Evolution of the Waste Characterization Process at Belgoprocess - 23071

Probably the most important process in radioactive waste management is the characterization of the radioactive material. The outcome of this process will lead to the selection of the best available technique for the further management of the material. Whenever possible, recycling or reuse of the materials should be the preferred option. In case reuse or recycling is not possible due to the properties and value of the material, the material becomes waste. Before the materials can be disposed, they need to be removed from regulatory control through the process of unconditional or conditional clearance. In some cases when the concentration of radioisotopes is simply too high, the material becomes radioactive waste. In order to make the selection of the best available technique possible, the material needs to be characterized correctly. Unfortunately, most scenarios use different types of waste acceptance criteria to define what waste can be accepted into their process. For example, the recycling option of metals by melting is mainly controlled by the total alpha and beta/gamma activity and dose rate. During the dose impact evaluation for the scenario of conditional clearance one should include all relevant radioisotopes. In Belgium the acceptance criteria of radioactive waste for surface disposal require the declaration of 63 radioisotopes and a number of chemical species (chloride, cellulose,...). The plethora of possible scenarios and their associated acceptance criteria makes it challenging to develop a uniform characterization methodology. To address this challenge Belgoprocess introduced a graded approach during the characterization process of materials generated during decommissioning of obsolete nuclear installations. Before the actual production of the material, a risk-based assessment on the application of the waste hierarchy is carried out. The input for such an assessment mainly comes from historical (process) information, field surveys and simulations. The outcome of the assessment is the management scenario that scores best in the waste hierarchy and for which the material is expected to meet the acceptance criteria. When simultaneously running numerous decommissioning and remediation projects, at different phases, some level of standardization for this assessment process is required. Therefore Belgoprocess developed and implemented a decision tree which guides the operators and health physics technicians on the floor through the process. This methodology is mainly used during the first phase of decommissioning during the removal of all materials and equipment inside the contaminated areas and hot cells. (authors)