Different amounts of boron compounds (i.e. boric acid and borax) are mixed with natural rubber to form a thermal neutron radiation shielding block. With proper treatment on natural rubber, uniform distribution of a boron compound can be achieved, which results in an enhancement of thermal neutron shielding capability. It is found that the neutron shield capability of those shielding blocks depends sensitively on both borax and boric acid's concentration, and the thickness of the shielding

more »

... Even though the boron content in a natural rubber shielding block mixed with boric acid is higher than that with borax at the same amount, the shielding blocks with borax can shield thermal neutron better due to the loss of boric acid by a bubble formation during the process. An inclusion of lead oxide (PbO 2 ) in the shielding block can slightly increase its thermal neutron shielding capability and results in good gamma ray shielding capability, in which a minimum thickness of shielding blocks is required to be effective.