Integral experiments for beryllium nuclear data benchmarking with DD neutrons

Kondo, Keitaro; Ochiai, Kentaro; Takakura, Kosuke; Onishi, Seiki; Sato, Satoshi; Konno, Chikara  ; Tatebe, Yosuke

An integral experiment with the DD neutron source of the FNS facility was began in order to verify the nuclear data related to transport calculations for DD neutrons. A characterization of the DD neutron source and an integral experiment for beryllium were presented in this conference. To evaluate the characteristics of the DD neutron source of FNS, the source term in which the energy and angular distributions of the generated neutron were described based on the reaction kinematics was built into a MCNP calculation, and the target assembly was modeled in detail. To verify this calculation, the reaction rate distributions of the In(n,n')In and Ni(n,p)Co reactions were measured at the distance of 10 cm. Measurements and the calculation agreed well, and we confirmed that the calculation was appropriate. As for the beryllium integral experiment, a beryllium pseudo-cylinder assembly of 45 cm in thickness and 63 cm in the diameter was built at the distance of 20 cm from the DD neutron source, and the neutron spectrum, the In(n,n')In reaction rate and the U fission rate in the assembly were measured. In the experiment, a tendency that the calculation underestimated the neutron flux above 0.5 MeV as the depth inside assembly became deep was found.