Research On Neutron Physical Properties Of CEFR MOX Fuel Loading

China experimental fast reactor(CEFR)is the first step in the development of China’s fast reactor engineering.It was designed filled with MOX fuel,but due to the restrictions at that time,it had to temporarily adopt the high concentration UO2 fuel imported from Russia with a enrichment of 64.6%.According to the development plan of fast reactor in China,it is necessary to realize the conversion from UO2 fuel to MOX fuel.Multi-faceted verification analysis of neutron physics,thermal hydraulics,and shielding is required for the refueling scheme to ensure the implementation of refueling.At the same time,research on MOX fuel loading in fast reactors is of great significance to the development of closed cycle of nuclear fuel in China.This topic focuses on the neutron physics part of the refueling program,and mainly studies the changes of effective proliferation factors and burnup reactivity,effective delayed neutron share,control rod value,temperature and power reactivity coefficient,sodium cavitation effect and power distribution in different refueling stages.The cross-section was generated using the fast reactor cross-section generation program MGGC independently developed by the North China Electric Power University IRPS Lab.The cross-section was made using 194 fission products to consider the effects of thousands of fission products during the burnup process,and 5 pseudo-fission products were produced.The multi-fuel burn-up cross-section database of the fast reactor in the ISOTXS format was merged to verify the accuracy of the burn-up cross-section library through international benchmark questions;the entire reactor at each refueling phase was performed using the core calculation program of the Argonne National Laboratory.Modeling,calculation of fuel consumption and calculation of neutron kinetic parameters.In order to make the calculation results reliable,based on the international fast reactor benchmark question BN-600,the feasibility analysis and verification of the above calculation procedures were performed.Through comparative analysis with the report,it is considered that the calculation procedures and processes adopted in this paper are reasonable and feasible.Using the above procedures for refueling calculations,the key neutron physical parameters at each stage of the refueling scheme were obtained and compared with the results of CIAE.Among them.the deviation of the effective proliferation factor obtained in each stage after correction is in the range of 280-787pcm,and the maximum loss of fuel consumption reactivity is 2%,which is much lower than 10%;the deviation of the effective delayed neutron share is 2.04%to 2.64%,And the fuel consumption process has shown a downward trend;most of the deviations in the value of the control rods are within 10%.Except for the lower total value of the adjustment rods,which results in larger deviations,the values of the remaining rods are less than 5.1%.After the MCNP program was revised,the results were also reduced to less than 15%;the deviation of temperature and power reactivity under the MOX equilibrium charge was between 4%and 14%;the deviation of sodium cavitation reactivity was between 11%and 15%Between;the maximum deviation of the power distribution is 8.6%,and the maximum deviation of the radial power crest factor is 2.1%.Through calculation and analysis.The results of the above parameters all meet the verification requirements and meet the design standards for refueling.It provides a reference for the engineering application of CEFR refueling.