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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 43897 | 12 January 2008 05:00:00 | Response | Bulletin 91-01 Loss of Double Contingency Criticality Safety Controls | During a project review for the recovery of uranium generated by the chemical laboratory in the Fuel Manufacturing/Operations (FMO) complex, it was discovered that ten (10) laboratory generated cans of material had been improperly stored on a conveyor system. The cans of material came from the FMO chemical laboratory that generated them from its process. The material consisted of both dry uranium powder/pellets and wet ammonium diurinate (ADU). Each can contained approximately 16kg of uranium. After the material was placed in the cans, it was given an incorrect material type indicating it contained only dry material. When the material was moved from the chemical lab to a storage area in preparation for processing, it was improperly stored on a conveyor which was only authorized for dry material. The second controlled parameter (mass of uranium in each can) was maintained at all times. Upon discovery of this condition, the ten (10) cans were immediately placed on skids on the conveyor to provide the necessary spacing between each can. While this did not result in an unsafe condition, this event is being reported pursuant to NRC Bulletin 91-01 within 24 hours of discovery. NUMBER AND TYPES OF CONTROLS NECESSARY UNDER NORMAL OPERAIING CONDITIONS: The basis of criticality safety relies on spacing of cans (geometry) and mass as independent criticality safety controls. NUMBER AND TYPES OF CONTROLS WHICH FUNCTIONED PROPERLY UNDER UPSET CONDITIONS: 1 - Mass control remained intact, thus no unsafe condition existed. NUMBER AND TYPES OF CONTROLS NECESSARY TO RESTORE A SAFE SITUATION: 1 - Control on can spacing was lost since skids were not used to separate moderated cans on the conveyor. SAFETY SIGNIFICANCE OF EVENTS: Low Safety Significance - independent control on mass remained intact - additional failure modes required before a criticality accident could occur. The as-found condition was analyzed and demonstrated to be safe. SAFETY EOUIPMENT STATUS: All ten (10) cans were placed on skids on the conveyor system and will await further processing. STATUS OF CORRECTIVE ACTIONS: Corrective and preventative actions will be identified as part of the incident investigation. The cans were improperly stored for several weeks. The licensee will be making notifications to NRC Region 2, the State of North Carolina and the New Hanover County Emergency Management Agency. | ||
| ENS 43359 | 11 May 2007 20:00:00 | Response | Bulletin 91-01 Loss of Double Contingency | During the quarterly shutdown and clean-out of a rotary press used for pressing UO2-Gd203 powder in FMO, it was observed that approximately half of the schedule 80, one-inch diameter Chlorinated Poly Vinyl Chloride (CPVC) tubes placed in the lower shaft casing of the press did not extend the full length of the cavity as required by the nuclear safety analysis. These tubes are credited as a fixed neutron poison inside the casing and must extend the entire length of the cavity in order for the unit to be demonstrated safe geometry for (LEU) enriched UO2 under optimal moderation conditions. The independent control on mass remained intact, thus no unsafe condition existed. The as-found condition was analyzed and demonstrated to be safe. The unit was in a shutdown condition and contained no Uranium at the time of the discovery. While this did not result in an unsafe condition, this event is being reported pursuant to NRC Bulletin 91-01 within 24 hours of discovery. NUMBER AND TYPES OF CONTROLS NECESSARY UNDER NORMAL OPERATING CONDITIONS The basis of criticality safety relies on geometry and mass as independent criticality safety controls. NUMBER AND TYPES OF CONTROLS WHICH FUNCTIONED PROPERLY UNDER UPSET CONDITIONS Mass control remained intact, thus no unsafe condition existed. NUMBER AND TYPES OF CONTROLS NECESSARY TO RESTORE A SAFE SITUATION Control on geometry demonstrated by current analysis. No uranium present at time of discovery. SAFETY SIGNIFICANCE OF EVENTS Low Safety Significance - independent control on mass remained intact - additional failure modes required before a criticality accident could occur. The as-found condition was analyzed and demonstrated to be safe. SAFETY EQUIPMENT STATUS Unit was shutdown for maintenance and will remain Shutdown until CPVC tube error corrected. STATUS OF CORRECTIVE ACTIONS Unit will remain shutdown pending final investigation results and implementation of additional preventive actions. The licensee will be notifying the North Carolina Radiation Protection Agency and the New Hanover County Emergency Management Agency. | ||
| ENS 42292 | 27 January 2006 20:00:00 | Response | 24 Hr Nrc Bulletin 91-01 Due to Criticality Controls Degradation | At approximately 1500 on January 27, 2006, operations leadership notified nuclear safety that five (5) loaded rod trays were discovered stored on a conveyor at the Automated Bundle Assembly Machine (ABAM). A physical barrier intended to limit the number of rod trays to four (4) had failed, and was not in place. This event constitutes a loss of geometry control. The independent control on moderation remained intact, thus no unsafe condition existed. This event is reported pursuant to NRC Bulletin 91-01 within 24 hours. The rod trays were removed from the conveyor, and the geometry control re-established within 4 hours. The ABAM unit has been shutdown pending investigation and implementation of additional corrective actions. The licensee will notify NRC Region 2, and State and Local authorities. | ||
| ENS 40336 | 18 November 2003 20:55:00 | Response | 24 Hr Nrc Bulletin 91-01 Due to Criticality Controls Degradation | At approximately 3:55 p.m. on November 18, 2003, the storage of miscellaneous items was noted in a hood in the chemical area. The items included valves, small diameter pipes, and other objects wrapped in plastic. The criticality safety basis for the hood is based upon not exceeding the UO-2 limit and the geometry of the objects in the hood. Since the geometry control is based upon only a single type of process component in the hood (e.g.: a limited number of 1" valves, or a maximum length of 1" pipe), the as found condition was not consistent with the documented analysis (only one type of component can be processed at a time). An assay confirmed less than 4 killograms uranium was contained in the components. Therefore, the mass limit was not exceeded. The mass control was not violated and no unsafe condition existed. The situation was corrected in less than four hours. This condition is reported within 24 hours pursuant to NRC bulletin 91-01 due to a degradation of criticality controls. Activities in the affected area have been suspended and the equipment tagged out until an investigation to determine the root cause and necessary corrective actions has been completed. |