Water Sorption and Gamma Radiolysis Studies for Uranium Oxides

Dissolution of Highly Enriched Uranium from the Idaho National Engineering and Environmental Laboratory

“…The dissolution of several grams of material from each sample in a closed system with the capability to measure and sample the offgas showed that essentially no gas was generated as the material dissolved. This observation was consistent with the presence of UO 3 which generates no offgas upon dissolution in nitric acid (HNO 3 ). The generation of hydrogen (H 2 ) during the dissolution of the HEU is not a concern.…”

“…Since the capability to purify uranium (U) was terminated at the Idaho National Engineering and Environmental Laboratory (INEEL) in the early 1990's, excess highly enriched uranium (HEU) from the cleanout of uranium trioxide (UO 3 ) production equipment will be shipped to the Savannah River Site (SRS) for disposition. The excess material will be dissolved in Phase I of HB-Line, purified by solvent extraction, and blended with normal U to an enrichment which can be used to fabricate fuel for Tennessee Valley Authority (TVA) reactors.…”

“…Initially, an examination of the HEU by x-ray diffraction showed that the material was a mixture of UO 3 and two monohydrated forms of UO 3 . Subsequent thermogravimetric analyses showed that the samples contained 8-9 wt% volatile components which were predominately water.…”

“…Since the HEU was removed from equipment utilized in the production of UO 3 , complete conversion to the intended product may not have occurred for all of the material. To determine the predominate forms of U in the samples from the INEEL, approximately 100 mg of each sample were analyzed by x-ray diffraction.…”

“…The time required to achieve complete dissolution of the HEU was measured in a series of smallscale experiments in which nominally 2.5 g of material were dissolved in 17 mL of nominally 3.5M HNO 3 . The dissolutions were performed in a 50 mL beaker with the pour spout removed.…”