Expert judgement-based risk factor identification and analysis for an effective nuclear decommissioning risk assessment modeling

There is a growing number of decommissioned nuclear facilities, and the trend of planned nucleardecommissioning projects does not show any decline. To ensure safe and economical nuclear decommissioning, a robust risk assessment model capable of evaluating all the risk factors associated with a nuclear decommissioning project is critical. This study identifies and evaluates novel nuclear decommissioning project risk factors. A comprehensive literature search is done to identify all the relevant risk factors. Then, an expert judgement approach is used in evaluating the identified risk factors and developing novel risk factors. The expert judgement technique is implemented using a web-based questionnaire containing all 81 identified risk factors from the literature search as a prompt. The respondents are sixty recognized nuclear-decommissioning experts. Forty-eight responses were received, while 9 responses were discarded based on predefined criteria. Resulting from the unique experience of the experts in managing nuclear-decommissioning projects, twenty-four additional novel risk factors are proposed. Moreover, a scoring metric is used to evaluate the proposed novel risk factors. The result shows that the facility pre-decommissioning radiological characteristics are a major risk factor with a median score of 5, while 50 other risk factors (61.7%) have a median score of 4, and 30 risk factors (37%) has a median score of 3 or 3.5. Calculating the risk factors with the percentage scores between 4 and 5 in each risk family, it is observed that legal and regulatory framework (85.7%), stakeholders (83.3%), and initial condition of the facility (77.8%) are the highest-ranking risk family. The result serves as a pilot study that presents critical information towards the design and implementation of robust risk assessment models for nuclear decommissioning.