Risk analysis of practical model facility for MOX fuel fabrication

Tamaki, Hitoshi ; Yoshida, Kazuo ; Hamaguchi, Yoshikane*

A Probabilistic Safety Assessment (PSA) procedure for MOX fuel fabrication facilities (MFFF) was developed at Japan Atomic Energy Agency from 2001 to 2005 and some improvement has been continued. The developed procedure consists of two steps. The first step called as preliminary PSA is carried out for selection of significant events with relatively higher risk among abnormal events that cause potentially release of radioactive materials. The second step is carried out to evaluate risks of the selected significant events in more detail. This step includes the accident scenario analysis, the evaluation of accident frequencies and consequences. The latter step is called as detailed PSA, because it is carried out in the same way of level 1 PSA and level 2 PSA for nuclear power plants. To understand a trend of risk-profile of typical MFFF, the developed procedure was applied to a model facility of MFFF that was based on the information of process design and handling quantities of materials obtained from open documents of a planned MOX fabrication plant in Japan. As the results of application of the procedure to the model plant, a risk-profile was obtained that was drawn by the risk of dominant accident sequences anticipated in whole process of the plant.