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| Entered date | Event description | |
|---|---|---|
| ENS 40151 | 12 September 2003 07:36:00 | NRC BULLETIN 91-01 24 HOUR NOTIFICATION At 0845 on 9/11/03, it was discovered that non-fissile negative air machines (NAMs) were not verified by two individuals to contain approved and properly installed filters, as specified in NCSA GEN-09, "Operation and Maintenance of Negative Air Machines". Procedure CP4-GP-BG2108, "Negative Air Machine and in-place HEPA System Internal Inspection and Filter Replacement", did not adequately flowdown requirements specified in NCSA GEN-09 was revised to make non-fissile portable negative air machines (NAMs) readily available for fissile use in emergency situations. Contrary to requirements specific in NCSA GEN-09, procedure CP4-GP-BG2108 did not include requirements for two individuals to perform independent verification that approved filters are selected and properly installed. This control prevents mass loadings of fissile material that are outside the scope of that analyzed in NCSE KY/S-249. SAFETY SIGNIFICANCE OF EVENTS: Double contingency was not maintained for non-fissile NAMs because the second verification was not performed. However, the non-fissile NAMs were not used for fissile material releases. The non-fissile NAMs have been subsequently verified to contain approved and properly installed filters. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR: In order for a criticality to be possible, a non-fissile NAM would have to be used in a fissile material release and greater than a safe mass of uranium would have to accumulate within the NAM in a configuration favorable for criticality. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): Double contingency for the accumulation of an unsafe fissile mass is maintained by implementing two controls on mass. ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS): This system has a process limit of (xx) wt% U235. NUCLEAR CRITICLITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: The first leg of double contingency is based on one individual verifying and documenting that approved filters are selected and properly installed. This control prevents loadings of fissile material that are outside the scope of that analyzed in NCSE KY/S-249. This verification was performed, therefore, this control was maintained. The second leg of double contingency is based on a different individual verifying and documenting that approved filters are selected and properly installed. This control prevents loadings of fissile material that are outside the scope of the analyzed in NCSE KY/S-249. Because this verification was not performed, this control was lost. No events have occurred to introduce fissile material into any non-fissile NAMs. Therefore, though the control was violated, the parameter was maintained. Since double contingency is based on two controls on one parameter, and one control was violated, double contingency was not maintained. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: 1. Non-fissile Nams verified to contain the correct filters and installed in the correct orientation. Completed 9/11/2003. 2. Procedure CP4-GP-BG2108 placed on hold pending revision to include independent verification requirements specific in NCSA GEN-09. Completed 9/11/2003. The NRC Senior Resident Inspector has been notified of this event. |