Study of subcritical neutronic device for Molybdenum-99 Production (SAMOP)

The increase of Tc-99m application for medical diagnostic has revealed various kind of innovations in producing that radioisotope, one of them is by using Subcritical Assembly for Molybdenum-99 Production (SAMOP). Now, BATAN is applying a SAMOP design to BAPETEN to get the approval. Therefore, BAPETEN needs to perform the neutronical assessment on that proposed SAMOP design for the purpose of safety aspect supervision. The proposed SAMOP design uses uranyl nitrate solution which has the density of 300 g Uranium/l. The reflector used is made of graphite with 20 cm of thickness. The materials used for the control rod and the coolant are boron carbide (B₄C) and water, respectively. The tool analysis used is SCALE 6.1 program. The main parameter analysed is criticality. There are two types of SAMOP design proposed, i.e. with the addition of TRIGA standard fuel elements and with the addition of peripheral tubes containing uranyl nitrate solution. The results show that the criticalities of SAMOP by using the TRIGA fuels are higher than that of peripheral tubes containing uranyl nitrate solution. By the addition of six TRIGA fuel elements and six peripheral tubes containing uranyl nitrate solution, the criticality values reach 0.98430 and 0.97532, respectively. When the position of control rod is fully down, the criticality values are 0.93514 if using TRIGA fuels and 0.92534 if using peripheral tubes containing uranyl nitrate solution. The proposed SAMOP design has fulfilled the main criteria of neutronical safety because the SAMOP system operation is within the subcriticality margin. (author)