Practical application of the MARSSIM process to the site release of a Uranium Conversion Plant following decommissioning

Abstract

The final stage in the decommissioning process consists of releasing a site and a building from regulatory control. In this study, we describe the practical application of MARSSIM process in performing a site remediation and conducting a final status survey and discuss the lessons learned. The release criterion for the site and the building were set up using site-specific parameters that were calculated using RESRAD and RESRAD-Build codes. The planning stage of the final status survey consisted of classifying the site, identifying the survey units and selecting the background reference area using the DQO process. The planning, implementation and assessment of the final status survey for the site and the building of the Uranium Conversion Plant were carried out to demonstrate that residual radioactivity levels meet the release criterion. The null hypothesis must reject in order to demonstrate the objective, null hypothesis is that residual radioactivity in the survey unit exceed the release criterion. The survey results containing the hot spots in the building, a nonparametric statistical test (Wilcoxon Rank Sum) was chosen for assessment due to the presence of the uranium contamination in background soil. The final status survey results showed that the release criteria were satisfied.