Radioactive Fission Waste of The Conversion of High-Enriched Uranium to Low-Enriched Uranium Target on ⁹⁹Mo Production

Abstract

In the past, 99mTc produced by PT. Industri Nuklir Indonesia (PT. INUKI) was carried out through the processing of a 99Mo parent radioisotope that was produced using high enriched uranium target. Due to restrictions on the use of high-enriched uranium (HEU) by the International Atomic Energy Agency, PT. INUKI has converted the process using a low enriched uranium (LEU) target. This study aims to determine the change of radioactive fission waste characteristics in 99Mo production due to the conversion process. The characteristics of radioactive fission waste generated from low-enriched uranium targets were calculated using ORIGEN 2.1 program. The results show that the radioactive fission waste contains radionuclides of activation products, actinides, and fission products. The conversion produced smaller activity of 99Mo compared to that of using the HEU target, which was 397 compared to 1010 Ci. The conversion generated radioactive fission waste with a smaller content of remaining 235U but greater content of actinides, particularly 239Pu. The activity of 239Pu in the radioactive fission waste from LEU was 29.1 μCi, approximately 19 times higher compared to that of using HEU, which was 1.52 μCi. After 50 years of decay, this radioactive fission waste was calculated to have a specific activity of 6.54x108 Bq/g, lower than that of the highly enriched uranium target, which was 3.01x109 Bq/g. This radioactive fission waste requires management with a high safety level.