Design of a compact detector for nuclear-fuel-rod enrichment detection

Abstract

Nuclear fuel rods are an important component of nuclear reactor operation. Current commonly used equipment adopting the neutron interrogation method for nuclear-fuel-rod enrichment detection has the disadvantages of large size, high manufacturing and operation maintenance costs, and extremely strict requirements for radiation protection. Therefore, a compact detector without radioactive sources has been designed that uses a passive method for the detection of 235U fuel rod enrichment. The test results show that the detector detects the γ-rays produced by the spontaneous decay of 235U nuclides effectively, where the absolute detection efficiency is about 5.94%. The average count rate at 185.7 keV has a good linear relationship with the corresponding enrichment of 235U. When the single-channel detection speed is 80 mm/min and the fuel rod with a matrix enrichment of 2.5%, the detector can obviously identify the anomalous pellets with enrichment deviations higher than 10%, and even distinguish the anomalous pellets with an enrichment of 2.60%. The design provides a stable performance and high confidence that meets the requirements of fuel-rod testing.