Calculation of neutronic parameter design for MTR reactor core using safety control rods

Abstract

Indonesia has three research reactors that are old, so it needs to be considered designing new research reactor. This new research reactor uses compact core, MTR type, low enrichment of 235U and a new fuel, U7Mo/Al. The advantage of using this new fuel is that it can be fabricated with high density up to 16 gU/cm3. However, on this research a density of uranium was varied from 4.5 -8.3 gU/cm3. The reactor core comprises 16 fuels and 4 control rods inserted into a 5 x 5 grids. Inside the core there are irradiation facilities comprising 4 holes at the edge and 1 in the middle of the core for radioisotope production. The reactor core is also equipped with 2 safety control rods to increase the safety of the reactor operation for one cycle. This research gets an optimal core configuration with maximum radioisotope production. Analysis was performed by calculating using the WIMSD-5B and Batan-FUEL computer programs. Optimal core design a cycle length of not less than 20 days and the reactor can be operated safely with a power of 50 MW producing a thermal neutron flux greater than 1.0x1015 n /cm2s. The calculation results show that for fuel loading a density of 6.52 gU /cm3 will obtain a thermal neutron flux of 1.03 x1015 n/cm2s. The cycle length can reach 32 days. It meets safety and acceptance criteria; however, it still requires a more negative reactivity of the control rod for safe operation at 50 MW compared to other densities.