Research of Radio-Frequency Cable for Remote Split-Body Guided Wave Radar Level Gauge in Harsh Environment

In some special places of nuclear power plant, split-type guided wave radar level measurement technology is needed, the common radio frequency(RF) cable is used for split-type, with the extension of the split-type distance, the signal attenuation is very large, resulting in the inability to receive the echo and can’t measure. Currently, almost all low attenuation RF cables that can be used for split-type measurement use foamed fluoroplastic media, but due to halogen and radiation resistance, isn’t suitable for use in nuclear power plants. From the analysis of the dielectric constant, dielectric loss angle, insulation strength and other properties of materials, polyimide, PU, EPR and other materials with excellent radiation resistance are not suitable as insulation materials for low attenuation RF cables; the RF cable of split guided wave radar level meter for nuclear power plants can only choose zero halogen materials PE/PO (cross-linked) with good radiation resistance as insulation and sheathing materials. The activation energy data of several common insulating materials (including the proposed PE/PO) were obtained by thermogravimetric and slicing methods to provide data support for the subsequent thermal aging test to identify the life of the developed cable. Using the data, suitable accelerated thermal aging tests can be conducted on the developed RF cables, proving the cables can meet the performance requirements of LSOHFR, low attenuation, and radiation resistance, and can meet the service life requirement of 60 years without replacement in nuclear power plants.