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Authors (affiliation): 1. Gatot Wurdiyanto (PRTSMMN – BRIN, Indonesia), 2. Aslina Br. Ginting (PRTDBBNLR – BRIN, Indonesia), 3. Hermawan Candra (PRTSMMN – BRIN, Indonesia), 4. Boybul (PRTDBBNLR – BRIN, Indonesia), 5. Arif Nugroho (PRTDBBNLR – BRIN, Indonesia), 6. Yanlinastuti (PRTDBBNLR – BRIN, Indonesia), 7. Erlina Noerpitasari (PRTDBBNLR – BRIN, Indonesia).
Since 2002, the Multi-Purpose Reactor G.A. Siwabessy (RSG-GAS) in Serpong, Indonesia has used U3Si2/Al nuclear fuel with a density of 2.96 gU/cm3. This reactor is operated using an U3Si2/Al fuel with an enrichment of 19.75 % and produce several fission products and heavy elements such as 137Cs, 134Cs, 90Sr, 235U, 238U, 234U, 236U, 239Pu, 148Th, and 143Ce. The spent fuel elements containing these radioactive elements have a very high level of radioactivity and have a very long half-life, so they cannot be disposed of in a radioactive waste storage area. However, the element of nuclear fuel still has a high enough economic value if it can be managed properly, especially 137Cs. In this paper, the source of the 137Cs is prepared from separating U3Si2/Al nuclear fuel elements so that it can be used to calibrate nuclear measuring instruments.
The separation methods of 137Cs in used fuel U3Si2/Al post irradiated was carried out using the cation exchange method using Lampung zeolite. The solvents used were 6 N HCl and HNO3 as a carrier. The preparation of the 137Cs source solution was carried out gravimetrically using a calibrated semi-micro balance. There were 15 point sources of 137Cs that prepared. The activity and impurity measurements were carried out using a gamma spectrometer, which was calibrated with a standard sources of 152Eu, 60Co and 137Cs that have traceability to the SI.
The results of the measurement of the 137Cs solution were very good with a homogeneous level below 1.5 %, and there was no significant impurity detected above 0.05% of the 137Cs. The measured specific activity values of 137Cs are 84.310 Bq/g with an expanded uncertainty of 3.8%, at k=2. From these results, the 137Cs source solution derived from the separation of spent nuclear fuel can be used as a secondary standard source to calibrate nuclear measuring instruments.
