Insufficient self-shielding correction in JSSTDL-300

Konno, Chikara  ; Ochiai, Kentaro; Onishi, Seiki

JSSTDL-300 is a multigroup library for shielding applications produced from JENDL-3.2. The self-shielding correction in JSSTDL-300 is probably inadequate due to the following two reasons, (1) the weighting function of Legendre order = 0 is applied for all Legendre orders, (2) the f-table of the scattering matrix is the same as that of the elastic scattering. Thus we examined the effects of these problems through a simple benchmark test, the model of which consisted of an aluminum, iron, nickel or copper sphere of 1 m in radius with a 20 MeV neutron source in the center. Neutron spectra in the sphere were calculated with ANISN and were compared with those obtained with MCNP4C. It was found out that the effects were different dependent to materials and were the largest for copper. Adequate f-table and weighting function should be adopted in generation of multigroup libraries.