Within the framework of the risk-oriented analysis for the Schneller Natriumgekühlter Reaktor (SNR)-300, a survey of expert opinion was conducted in 1982 to obtain a probability distribution for the work energy release caused by an unprotected loss-of-flow (ULOF) accident. A comprehensive questionnaire on the relevant phenomena was distributed to experts from 18 organizations involved in fast breeder safety. Basic to the probabilistic procedure are the two customary concepts of probability:

  1. probability in its interpretation as limit of relative frequency
  2. probability in its interpretation as degree of belief.
As one of the results for the ULOF accident, a subjective estimate of 0.3 % was arrived at on the basis of the experts’ opinions for the probability of the work energy release exceeding the design value of the SNR-300 reactor vessel and plug.