Joint EC/USNRC expert judgement driven radiological protection uncertainty analysis

Area of Science:

• Nuclear Engineering
• Risk Assessment
• Computational Modeling

Background:

• COSYMA and MACCS are probabilistic accident consequence codes developed by the European Commission and US NRC.
• These codes assess risks from hypothesized nuclear accidents.

Purpose of the Study:

• To conduct an uncertainty analysis of the COSYMA and MACCS codes.
• To systematically derive credible probability distributions for code input variables.

Main Methods:

• A joint project sponsored by the European Commission and US NRC.
• Formal expert judgment elicitation and evaluation process.
• Eight expert judgment exercises were performed.

Main Results:

• Development of probability distributions for input variables of COSYMA and MACCS.
• Findings from eight expert judgment exercises are described.

Conclusions:

• The expert judgment process provides a method for deriving traceable probability distributions.
• This work supports improved uncertainty analysis in nuclear accident consequence modeling.