[en] Object: To obtain the same order of rinsing effect as with sand blasting by so arranging as to issue ice pieces of a predetermined size under a jet pressure and causing them to strike the rinsing surface of the apparatus contaminated by a radioactive contaminant, thereby removing the contaminant with the impact force produced. Structure: Pure water in a water supply tank is supplied to both a high pressure water system and an ice supply system. The pure water flowing into the high pressure water system is pressurized by a pressurizing pump into high pressure water which is fed to a mixer. Meanwhile, the pure water entering the ice supply system is frozen into ice by an ice making machine and then pulverized by an ice pulverizer into ice pieces, which are supplied to the mixer under a pressure provided by an air compressor. The high pressure water reaching the mixer and the ice pieces under the issuing pressure are mixed together in the mixer and issued from a jet nozzle toward the rinsing surface contaminated with a radioactive contaminant, whereby the rinsing surface is rinsed by the impact force produced as it is struck by the ice pieces and water. The ice pieces after use melt to form water which is recirculated to the water supply tank. (Kamimura, M.)

[en] Object: To safely place a cask in proper storing position, when trouble of cask fall occurs, without coming into collision with wall surfaces and bottom in a fuel storing pool, thereby preventing breakage of the wall surfaces and bottom in the pool. Structure: A cylindrical cylinder, of which upper part is opened and which has an inlet and an outlet for liquid, is erected within the pool filled with liquids to a predetermined level. A float type bed seat having a buoyancy is vertically slidably received within the cylinder. Thus, when the cask is fallen as a result of breakage of suspension lugs or the like, the float type bed seat causes a part of the liquid to be discharged through the inlet whereas the other part thereof to be flown onto the float type bed seat through a clearance between the bed seat and the cylinder, thus allowing the cask to move down and to be seated on the bottom of the pool. (Kamimura, M.)

[en] Spent fuel assemblies are at first washed in a washing step and radioactive cruds deposited on the outer surface of fuel rod cladding tubes are washed off. Then, they are separated into fuel assembly main bodies and channel boxes as outer frames in a separation step. The separated fuel assembly main bodies are stored in a storage cask in a storage step. Since spent fuel assemblies in the storage cask are stored after washing, it is possible to prevent contamination in the storage cask and contamination of a pool upon taking out spent fuels after completion of storage. Since the storage cask can be handled safely by preventing the contamination, a highly reliable storage method for spent fuels can be attained. (T.M.)

[en] Object: To spray chipped ice and high temperature water alternately on the surface of apparatuses contaminated by radioactivity for decontamination. Structure: Pure water in a feedwater tank separately flows into a high pressure water system and an ice feeding system. The pure water flown into the high pressure water system is pressurized by a pressure pump and heated by high pressure water or a heater into high temperature water, which reaches a spray nozzle. On the other hand, the pure water flown into the ice feeding system is frozen by an ice making machine into ice, after which it passes through an ice crusher and is formed into chipped ice of a predetermined size. After being applied with injection pressure by means of an air compressor, they reach a mixer. The high pressure water and chipped ice at injection pressure, which reached the mixer, are mixed therein and emit through the nozzle toward the surface to be washed, so that the surface to be washed are washed by the shock of chipped ice and water and the high temperature water is alternately emitted against the surface to be washed to weaken contaminated substance to increase the washing effect. (Kawakami, Y.)

[en] Pellet-like dry ice or ice is jetted to the outer surface of a radioactively contaminated equipment in water in a state where water is shielded by a gas, to clean the equipment by the impact shock upon collision of the dry ice or the ice. This enables decontamination of the equipment during use in water, which has been impossible so far by a dry ice blast method and ice blast method and, in addition, this enables reduction of radiation exposure, improvement of operation environment, saving of decontamination operation, reduction of secondary wastes and improvement of economy. (T.M.)

