Radiolytic Gas Generation in Chemically-bonded Iron Phosphate Ceramic Forms used for Immobilization of Plutonium Ash Residues

Abstract

AbstractIron phosphate ceramic (IPC) samples were prepared with plutonium-238, and radiolytic gas generation was detennined for exposure times of up to 195 days. The specific activity of the synthesized IPC samples was 1.91 mCi/g. The composition of the generated gases was determined to contain mainly H, and lower amounts of O2, CO2 and CO. The molecular hydrogen G value (molecules of H2 per 100 eV absorbed dose) depended on the sample preparation methodology, ranging from 0.07 at 79 days for sample IPC-2 to 0.34 at 119 days for sample IPC-1. This difference could be due to different total amount (wt.%) of free water resulting in sample preparation. The leach rate data for radioactive and non-radioactive IPC samples obtained by the ANSI/ANS 16.1 procedure resulted in Leachability Indexes of 13.7 for Pu and 15.4 for Ce, above the NRC LLW acceptance minimum index of 6.