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Sanada, Yukihisa; Takamura, Yoshihide; Urabe, Yoshimi; Tsuchida, Kiyofumi; Nishizawa, Yukiyasu; Yamada, Tsutomu; Sato, Yoshiharu; Hirayama, Hirokatsu; Nishihara, Katsuya; Imura, Mitsuo; et al.
JAEA-Research 2014-005, 67 Pages, 2014/05
JAEA-Research-2014-005.pdf:52.68MB
Distribution of radiocesium existing on the waterbed such as lake or pond was concerned about at the present that passed for two years by an accident. Here, the direct measurement technique of the radiocesium concentration (in-situ measurement technique) was developed. This method was used an plastic scintillation detector (p-Scanner). This detector carried out quick measurement of a large area. In addition, the count-rate of p-Scanner was converted to the radiocesium concentration (Ba/kg-wet) by comparative measurement of 
-ray spectrometer. We applied the technique to the agricultural pond in Fukushima and made a map of distribution of radiocesium concentration.
Yasuda, Atsushi; Ueta, Shohei; Aihara, Jun; Ishibashi, Hideharu*; Sawa, Kazuhiro
JAEA-Technology 2008-083, 11 Pages, 2009/01
JAEA-Technology-2008-083.pdf:3.14MB
The Very-High-Temperature Reactor (VHTR) is one of the candidates for the Generation IV nuclear energy system. ZrC coated fuel particles are expected to make the performance of the VHTR higher. Therefore, we are investigating the ZrC-coating process. From April 2007 to March 2008, ZrC-outer pyrolytic carbon (OPyC) layer continuous coating tests were carried out with the nonnuclear particles and we succeeded to coat continuously the ZrC layer and the OPyC layer with the thicknesses up to about 27 and about 48 
m, respectively, in the batch scale of 100 g.
Aihara, Jun; Ueta, Shohei; Yasuda, Atsushi; Ishibashi, Hideharu; Mozumi, Yasuhiro; Sawa, Kazuhiro; Motohashi, Yoshinobu*
Journal of the American Ceramic Society, 92(1), p.197 - 203, 2009/01
Times Cited Count：7 Percentile：42.38(Materials Science, Ceramics)The ZrC coating layer was fabricated with bromide process at JAEA. In a later stage of the project, we have successfully kept nominal deposition temperature almost constant. Microstructures of the ZrC layers, of which nominal deposition temperatures were able to measure, were characterized by means of TEM and STEM and the results were compared and discussed with those obtained for different batches including those reported in a previous study. The ZrC grains were oriented in the ZrC layers deposited at about 1630 K. This feature was rather different from that reported in the previous study. The formation of fairly different PyC structures was found on the PyC/ZrC boundary as well as around the pores existing near the boundary. Fibrous carbons were observed on the PyC/ZrC boundary produced in a batch deposited at a higher temperature (nominal temperature was 1769 K); no such fibrous carbons were found in a batch deposited at a lower temperature (nominal temperature was 1632 K).
Ueta, Shohei; Aihara, Jun; Yasuda, Atsushi; Ishibashi, Hideharu; Takayama, Tomoo; Sawa, Kazuhiro
Journal of Nuclear Materials, 376(2), p.146 - 151, 2008/05
Times Cited Count：58 Percentile：95.62(Materials Science, Multidisciplinary)The Very-High-Temperature Reactor (VHTR) is the one of the most promising candidates for the Generation IV Nuclear Energy System. The VHTR fuel should exhibit excellent safety performance up to burn-ups of about 15 to 20%FIMA and fluences of 6
10
n/m
(E
0.1 MeV). There is no experimental data which has proved the intactness of conventional SiC-coated fuel particles under such severe condition. Japan Atomic Energy Agency (JAEA) developed Zirconium carbide (ZrC)-coated fuel particles which is expected to maintain its intactness under higher temperature and burn-up compared with SiC-coating layer. JAEA has newly started the development of coating process by large-scale and of inspection method, and the irradiation of ZrC-coated particles from 2004. The fabrication tests of ZrC-coating have been started by new-series coater, and uniform ZrC coating layer has successfully been fabricated by the improvement of temperature control technique.
Ueta, Shohei; Aihara, Jun; Yasuda, Atsushi; Ishibashi, Hideharu; Mozumi, Yasuhiro; Sawa, Kazuhiro; Minato, Kazuo
Hyomen, 46(4), p.222 - 232, 2008/04
Japan Atomic Energy Agency (JAEA) is developing the zirconium carbide (ZrC) coated fuel particle which has better refractoriness and chemical stability than the conventional silicon carbide (SiC) coated fuel particle. In the present study, ZrC coating tests were carried out by the enlarged 200 g-scale ZrC coater comparing with the previous study. Finally, the stoichiometric ZrC layer was successfully fabricated by obtaining relationships between properties of ZrC, coating temperature and batch size through coating tests. In addition, not only inspection methods for coating thickness and density, but also treatment technique to remove pyrocarbon (PyC) layer were developed in order to evaluate the quality of the ZrC coated fuel particle. Present R&D will contribute to the practicability of the ZrC coated fuel particle as a fuel for the advanced high temperature gas cooled reactor such as the Very High Temperature Reactor (VHTR).
