Assessment of molybdenum powder discharge from Tehran research reactor due to a human error

The assessment of the absorbed doses around the nuclear reactors in normal operation and emergency condition is urgent for nuclear reactors safety. In this study the total effective dose equivalent (TEDE) for public and personnel for active molybdenum powder discharge from the 5 MW Tehran Research Reactor (TRR) due to human error using HOTSPOT 2.07 health physics code was evaluated. It was assumed that removal of the irradiated Mo quartz ampoule from the aluminum during the process can be due to a human error, e.g. the ampoule may be broken followed by discharge of the molybdenum powder in the form of gas and particulate on the universal cell then dispersed in atmosphere by radioisotopes laboratory stack. The HOTSPOT 2.07 code uses a Gaussian plume model to calculate the air concentration and dose from radioactivity releases to the atmosphere. The atmospheric stability classes (A–F) with different wind speeds at various downwind distances up to 100 km from the reactor site were assumed for dispersion calculation. Results of simulation show that the TEDE values of molybdenum powder discharge from TRR were lower than the permissible effective dose.