Shielding experiment for new concrete with high concentration of boron by using DT neutrons, 2; Shielding experiment by using DT neutrons

Sato, Satoshi; Shionaga, Ryosuke*; Nose, Hiroyuki*; Konno, Chikara  ; Nakashima, Hiroshi

In order to study the neutron shielding performance of the new concrete with high concentration of boron, the shielding experiment has been performed by using the DT neutron source at FNS in JAEA. The experimental mockup of the concrete with high concentration of boron was 40 cm in height, 40 cm in width and 60 cm in thickness. The distance between the DT neutron source and the mockup was 20 cm. Niobium and gold foils were inserted every 5 cm in depth along the center of the mockup. Reaction rates were measured on the Nb(n,2n)Nb and Au(n,gamma)Au reactions. A calculation with MCNP and FENDL-2.1 was done for the experiment. The calculation results agreed well with the measured ones in the both reaction rates. Another calculation was also conducted on the condition that the experimental mockup was replaced by the ordinary concrete. The reaction rate of the Au(n,gamma)Au reaction in the new concrete with high concentration of boron was about 1/40 of that in the ordinary concrete at the position of 50 cm in depth, and it was confirmed that the new concrete with high concentration of boron could reduce the neutron flux of low energy.