Uncertainty Analysis of Measuring Thermal Neutron Fluence Rate by Using ²³⁵U Fission Ionization Chamber And Gold Foil-Activation Methods

The basic principle of measuring the thermal neutron fluence rate by using ²³⁵U fission ionization chamber and gold foil-activation methods was discussed in the paper. And the standard uncertainty factors in the measuring process, such as the neutron decay, the fission count rate, the total average reactive cross section, and the gold foil-activity were evaluated. The calculated relative combined standard uncertainty for both measuring methods can meet the requirement of 2%-5%.The ways on minimizing the uncertainty of measuring results were discussed.