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.

Compact neutron sources for energy and security

Uesaka, Mitsuru*; Kobayashi, Hitoshi*; Kureta, Masatoshi; Nakatsuka, Shigehiro*; Nishimura, Kazuya*; Igashira, Masayuki*; Hori, Junichi*; Kiyanagi, Yoshiaki*; Tagi, Kazuhiro*; Seki, Toshichika*; et al.

Reviews of Accelerator Science and Technology, 8, p.181 - 207, 2015/00

https://doi.org/10.1142/S1793626815300108

We choose nuclear data and nuclear material inspection for energy application and nondestructive testing of explosive and hidden nuclear materials for security application. 90 keV electrostatic accelerators of deuterium are commercially available for nondestructive testing. For nuclear data measurement, electrostatic ion accelerators and L-band and S-band electron linear accelerators (linac) are used for the neutron source. Compact or mobile X-band electron linac neutron sources are under development. Compact proton linac neutron source is used for nondestructive testing especially water in solids. Several efforts for more neutron intensity using proton and deuteron accelerators are also introduced.

Super ODS steels R&D for fuel cladding of next generation nuclear systems, 3; Development of high performance attrition type ball mill

Okuda, Takanari*; Fujiwara, Masayuki*; Nakai, Tatsuyoshi*; Shibata, Kenichi*; Kimura, Akihiko*; Inoue, Masaki; Ukai, Shigeharu*; Onuki, Somei*; Fujisawa, Toshiharu*; Abe, Fujio*

Proceedings of 2009 International Congress on Advances in Nuclear Power Plants (ICAPP '09) (CD-ROM), p.9229_1 - 9229_4, 2009/05

Oxygen content in ODS ferritic steel is the most important element to determine the mechanical properties. The oxygen contamination from the air is perfectly prevented by using new designed ball mill and the subsequent process control. Zr, Hf and Ti added ODS steels with three oxygen levels for the evaluation tests are fabricated.

Nano-mesoscopic structural characterization of 9Cr-ODS martensitic steel for improving creep strength

Otsuka, Satoshi; Ukai, Shigeharu; Sakasegawa, Hideo; Fujiwara, Masayuki; Kaito, Takeji; Narita, Takeshi

Journal of Nuclear Materials, 367-370(1), p.160 - 165, 2007/08

https://doi.org/10.1016/j.jnucmat.2007.03.004

This paper describes the effect on creep strength and microstructure of 9Cr-oxide dispersion strengthened martensitic steel (9Cr-ODS steel) brought by the differences in titanium concentration and consolidation temperature. The increase of titanium concentration to 0.30-0.35wt% was shown to provide remarkable improvement of creep strength accompanied by the increase of residual-alpha ferrite. The elevation of hot-extrusion temperature notably degraded the creep strength, however, appeared to increase the volume fraction of residual-alpha ferrite. Creep deformation process of 9Cr-ODS steel was discussed to explain these results based on microstructure observations.

Effects of tungsten on microstructure and high-temperature strength of oxide dispersion strengthened (ODS) martensitic steel

Narita, Takeshi*; Ukai, Shigeharu; Kaito, Takeji; Otsuka, Satoshi; Fujiwara, Masayuki

JAEA-Research 2006-050, 85 Pages, 2006/10

JAEA-Research-2006-050.pdf:133.32MB

In 9Cr ODS martensitic steel, tungsten(W) is a solid solution strengthening element, whose addition increases high-temperature strength by the combined effect with oxide dispersion strengthening. However, its excessive addition results in the increase of ferrite phase causing precipitation of intermetallic compound (Laves phase) under high temperature irradiation condition and thus ductility degradation. The amount of W addition therefore should be as low as possible. In this report, the effects of W on microstructure and high temperature mechanical properties of 9Cr ODS martensitic steels were examined for obtaining insights into optimum W concentration in terms of high-temperature strength and ductility. The results obtained are as follows: (1)In the 9CrODS martensitic steel, addition of W exceeding 2mass% is shown to cause precipitation of Laves phase which degrades the ductility and fracture toughness. It can be said that the current specification of W concentration, i.e. 2mass%W, is appropriate. (2)Hardness and tensile strength is shown to increase with W concentration. This increase is caused by the increase of solid solution strengthening and residual-alpha ferrite. The retainment of residual-alpha ferrite is enhanced by the addition of W (ferrite former element). The improvement of tensile strength at 973K provided by the solid solution strengthening is shown to be equivalent to that provided by the retainment of residual-alpha ferrite. (3)It would be open task to explorer an improved alloy design concept, i.e. decrease of W as low as possible and increase of residual-alpha ferrite. The degradation of high-temperature strength by decreasing W addition can be made up by the increasing fraction of residual-alpha phase that is provided by reduction of austenite former elements and increasing addition of ferrite former elements.

