Abstract: A spent oxide form nuclear fuel in a spent nuclear fuel assembly which has been taken out from a light water reactor is reacted with fluorine in fluorination treatment process and then separated into gaseous UF6 and solid converted fluoride. The UF6 is purified in UF6 treatment Process. In electrolysis using fused fluoride process, the converted fluoride is dissolved into a fused fluoride salt (a mixture of LiF and BeF2) filled into an electrolysis cell of an apparatus for electrolysis. A first electrode, which is an anode, and a second electrode, which is a cathode, are submerged into the fused fluoride. A mixture of the oxides Li2O and BeO are added to the fused fluoride. A metallic plutonium and a metallic uranium contained in the fused fluoride is deposited onto the second electrode by energizing of the first and second electrodes.

Abstract: Most part of an amount of uranium contained in the spent nuclear fuel is removed by making fluorine or a fluorochemical act on the spent nuclear fuel to convert the uranium into UF6, and the uranium is purified through a simple method of distilling the UF6 together with a absorbent. After removing the most part of the amount of uranium, the remaining nuclear fuel material is dissolved and then transferred to an extraction process to recover plutonium. By doing so, a small sized dry process can be employed as a uranium purification process. Since the nuclear fuel material is dissolved and extracted after removing most part of an amount of uranium, a volume of processing solution can be reduced and the machine installation scale can be made small. Accordingly, the reprocessing facility can be extremely downsized.

Abstract: A subterranean environment evaluating apparatus and method, which measure, e.g., the geologic distribution coefficient in a subterranean environments using, e.g., a pit formed by boring. The subterranean environment evaluating apparatus comprises a geologic evaluation sensor, a pump, an analyzer, a PC, a data transmitter, etc., and it is disposed in the pit formed underground by boring. The geologic evaluation sensor is disposed to form a thin layer channel defined by the surface of a rock bed. Groundwater mixed with a tracer is caused to flow through the sensor, and the analyzer measures a change of tracer concentration in the groundwater between before and after contact of the groundwater with the rock bed. The PC determines a breakthrough curve from the change of tracer concentration, thereby calculating the distribution coefficient (Kd) between the rock bed and the groundwater and the effective diffusion coefficient of the rock bed.

Abstract: It is an object to increase a reprocessing speed of spent nuclear fuel and to obtain uranium having a high purity and a plutonium mixture reusable as it is at a low cost through a simple procedure. The spent nuclear fuel 1 is subjected to fluorination using fluorine 2 in a fluorination step 3, and as a result, uranium, a mixture of uranium and plutonium and a fission product are separated and recovered independently of one another. The plutonium fluoride volatilized in the fluorination is recovered along with a fixing agent and then passed through an oxidative conversion step 8, thereby recovering a mixture of uranium and plutonium oxides 9. Since the uranium can be recovered in a high purity, it is managed very easily when reused or saved. Further, since the uranium and plutonium are recovered as a mixture thereof, fuel reproduction cost is decreased and prevention of proliferation is strengthened.

Abstract: A subterranean environment evaluating apparatus and method, which measure, e.g., the geologic distribution coefficient in a subterranean environments using, e.g., a pit formed by boring. The subterranean environment evaluating apparatus comprises a geologic evaluation sensor, a pump, an analyzer, a PC, a data transmitter, etc., and it is disposed in the pit formed underground by boring. The geologic evaluation sensor is disposed to form a thin layer channel defined by the surface of a rock bed. Groundwater mixed with a tracer is caused to flow through the sensor, and the analyzer measures a change of tracer concentration in the groundwater between before and after contact of the groundwater with the rock bed. The PC determines a breakthrough curve from the change of tracer concentration, thereby calculating the distribution coefficient (Kd) between the rock bed and the groundwater and the effective diffusion coefficient of the rock bed.

Abstract: It is an object to increase a reprocessing speed of spent nuclear fuel and to obtain uranium having a high purity and a plutonium mixture reusable as it is at a low cost through a simple procedure.

Abstract: Most part of an amount of uranium contained in the spent nuclear fuel is removed by making fluorine or a fluorochemical act on the spent nuclear fuel to convert the uranium into UF6, and the uranium is purified through a simple method of distilling the UF6 together with a absorbent. After removing the most part of the amount of uranium, the remaining nuclear fuel material is dissolved and then transferred to an extraction process to recover plutonium. By doing so, a small sized dry process can be employed as a uranium purification process. Since the nuclear fuel material is dissolved and extracted after removing most part of an amount of uranium, a volume of processing solution can be reduced and the machine installation scale can be made small. Accordingly, the reprocessing facility can be extremely downsized.

Abstract: A dissolved substance contained in a solution is oxidized or reduced by adding a particulate semiconductor photocatalyst and a water-soluble electron acceptor or donor for the particulate semiconductor photocatalyst to a solution containing a dissolved substance, and irradiating the particulate semiconductor photocatalyst in the solution with an electromagnetic wave having an energy high enough to excite the particulate semiconductor photocatalyst, or by adding a particulate semiconductor photocatalyst and a water-soluble electron acceptor or donor for the particulate semiconductor photocatalyst to a solution containing a dissolved substance and irradiating the particulate semiconductor photocatalyst in the solution with an electromagnetic wave having an energy high enough to excite the particulate semiconductor photocatalyst and having a wavelength outside the absorption wavelength region of a precursor substance capable of producing an oxidation or reduction reaction-inhibiting substance, whereby (1) ions o