Modeling and simulation of release of radioactivity from a typical MTR type research reactor under accidental conditions

Source term evaluation for a typical MTR type system has been carried out. For this purpose, a Matlab based program has been developed which used the Origen-2 code as a subprogram. The isotope inventory of the core of a typical MTR system has been done following a 180 days of full-power operation. The case of flow blockage accident with instantaneous release of radioactivity to containment air has been studied. The resulting source term for noble gases, for iodine, and for aerosols has been carried out for normal, emergency and for isolation states of the containment. The dependence of source term on values of exhaust rates has been studied and a typical trend of initial increase followed by approach to saturation value has been observed in all cases. The dependence of the containment retention factor on various radionuclides and on exhaust rates has also been studied in this work.