The PSIodine Code: A computer program to model experimental data on iodine and other species in irradiated CsI solutions sparged with argon, air, or nitrous oxide

摘要: Abstract Experimental study programmes were carried out at Paul Scherrer Institute (PSI), Switzerland on iodine behaviour under conditions relevant to postulated severe-accidents in NPP containments. To interpret the results obtained from bench-scale, gas-sparged and irradiated iodide solutions, a mechanistic computer code (PSIodine) was developed using FACSIMILE Software provide data for comparison. The models reactions oxidation states −1 +5 solution strong (N 2 O-saturated) weak oxidising (argon- air-saturated) conditions. An empirical model transport I other species gas space by bubbles (sparging). By measured mass transfer rates specific reaction vessels, need apply assumptions, e.g., uniform estimated bubble sizes concentration, diffusion coefficients, circumvented. same rate irradiation of CsI solutions with without additional ions, % yields initial chemical can be compared. Reaction changes due evaporation are also modelled. predicted experimental (I fractional releases, pH H O formation) correlate well concentrations 4.0 × 10 −5 1.0 × 10 −3  mol dm 4.6–7.1 systems air-sparged solutions). Data correlations O-saturated solutions) satisfactory. Irradiated containment atmospheres generate oxides nitrogen, which form nitrate nitrite ions sump. Nitrate up 5.0 × 10 argon or lower release ( Cripps et al., 2011 ). confirms observed trend releases range 4.6–7.1. Silver aerosols control rods PWR severe accidents AgI. decomposition aqueous colloidal suspensions AgI investigated 188 Re as an situ beta-radiation source Guntay 2005 Under conditions, large fractions released. described predicts support interpretation direct particle surfaces.