Investigating the emitted dose from small and large out-of-tank irradiation channels of a low power research reactor through calculation and measurement

Two external neutron beamlines of small and large sizes have been installed in the Isfahan Miniature Neutron Source Reactor (MNSR) pool in recent years to perform neutron radiography as well as irradiation experiments for large samples out of biological shield of reactor. These channels are located outside the reactor tank and exit vertically tangentially from the biological shield of the reactor, which is the pool water. These channels, that were not included in the initial design of MNSR, actually generate neutron beam lines in the reactor hall, about ۶ meters away from the reactor core. In this study, the delivered neutron and gamma dose rates at the outlet of these channels at the maximum power of reactor, i.e. ۳۰ kW, has been determined through simulation and experiments. Results shows that the calculated and measured gamma dose rates at the outlet of the large size channel are ۴۵.۸۱ ± ۳% and ۴۷.۳۲ ± ۶% mSv.h-۱, respectively and the calculated and measured neutron dose rates are ۱۱.۷۲ ± ۵% and ۱۱.۳۱ ± ۳% mSv.h-۱, respectively. In the case of small size channel, the calculated and measured gamma dose rates at the outlet of this channel are ۱۰.۵۳ ± ۴% and ۱۰.۲۲ ± ۶% mSv.h-۱, respectively and the calculated and measured neutron dose rates are ۲.۲۲ ± ۵% and ۲.۱۱ ± ۸% mSv.h-۱, respectively. Also, the neutron and gamma dose rate distribution in the reactor hall for different modes of operation of these two channels were qualitatively determined.

کلیدواژه ها:

Neutron dose rate ، Gamma dose rate ، MNSR ، Neutron beamline ، Dosimetry ، MCNP simulation