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Journal Articles

Release behaviors of elements from an Ag-In-Cd control rod alloy at temperatures up to 1673 K

Nagase, Fumihisa; Otomo, Takashi; Uetsuka, Hiroshi*

Nuclear Technology, 208(3), p.484 - 493, 2022/03

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

An Ag-In-Cd control rod alloy was heated in argon or oxygen at 1073-1673 K for 60-3600 s and the release behavior of the elements was examined. Complete liquefaction of the alloy occurred between 1123 and 1173 K, and elemental release was quite limited below the liquefaction temperature. In argon, almost all of the Cd content was released within 3600 s at $$>$$ 1173 K and within 60 s at $$>$$ 1573 K, while the released fractions of Ag and In were $$<$$ 3% and $$<$$ 8%, respectively. In oxygen, the release of Cd, which was quite small at temperatures up to 1573 K, drastically increased to $$sim$$ 30-50% at 1673 K for short periods. Releases of Ag and In were also small in oxygen under the examined conditions. Comparison with the experimental data suggests that conventional empirical release models may underestimate the Cd release at lower temperatures just after control rod failure in severe accidents.

Journal Articles

Implementation of a low-activation Au-In-Cd decoupler into the J-PARC 1 MW short pulsed spallation neutron source

Teshigawara, Makoto; Ikeda, Yujiro; Oi, Motoki; Harada, Masahide; Takada, Hiroshi; Kakishiro, Masanori*; Noguchi, Gaku*; Shimada, Tsubasa*; Seita, Kyoichi*; Murashima, Daisuke*; et al.

Nuclear Materials and Energy (Internet), 14, p.14 - 21, 2018/01

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

We developed an Au-In-Cd (AuIC) decoupler material to reduce induced radioactivity instead of Ag-In-Cd one, which has a cut off energy of 1eV. In order to implement it into an actual moderator-reflector assembly, a number of critical engineering issues need to be resolved with regard to large-sized bonding between AuIC and A5083 alloys by the hot isostatic pressing process. We investigated this process in terms of the surface conditions, sizes, and heat capacities of large AuIC alloys. We also show a successful implementation of an AuIC decoupler into a reflector assembly, resulting in a remarkable reduction of radioactivity by AuIC compared to AIC without sacrificing neutronic performance.

Journal Articles

Validation of PHITS spallation models from the perspective of the shielding design of transmutation experimental facility

Iwamoto, Hiroki; Meigo, Shinichiro

EPJ Web of Conferences, 153, p.01016_1 - 01016_9, 2017/09

 Times Cited Count:2 Percentile:83.14

Journal Articles

Implementation of tetrahedral-mesh geometry in Monte Carlo radiation transport code PHITS

Furuta, Takuya; Sato, Tatsuhiko; Han, M. C.*; Yeom, Y. S.*; Kim, C. H.*; Brown, J. L.*; Bolch, W. E.*

Physics in Medicine & Biology, 62(12), p.4798 - 4810, 2017/06

 Times Cited Count:10 Percentile:56.96(Engineering, Biomedical)

A new function to treat tetrahedral-mesh geometry, a type of polygon-mesh geometry, was implemented in the Particle and Heavy Ion Transport code Systems (PHITS). Tetrahedral-mesh is suitable to describe complex geometry including curving shapes. In addition, construction of three-dimensional geometry using CAD software becomes possible with file format conversion. We have introduced a function to create decomposition maps of tetrahedral-mesh objects at the initial process so that the computational time for transport process can be reduced. Owing to this function, transport calculation in tetrahedral-mesh geometry can be as fast as that for the geometry in voxel-mesh with the same number of meshes. Due to adaptability of tetrahedrons in size and shape, dosimetrically equivalent objects can be represented by tetrahedrons with much fewer number of meshes compared with the voxels. For dosimetric calculation using computational human phantom, significant acceleration of the computational speed, about 4 times, was confirmed by adopting the tetrahedral mesh instead of the voxel.

Journal Articles

Development of numerical modeling assistance system for finite element analysis

Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Suzuki, Yoshio

Nihon Kikai Gakkai Dai-24-Kai Sekkei Kogaku, Shisutemu Bumon Koenkai Koen Rombunshu (USB Flash Drive), 9 Pages, 2014/09

In this paper, a numerical analysis's controlling and managing system is suggested, which controls the modelling process and data treating for structural robustness, although a numerical analysis's manager only controls a structural analysis by finite element method. The modeling process is described by the list of function ID and its procedures in a data base. The analytical modeling manager executes the process by order of the lists for simulation procedures. The manager controls the intention of an analysis by changing the analytical process one to another. Modeling process was experimentally found that may subject to the intention of designing index. In the numerical experiments, K, supercomputer is utilized by using parallel computing resource with the controlling and managing system.

