Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
*; Ijiri, Yuji*; *; *
JNC TN8400 2000-021, 66 Pages, 2000/04
JNC-TN8400-2000-021.pdf:4.38MB
A reliability evaluation for radionuclide transport analysis code, MATRICS, used in radionuclide transport analysis in the natural barrier system PA in H12 report has been carried out. Sensitivity analysis to radionuclide transport parameter in MATRICS and analytical solution has been performed, and the results of each analysis have been compared. Additionally sensitivity analysis using Talbot Method, Crump method and Hosono method has been carried out, and the results of each inverse Laplace transform method has been compared. The conclusions obtained from the results of the evaluation are summarized as follows, (1)In case of the infinite matrix diffusion distance, an error among the results of each calculation is maximum about 0.4% in the range of Pe number from 1.0 to 100. And, an error among the results of each calculation is maximum about 5.5% in the range of transmissivity from 1.0
10
to 1.010
(m
/s). (2)In case of the finite matrix diffusion distance (0.03
1.0(m)), an error among the results of each calculation is maximum about 0.7% in the range of Pe number from 1.0 to 100. And, an error among the results of each calculation is maximum about 2.4% in the range of transmissivity from 1.010 to 1.010(m/s). 3)By comparing Talbot method with other inverse Laplace transform method, Talbot method is confirmed to give similar results with other inverse Laplace transform method in the range of Pe number from 5.010
to 2.010
, and that of transmissivity below 1.010
(m/s). Therefore, it is concluded that the reliability of MATRICS are confirmed by conducting sensitivity analysis in the range of Pe number and transmissivity coefficient used in H12 report.
Muroi, Masayuki*
JNC TJ8400 2000-042, 142 Pages, 2000/02
JNC-TJ8400-2000-042.pdf:14.6MB
Hyperalkaline pore water of cementitious material used in TRU waste repository would react with bentonite and cause the increased porosity and the loss of the swelling and sorption ability. This work is a modelling study on bentonite-cement pore water. The possible extent of reaction between bentonite and cement pore water was simulated using the PRECIP reaction-transport code. Three cement pore fluid compositions (leachates 1,2 and 3) were reacted with a 1-D, 1m flowpath of bentonite (+ sand) at 25 and 70
C. Key minerals were allowed to dissolve and precipitate using kinetic reaction mechanism. Leachate 1 was the most aggressive fluid (highest pH, Na and K), and leachate 3 (1owest pH, Na and Ca) the least aggressive. Simulation with leachate 1 showed total removal of primary bentonite minerals up to 60 cm from the contact with cement after 1000 years. The maximum porosity increase observed was in leachate 1(up to 80-90%) over a narrow zone 1-2 cm. Simulations with all fluids showed total filling of pore with CSH minerals in a zone very close to the interface with the cement, whereas zeolites and sheet silicates formed far away. For a given leachate composition, there was little difference in the profiles at the two temperatures studied. It was suggested that bentonite alteration was not sensitive to the kinetic parameters over the conditions studied. The conceptual model chosen for the modelling study assumed that there was an unlimited amount of cement pore fluid available for reaction with bentonite so that the results of the simulations represent a conservative (pessimistic) estimate. There were a number of uncertainties associated with the modelling which relate to assumptions concerning: the kinetic mechanisms for dissolution and growth of minerals at elevated pH; evolving surface areas of minerals with time; thermodynamic data for CSH minerals, zeolites and aqueous species at high pH; the synergy between changing porosity and fluid ...