Search

The power peaking factor (PPF) is an important parameter that needs to be considered to maintain the reactor's stability, safety and efficiency. The present study discusses the power density distribution in the reactor core by calculating the PPF to increase the reactor safety margin and minimize the possibility of a high power density at a certain point causing core failure in the Molten Salt Reactor (MSR), which is one of the Generation-IV reactors with fuel and coolant dissolved in molten salt. Important parameters discussed in the present study are the distribution of the reactor core region and the fuel composition in each region during the reactor operation time of 2,000 days. Analysis was performed for 3 different thermal power: 150, 450 and 1,000 MWth as a representative to determine the behavior of PPF at small to large power by taking the reference design of the FUJI U3 reactor developed by ITMSF (International Thorium Molten-Salt Forum) Japan. FliBe (Lithium and Beryllium Fluoride) is used as the coolant, and the fuel mixture is 233UF4-ThF4. The calculation was conducted using SRAC2006 with PIJ and CITATION modules that solve the neutron diffusion equation providing power distribution values and effective multiplication factors. As a result, the MSR with 4 core regions produces a more balanced power distribution, a better PPF value, and a good effective multiplication factor for 2,000 days of operation time compared to the reference design. [ABSTRACT FROM AUTHOR]

In this research, the design and evaluation of reactor physics experiments in support of MSR development are discussed. The reference MSR is a 600 MW (thermal), fast neutron spectrum reactor using a mixture of NaCl–CaCl 2 –UCl 3 –PuCl 3 as fuel. An MSR core was designed with the composition of the fuel and the core geometry based on several references. The reactor physical characteristics were calculated for the core using the ERANOS code system. The results show that the reactor can be critical with a compact size and has high passive safety with negative temperature feedback coefficients. A control rod bundle made of stainless steel without the need for strong neutron absorbers was designed. It is expected that reactor physics experiments are needed for MSR development. To design reactor physics experiments for the MSR, the current research target is to use the existing critical assembly in Japan, KUCA, to its maximum potential. Several configurations are proposed and the representativity factor of the experiments to the MSR was evaluated. The results show that the designed configurations have a relatively low representativity. Therefore, a configuration based on the ZPPR using plutonium fuel and with a large size was designed. The results demonstrate that the experimental configuration is very similar to the MSR. This suggests that to design reactor physics experiments for MSR, a critical facility like the ZPPR should be built in the future. • Design and analysis of a 600 MW (thermal) chloride fueled Molten Salt Reactor (MSR). • Experimental configurations for R&D based on Kyoto University Critical Assembly. • Experimental configurations are evaluated using the representativity factor. • Experiments in KUCA reach r R E ≈ 0.6. • Experiments based on the ZPPR facility are designed leading to r R E > 0.9. [ABSTRACT FROM AUTHOR]

• Neutronics design for molten salt ADS was performed to transmute TRU nuclides. • The MARDS (Molten salt AcceleratoR Driven System) concept is proposed. The concept has four features to realize the effective TRU trasmutation. • The concept can transmute about 100–120 kg plutonium per year. • The concept can employ a circular accelerator and transmute TRU effectively. Treatment of plutonium separated from spent fuel has been one of the most important issues in the utilization of nuclear power in Japan. This study investigates a molten salt accelerator-driven system (ADS) to transmute transuranic (TRU) nuclides to address the issue. This study proposes the MARDS (Molten salt AcceleratoR Driven System) concept which has four features: employment of chloride, no dedicated spallation target, non-contact between beam window and fuel salt and modularized core. Neutronics calculation for the MARDS concept was performed for a condition of 400 MW thermal power with 800 MeV proton beam. The calculation results showed that the maximum proton beam current was about 7 mA and about 100–120 kg plutonium could be transmuted during one-year operation. The result indicates that the MARDS concept can employ a circular accelerator instead of LINAC and transmute TRU effectively. [ABSTRACT FROM AUTHOR]