Radiation chemistry in solvent extraction: FY2010 Research

Abstract

This report summarizes work accomplished under the Fuel Cycle Research and Development (FCR&D) program in the area of radiation chemistry during FY 2010. The tasks assigned during FY 2010 included:x Development of techniques to measure free radical reaction kinetics in the organic phase.x Initiation of an alpha-radiolysis programx Initiation of an effort to understand dose rate effects in radiation chemistryx Continued work to characterize TALSPEAK radiation chemistry Progress made on each of these tasks is reported here. Briefly, a method was developed and used to measure the kinetics of the reactions of the •NO 3 radical with solvent extraction ligands in organic solution, and the method to measure •OH radical reactions under the same conditions has been designed. Rate constants for the CMPO and DMDOHEMA reaction with •NO 3 radical in organic solution are reported. Alpha-radiolysis was initiated on samples of DMDOHEMA in alkane solution using He ion beam irradiation and 211 At isotope irradiation. The samples are currently being analyzed for comparison to DMDOHEMA J-irradiations using a custom-developed mass spectrometric method. Results are also reported for the radiolytic generation of nitrous acid, in J-irradiated nitric acid. It is shown that the yield of nitrous acid is unaffected by an order-of-magnitude change in dose rate. Finally, recent results for TALSPEAK radiolysis are reported, summarizing the effects on solvent extraction efficiency due to HDEHP irradiation, and the stable products of lactic acid and DTPA irradiation.In addition, results representing increased scope are presented for the radiation chemistry program. These include an investigation of the effect of metal complexation on radical reaction kinetics using DTPA as an example, and the production of a manuscript reporting the mechanism of Cs-7SB radiolysis. The Cs-7SB work takes advantage of recent results from a current LDRD program to understand the fundamental chemistry of nitration under radiolysis conditions. Finally, work toward understanding the chemistry of irradiated formic acid is presented. This is important because all organic compounds eventually produce formic acid under long-term irradiation.