Lessons learnt in metallic materials clearance projects

The operational and decommissioning waste minimization can be achieved by appropriate management of residual materials. Two main categories are dominant in non-activated residual materials, one of them is the metallic materials the other is the building debris. The availability of specific clearance standards (i.e. clearance levels) allows to define, plan, execute and closure comprehensive projects to deal with those contaminated materials. The conceptual approach is based on use of a derived quantity namely Residual Activity Index (RAI), systematic use of Data quality Objectives in different characterization stages, selection of appropriate measurement equipment to segregate and sentencing the materials and a set of Decision rules based on non-parametric tests of hypothesis. All this elements has been tested and implemented in different projects permitting to clear more than 1000 tons. Finally the data quality analysis has permitted to validate the non parametric hypothesis testing used in a cost-effective way and to demonstrate that probability distributions are contaminated distributions because the use of limits of detection of the measurement equipment.