Companies quizzed over yellowcake spill

Nuclear regulators in the USA and Canada are investigating an incident at a Canadian uranium refinery when the lid of a drum containing uranium oxide from a plant in the USA blew off, leading to the exposure of three workers to airborne uranium.

Nuclear regulators in the USA and Canada are investigating an incident at a Canadian uranium refinery when the lid of a drum containing uranium oxide from a plant in the USA blew off, leading to the exposure of three workers to airborne uranium.

Blind River (Image: Cameco)

The Canadian Nuclear Safety Commission (CNSC) and the US Nuclear Regulatory Commission (NRC) have now formally issued Cameco and Uranium One with notices to provide it with full information on the steps they are taking to investigate the causes of the incident and make sure that it does not recur.

The incident occurred on 23 June at Cameco's Blind River uranium conversion plant, when workers attempted to open a drum of uranium oxide (yellowcake) from Uranium One's Willow Creek facility in Wyoming. An unexpected build-up of pressure in the 55-gallon (208-litre) drum caused the lid to blow off when workers loosened a ring clamp, ejecting about 26 kilograms of material into the air. Three workers, who were not wearing respirators, were exposed to airborne uranium.

Several other drums from Willow Creek were subsequently found to be showing signs of internal pressure. Cameco has suspended processing of unopened containers of yellowcake from Willow Creek pending the development of a plan to do so safely, and Uranium One has suspended all shipments from Willow Creek until it determines how the drums became pressurized. The NRC notes that similar events occurred at several facilities in 1998. In response, the industry adopted the process of leaving yellowcake drums unsealed for at least three hours after filling to ensure they had cooled adequately.

The NRC has now issued a Confirmatory Action Letter, in response to which Uranium One has agreed to investigate the cause of the event, develop a course of action to ensure the safety of any other unopened drums already shipped from the Willow Creek facility, and develop a corrective action plan to ensure the safety of continued storage, shipping or further processing of the yellowcake.

For its part, the CNSC has formally requested information from Cameco on current practices to protect workers from exposure to airborne uranium at Blind River and an analysis of lessons learned from the medical aid and emergency response procedures followed during the incident. It has also asked the company to confirm that "appropriate interim corrective measures", such as mandatory use of respirators, are now in place and will remain until permanent measures are taken to prevent a recurrence. Finally, Cameco is to work in consultation with the Willow Creek facility to identify the root causes for the unexpected generation of pressure in the drums and development of corrective measures.

Yellowcake is not highy radioactive but is a toxic material, and the NRC noted that any adverse health impacts on the exposed workers would likely be from chemical, rather than radiological, effects.

Researched and written
by World Nuclear News