Supplement to radiation shielding analysis of JOYO (C)

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Kondo, Ryoichi*; Ozawa, Takeshi*; Horie, Junnosuke*; Handa, Hiroyuki*

Kondo, Ryoichi*; Ozawa, Takeshi*; Horie, Junnosuke*; Handa, Hiroyuki*

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A supplemental study on the JOYO's shielding analysis was performed focussing attention on the behavior of neutron and -ray fluxes around the detector guide tube of channel a and on the evaluation of the primary sodium activation with use made of the two-dimensional discrete ordinates transport code. It has been found out that secondary rays emitted from a thin guide tube material of SS-304 has a strong effect of enhancing gamma doserates in the guide tube penetrating through a graphite shielding. The effect of the guide tube penetrating a heavy concrete pedestal has been revealed to be a streaming of neutrons and gammas. It can be concluded that the effect of the detector guide tube on the neutron and ray should be taken into account when comparing the calculated values with experimental values. The neutron flux distribution in the full reactor lower axial two dimensional geometry has been calculated and used, together with the results obtained by the upper axial two dimensional a