Safety Assessment Framework for Nuclear Power Plant Decommissioning Workers

Considering that the nuclear power plants have a licensed lifetime, the need for research on decommissioning is increasing along with the number of aging plants globally. Unlike the dismantling of other buildings, the decommissioning of a nuclear power plant involves radiation risk, which necessitates a new systematic safety assessment to reduce this risk. This paper proposes a framework for the safety assessment of workers in nuclear power plant decommissioning. The first step of the process is accident identification, in which initiating events caused by mechanical failures or human errors are identified and categorized in accordance with their causes. The second step is frequency analysis, in which worker exposure in normal conditions is evaluated to derive the work time for each required task, and possible events that may happen during each task are derived through both a hazard and operability study and a failure mode and effect analysis. The third step, consequence analysis, models accident scenarios using the dose assessment program VISIPLAN, and evaluates worker exposure in those accident scenarios. The last step is risk analysis, where radiological risk is calculated quantitatively by the frequencies and exposure results of potential accidents. By performing the safety evaluations according to the proposed framework, the safety of workers in nuclear power plant decommissioning may be increased.