| Summary: | 碩士 === 國立臺灣大學 === 農業工程研究所 === 83 === The EQ3NR geochemical equlibrium model and HYDROGEOCHEM
geochemical transport model are used to simulate the
radionuclides transport through concrete barrier made from four
brand cements, "TAIWAN " , "ASIA" , "CHIA SHIN" , "UNIVERSAL".
reaction is incorporated into the geochemical transport model to
account the variation of concentraion due to nuclides decay on
the simulating domain and boundary. After validating the models, four nuclides, Co-60 Sr-90 Cs-137 I-129, are selected for modeling release from the waste canister. Three transport
schemes included
<1> diffusion under a constant concrete porosity,
<2> advection and diffusion/dispersion under a constant
concrete porosity,
<3> advection and diffusion/dispersion under a changable
concrete porosity are investigated. An one-dimensional
reactive radionuclides transport for aqueous complextion,
oxidation/reduction, dissolution/precip concerntration are
similar for four brand concrete barriers, (2) only Co(OH)2(s) precipitated at the interface of the waste canister and the
bottom of concrete, (3) the maximum concentration of Co-60,
Sr-90, Cs-137 appear on 50, 100, 100 years respectivel simulated
time increases at the bottom concrete and backfill clay
interface. (4) the nuclides concerntration are similar for both
types <1> and <2> transport schemes, (5) the nuclides
concerntration of type <3> transport schemes are one order of
magnitude greater than type <1> and <2> transport schemes at the
bottom concrete and backfill clay interface. It suggests that
adsorption/desorption reactions should be included in the
reactive radionuclide transport model in the future study.
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