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One of the high-priority research activities in BATAN is designing a new MTRtype research reactor with a new fuel. The core follows a compact core model that consists of 16 fuels and 4 control rods. The increasing heat flux at the fuel will cause the temperature of the fuel and cladding to increase so that the coolant flow rate needs to be increased. However, the coolant flow rate in the fuel element is limited by the thermal-hydraulic stability in the core. Therefore, dynamic analysis is important in evaluating the design and operation of nuclear reactor safety. The objective of this research work is to carry out a dynamic analysis for a conceptual MTR research reactor core fuelled with the low-enrichment U9Mo-Al dispersion. The calculations were performed using WIMSD-5B, Batan-2DIFF, Batan-3DIFF, POKDYN, and MTRDYN codes. Steady-state thermal-hydraulic parameters and dynamic analysis were determined using the MTRDYN code. The calculation results show that the maximum temperatures of the coolant, cladding, and fuel meat with the uranium density of 3.96 g cm-3 are 76.01 °C, 192.02 °C, and 196.24 °C, respectively. The maximum value of fuel meat temperature for safety limit is 210 °C, which means that the maximum temperatures fulfill the design limit, and therefore the reactor operates safely at the nominal power. The dynamic analysis shows that inherent safety can protect the reactor operation when insertion of reactivity occurs in the core.

The main safety parameters of Multipurpose Reactor–Gerrit Augustinus Siwabessy (RSG-GAS) have never been evaluated periodically and neutronically require to be evaluated in terms of stuck rod reactivity, shut-down margin and temperature reactivity coefficient are treated by experiment. Meanwhile, power peaking factors and maximum fuel burn up are treated by calculations. The diffusion method did the calculation using the computer code. Safety parameters are very important aspects for the operation and design improvement. The results of the experiment and calculation about the safety parameters of RGS-GAS core are utilized for safety evaluation as part of a research reactor operation Periodic Safety Review (PSR). It presents reactor calculations as a method for their determination assuming use of computer codes such as WIMSD-5B using ENDF.BVII.0 and BATAN-FUEL. According to the experimental data and calculation, neutronic safety parameters have met the safety analysis report such as reactivity coefficient is negative and met the shutdown margin at stuck rod condition nothing has violated the safety margin. The results can be used as the periodic safety review for renewal operation license from Nuclear Energy Regulatory Agency of Indonesia (BAPETEN) as the regulator body. These results also can be used as a reference for new research reactor MTR type advanced design in the future.

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