KICHE 1.3: Kinetics of Iodine CHEmistry KInetics of CHemical Evolution.
Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki-ken, Japan, through the OECD Nuclear Energy Agency Data Bank, Issy-les-Moulineaux, France.
F95; Linux (C00796PCX8600) (NEADB ID: NEA-1865/01).
KICHE numerically solves the mechanistic model for iodine chemical reactions in the containment vessel of light water reactors during a severe accident. The system is a vessel containing gas and aqueous phases and walls simulating the containment vessel or a part of it. The vessel inside is at an assumed temperature, pressure and irradiation (mainly gamma-rays from fission products) condition. Iodine released from the damaged core is mainly non-volatile iodide, and it is readily absorbed in water by the containment spray. However, the irradiated condition in the containment may cause radiation chemical reactions converting iodide into volatile iodine species such as elemental iodine or organic iodine that eventually releases to the gas phase. The purpose of the model is to evaluate the amount and the species of volatile iodine released by such radiation chemical effects.
KICHE simulates such chemical behavior of iodine under
irradiation by mechanistic model. The system is dominated by reactions specific
to an irradiated environment, in which chemical effects by water radiolysis
products (radicals) prevail. Thus the primary reaction field is the aqueous
phase. In a so-called mechanistic model, the generation and interactions of
water radiolysis products, their reactions with iodine species, and some
non-chemical processes such as adsorption and interface mass transfer are
handled. Those reactions and transfer laws are converted into a set of ordinary
differential equations and solved numerically. Each reaction and rate constant
is given by referring a database constructed with knowledge from fundamental
researches. On the other hand, a semi-empirical model uses a more simplified
overall reaction set (especially, water radiolysis is not treated directly)
with rate constants tuned on experimental data. While the mechanistic model has
a large number of reactions and needs more computer resource than the
semi-empirical model, the advantage is its versatility and the availability as
a tool for examination of mechanisms. Also, recent PCs and usage of an implicit
scheme on the time integration make the mechanistic model practical enough.
The system to be simulated has its attributes described in the input file such as aqueous and gaseous volumes, wall surface areas, gas-liquid interface area, temperature, dose rate and so on. The system volume is called "cell". At present KICHE handles one cell only. Extension to more cells is possible, working on the code.
Less than 10 minutes on most modern computers.
Fortran 95 compiler.
10.a Documentation included in package:
Kiyofumi Moriyama, Yu Maruyama and Hideo Nakamura: “Kiche: A Simulation Tool for Kinetics of Iodine Chemistry in the Containment of Light Water Reactors Under Severe Accident Conditions,” JAEA-Data/Code 2010-034 (December 2010).
The package will be transmitted in a self-extracting executable containing source, data files, sample problems, documentation and reference materials.