, double contingency is based on two controls on one parameter and one of the controls (unlikely argument) failed. Therefore double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: 1. Correct NMC&A database for this cylinder to show the correct assay in the cylinder and that the cylinder is fissile. |
| ENS 40860 | 9 July 2004 17:45:00 | At 1550, on 07-08-04 the Plant Shift Superintendent was notified that three centrifugal compressor impellers were received as part of a shipment from Portsmouth GDP. The existence of the impellers was not recognized as being part of this shipment and, as a result, applicable NCS (Nuclear Criticality Safety) controls were not implemented. NCSA GEN-20 requires receipt of documented NDA (Non Destructive Analysis) inspections of equipment prior to receipt (unloading) in the shipping/receiving area and completion of a second NDA prior to removing the equipment from the shipping/receiving area to a location within the plant. The purpose of this control is to ensure that equipment containing greater than a safe mass will not be received from offsite. The three centrifugal compressor impellers have subsequently been characterized as a group, by NDA, to be less than the safe mass assuming 100 wt.% 235U. SAFETY SIGNIFICANCE OF EVENTS: NDA measurements have been completed and the results indicate less than a safe mass of uranium. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR): In order for a criticality to be possible, greater than a critical mass of uranium would have to be present in the equipment in a configuration favorable for a criticality. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC): Double contingency is maintained by implementing two controls on mass. ESTIMATED AMOUNT ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): The group of equipment contains less than the safe mass assuming 100 wt.% 235U. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEMS) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency relies on the review of characterization results prior to receipt (unloading) at PGDP. Characterization results were not reviewed prior to receipt. The three centrifugal compressor impellers have subsequently been characterized as a group, by NDA, to be less than the safe mass assuming 100 wt.% 235U. Although, the NCS controls were violated, the parameter was maintained. The second leg of double contingency relies on an independent NDA measurement prior to release from the shipping/receiving area. NDA characterization did not occur prior to release from the shipping/receiving area. The three centrifugal compressor impellers have subsequently been characterized as a group, by NDA, to be less than the safe mass assuming 100 wt% 235U. Although, the NCS controls were violated, the parameter was maintained. Although the parameter was maintained, double contingency is based on two controls on one parameter. Therefore, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED : 1. Post equipment according to CP2-MA-MT1034. Completed 07/09/04 The NRC Resident lnspector has been notified of this event. PGDP Problem Report No. ATRC-04-2682, PGDP Event Report No. PAD-2004-18; Event Worksheet #40860 Responsible Division: Maintenance |