[en] Small angle neutron scattering study was performed in sintered Nd-Fe-B permanent magnets. The 99% enriched ¹¹B isotope was used to avoid high neutron absorption of ¹⁰B in natural boron. In all the samples examined, the intensity of scattered neutrons was proportional to the q^-4 for q<0.5 nm^-1, irrespective of the direction of q. For q>0.5 nm^-1, on the other hand, the intensity was markedly higher than that expected from the q^-4 dependence. These results show that there exists a neutron scatterer with a dimension of less than 10 nm, which is considered to be a Nd-rich grain boundary phase in the matrix of Nd₂Fe₁₄B phase. In the sample with Al and Cu additives, we observed a small but finite increase of intensity as compared with the sample without Al and Cu additives for the q range of 0.1< q<1 nm^-1. Since Al- and Cu-containing samples have higher coercivity, this result suggests that there is a correlation between the density of neutron scatterer at a Nd-rich grain boundary and the coercivity. (author)

[en] A fuel assembly is supported in a fuel pool in a state being disposed in a channel box. A plurality of ultrasonic wave oscillators are made vertically movably by an elevating mechanism for irradiating ultrasonic waves from the outside of a material to be cleaned (fuel assembly) from two directions. Ultrasonic waves are irradiated to the fuel assembly while elevating the ultrasonic wave oscillator. This removes solid contents such as radioactive cruds or scales deposited on an inner surface of the channel box or a plurality of fuel rods contained in the channel box. Removed solid contents are sucked to a discharge pump together with pool water, and transported to a capturing filter by way of a discharge pipeline. With such procedures, solid contents such as highly sticking radioactive cruds deposited on a hollow square-like material to be cleaned can be cleaned efficiently and safely. (I.N.)

[en] The purpose is to examine the combined effect of irradiation with anticancer drugs on uterine cancer, SKG-IIIb cells, cultured from squamous cell carcinoma of uterine cervix, were used in this study. Anticancer drugs were CDDP 1 μg/ml, BLM 10 μg/ml, and the radiation was ⁶⁰Co 0.5 Gy. The results were as follows: The growth of cells was the most strongly suppressed by the exposure to radiation after CDDP administration. By the exposure to radiation after anticancer drugs administration, the morphorogic damage of cells was revealed both by a light microscope and a scanning electron microscope. Flow cytometric measurement revealed that anticancer drugs changed DNA distributions of cells: the accumulation of exposed cells in S phase was showed and the cell cycle progression was delayed. DNA histograms showed no accumulation of cells in G₂⁺M phase that were most effective phase to irradiation in 24 hours after anticancer drugs administration, but partial synchronization in G₂⁺M phase in 48 hours after BLM administration. These results indicate that the combined therapy of anticancer drugs and irradiation on uterine cancer is effective and timely irradiation will be more effective. (author)

[en] Purpose: To obtain a processing and disposing container at low level radioactive wastes, excellent in corrosion and water resistance, as well as impact shock resistance for the retrieval storage over a long period of time. Constitution: The container is constituted with sands and pebbles as aggregates and glass fiber-added unsaturated polyester resins as binders. The container may entirely be formed with such material or only the entire inner surface may be formed with the material as liners. A container having excellent resistance to water, chemicals, freezing or melting, whether impact shock, etc. can be obtained, thereby enabling retrieval storage for radioactive wastes at the optimum low level. (Takahashi, M.)

[en] In a method of pelletizing radioactive wastes by drying radioactive wastes to form powders then pelletizing them by compression molding, fibrous materials having an adsorption property relative to the radioactive materials and also having an aspect ratio of from 20 to 400 are added to the powders, then the powders are compression molded to form and solidify pellets. In this case, the fibrous materials comprise at least one of fibrous active carbon having a specific surface area of not less than 10m²/g, an ion exchange fibers having an ion exchange volume of not less than 0.1meq/g, and alkali titanate fibers having an ion exchange volume of not less than 0.1meq/g. According to the present invention, since the pellets are solidified in a state where the fibrous materials are dispersed uniformly in the pellet, if the aspect ratio of the fibrous materials is within a range of from 20 to 400 not being limited to a conventional narrow range, the strength of the pellet can be ensured and radioactive materials can be prevented from leakage. (T.M.)