MACBECE (Mechanical Analysis system considering Chemical transitions of BEntonite-based and CEment-based materials) is an analysis system to evaluate the long term mechanical behavior in the TRU (TRans Uranium) waste disposal system. TRU wastes are low level radioactive wastes that include long-lived nuclides. MACBECE is the system to calculate mechanical and chemical behavior in the near field including engineered barriers in the TRU waste disposal system, and subsequently to evaluate the hydraulic property in various components. MACBECE can evaluate the mechanical/ hydraulic alterations of two types of barrier materials, cement-based and bentonite-based materials. These materials, in the long-term, may be altered internally by chemical reaction. To evaluate the long-term mechanical behavior due to the chemical transitions, the nonlinear elastic model for the cement-based materials and the elasto-viscoplastic model for the bentonite-based materials were applied, based on the data from various laboratory tests. Also, proposed models based on the data from permeability tests were applied to evaluate the alteration of hydraulic conductivity. So as to realize the high reliable evaluation, the variable-compliance-type constitutive model proposed by Okubo (1992) was newly adopted for the rock creep evaluation in MACBECE. This creep model can express analytically nonlinear visco-elastic behavior and the over-peak-strength state behavior. This paper focuses on the adoptability of rock creep model in MACBECE. Applicability of the rock creep model is verified by conducting the numerical simulations with the long-term mechanical interaction between the TRU waste disposal system and the host rock.
A simple and rapid high-performance liquid chromatographic method was developed for the simultaneous separation and identification of six different tetracycline antibiotics (minocycline, oxytetracycline, tetracycline, dimethylchlortetracycline, chlortetracycline, and methacycline) in bovine kidney, plasma and urine. The antibiotics were separated at ambient temperature on a μ-Bondapak C18 column using a mobile phase [water 760 ml, acetonitrile 240 ml, N,N′-dimethylfolmamine 60 ml, ethanolamine 5.0 ml and Na2HPO4 5.2 g, pH 2.5] at a flow rate of 1.5 ml/min. A variable-wavelength detector set at 254 nm, 0.05 AUFS and a recorder set at 4mm/min were used for the detection. The entire mixture was resolved in less than 12 min by this method. The limits of detection for the tetracyclines ranged from 1.25 to 0.125 μg/ml. Recoveries of tetracyclines from biological samples were 72.3 - 80.6% kidney, 78.2 - 83.7% in plasma and 80.2 - 88.4% in urine, respectively. The method was sensitive, reproducible, and applicable to the quantitative analysis of tetracyclines in biological samples.
IntroductionIn recent years, interest has increased concerning the environmental problem of global warming caused by carbonic acid gas exhaust from burning petroleum fuel. This is because hot dry rock energy and nuclear power plants have been increased again, and because the storage of high level radioactive waste disposal generated by nuclear power plants has been planned in rock caverns several hundred metres under the surface. Studies of these rock structures must not only evaluate the stability of rock structures themselves but also underground seepage flow caused by thermal conduction.Concerning these problems, Ohnishi et al. [1] studied details of the relations between each parameter including physical meanings in the seepage-thermomechanical coupling quasi-static problem and the discretized finite element method using Sandhu 1-2 [2]. They also investigated the discontinuous planes in which cracks and joints existing in rock mass have an important influence for evaluating the local stabilities of the excavated rock surface of slopes and underground caverns. Yoshinaka et al. [3] classified cracks and joints into the four types of small cracks: cracks, joints, shear bands and faults by focusing on the factor of length. Following this study, Sasaki[4] classified them into the two types of non-oriented small cracks and oriented joint sets and presented multiple yield models in which cracks and joints are considered as opening and slip by excavation.The authors developed the deformation-seepage-heat conduction coupled analysis code by using Ohnishi's formulations for the simple handling of nonlinearity. In order to express the influence of joint sets existing in rock mass, the compliance matrix methods presented by Cho[5] are employed. Thus, the anisotropy of deformability and permeability caused by arbitrary oriented joint sets in rock mass can be expressed and presented formulations are examined to confirm the applicability by using underground cavern models containing joint sets.
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