High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

https://doi.org/10.1016/C2018-0-05383-9

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

traps in 6H-SiC studied with Laplace deep level transient spectroscopy

Koizumi, Atsushi*; Markevich, V. P.*; Iwamoto, Naoya; Sasaki, Sho*; Oshima, Takeshi; Kojima, Kazutoshi*; Kimoto, Tsunenobu*; Uchida, Kazuo*; Nozaki, Shinji*; Hamilton, B.*; et al.

Applied Physics Letters, 102(3), p.032104_1 - 032104_4, 2013/01

https://doi.org/10.1063/1.4788814

Defects in an electron-irradiated 6H-SiC diode studied by alpha particle induced charge transient spectroscopy; Their impact on the degraded charge collection efficiency

Iwamoto, Naoya*; Koizumi, Atsushi*; Onoda, Shinobu; Makino, Takahiro; Oshima, Takeshi; Kojima, Kazutoshi*; Koike, Shumpei*; Uchida, Kazuo*; Nozaki, Shinji*

Materials Science Forum, 717-720, p.267 - 270, 2012/05

https://doi.org/10.4028/www.scientific.net/MSF.717-720.267

In this study, we carried out an attempt to identify the defects responsible for the degraded charge collection efficiency of the 6H-SiC pn diode irradiated with 1 MeV electrons by the alpha particle induced charge transient spectroscopy. To form defects in the SiC crystal, one of the diodes was irradiated with 1 MeV electrons at a fluence of 110 /cm. Collected charges of the diodes were measured in room temperature using 5.486 MeV alpha particles from Am source. After the electron irradiation, the collected charge of the diode at a reverse bias of 100 V decreased to 84% of its initial value. In order to investigate the relationship between degradation of collected charge and defects in detail, time-dependent collected charges of the diodes were measured in temperature ranges from 170 K to 310 K. As a result, two distinct peaks labeled X and X are found for the electron-irradiated diode, and their activation energies are estimated to be 0.30 and 0.47 eV, respectively. These two peaks are considered to correspond to the defect levels introduced by the electron irradiation. In particular, when the diodes are used in room temperature, X is more critical to the charge collection than X.

Refreshable decrease in peak height of ion beam induced transient current from silicon carbide metal-oxide-semiconductor capacitors

Oshima, Takeshi; Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Deki, Manato; Nozaki, Shinji*

AIP Conference Proceedings 1336, p.660 - 664, 2011/05

https://doi.org/10.1063/1.3586184

Metal-Oxide-Semiconductor (MOS) capacitors were fabricated on n-type 4H- and 6H-SiC epitaxial layers, and transient currents induced in SiC MOS capacitors by ion incidence were investigated. Transient Ion Beam Induced Current (TIBIC) measurements were performed using 15 MeV oxygen ions. As a result, the TIBIC peak height decreased with increasing number of incident ions. For example, the TIBIC signal peak for a 4H-SiC MOS capacitor at a reverse bias of 15 V was 0.18 mA at the beginning. The peak decreased to be 0.10 mA after 1800 ion irradiation. After that, the forward bias of 1 V was applied to the MOS capacitor and the TIBIC measurements were carried out under the same conditions. As a result, the peak height was recovered to be 0.18 mA. In general, the response of charge de-trapping by deep levels in wide bandgap semiconductors is very slow and they act as fixed charge. Since dense electron-hole pairs are generated by ion incident and holes move to the SiO/SiC interface by the electric field (applied reverse bias). Therefore, the decrease in TIBIC signal peak can be interpreted in terms of the recombination of negatively charged acceptor type deep levels with ion induced holes.

Transient analysis of an extended drift region in a 6H-SiC diode formed by a single alpha particle strike and its contribution to the increased charge collection

Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Oshima, Takeshi; Kojima, Kazutoshi*; Koizumi, Atsushi*; Uchida, Kazuo*; Nozaki, Shinji*

IEEE Transactions on Nuclear Science, 58(1), p.305 - 313, 2011/02

https://doi.org/10.1109/TNS.2010.2096432

no abstracts in English

Enhanced charge collection in drain contact of 6H-SiC MOSFETs induced by heavy ion microbeam

Onoda, Shinobu; Vizkelethy, G.*; Makino, Takahiro; Iwamoto, Naoya; Kojima, Kazutoshi*; Nozaki, Shinji*; Oshima, Takeshi

Proceedings of 9th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-9), p.230 - 233, 2010/10

Change in current induced from silicon carbide metal-oxide-semiconductor capacitors by oxygen ions

Oshima, Takeshi; Iwamoto, Naoya; Onoda, Shinobu; Makino, Takahiro; Deki, Manato; Nozaki, Shinji*

Proceedings of 9th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-9), p.85 - 88, 2010/10

Decreases in charge collection efficiencies of 6H-SiC diodes due to low-energy electron irradiations

Iwamoto, Naoya; Onoda, Shinobu; Oshima, Takeshi; Kojima, Kazutoshi*; Koizumi, Atsushi*; Uchida, Kazuo*; Nozaki, Shinji*

no journal, , 

no abstracts in English

Spatial dependence of transient currents induced in 6H-SiC MOSFETs by single heavy ion

Onoda, Shinobu; Iwamoto, Naoya; Makino, Takahiro; Kojima, Kazutoshi*; Nozaki, Shinji*; Oshima, Takeshi

no journal, , 

no abstracts in English

Transient currents observed from drain contact of 6H-SiC MOSFETs induced by single heavy ion

Onoda, Shinobu; Iwamoto, Naoya; Makino, Takahiro; Kojima, Kazutoshi*; Nozaki, Shinji*; Oshima, Takeshi

no journal, , 

no abstracts in English