ENS 41316

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v t e ENS Event
21:00 Jan 7, 2005
Title	* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Event Description	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. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * FAULTY PROGRAMMABLE LOGIC CONTROLLER (PLC) FOR OXIDE DISSOLUTION OPERATION The Nuclear Fuel Services, License # [DELETED], reported that a faulty PLC evoked an event that degraded the safety conditions of the plant. Their comments are described below in a statement/answer format. The statement is cited first and the answer follows. Actual or potential health and safety consequences to the workers, the public, and the environment, including relevant chemical and radiation data for actual personnel exposures to radiation or radioactive materials or hazardous chemicals produced from licensed materials (e.g., level of radiation exposure, and duration of exposure): There were no actual health and safety consequences to workers, the public, or the environment. There were also no personnel exposures to radiation, radioactive materials, or hazardous chemicals produced from licensed materials. The potential Nuclear Criticality Safety (NCS) consequences for workers were low given the very low likelihood of adding a sufficient mass of a more reactive/incorrect material type to the system. The sequence of occurrences leading to the event, including degradation or failure of structures, systems, equipment, components, and activities of personnel relied on to prevent potential accidents or mitigate their consequences: On January 7, 2005, it was determined that the Programmable Logic controller (PLC) for the oxide dissolution operation had a negative holdup value. Upon investigation, a negative holdup value in the PLC results in the PLC using an artificially high mass limit. This could allow the system mass limit to be exceeded. The PLC is an item relied upon for safety and is credited as one of the mass controls in the safety basis. Discuss whether remaining structures, systems, equipment components, and activities relied on to prevent potential accidents or mitigate their consequences are available and reliable to perform their function: The remaining activities relied on to prevent potential accidents are available and reliable to perform their function. Operations personnel verified that the correct material type and quantity was added to the system. Actions taken in response to the event: The operation was shutdown until compensatory measures can be put in place. Safety Significance of Event: The safety significance was low for the event given the very low likelihood of adding a sufficient quantity of a more reactive/incorrect material type to the system. A more reactive/incorrect material type was not added to the system. It should also be noted that this other/incorrect material type is not present in the facility. Brief scenario of how a criticality could occur: In order for a criticality to occur, multiple occurrences of an excessive amount of a more reactive/incorrect material type would have to be added to the system. What are the controls or control systems and the failures or deficiencies? The controls were limitations on the mass and material types input into the system. The PLC is used to control the mass input into the system. The PLC for the oxide dissolution operation had a negative holdup value. Upon investigation, a negative holdup value in the PLC results in the PLC using an artificially high mass limit. This could allow the system mass limit to be exceeded. The PLC is an item relied upon for safety and is credited as one of the mass controls in the safety basis What are the corrective actions taken and when was each implemented? On January 7, 2004, the operation was shut down. Compensatory measures are in the process of being developed. The licensee notified the NRC Resident Inspector. * * UPDATE ON 05/11/08 BY J KOZAL * * * 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 41316 +/-
Where
Nuclear Fuel Services Inc. Erwin, Tennessee (NRC Region 2)
License number:	SNM-124
Reporting

Part 70 App A (B)(2)
Time - Person (Reporting Time:+-3.5 h-0.146 days <br />-0.0208 weeks <br />-0.00479 months <br />)
Opened:	Randy Shackelford 17:30 Jan 7, 2005
NRC Officer:	John Knoke
Last Updated:	May 11, 2008
41316 - NRC Website
v • d • e

v t e Emergency Notification System
Nuclear Fuel Services Inc. with Part 70 App A (B)(2)
WEEKMONTHYEAR2022-10-05T19:00:00 [Table view]
[ENS list for Nuclear Fuel Services Inc.]

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