The fission isotope target tube was irradiated in a special fuel element of SPRR-300. A positioner for the irradiation assembly was made to practise putting

fetching

and locating the tube

and fixing the electric thermo-couples lead wires

and so on. The axial distribution of neutron fluence rate

the neutron fluence rates at the water gap

and outer and inner walls of the tube were measured. After the reactiveness of the tube was obtained

temperatures at the walls of the tube and at water of the reactor pool were measured at five power steps. The thermal neutron fluence subsidence factor measured is basically in conformity with the self-shield factor deduced from the report of the producer of the tube. By comparing temperatures measured of the outer wall of the tube with those calculated

it is thought that the thermo physical parameters given by the tube’s producer are accurate.