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NEA-1865 KICHE 1.3.

KICHE 1.3, Kinetics of Iodine Chemistry in the Containment of LWRs under Severe Accident Conditions

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1. NAME OR DESIGNATION OF PROGRAM:  KICHE 1.3
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2. COMPUTERS
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Program name Package id Status Status date
KICHE 1.3 NEA-1865/01 Tested 21-JUL-2011

Machines used:

Package ID Orig. computer Test computer
NEA-1865/01 Linux-based PC,PC Windows Linux-based PC
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3. DESCRIPTION OF PROGRAM OR FUNCTION

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.
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4. METHODS

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.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM
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6. TYPICAL RUNNING TIME

A few minutes for the test cases on linux UBUNTU virtual machine running on PC Intel 686 32 bit 512 MB RAM.
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7. UNUSUAL FEATURES
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8. RELATED OR AUXILIARY PROGRAMS
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9. STATUS
Package ID Status date Status
NEA-1865/01 21-JUL-2011 Tested at NEADB
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10. REFERENCES
NEA-1865/01, included references:
- 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)
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11. HARDWARE REQUIREMENTS
NEA-1865/01
Tested at NEA DB on:
Virtual machine Intel(R) 686 32 bit 512 MB ram running Linux UBUNTU Lucid 10.04.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NEA-1865/01 FORTRAN-95
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13. SOFTWARE REQUIREMENTS
NEA-1865/01
Tested at NEA DB with Linux f95 compiler.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

Makefile in src directory should be modified to comply with the compiler used.
According to some compiler or OS used, the blank lines in the input test cases should be removed.
The bin/kiche script in some OS linux should be slightly modified if errors are encountered in running the procedure.
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15. NAME AND ESTABLISHMENT OF AUTHORS

Kiyofumi MORIYAMA, Yu MARUYAMA, Hideo NAKAMURA
Reactor Safety Research Unit
Nuclear Safety Research Center
Japan Atomic Energy Agency
Tokai-mura, Naka-gun, Ibaraki-ken
Japan
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16. MATERIAL AVAILABLE
NEA-1865/01
Fortran source codes
Makefiles
Database files
Electronic documentation
Three test cases
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17. CATEGORIES
  • G. Radiological Safety, Hazard and Accident Analysis
  • U. Chemistry

Keywords: LWR reactors, aqueous solutions, chemical reactions, containment, coolant, iodine, kinetics, light-water reactors, safety assessment, severe accident.