SAFETY DURING WHOLE LIFE TIME – AN IMPORTANT ASPECT IN SAFETY ASSESSMENT OF SEALED RADIOACTIVE SOURCES

Many sealed sources with long half-life isotopes commonly used in industry or medicine have a long working life, up to several decades. Source integrity must be guaranteed in transport and use at any time. On the one hand, safety during the working life has to be ensured by the source design. Its strain has to be tested. On the other hand, source durability depends on the specific operating conditions. BAM has to assess the suitability of a source design for safe transport and use also for a longer service life in different domains: BAM is the competent authority for approvals for special form radioactive material (in regulations for transport) and for type testing of devices with inserted radioactive material (in the German Radiation Protection Ordinance). Furthermore, BAM has to give an expert opinion if applicants want to extend the period of the required yearly leak test for high activity radioactive sources. In all these domains BAM has to assess if design and additional arrangements are qualified and guaranteed to prevent a release of radioactive content under the mechanical, chemical and physical operating conditions of the specified working life. As a result, limits for the duration of validity of the special form status of a source or a type approval of a device are specified and, in many cases, special additional responsibilities for users, like periodical control and test measurements, have to be specified as binding conditions. This paper will present BAM’s experiences and show which aspects should be considered in assessment of a lifetime limit of sealed sources.