Thermoanalytical investigation of the reactions causing the transuranic waste drum breach that occurred in the Waste Isolation Pilot Plant

Abstract

In February 2014, an energetic gas-producing chemical reaction occurred in remediated plutonium processing waste emplaced in the Waste Isolation Pilot Plant causing the drum's seal to fail and release radioactive material into and outside of the plant. This article provides results of our probative study using simultaneous thermogravimetric and differential thermal analysis and accelerating rate calorimetry to determine the thermal sensitivities of selected simulated characteristic remediated wastes such as hydrogen-and hydrogen, metaltriethanolamine nitrates and nitric acid solidified and stabilized with wheat-based pet litter. These studies found that these nitrate wastes were chemically unstable and susceptible to gasproducing thermal runaway reactions. If undried or partially dried, self-sustaining or accelerating-exothermic reactions were delayed in nitrate-and organic-containing materials to above 100°C while air-dried nitric acid and pet litter began self-heating exothermic reactions near 30°C that led to thermal runaway. Caution must be exercised when managing nitratecontaining wastes.

Waste Control Specialists Technical Review Team Report

“…The samples were heated using a heat/wait/search mode. The primary difference between the two ARC experiments was that one contained 7.5 g of dried 3.5 M nitric acid saturated sWheat Scoop ® [10] and the other contained 6.9 g of dried 3.5 M nitric acid saturated sWheat Scoop ® [38]. The difference in sample size makes a slight difference in the available gas volume within the sample vessels.…”