ERWIN — A recent event report submitted to the Nuclear Regulatory Commission from Nuclear Fuel Services details the events leading to a recent nitric acid leak at the Erwin facility and the incident’s impact.
At around noon Jan. 9, a nitric acid leak occurred in an outdoor chemical storage area at NFS. According to a release issued at that time by NFS, the nitric acid was contained by a dike designed for such a purpose.
Following the incident, facility operations went into a “safe shutdown,” in which operations in certain areas were temporarily halted and NFS procedure was followed to ensure these areas were in stable condition. As a precaution, NFS employees working in areas near the leak were redirected to another NFS facility, and two employee were seen by NFS medical staff due to possible exposure to nitric acid vapor and were released. No injuries were reported as a result of the incident.
According to the Feb. 8 event report, the nitric acid dike located outside in the facility’s Bulk Chemical Storage Area was being prepared for refurbishment and the facility’s nitric acid tank had been drained to prepare for this work.
A nitric acid tanker was procured to provide nitric acid to NFS, and new piping, valves and a flow totalizer were installed in the nitric acid dike to support temporary service from the nitric acid tanker to NFS facilities, the report states. This temporary service installation was completed Jan. 4.
Upon first use of the equipment Jan. 9, the transfer was monitored for leaks during the first 15 minutes of the transfer and no leaks were observed, according to the report.
“However, within the first hour of service, nitric acid was observed leaking into the dike,” the report said. “When the leak was observed, NFS dispatched responders to the scene and activated the Emergency Response Organization.”
Subsequent investigation into the incident revealed that the installed in-line flow totalizer was not compatible with nitric acid and failed after approximately an hour of service, which led to the leakage of approximately 750 gallons of nitric acid into the containment dike, according to the report.
“Equipment in the (Highly Enriched Uranium) and Production Facilities did not fail or malfunction,” the event report said.
According to the report, there were no radiological hazards associated with the event.
“The chemical hazards involved with the event include those associated with liquid nitric acid, nitric acid vapor and other nitrogen compound vapors,” the report said. “There were no NRC- licensed materials and no hazardous chemicals produced from licensed material associated with the event. No radiological or chemical materials were released from the NFS site. Meteorological conditions were such that the vapors remained on-site, and were dissipated by light rain.”
The report further states that there were “no actual safety consequences to the workers, the public, or the environment” as a result of the incident.
Air sampling for nitric acid vapors in the area of the event, and monitoring results indicated only the presence of fumes and no hazardous concentrations of nitric acid vapors, according to the report. It further states that as a precautionary measure, storm water discharge points were closed and sampled. The results of the samples did not indicate an pH level decrease, the report states.
“The incident had no off-site impact,” the report said. “The event did not meet the criteria of an Alert or Area Classification in accordance with the NFS Emergency Plan.”
Meg Lockhart, spokeswoman for the Tennessee Department of Environment and Conservation, said in an email sent Friday that although no radioactive materials were associated with the event, NFS is required to notify the NRC.
Lockhart’s email said TDEC had no direct regulatory authority over “the management, storage and transportation” of products, and enforcement would not come from TDEC.
“However, based on our regulatory authority in this matter, the Division of Solid Waste Management did investigate the spill from a disposal standpoint. The release was due to the failure of a flow regulator into the secondary containment area. Recovery and cleanup started immediately,” Lockhart’s email said.
Lockhart also wrote that the nitric acid and three inches of rainwater were pumped to four 300-gallon totes. Lime was spread in the containment and flushed with water, which was also collected, she said.
“The totes were labeled as containing hazardous waste. The waste will be manifested off-site or metered into their wastewater treatment system,” Lockhart wrote.
Joey Ledford, public affairs officers for the NRC, said NRC resident inspectors at NFS reviewed the incident, but because no radiological materials were associated with it, the event does not fall under the NRC’s regulatory purview.
NFS spokeswoman Lauri Turpin said the incident was a good example of NFS personnel’s response in the event of such as incident.
“I think the most important thing is no one was injured, there was no impact on the environment, the leak was entirely contained in the dike and all NFS personnel responded quickly and appropriately,” she said.