Effect of Boron Impurity and Graphite Thermal Neutron Scattering on Criticality Calculation of Indonesian Experimental Power Reactor (Suwoto, H. Adrial, W. Luthfi, T. Setiadipura, Zuhair)

Abstract. The structural materials of Indonesian Experimental Reactor (RDE) is made from graphite that dominate
material used on core structure. So that graphite material is very important role, both as core structure material, reflector
and also as a moderator and fuel layer and fuel matrix. In thermal neutron energy range, the neutron scattering collision
in moderator material such as graphite influences the neutron cross-section and the resulting energy distribution, so that
neutrons will get an increase in energy for excitation in the material. Due to high neutron absorption cross section, boron
and its compounds find extensive application in the nuclear industry. In actually it is very difficult to obtain pure uranium
or thorium dioxide without any other substance. Usually uranium dioxide or thorium kernel always has impurity material
like boron. Boron is one of the materials that has strong neutron absorber, specially for Boron-10.The research starting
from modeling of kernel TRISO coated fuel particle, spherical pebble fuel and full core modeling by involving multiple
heterogeneity calculations. Boron impurities in the TRISO kernel coated fuel particles was carried out with 27 data varied
concentration of boron are 0ppm, 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, 9ppm, 10ppm, 15ppm, 20ppm,
25ppm, 30ppm, 35ppm, 30ppm, 35ppm, 40ppm, 45ppm, 50ppm, 60ppm, 70ppm, 80ppm, 80ppm, 90ppm and 100ppm.
All calculation analysis will be done using Monte Carlo MCNP6 with continuous neutron energy cross section taken
from ENDF/B-VII file. Investigation of multiplication factor effect due to thermal neutron scattering crossing data S(