We studied the structure and bonding of uranyl carboxylic complexes by B3LYP hybrid density functional theory calculations． The geometry of uranyl oxalate 1:3 complex was discussed in terms of relative energy difference among the isomers． It was found out that there are several isomers that lie close in energy． The complexation of uranyl ion with formic and acetic acid was interpreted as the interaction of the HOMO (highest occupied molecular orbital) of carboxylic acid and the LUMO (lowest unoccupied molecular orbital) of uranyl ion． Consequently, uranyl formate favors monodentate coordination while the acetate favors bidentate coordination．

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  A new method was discussed to define parameters indicating the extent of colloid deposition onto solid surface, which are important to evaluate the effects of colloid filtration on radionuclide transport in a radioactive waste repository. The deposition coefficients for colloid transport in porous media were determined by the observation of colloid deposition in a parallel-plate channel. The values that were independently derived did not exceed twice as much as deposition coefficients determined by ordinary method, in which the colloid transport model was fitted to colloid breakthrough data obtained from column experiments.

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  The Horizontal Modular Storage System is the dry storage system for the spent nuclear fuel, which was developed in the USA. It is one of the candidacy concepts for the interim spent fuel storage facility installed at away from reactor in Japan. We performed the conceptual design to reduce cost and to meet Japanese safety guidelines, rules and standards, fuel specifications and seismic conditions.
  To meet Japanese conditions, the heat removal characteristic, the shielding characteristic, the aseismic characteristic and the required space are improved.
  We also performed the experiments of the thermal hydraulics in the canister to confirm the heat removal characteristic of the system. The results show that the natural convection of the helium in the canister is effective to remove the residual heat from the spent fuel and the effect is improved when the helium is pressurized.
  The storage experience in the USA and the results of this study show, the Horizontal Modular Storage System is acceptable for the interim spent fuel storage facility installed in Japan.

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  The International Commission on Radiological Protection which has published various recommendations on the radiation protection describes the system of radiation protection on the disposal of radioactive waste in Publication 46, 77 and 81. Especially, Publication 81, Radiation Protection Recommendations as Applied to the Disposal of Long-lived Solid Radioactive Waste, was published in order to supplement, update and clarify the material in Publication 46 published in 1985 in consideration of the recent international progress in the disposal of radioactive waste. At present, the study is in progress to materialize the concept and the safety regulation of geologic disposal in Japan, and it is important to reflect appropriately these international publications.
  This paper explains each paragraph in Publication 81 in order to understand the system of radiation protection on the geologic disposal fully and concretely, paying attention to the mutual relationship among each paragraph, the development of ICRP recommendations and the relationship to other publications.

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