Majorana DUSEL R&D Final Report

This report summarizes the work performed at PNNL under the project Majorana Neutrinoless Double Beta Decay DUSEL R&D over the period of FY07-FY09

Majorana DUSEL R&D Final Report

This report summarizes the work performed at PNNL under the project Majorana Neutrinoless Double Beta Decay DUSEL R&D over the period of FY07-FY09

Rhenium Solubility in Borosilicate Nuclear Waste Glass: Implications for the Processing and Immobilization of Technetium-99

The immobilization of technetium-99 (⁹⁹Tc) in a suitable host matrix has proven to be a challenging task for researchers in the nuclear waste community around the world. In this context, the present work reports on the solubility and retention of rhenium, a nonradioactive surrogate for ⁹⁹Tc, in a sodium borosilicate glass. Glasses containing target Re concentrations from 0 to 10 000 ppm [by mass, added as KReO₄ (Re⁷⁺)] were synthesized in vacuum-sealed quartz ampules to minimize the loss of Re from volatilization during melting at 1000 °C. The rhenium was found as Re⁷⁺ in all of the glasses as observed by X-ray absorption near-edge structure. The solubility of Re in borosilicate glasses was determined to be ∼3000 ppm (by mass) using inductively coupled plasma optical emission spectroscopy. At higher rhenium concentrations, additional rhenium was retained in the glasses as crystalline inclusions of alkali perrhenates detected with X-ray diffraction. Since ⁹⁹Tc concentrations in a glass waste form are predicted to be <10 ppm (by mass), these Re results implied that the solubility should not be a limiting factor in processing radioactive wastes, assuming Tc as Tc⁷⁺ and similarities between Re⁷⁺ and Tc⁷⁺ behavior in this glass system

FY 2009 Progress: Process Monitoring Technology Demonstration at PNNL

Pacific Northwest National Laboratory (PNNL) is developing and demonstrating three technologies designed to assist in the monitoring of reprocessing facilities in near-real time. These technologies include 1) a multi-isotope process monitor (MIP), 2) a spectroscopy-based monitor that uses UV-Vis-NIR (ultraviolet-visible-near infrared) and Raman spectrometers, and 3) an electrochemically modulated separations approach (EMS). The MIP monitor uses gamma spectroscopy and pattern recognition software to identify off-normal conditions in process streams. The UV-Vis-NIR and Raman spectroscopic monitoring continuously measures chemical compositions of the process streams including actinide metal ions (uranium, plutonium, neptunium), selected fission products, and major cold flow sheet chemicals. The EMS approach provides an on-line means for separating and concentrating elements of interest out of complex matrices prior to detection via nondestructive assay by gamma spectroscopy or destructive analysis with mass spectrometry. A general overview of the technologies and ongoing demonstration results are described in this report