Criticality accidents detection, minimum accident of concern and slow kinetic criticality excursions: experimental data and discussions for solution systems - 6-02

This paper deals with the detection of criticality accidents and the concept of minimum accident of concern, applied for solution systems only. This paper presents a summary of main results obtained from CRAC, SILENE, TRACY and SHEBA experiments with slow kinetic criticality excursions. Then, based on a simple model, an investigation is carried out about the link between the kinetics of the criticality accident, the threshold for the detection of the criticality accident and doses received by personnel for solution systems. This investigation shows that for rapid transients, the dose for a worker is not dependent on the detection threshold when the criticality accident is detected by the CAAS (criticality accident alarm system). The detection of the criticality accident is nevertheless important in this case because it reduces the dose received after the first spike. Then, for slow kinetic criticality accident, the dose received by personnel is strongly dependent on the detection threshold. Finally, the slow kinetic experiments could lead to important doses for personnel (in a relatively short time) if these excursions are not detected. So, slow kinetic criticality excursions have to be taken into account in analysis of criticality accidents