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Nuclear Event – Radiological Incident, Uranium Fuel Cycle Facility: Chemical Processing Malfunction, Nuclear Fuel Services, Virginia

2016/06/22

Technological Hazard –  Radiological Incident

Nuclear Event in USA on Monday, 20 June, 2016 at 13:30 [EDT]

North America – USA | State of Virginia, Campbell County, BWXT Nuclear Operations Group, Lynchburg
Eyeball Location: 37°24’47.1″N 79°03’48.4″W
Event:  UNANALYZED CONDITION – CHEMICAL PROCESSING MALFUNCTION

URANIUM FUEL FABRICATION – UNANALYZED CONDITION DUE TO A CHEMICAL PROCESSING MALFUNCTION

“I. EVENT DESCRIPTION: High enriched scrap fuel material is processed in BWXT NOG-Lynchburg’s Uranium Recovery facility to reclaim as much of the uranium as possible. The material is dissolved in acid and transferred to a series of horizontal columns where the acid is neutralized. The solution may be transferred to a set of accountability weigh columns for measurement prior to entering the uranium extraction process. The solution is subsequently transferred to a series of horizontal feed columns. Process water is used to periodically flush the horizontal columns during cleanup for materials accountability.

“On June 9, 2016, a BWXT Nuclear Criticality Safety (NCS) engineer was notified that a bluish tint had been observed in the favorable geometry process water connection to the horizontal columns. By procedure, a blue dye is added to the acid to aid in its identification in the event of a spill. Further evaluation determined that the favorable geometry process water line was directly connected to the horizontal column system and the presence of the blue dye indicated a potential backflow of uranium bearing solution into the water line. The favorable geometry water line is under constant water pressure. The valves controlling the water flow are normally closed. There is also a check valve in the line to prevent backflow. The line is supplied from a favorable geometry header on the mezzanine above. The header supplies water to other processes in Uranium Recovery, including an unfavorable geometry hot water heater.

“The Integrated Safety Analysis (ISA) was reviewed and an accident sequence for this potential backflow could not be identified. On June 9, 2016 at 1330 [EDT] it was the determined the accident sequence was unanalyzed and not properly documented in the ISA. Although IROFS [Items Relied on for Safety] listed for other accident sequences were applicable to the backflow scenario, the performance requirements of 10 CFR 70.61 were not maintained. As documented in the ISA, criticality was not ‘highly unlikely.’

“II. EVALUATION OF THE EVENT: Backflow into the favorable geometry water line can only be achieved by a forced flow to overcome the water pressure in the line. The only source for this pressurized flow is during the transfer from the accountability weigh columns to the horizontal column system. The solution is transferred using an air diaphragm pump. A trained and qualified operator opens the valve to initiate the transfer of solution from the accountability weigh columns to the horizontal columns (an uncredited control). The transfer of solution to the horizontal columns is monitored by a trained and qualified operator (an uncredited control). The water heater is substantially upstream of the supply line to the horizontal columns. The direction of flow of the process water in the supply header is away from unfavorable geometry hot water heater. The process water header is a favorable geometry (a credited IROFS). An operator checks the process water pressure on a daily basis (a credited IROFS). If the above existing IROFS and uncredited controls were considered in an ISA accident sequence, the likelihood of a criticality could be demonstrated to be highly unlikely. However, these uncredited controls are not designated as IROFS. Although the as-found condition presented no safety concern, the scenarios as documented in the ISA did not demonstrate that the performance requirements of 10 CFR 70.61 were maintained. There was no immediate risk of a criticality or threat to the safety of workers or the public as a result of this event.

“Ill. NOTIFICATION REQUIREMENTS: BWXT is making this 24 hour report in accordance with 10 CFR 70, Appendix A, (b)(1), ‘Any event or condition that results in the facility being in a state that was not analyzed, was improperly analyzed, or is different from that analyzed in the Integrated Safety Analysis, and which results in failure to meet the performance requirements of 70.61.’

“IV. STATUS OF CORRECTIVE ACTIONS: A section of the piping from the process water supply header was removed to physically isolate the process water supply from the horizontal columns. Criticality is no longer credible. The hot water heater is the only unfavorable geometry connected to the process water system in the Uranium Recovery facility. The hot water heater was assayed with a gamma survey instrument in several locations along the bottom and up the sides. No counts above background were detected. In addition, multiple liquid samples were taken from the bottom of the water heater and a cartridge filter housing prior to the hot water heater. All samples were well counted and determined to be below the Minimum Detectable Activity (MDA). An investigation of the root causes of this event is ongoing. Corrective actions will be determined as a result of the investigation.”

The licensee has notified the NRC Resident Inspector and Region II personnel.

Source: NRC  Event Number: 51998


Nuclear Operations Group

HEU FABRICATION & SCRAP
Region: 2

B&W Nuclear Operations Group, Inc. (B&W NOG) specializes in the design and manufacture of nuclear products and services for U.S. government applications. B&W NOG has four operating locations throughout the United States. B&W NOG’s Barberton, Ohio, and Mount Vernon, Indiana, locations specialize in the design and manufacture of large, heavy components. B&W NOG facilities in Lynchburg, Virginia, and Euclid, Ohio, design and supply components for United States government programs. Nuclear Fuel Services, Inc. (NFS) is a subsidiary of B&W NOG, located in Erwin, Tennessee. B&W NOG’s headquarters are located in Lynchburg, Virginia

Nuclear Fuel Services, Erwin, TN
Uranium Fuel Fabrication
(active facility; undergoing partial decommissioning)

Previous Events

Nuclear Regulatory Commission, United States (May 12, 2008). “NRC Event Notification Report 42393 for May 12, 2008
Nuclear Regulatory Commission, United States (May 12, 2008). “NRC Event Notification Report 42411 for May 12, 2008”

Related

Mansfield, Duncan (August 20, 2007). “Tenn. Nuclear Fuel Problems Kept Secret”

Background

Subsidiary Nuclear Fuel Services has a major facility in Erwin. It began operation in 1957 as the Davison Chemical Division of the W.R. Grace Company. Production activities at the Erwin facility include preparing enriched uranium to be processed into nuclear reactor fuel, processing uranium hexafluoride into other uranium compounds, and downblending high-enriched uranium to convert it to a low-enriched form for use in commercial nuclear reactors. Historically the facility also worked with thorium compounds.

Public Health Assessment, Nuclear Fuel Services, Inc., Erwin, Unicoi County, Tennessee; EPA FACILITY ID: TND003095635, Agency for Toxic Substances & Disease Registry, May 29, 2007

–From Wikipedia

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