Journal Articles

Advanced design of high-intensity beam transport line in J-PARC

Sakamoto, Shinichi; Meigo, Shinichiro; Fujimori, Hiroshi*; Harada, Masahide; Konno, Chikara; Kasugai, Yoshimi; Kai, Tetsuya; Miyake, Yasuhiro*; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 562(2), p.638 - 641, 2006/06

 Times Cited Count:8 Percentile:51.6(Instruments & Instrumentation)

Materials and Life Science Facility of Japan Proton Accelerator Research Complex (J-PARC) is an experimental facility where neutron and muon beams are provided as powerful probes. They are generated with high-intensity proton beam supplied through a 3-GeV proton beam transport (3NBT) line. Its beam optics and components were designed to transport the proton beam of large emittance with extremely low loss rate. The 3NBT accommodates an intermediate target that causes large beam loss. The scheme of the cascade target system was carefully devised to overcome difficulties due to high radiation.

Journal Articles

Vaporization behaviour of Pu-Cd intermetallic compounds

Nakajima, Kunihisa; Nakazono, Yoshihisa; Arai, Yasuo

Recent Advances in Actinide Science, p.448 - 450, 2006/06

A pyrochemical process for the metallurgical treatment of the spent nuclear fuels contains the Cd-distillation step, where Pu is recovered as a residue. For understanding this Cd-ditillation behavior the samples of PuCd$$_{2}$$+PuCd$$_{4}$$ and PuCd$$_{4}$$+PuCd$$_{6}$$ were prepared and Knudsen-cell mass-spectrometric measurements were carried out to determine the vapour pressures of Cd(g) over these samples. Further,the thermodynamic quantities of PuCd$$_{2}$$ and PuCd$$_{4}$$ were evaluated from these vapour pressures.

Journal Articles

Distillation of cadmium from uranium-plutonium-cadmium alloy

Kato, Tetsuya*; Iizuka, Masatoshi*; Inoue, Tadashi*; Iwai, Takashi; Arai, Yasuo

Journal of Nuclear Materials, 340(2-3), p.259 - 265, 2005/04

 Times Cited Count:23 Percentile:81.54(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

The Role of high-injection effects on the transient ion beam induced current response of high-speed photodetectors

Laird, J. S.; Hirao, Toshio; Onoda, Shinobu*; Kamiya, Tomihiro

Nuclear Instruments and Methods in Physics Research B, 219-220, p.1015 - 1021, 2004/06

 Times Cited Count:7 Percentile:46.34(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Electrode reaction of the Np$$^{3+}$$/Np couple at liquid Cd and Bi electrodes in LiCl-KCl eutectic melts

Shirai, Osamu; Uozumi, Koichi*; Iwai, Takashi; Arai, Yasuo

Journal of Applied Electrochemistry, 34(3), p.323 - 330, 2004/03

 Times Cited Count:27 Percentile:52.61(Electrochemistry)

The electrode reactions of the Np$$^{3+}$$/Np couple at liquid Cd and Bi electrodes were investigated by cyclic voltammetry at 723, 773 and 823 K in LiCl-KCl eutectic melt. It was found that the diffusion of Np$$^{3+}$$ in the salt phase was a rate-determining step in the cathodic reaction when the concentration of NpCl$$_{3}$$ was less than about 1 wt.% and the liquid Cd or Bi phase was not saturated with Np. The redox potentials of the Np$$^{3+}$$/Np couple at liquid Cd electrode at 723, 773 and 823 K were observed more positively than those at Mo electrode by 0.158, 0.140 and 0.126 V, respectively. The potential shift would result from a lowering of activity of Np in Cd phase according to the alloy formation of NpCd$$_{11}$$ at 723 K and NpCd$$_{6}$$ at 773 and 823 K. The redox potentials of the Np$$^{3+}$$/Np couple at liquid Bi electrode at 723, 773 and 823 K were more positive than those at Mo electrode by 0.427, 0.419 and 0.410 V, respectively, which would be attributable to a lowering of activity of Np in Bi phase according to the formation of NpBi$$_{2}$$.

Journal Articles

Development of Decommissioning Engineering Support System(DEXUS) of the Fugen Nuclear Power Station

Iguchi, Yukihiro*; Kanehira, Yoshiki*; Tachibana, Mitsuo*; Johnsen, T.*

Journal of Nuclear Science and Technology, 41(3), p.367 - 375, 2004/03

The Fugen Nuclear Power Station (NPS) was shut down permanently in March 2003, and preparatory activities are underway to decommission the Fugen NPS. An engineering system to support the decommissioning is being developed to create a dismantling plan using state-of-the-art software such as 3-dimentional computer aided design (3D-CAD) and virtual reality (VR). In particular, an exposure dose evaluation system using VR has been developed and tested. The total system can be used to quantify radioactive waste, to visualize radioactive inventory, to simulate the dismantling plan, to evaluate workload in radiation environments and to optimize the decommissioning plan. The system will also be useful for educating and training workers and for gaining public acceptance.

