Activity emission model for VVER 440/213 reactor LOCA

Highlights: • Numerical model for VVER-440/213 LOCA activity emission was developed. • The model was used for three types of radio-nuclides (elementary ¹³¹I, ¹³³Xe, ¹³⁷Cs) isotopes. • Three cases of LOCA events were calculated. • Sensitivity to starting time of the fuel damage was examined. - Abstract: A VVER-440/213 activity emission model has been developed in order to describe the activity release process in a case of a LOCA (Loss Of Coolant Accident) event. The model uses calculated and measured data. The pressure of the hermetic rooms in a LOCA event is calculated, the leakage from the hermetic rooms at certain pressure is measured, the model also considers the starting time of the fuel damage. For the estimation of the fission products release from the fuel damage the EUR conservative approach was used. The model also deals with filtering of the emitted fission products and considers the activity changes for the given nuclides by time. Three nuclides were used for our calculations. One noble gas ¹³³Xe the behaviour of which is supposed to be similar to all other noble gases. The other two nuclides are very important from radiation protection point of view. For learning about short term contamination the ¹³¹I was chosen, for long term consequences the ¹³⁷Cs was taken