Experience with IEC standard 544 to assess radiation damage of organic insulating materials

The essential topics of IEC Standard 544 are presented which contains four parts: I Radiation interaction, II Procedures for irradiation, III Test procedures for permanent effects and IV Classification system for Service in radiation environments. The topics described include test procedures, critical parameters and end-point criteria, dose rate and the Radiation Index. Experience at CERN is reported which is based on radiation testing of many hundreds of organic insulating materials supplied by a large number of different manufacturers. The experience with rigid plastics, eg. epoxy resins, were extremely positive, whereas with flexible plastics, mainly cable insulation and sheath materials, several difficulties did occur. It was however found that the recommended procedure to assess the dose rate effect clearly allows to identify materials where this effect is of importance and that the Radiation Index is a simple and clearly defined tool to rank materials according to their radiation resistance. (author). 6 refs, 4 figs, 4 tabs