Measurement of fast neutrons with 238U-coated fission chamber

A fission chamber with two layers of 238U fissile materials has been developed for the measurements of fast neutrons. The developed fission chamber has been tested by 60Co gamma source and 252Cf neutron source. The results have indicated that it is very easy to cut off the gamma rays from the neutrons by using a discriminator, when the fission chamber works in the pulse mode. The detector works well, even if the static air is used as the filling gas. To discuss the application of the detector, Monte Carlo simulations have been performed by considering four 238U-coated fission chambers located outside the spallation target for the fast neutron measurement from spallation reaction. The simulation results have indicated that the detector can be used to measure the fast neutron flux and neutron flux ratio of four fission chambers. Furthermore, a 238U-coated fission chamber can be used within a reactor for longer time, in comparison with a 235U-coated fission chamber.