Keywords: probabilistic safety assessment, Bayesian reliability analysis, human reliability analysis, technique for human error rate prediction, THERP, event trees, received dose, radiological risks, radiation monitoring, monitor calibration, Brazil, nuclear power stations, low radiation
An update of the probabilistic safety assessment of the Radiation Monitor Calibration Laboratory of a Brazilian nuclear power station
In 2001, a probabilistic safety assessment of the Radiation Monitor Calibration Laboratory of a Brazilian nuclear power station was performed to estimate its radiological risk. Owing to the lack of data, many conservative assumptions were considered. The purpose of this paper is to obtain the updated laboratory radiological risk. A human reliability analysis of the procedure for calibrating the monitors was performed by applying the Technique for Human Error Rate Prediction (THERP) methodology. For facing the lack of failure data, the Bayesian approach was used for the calculation of the irradiator failure probability. The exponential distribution was used to model the failure times of the electronic dosimeters. The radiological risk was obtained through an event tree, in which all relevant scenarios were considered. Although more accident scenarios were considered in the analysis, like external events, the approach was by no means conservative, and a radiological risk about one order of magnitude smaller was obtained.