Release measurements for materials out of controlled areas

Large amounts of dismantled materials from nuclear power plants show such a weak level of radioactivity that they could be released after decision measurements. Till some years ago, the decision measurements taken for the release were based only on determining the mass-specific activity of samples by means of gamma spectrometry and/or manual sequential measurements of the surface activity with large area gas flow counters. The choice of an appropriate measuring method, the layout of the release measurement facility (RMF), the way of preparing the material and the development of smart release procedures are very important for a large throughput and an economic performance of the release process. NIS and RADOS have developed RMF based on gross gamma activity. The NIS-RMFs have been applied for the last 10 years for decision measurements in different operated but also in dismantled nuclear power plants. Together with RMFs from RADOS, more than 12,000 Mg of various types of materials have been measured up to now with this method in Germany.