Journal Articles

Electrochemical behaviors of uranium and plutonium at simultaneous recoveries into liquid cadmium cathodes

Uozumi, Koichi*; Iizuka, Masatoshi*; Kato, Tetsuya*; Inoue, Tadashi*; Shirai, Osamu*; Iwai, Takashi; Arai, Yasuo

Journal of Nuclear Materials, 325(1), p.34 - 43, 2004/02

 Times Cited Count:106 Percentile:98.87(Materials Science, Multidisciplinary)

Experiments were conducted on simultaneous recovering of uranium and plutonium electrochemically into laboratory scale liquid cadomium cathodes(LCCs) at different U/Pu ratios in the salt phase. The influence of the salt composition on the recovered amount of uranium and plutonium, the morphology of uranium and plutonium in the LCCs, and the behavior of americium were examined. It was shouwn that there is a threshold in the U/Pu ratio in the salt phase for the successful simultaneous recovery of uranium and plutonium up to 10wt% in high current efficiencies.

Journal Articles

Recovery of plutonium and uranium into liquid cadmium cathodes at high current densities

Kato, Tetsuya*; Uozumi, Koichi*; Inoue, Tadashi*; Shirai, Osamu*; Iwai, Takashi; Arai, Yasuo

Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.1591 - 1595, 2003/11

Electrolysis experiments were carried to recover plutonium and uranium into liquid cadmium cathodes from molten salt at high cathode current densities. In the electrolysis at 101mA/cm$$^{2}$$, 10.4wt.% of heavy metals in the cathode was recovered at almost 100% of current efficiency. In the electrolysis at 156mA/cm$$^{2}$$, the cathode potential ascended after approximately 8wt.% of heavy metals was recovered and some deposit was observed outside of the crucible.

Journal Articles

Uptake of cadmium by synthetic mica and apatite; Observation by micro-PIXE

Kozai, Naofumi; Onuki, Toshihiko; Komarneni, S.*; Kamiya, Tomihiro; Sakai, Takuro; Oikawa, Masakazu*; Sato, Takahiro

Nuclear Instruments and Methods in Physics Research B, 210, p.513 - 518, 2003/09

 Times Cited Count:8 Percentile:51.11(Instruments & Instrumentation)

This study examined removal of cadmium from solution by two materials with high sorptivity for cadmium: a synthetic mica named Na-4 mica and an apatite. At an initial Cd concentration of 1$$times$$10$$^{-4}$$M and a starting pH of 3, the distribution coefficient of Na-4 mica for Cd (8.4$$times$$10$$^{5}$$ml/g) was one order of mgnitude of higher than that of apatite (8.2$$times$$10$$^{4}$$ml/g). On the other thand, micro-PIXE anaysis for a mixture of equal mass of Na-4 mica and apatite contacted with Cd solution under the same conditions revealed that Cd was selectively taken up by the apatite in the mixture, while Cd was not detected on the Na-4 mica in the mixture. This result by micro-PIXE analysis is not what is expected from the above distribution coefficient values of Na-4 mica and apatite. This result can be explained by irreversibility of the uptake and the difference in kinetics of the uptake by the Na-4 mica and apatite.

Journal Articles

Interaction between small-scale zonal flows and large-scale turbulence; A Theory for ion transport intermittency in tokamak plasmas

Li, J.; Kishimoto, Yasuaki

Physical Review Letters, 89(11), p.115002_1 - 115002_4, 2002/09

 Times Cited Count:31 Percentile:77.96(Physics, Multidisciplinary)

Interaction between small-scale zonal flows and large-scale turbulence is investigated. The key mechanism is identified as radially non-local mode coupling. Fluctuating energy can be non-locally transferred from the unstable longer to stable or damped shorter wavelength region, so that turbulence spectrum is seriously deformed and deviated from the nonlinear power law structure. Three-dimensional gyro-fluid ion temperature gradient (ITG) turbulence simulations show that an ion transport bursting behavior is consistently linked to the spectral deformity with the causal role of ITG-generated zonal flows in tokamak plasmas.

Journal Articles

Electrode reaction of the U$$^{3+}$$/U couple at liquid Cd and Bi electrodes in LiCl-KCl eutectic melts

Shirai, Osamu; Uozumi, Koichi*; Iwai, Takashi; Arai, Yasuo

Analytical Sciences (CD-ROM), 17(Suppl.), p.959 - 962, 2002/03

no abstracts in English

Journal Articles

Radiation induced segregation and freely migrating defects

Iwase, Akihiro

Materia, 41(1), p.20 - 27, 2002/01

no abstracts in English

Journal Articles

Temperature dependence of heavy ion induced current transients in Si epilayer devices

Laird, J. S.; Hirao, Toshio; Onoda, Shinobu; Mori, H.; Ito, Hisayoshi

Proceedings of 6th European Conference on Radiation and its Effects on Components and System (RADECS 2001) (CD-ROM), 7 Pages, 2002/00

no abstracts in English

Journal Articles

High-energy particle transport code NMTC/JAM

Niita, Koji*; Takada, Hiroshi; Meigo, Shinichiro; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research B, 184(3), p.406 - 420, 2001/11

 Times Cited Count:77 Percentile:97.82(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

A Design stufy of hydrogen isotope separation system for ITER-FEAT

Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka

JAERI-Tech 2001-027, 29 Pages, 2001/03


no abstracts in English

81 (Records 1-20 displayed on this page)