The Office of Emergency Management began treating barrels of remediated nitrate in December 2017. Treatment, which began in December, involved removing the UNS waste from drums and mixing it with water and zeolite – an inert material – to render the waste non-reactive. The resulting mixture is in solid form and was repackaged in new drums in accordance with EM Waste Isolation Pilot Plant (WIPP) requirements. The treated nitrate salt drums are being stored at LANL, and will eventually be shipped to WIPP for disposal. The Department of Energy announced Tuesday the completion of remediation of the remaining drums.
Los Alamos lab finishes treating drums of nitrate salt waste

By SUSAN MONTOYA BRYAN, Associated Press

ALBUQUERQUE (AP) — Workers at Los Alamos National Laboratory have finished treating more than two dozen drums of waste containing some of the same ingredients that caused a 2014 radiation release at the federal government's underground repository, the U.S. Energy Department announced Tuesday.

Agency and lab officials in an online newsletter called the treatment of the 27 drums a milestone for the northern New Mexico lab as it works to clean up contamination.

The containers of nitrate salt waste had not previously been treated, so crews over the last three months mixed the waste with water and an inert material to neutralize the contents' reactive characteristics.

In the case of the container that ruptured in 2014, that waste had been inappropriately treated before being shipped to southern New Mexico's Waste Isolation Pilot Plant. It was mixed with organic cat litter to absorb moisture, resulting in a chemical reaction and the radiation release that forced the repository to close for nearly three years.