[en] Nitrogen oxides used for desorbing iodine and oxidizing plutonium in a process for spent nuclear fuel reprocessing are prepared by electrolysis of nitric acid. Waste nitric acid recovered from the main reprocessing system is reused as the feed for the nitrogen oxides preparation. It is not necessary to supply nitric acid and sodium nitrite for preparing the nitrogen oxides from outside of the system, and the quantity of the liquid waste to be treated is reduced. (Author)

[en] In a nuclear fuel reprocessing method for supplying nitrogen oxides used for driving out iodine and for oxidizing plutonium, according to the present invention, nitric acid is decomposed in a nitrogen oxide production step to form nitrogen oxides. The nitrogen oxides formed are supplied to the reprocessing step described above. Excess nitric acid recovered from the reprocessing step is recycled to the nitrogen oxide production step. Accordingly, the amount of wastes discharged from the reprocessing step is remarkably reduced. (T.M.)

[en] If an aqueous solution of nitric acid is electrolyzed, O₂ gas is evolved at an anode and NOx is evolved at a cathode. Nitric acid is electrolyzed in an electrolytic vessel by utilizing the phenomenon, and NOx generated by electrolysis is taken out being carried on a carrier gas from the electrolytic vessel and supplied to a nuclear fuel reprocessing step. Dilute nitric acid remained in the vessel is concentrated by evaporation and the obtained concentrated nitric acid is recycled to the electrolytic vessel and electrolyzed together with wastes. Only distilled water is discarded with addition of a necessary neutralizer. With such procedures, NOx gases used in the nuclear fuel reprocessing step can be supplied by the decomposition of nitric acid. Accordingly, NaNO₃ is not generated, different from the case of prior art, and the amount of the wastes can be reduced extremely. (T.M.)

[en] The present invention provides a neutral particle injection device useful for additionally heating plasmas generated in a thermonuclear device utilizing magnetic fields to confine plasmas. Namely, a neutralization cell portion comprises a magnetic shield for shielding external magnetic fields to prevent deflection of charged particle beams and a gas cell for maintaining the pressure of a charge-exchange gas for neutralizing charged particle beams. In this case, the magnetic shield comprises a high temperature super conductive material. In addition, the magnetic shield comprising the high temperature conductive material also serves as a gas cell. When external magnetic fields such as magnetic fields leaked from a thermonuclear device are applied to the superconductive magnetic shield, Meissner current is flown on the surface of the magnetic shield. Since the magnetic fields formed by the Meissner current off-set the external magnetic fields at the inside of the shields, the external magnetic fields are shielded sufficiently. As a result, magnetic fields of several kilo gauss can be shielded to 1/1000,000. (N.H.)

[en] This investigation aims at an analytical method for calculating neutron bulk shielding in a medium-energy accelerator facility on the basis of the modified Moyer model. Shielding parameters for the analytical formula are obtained using the ANISN one-dimensional discrete ordinate code and the MCNP three-dimensional Monte Carlo code. The dose attenuation length of a concrete shield, which is the most important parameter, is obtained as a function of neutron energies from 0.2 MeV to 400 MeV and of shield thickness from 1 m to 7 m. The equation is also applicable to the estimation of neutron oblique penetration through a concrete shield, so the correction factor for oblique penetration is introduced into the analytical formula. It is expressed as the ratio of dose equivalent as calculated with MCNP for penetration through a relatively thin (1 or 2 m thick) concrete slab shield to that with the analytical equation developed in this work

[en] The present invention provides a neutral particle injection device useful for additionally heating generated plasmas in a thermonuclear device utilizing magnetic fields to confine plasmas. Namely, a cryopump for evacuating channels of charged particle beams is made of a superconductive material. A magnetic shield utilizing a Meissner effect is also provided by using the superconductive material. Then, since the cryopump and the vacuum vessel also having the effect of the magnetic shield at high shielding rare are provided, the structure is simplified as a whole and reduced in the size, and the installation space can be saved. Since the Meissner effect at a cryogenic temperature is utilized as a magnetic shield, magnetic fields of several kilogauss can be reduced to 1/100,000. Since the thickness of the material to be used both for the magnetic shield and the cryopump can be reduced to about several millimeters, the weight of the neutral particle injection device can be reduced. (I.S.)

[en] Materials and Life science Facility (MLF) is for researches on the structure and the function of materials and biological samples through scattering or diffraction experiments using neutrons and muons produced by 1MW proton beam. The central apparatus is a pulsed spallation neutron source. The target is a circulating mercury and the moderator is a supercritical hydrogen circulating in a closed loop. Thus the produced neutrons will form sharp pulses and the intensity will be highest in the world. The facility will be constructed until the middle of 2007 and the commissioning will be finished until the beginning of 2008. (K.Y.)

[en] A simple phenomenological analysis using the moving source model has been performed on the neutron energy spectra produced by bombarding thick targets with high energy heavy ions which have been systematically measured at the Heavy-Ion Medical Accelerator (HIMAC) facility (located in Chiba, Japan) of the National Institute of Radiological Sciences (NIRS). For the bombardment of both heavy ions and protons in the energy region of 100-500 MeV per nucleon, the moving source model incorporating the knock-on process could be generally successful in reproducing the measured neutron spectra within a factor of two margin of accuracy. This phenomenological analytical equation is expressed having several parameters as functions of atomic number Z_p, mass number A_p, energy per nucleon E_p for projectile, and atomic number Z_T, mass number A_T for target. By inputting these basic data for projectile and target into this equation we can easily estimate the secondary neutron energy spectra at an emission angle of 0-90 deg. for bombardment with heavy ions and protons in the aforementioned energy region. This method will be quite useful to estimate the neutron source term in the neutron shielding design of high energy proton and heavy ion accelerators

[en] The mechanism of the occurrence of diamagnetic currents in sp³-type electronic states in alkanes and pure diamonds is suggested, from analogy with the nondissipative diamagnetic currents in closed-shell electronic structures in aromatic hydrocarbons such as polyacenes and annulenes with microscopic sizes. It is found that most of all electrons can form electron pairs originating from attractive Coulomb interactions between two electrons with opposite momenta and spins occupying the same orbitals in pure diamonds with macroscopic sizes at 298 K. In principle, diamagnetic currents in alkanes and pure diamonds can be expected to occur by such electron pairing. The diamagnetic conducting transition temperature T_c^neutralNsp3 values for macroscopic sized diamonds with large valence-conduction band gaps are estimated to be much larger than the superconducting transition temperatures T_c,BCS values for the conventional superconductors with small valence-conduction band gaps. Even very small ratio of impurities or dopants would destroy possible nondissipative diamagnetic current states in the diamonds with macroscopic sizes. Therefore, very pure diamonds exhibiting nondissipative diamagnetic currents are very difficult to be produced up to now, and diamonds with impurities would become insulator or semiconductor. The technology which enables us to produce very pure diamonds in which no impurities exist is awaited to investigate whether such pure diamonds become nondissipative diamagnetic current states or not at 298 K

[en] Material and life science test facility is under the construction as a part of the Japan proton accelerator research complex (J-PARC) that utilizes an immense proton power (1-MW) accelerator. A 1-MW pulse spallation neutron source, that is the main facility at the material and life science test facility, is one of the world largest spallation neutron sources, utilizing a mercury target and liquid or supercritical hydrogen moderators. The neutron source has been designed and fabricated to exploit a state-of-the-art technology of the spallation neutron source engineering, expecting to produce one or two orders higher neutron intensity than that of the conventional neutron sources at the cold neutron regime. (author)