USE OF SMALL ISOTHERMAL CALORIMETERS TO MEASURE THE RADIATION DOSE RATE IN C02/GRAPHITE RIGS

摘要

A study has been made of the performance of two types of isothermal calorimeter designed by Research Group to measure the radiation dose rate to graphite irradiated in the CO2/graphite rigs operated in Materials Testing Reactors. Both can be used successfully, but the Mk III calorimeter is to be recommended since it is not subject to the Compton interchange effect and can be electrically calibrated during use. The Mk I calorimeter was calibrated against the Mk III and the factor so obtained can be used to correct the results obtained from other Mk I instruments. An axial survey was also carried out in barrel 3 of the PLUTO 7V4. multi-barrel rig. Calculations indicate that about half the total dose rate in this rig arises from (n,Y) reactions in the pressure vessel.