Study on Thermal Neutron Trap in Core of HFETR

In this paper, the thermal neutron traps are studied for HFETR by transport method and diffusion method. The calculation results show that the best radius is 6.0cm for water thermal neutron trap and the maximal thermal flux is 3.1～3.7 times of the one in the non-trap core;and for beryllium-water thermal neutron trap, the best radius is 7.5cm（diffusion method） and 2.5cm（transport method）, respectively and the maximal thermal flux is 3.2～4.0 times of the one in the non-trap core.