Study of gamma irradiation effects on coaxial cables

In nuclear industry, RG58C/U cables are widely used in high radiation environments. The incident gamma rays knock out electrons from cable core to the outer shield and hence, results in flow of current. Moreover, radiations also induce conductivity in the dielectric resulting in an increase in the leakage current. The two processes cause a steady state radiation induced current in the coaxial cable. This radiation induced current degrades the actual signal from the detector. In this paper, the initial experimental results performed at Pakistan Institute of Nuclear Science and Technology (PINSTECH) and Nuclear Medicine Oncology and Radiotherapy Institute (NORI) are presented. It is observed that radiation induced current has a prompt jump and then raises slowly to a saturation value around 35 pA. RG58C/U coaxial cable was exposed to different dose rates and the normalization factors were determined to be 4.66×10^-14 Coul/rad.cm and 2.52×10^-14 Coul/rad.cm for spent fuel element and Co-60 sources respectively.