Modeling and simulation of radio-iodine released inside the containment as result of an accident

• Semi Kinetic modeling for in-containment iodine activity.
• Development Iodine Activity Released in Containment air (IARIC) code in FORTRAN.
• Modeling and Simulation of iodine activity with containment response.

Significant amount of radioactive iodine could release from a commercial Nuclear Power Plant (NPP) in case of accident or due to rapture in primary loop piping. Quantification of iodine inside the containment is essential to study during normal or emergency situations of a NPP because it delivers the thyroid and lungs dose to workers in control room and in the surroundings. In this work, a semi kinetic model Iodine Activity Released in Containment air (IARIC) has been developed for parametric sensitivity study of iodine inside the containment. The model has been developed and implemented in FORTRAN 90 which contains deterministic and as well as a kinetic approach. The IARIC uses the isotope inventory evaluated by ORIGEN2 code (Croft, A. G., 1980) and isotopes data to determine the quantification of airborne iodine and its isotopes as a function of time. The sensitivity analysis of airborne iodine has been carried out as time dependent functions of recirculation rate, leakage rate, release rate with coolant, time dependent mixing rate in coolant. The effect of spray flow rate and spray droplet size has also been investigated. Kinetic simulation with continuous source of iodine as time dependent function of mixing rate (wx) shows that wx has a significant effect on airborne iodine activity. The iodine spray cleanup rate evaluated by IARIC are 3.22 h−1 and 6.68 h−1 which are in consistent with the rate found in literature.