WIPP radiation under investigation

27 February 2014

While investigations continue into the source of airborne radiation detected within the Waste Isolation Pilot Plant (WIPP) in New Mexico, initial sample results suggest that 13 workers received external doses.

WIPP tunnel 460 (NWP)
Workers in one of WIPP's tunnels, carved out of a salt formation (Image: NWP)

The WIPP plant is owned by the US Department of Energy (DoE) and operated by Nuclear Waste Partnership LLC (NWP). The facility disposes of transuranic waste packages from the US military in an underground salt formation.

An underground monitor detected airborne radiation within the plant on 14 February. There were no workers underground at the time but, as a precautionary measure, all those at the surface were checked for external contamination. Filters on the underground plant's vents removed at least 99.87% of contaminants from the air, but trace amounts of americium and plutonium were subsequently detected by an above-ground sampling station near the plant.

The DoE and NWP have now notified 13 workers that they had tested positive for radiological exposure. These workers will be requested to provide additional medical samples to determine the extent of any exposure.

The DoE said, "It is premature to speculate on the health effects of these preliminary results, or any treatment that may be needed." It added that indications suggest that airborne radioactive material "was likely at very low levels."

The department noted that the transuranic radionuclides involved in this event was predominantly americium-241 - a radionuclide used in smoke detectors and a contaminant in nuclear weapons manufacturing.

No shipments of waste were scheduled to be delivered to the plant between 14 February and 10 March as the facility had entered an annual maintenance outage. Since the radiological event, only essential staff have been allowed on site.

The radiological event occurred just one week after one of the trucks used to haul salt underground at WIPP caught fire, but as yet the two events have not been linked.

Researched and written
by World Nuclear News