EXPOSURE BUILDUP FACTORS OF UO2 USING THE MONTE-CARLO METHOD

When the gamma dose rate around an irradiated nuclear reactor fuel ele ment is calculated, it is important to know the attenuating characteri stics of the fuel element itself, one of them being the buildup factor . Exposure buildup factors of uranium dioxide (UO2) for ten gamma-ray energies (0.050 to 10.0 MeV) have been computed for ten material thick nesses (0.5 to 10.0 mean free paths) using the MCNP code. The accuracy of the MCNP model was checked by computing the buildup factors of oxy gen and uranium and comparing these results with the data given in the literature for these elements. The results indicate that the UO2 expo sure buildup factors, for the energies and distances studied, are clos e to those of uranium.