Sample pretreatment for the determination of gamma emitting nuclides in dry radioactive waste using a dry ashing and high-performance microwave digestion system

摘要

A sample pretreatment procedure for the dry radioactive waste such as paper, cotton, vinyl, and plastic generated from nuclear power plants (NPPs) was established to determine the activity concentrations of 60Co and ~(137)Cs. Because the volatility of cesium is temperature-dependent, the heating temperature was examined from 300 to 650 ℃. Although the cesium was not volatile until 500, 450 ℃ was selected to save time. Cesium with a paper towel and a planchet of stainless steel were quantitatively recovered at 450 ℃. The produced ash was completely dissolved with 10 mL of HNO_3, 4 mL of HCl, and 0.25 mL of HF in a highperformance microwave digestion system using a nova high temperature rotor at 250 ℃ for 90 min until 0.2 g was reached. This procedure was applied to low and intermediate level radioactive wastes generated from NPPs.