Aihara, Jun; Ueta, Shohei; Yasuda, Atsushi; Ishibashi, Hideharu; Takayama, Tomoo; Sawa, Kazuhiro; Motohashi, Yoshinobu*
Journal of the American Ceramic Society, 90(12), p.3968 - 3972, 2007/12
Japan Atomic Energy Agency (JAEA) has started to study and develop ZrC coated fuel particles for advanced high temperature gas cooled reactors. This paper mainly focuses on the microstructures of the ZrC and isotropic dense pyrolytic carbon (PyC) coating layer produced in the early stage of the project. The structure of free carbon region in the ZrC coating layer appears to be such that c-plane was along with the ZrC grain boundary. It appears that the existence of the free carbon phase, especially with such structure, deteriorates the fission product (FP) retention performance in addition to the mechanical strength of ZrC. The PyC coating layer appears to be a medium-range ordered amorphous structure.
Takayama, Tomoo*; Ueta, Shohei; Aihara, Jun; Yasuda, Atsushi*; Ishibashi, Hideharu*; Sawa, Kazuhiro
JAEA-Research 2007-061, 32 Pages, 2007/09
JAEA-Research-2007-061.pdf:15.93MB
As the conventional SiC coated fuel particle, the ZrC coated fuel particle is proposed as a fuel for the Very High Temperature Gas-cooled Reactor (VHTR) which is one of Generation IV nuclear reactors. Applicability of inspection methods of SiC-coated fuel particle for ZrC-coated fuel particle has been examined by comparing properties of ZrC with SiC. It was suggested that hardness, absorption X-ray coefficient, density, oxidation-resistant and chemical stability of SiC were dominant properties for conventional inspection methods such as SiC coating layer thicknesses, coating layers densities for both SiC and O-PyC layers, thorough-coatings failure fraction and SiC coating layer failure fraction. With regards to the applicability of the inspection for the SiC-coated particle, some difficulties are revealed on coating layers densities for both ZrC and O-PyC layers and of ZrC failure fraction, and it was suggested that they were major issues to be solved.
Ueta, Shohei; Aihara, Jun; Yasuda, Atsushi; Ishibashi, Hideharu; Sawa, Kazuhiro
no journal, ,
Developments of the technology for Zirconium Carbide (ZrC) coated fuel particle, which is one of candidates as Very High Temperature gas-cooled Reactor (VHTR) fuels, are on the progress. The following studies were carried out to investigate the irradiation performance of ZrC coating layer; a irradiation test, post irradiation examinations with ZrC coated dummy particle and fuel performance modeling for fuel and safety design. For the irradiation test, it can be said that the performance of ZrC coating layer against neutron irradiation is the most important. In this viewpoint, irradiation test will be carried out by High Flux Isotope Reactor (HFIR) in Oak Ridge National Laboratory (ORNL), and irradiation condition should be settled over 610n/m of fast neutron flux, as much as that of VHTR condition. For post irradiation examinations, failure integrity measurement, ceramography and SEM observation should be carried out to develop fuel failure model of ZrC coated fuel particles.
Aihara, Jun; Ueta, Shohei; Yasuda, Atsushi; Ishibashi, Hideharu; Sawa, Kazuhiro; Motohashi, Yoshinobu*
no journal, ,
no abstracts in English
Aihara, Jun; Ueta, Shohei; Yasuda, Atsushi; Ishibashi, Hideharu; Sawa, Kazuhiro; Motohashi, Yoshinobu*
no journal, ,
Japan Atomic Energy Agency (JAEA) has started to study and develop ZrC coated fuel particles for advanced high temperature gas cooled reactors. The ZrC coating layers were fabricated with bromide process at JAEA. We report in this study the microstructures of the ZrC coating layers deposited in the second year of the project. We already reported the microstructure of the one deposited in the first year of the project last year. The ZrC coating layer deposited at lower temperatures contains less free carbons. The crystal grains of ZrC were columner in shape and oriented in the region containing less free carbons. The orientation was different from the one reported in the last year. In addition to the stoichiometry of the ZrC layer, the microstructure of PyC/ZrC boundary also depended on the deposition temperature. The fibrous carbon structure is observed at PyC/ZrC boundary when the ZrC layer is deposited at higher temperature but not when ZrC layer is deposited at lower temperature.
