Diluted plutonium dumped at Carlsbad nuclear waste disposal site

Federal nuclear waste officials announced last month a shipment of diluted surplus weapons-grade plutonium was dumped at a repository near Carlsbad after it was shipped from South Carolina to New Mexico, amid criticism from state nuclear watchdog groups.

The shipment contained plutonium that was diluted using a process known as “downblending,” which lowered its radioactivity to meet the requirements of the waste isolation pilot facility at which the US Department of Energy is disposing of transuranic (TRU) nuclear waste in an underground salt storage facility.

It was brought to the WIPP from the DOE’s Savannah River Site, a laboratory where the federal government is developing nuclear weapons.

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After downblending, the waste meets the definition of TRU waste, according to an announcement by the DOE’s National Nuclear Security Administration (NNSA), and can be legally disposed of at WIPP.

A view of the Savannah River Site K Area Complex where plutonium downblending operations are taking place.

Disposal at WIPP was in response to a 2020 agreement between the DOE and the state of South Carolina that provided for the removal of 9.5 tonnes (MT) of plutonium waste from the state, achieved after years of negotiation and litigation.

The waste was first taken to Savannah River to be irradiated in a mixed oxide (MOX) facility to convert the nuclear waste into fuel.