Investigations into the safe operation of research reactors. AP 1 Influence of specific facilities in research reactors on safety

This report summarizes the results of work on the influence of specific facilities in research reactors on safety. One focus of the work was on creating a methodology for the safety-related classification of experimental facilities and devices in research reactors. Based on the IAEA Safety Guide SSG-24, which distinguishes four safety categories for experimental facilities and devices depending on the safety significance, a classification was carried out in this project. For this purpose, four independent safety categories were defined for the protection objectives - compliance and maintenance of control of reactivity, cooling of the fuel elements and limitation of the release of radioactive substances (maintenance of the barriers) - in order to assign the consequences of failure, incorrect operation or operation in relation to compliance with the protection objectives and thus determine the safety significance. Based on this, a generic classification was made for various experimental facilities and devices (jet tubes, cold source, hot source, pneumatic tube systems, converter plate, irradiation/doping systems, thermal column), which reflects the safety significance of these facilities. In addition, the consequences of accidents and their effects on the safety of the system for selected experimental facilities (jet pipes and cold source) were examined using a generic ATHLET model of a research reactor.