Characteristics of Fiber Reinforced Concrete as Barrier Materials for Nuclear Waste

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In the present research, the engineering properties of fiber reinforced concrete are studied, as barrier materials for nuclear waste. Results obntained are described, as follow ;1. To determine the plausible permability of concrete, the method based on the seepage depth of NaCL solution and the finite element analysis (FEM) is investigated. Although it takes more than a week in the conventional method, the present method requires one day or so, by employing the same apparatus. In the former research (last year), the analysis of the permeability was based on the one-dimensional exact solution. To take the effect of the specimen geometry, the modification based on the FEM analysis is proposed and plausile permeability coefficients are determined in steel-fiber reinforced concrete. Results show no particular effect of fiber on the permeability, compared with normal concrete.2. The numerical mathods based on the FEM and the boundary element method (BEM) were developed. According to results of the simulation analysis on the diffusion of fission products, it is found that the diffusion effect is limitedly observed near the surface, while the convective effect distributes the products soreadly. Therefore, materials of low permeability are desirable for the barrier.3. On the basis of the state of the art review, the importance of acoustic emission (AE) monitoring is cited. Then, fundamental research on AE waveforem analysis is performed to develop the monitoring device for cracking.