Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 41197 | 15 November 2004 19:00:00 | THIS IS NOT A NEW REPORT. This event report was originally withheld from public release under the NRC's policy for protecting sensitive unclassified information. The NRC has reevaluated this policy and is now making this event report available to the public with suitable redactions. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * WET OFFGAS (WOG) LINE CALCULATION WAS NOT PERFORMED. Raffinate column WOG Vent (DELETED) is not sized appropriately to handle flow in the event of overflowing of (DELETED) combined with a loss of DI water pressure and a failure of DI water valve when transferring SNM material from sump columns ((DELETED) or (DELETED) using (DELETED)). This would prevent transferring SNM material into an unfavorable geometry tank. The WOG line is specified as IROFS (DELETED) and is listed as (DELETED) in the Recovery Deionized Water Nuclear Criticality Safety Evaluation Risk Indexing Supplement. Setpoint analysis was believed to be completed on all Recovery WOG lines. It was determined that this WOG line calculation was not performed at November 15, 2004. As such, IROFS (DELETED) was not reliable and available on (DELETED) and (DELETED) transfers to (DELETED) which occurred on October 28, November 2 and November 11, 2004. (DELETED) has been taken out of service. A follow-up memo to Operations will be provided to prevent the use of the pump and (DELETED). Defense in-depth measures that were available are as follows: 1. Pumping operations did not overflow (DELETED). 2. Deionized water line to (DELETED) was pressurized (DELETED). 3. Administrative Control listed in the NCSE specified that the operator shut valve (DELETED) upon a loss of DI water pressure. This control is flowed down into the operating procedure. 4. Valve (DELETED) listed as a configuration controlled item was available to be closed upon a loss of pressure in the DI water line. 5. The WOG line was positioned lower than the DI water input line and listed as a configuration controlled item as such. There are no actual potential health and safety consequences to workers, the public or the environment due to defense in depth and configuration control items in place. In additional, overflow (DELETED) did not occur (DELETED). What is the safety significance of the event? Not in compliance with 10CFR70.61. However criticality was not a concern due to defense-in-depth controls and configuration control equipment installed at the time. Brief scenario(s) of how criticality could occur: Transfer of SNM during a backflow scenario into DI water line and subsequent unfavorable geometry tankxx-001. What is the control(s) or control system(s) and the failure(s) or deficiencies? IROFS(DELETED) WOG line on (DELETED). What are the corrective actions taken and when was each implemented? (DELETED) has been taken out of service on 11/15/04. The NRC Resident Inspector was notified of this event by the licensee.
THIS IS NOT A NEW REPORT. This event report was originally withheld from public release under the NRC's policy for protecting sensitive unclassified information. The NRC has reevaluated this policy and is now making this event report available to the public with suitable redactions. |
| ENS 41149 | 27 October 2004 10:37:00 | THIS IS NOT A NEW REPORT. This event report was originally withheld from public release under the NRC's policy for protecting sensitive unclassified information. The NRC has reevaluated this policy and is now making this event report available to the public with suitable redactions. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * FAILURE OF SAFETY SYSTEM CAUSING UNFAVORABLE GEOMETRY The licensee reported a transfer of low concentration HEU solution from favorable to unfavorable geometry was initiated upon sampling data that was not representative of the solution. The solution has been determined to be above the transfer concentration limit. Verification of HEU concentration is an administrative "item relied on for safety" (IROFS) for the accident sequence. The remaining IROFS for the accident sequence is an inline radiation detector that automatically closes redundant block valves. This system performed as designed. The system was placed in a safe shutdown condition and the solution remains in a favorable geometry. Mass is controlled in the unfavorable geometry tank by limiting the volume and concentration of transfers into it. The failed control is administrative sampling and verifying the concentration is below the limit. The licensee states the solution will be reprocessed to lower concentration prior to discharge. The licensee has informed the NRC Resident Inspector.
THIS IS NOT A NEW REPORT. This event report was originally withheld from public release under the NRC's policy for protecting sensitive unclassified information. The NRC has reevaluated this policy and is now making this event report available to the public with suitable redactions. |
| ENS 41097 | 6 October 2004 10:42:00 | THIS IS NOT A NEW REPORT. This event report was originally withheld from public release under the NRC's policy for protecting sensitive unclassified information. The NRC has reevaluated this policy and is now making this event report available to the public with suitable redactions. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * SAFETY RELATED NEEDLE VALVES IN INCORRECT POSITION POTENTIAL HEALTH AND SAFETY CONSEQUENCES: Potential vulnerability to workers and public of a high consequence event involving failure of safety controls that were designed to prevent a hydrogen explosion in the BLEU Preparation Facility U-Aluminum Dissolution gloveboxes/dissolvers. SEQUENCE LEADING TO EVENT: Rotometers FIC-1F14A, 1C01, and 1D01 needle valves were closed on the U-Aluminum dissolver system. FIC-1C01 and FIC-1D01 or FIC-1F14A needed to be open to allow a nitrogen purge in the dissolver to protect against a Hydrogen explosion in the enclosure or at the dissolver/enclosure interface. PREVENTION OR MITIGATION: Other controls were in place to partially mitigate a potential hydrogen explosion that was analyzed in support of the Integrated Safety Analysis for the operations at Bldg. (DELETED). A nitrogen trickle system provides sufficient flow of nitrogen to the dissolvers during dissolution to provide 5 volumetric changeouts in 30 minutes. The trickle nitrogen flow was available for the operator to access the dissolvers one hour after dissolution. Enclosures 1C01/1C11 and 1D01/1D11 did have an air sweep to the enclosure ventilation system. Should hydrogen have leaked or migrated to the enclosure upon opening of the dissolver lid, the purge would have maintained the hydrogen concentration below the lower explosive limit. ADDITIONAL ACTIONS: Upon discovery of valve closure, valves were immediately opened and Safety Department notified. EVENT STATUS: Terminated. The licensee notified the NRC Resident Inspector.
THIS IS NOT A NEW REPORT. This event report was originally withheld from public release under the NRC's policy for protecting sensitive unclassified information. The NRC has reevaluated this policy and is now making this event report available to the public with suitable redactions. |