Plutonium dioxide dissolution in glass

Abstract

Executive SummaryTo prove the technical and economic feasibility of the dispositioning of excess weapons usable materials by vitrification, it is necessary to demonstrate that PuO2 feedstock can be dissolved in glass in sufficient quantity and in less than 8 h. The objective of this study is to demonstrate a high Pu02 solubility in glass and to identify the rough time scale required for Pu02 dissolution in a candidate immobilization glass. The results of this study confirm that the Pu solubility can be as high as 10 wt% in glass (1 1.4 wt% P u 0 2 ) and the time required for dissolution of Pu@ in glass was less than 4 h in every case and as low as 1 to 2 k This time requirement is based on a single glass composition and two P u 0 2 source materials with similar particle size distributions (PSD); one high-fired and one low-fmd. Temperature, glass composition, and PSD of PuO2 are suspected being the major factors in PuO2 dissolution rates in glass. Additional tests are required to examine the effects of temperature, PSD, and glass composition on Pu02 dissolution kinetics.

Calculation of Neutron Production Rates and Spectra from Compounds of Actinides and Light Elements

“…It was noted in [24] the uncertainty in the content of 238 Pu in the glass was about 5% and yields may be underestimated by as much as 10% due to the calibration with 252 Cf source (spectral differences). However, the dimensions of particles of PuO2 in glass may be ~ 0.1-5 µm [26]. For 1.5 µm radius of particles NEDIS-2.0 outputs 4970, 474, 168 n/s and agreement with the measurements are ~ 3%.…”

Plutonium Feed Impurity Testing in Lanthanide Borosilicate (LaBS) Glass

“…The basis for the use of HfO 2 as a surrogate for PuO 2 in borosilicate glasses from a solubility perspective has been documented [8]. Therefore, insolubility of HfO 2 at these concentrations is not unexpected since the solubility limit of PuO 2 in LaBS glass was found to be 13.4 wt % [1]. The results of the PCTs indicated that each of the study glasses was highly durable as compared to the Environmental Assessment (EA) glass, which is used as a benchmark for defense-related waste glasses destined for the U.S. federal repository [9].…”

“…A significant effort to develop a glass formulation and vitrification process to immobilize plutonium was completed in the mid-1990s to support the PIP. The LaBS glass formulation was found to be capable of immobilizing in excess of 10 wt% Pu and to be very tolerant of impurities [1][2]. Thus, this waste form could be suitable for the disposition of plutonium owned by the DOE-EM that may not be well characterized and that may contain high levels of impurities.…”

Variability Study to Determine the Solubility of Impurities in Plutonium-Bearing, Lanthanide Borosilicate Glass

“…The LaBS glass formulation was found to be capable of immobilizing in excess of 10 wt% Pu and to be tolerant of the impurities accompanying the plutonium material streams. 1,2 Thus, this waste form could be suitable for the disposition of plutonium owned by the DOE-EM that may not be well characterized and that may contain high levels of impurities. However, the relative tolerance of the glass composition to the various feed impurities needs to be studied.…”

“…A glass study is underway at the Savannah River National Laboratory (SRNL) to investigate glass formulations and to conduct performance testing to support plutonium (Pu) disposition [1]. Sixty (60) glasses have been selected to be batched and fabricated as part of this study.…”