Spill at Wyoming uranium mine triggers NRC ‘special investigation’

The U.S. Nuclear Regulatory Commission launched a “special investigation” today to determine if workers were exposed to “yellowcake” after an incident at Uranium One USA Inc.’s Irigaray and Christensen Ranch in-situ uranium mine in northeast Wyoming.

Uranium mine black bloxes at the Christensen Ranch

Black boxes cover wellheads at the Christensen Ranch in-situ uranium mine near the Pumpkin Buttes in the southern Powder River Basin. (Dustin Bleizeffer/WyoFile - click to enlarge)

According to a NRC press release, the incident occurred on Sunday. Two workers were in the vicinity of a “dryer” containing yellowcake — yellow uranium oxide powder — when they heard an alarm and the dryer automatically shut down.

The yellowcake dryer is located inside an enclosed building.

“It appears that a seal on the dryer may have broken, causing the yellowcake powder to escape,” the NRC stated in the press release. “Current information indicates there were no major safety impacts or release to the environment as the dryer is housed inside a pressurized sealed room within a building.”

In an unrelated incident, Wyoming environmental regulators recently issued the same mine operator a notice of violation (NOV) related to a 10,000 gallon spill of brine in August.

Because of the incident on Sunday, a NRC inspector traveled to the Wyoming uranium mine on Wednesday to determine whether workers were exposed to yellowcake, and to evaluate the operator’s corrective actions already in the works.

NRC spokeswoman Lara Uselding told WyoFile that it appears the workers were wearing proper protective clothing to avoid exposure to the uranium material. To determine whether there was an exposure, air samples will be analyzed. Also, the workers underwent urinalysis testing.

“We got results back today, and uranium was non-detectable … So they had no intake of uranium,” Donna Wichers, Uranium One senior vice president of in-situ operations, told WyoFile in a phone interview on Wednesday.

Both Uselding and Wichers said that radiation from yellowcake is low enough to be a secondary human health concern compared to ingesting the uranium ore. “Because it’s a heavy metal,” said Wichers. “It would be just like if you ingested lead or any other heavy metal.”

Wichers described the entire incident as a “non-event,” and said the NRC inspector was scheduled to visit the mine anyway. She said once the NRC decided to launch a special investigation, part of the agency’s protocol is to issue a press release, “Which we tried to talk them out of,” Wichers said.

The NRC will issue a public report of the investigation within 45 days.

The Irigarary and Christensen Ranch in-situ uranium facilities ceased production in 2000 while reclamation activities continued for several years. The mine changed ownership, and after several years of state and federal permitting, the mine resumed production in January.

On September 19, the Wyoming Department of Environmental Quality issued a notice of violation (NOV) to Uranium One related to an August spill at the Irigaray plant in Johnson County of up to 10,000 gallons of sodium chloride brine, which is used to strip uranium-bearing ore from the production solution. The brine entered a dry ephemeral stream adjacent to the facility.

According to the NOV, Uranium One failed to meet DEQ’s timely reporting requirements related to a spill. Wichers said there was a misunderstanding about whether an email notification qualified as written notification. She said DEQ did not require any remediation of the area effected by the spill.

— Contact Dustin Bleizeffer, WyoFile editor-in-chief, at 307-577-6069 or dustin@wyofile.com.

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Published on October 5, 2011

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