Effect of excess oxygen concentration on high-temperature strength of ODS martensitic steel

Otsuka, Satoshi; Ukai, Shigeharu; Fujiwara, Masayuki; Kaito, Takeji; Narita, Takeshi

JNC TN9400 2005-034, 197 Pages, 2005/08

JNC-TN9400-2005-034.pdf:28.06MB

Oxide dispersion strengthened(ODS) martensitic steel (9CrODS steel) has been identified as an attractive candidate for advanced fast reactor (FR) fuel cladding tube because of its superior high-temperature strength and radiation resistance. Our recent activities revealed that high-temperature strength of different lots of the cladding tubes is inconsistent each other, even though the same manufacturing process was applied to these tubes. This inconsistency means a critical problem that high-strength 9CrODS steel cladding tubes can not be manufactured reliably and consistently. In this report, a microstructure control technique for consistently and reliably manufacturing high-strength 9CrODS steel cladding tubes are examined based on a series of data concerning effect of excess oxygen concentration on high temperature strength and microstructure of 9CrODS steel.

Manufacturing test of large scale hollow capsule and long length cladding in the large scale oxide dispersion strengthened (ODS) martensitic steel.

Narita, Takeshi; Ukai, Shigeharu; Kaito, Takeji; Otsuka, Satoshi; Fujiwara, Masayuki

JNC TN9400 2004-011, 141 Pages, 2004/04

JNC-TN9400-2004-011.pdf:12.79MB

Mass production capability of ODS martensitic steel claddinghas been evaluated in the feasibility studies on commercialized fast reactor cycle system. In this study, Manufacturing the large scale mother tube which has a high degree of accuracy in size, has been successfully carried out using large scale hollow capsule. For reducing the manufacturing cost of the ODS steel claddings, manufacturing process of the mother tubes using a large scale hollow capsules is promising.

Improvement of 9Cr-ODS martensitic steel properties by controlling excess oxygen and titanium contents

Otsuka, Satoshi; Ukai, Shigeharu; Fujiwara, Masayuki; Kaito, Takeji; Narita, Takeshi

Journal of Nuclear Materials, 329-333(Part A), p.372 - 376, 2004/00

https://doi.org/10.1016/j.jnucmat.2004.04.043

The effects of different percentages of excess oxygen and titanium on the mechanical property and microstructure of 9Cr-ODS steel were investigated in the wide range of excess oxygen from 0.03wt% to 0.18wt%. It was shown that the controlling of the atomic ratio between excess oxygen and titanium (x in TiOx) around 1.0 is indispensable for the high-temperature strength improvement.

Beam-palarization asymmetries for the (,) and (,) reactions for =1.5-2.4 GeV

Zegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.

Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08

https://doi.org/10.1103/PhysRevLett.91.092001

no abstracts in English

Development of manufacturing method of excess oxygen controlled ODS martensitic steel

Fujiwara, Masayuki; Otsuka, Satoshi; Kaito, Takeji; Narita, Takeshi; Ukai, Shigeharu

JNC TN9400 2003-008, 32 Pages, 2003/03

JNC-TN9400-2003-008.pdf:4.73MB

ODS martensitic steel is a prospective candidate cladding matenal for the advanced Fast Breeder Reactor (FBR) core components. A previous result showed that the high temperature strengths were deteriorated by the oxide particle coarsening and the reduction of the residual-alpha grains as excess oxygen (EX.O) increased. In this study, the manufacturing conditions for reducing excess oxygen were examined in order to obtain the target strength. High excess oxygen steels with higher YO addition were also manufactured with the intention of manufacturing the steel which has both fully martensitic microstructure and enough high temperature strength. The derived results can be summarized as follows. (1)It was shown that 0.04wt% excess oxygen was brought from the pre-alloyed raw powders, and 0.04-O.l wt% excess oxygen was mixed in the powders during the Mechanical Alloying(MA). (2)It was shown that excess oxygen could be reduced less than 0.1wt% by applying an ultra high purity Ar gas (99.9999wt%Ar) to MA atmosphere as well as reducing the agitating energy by using pin agitator with shorter length. (3)Residual alpha-grains and transformed alpha-grains were mixed in the furnace-cooled low excess oxygen steels (0.1wt%EX.O). These steels are expected to have the equal high temperature strength to Mm11 because their Vickers hardness is approximately the same Mm11. (3)Full martensitic microstructure was obtained in the higher YO and excess oxygen-added steels (E1,E2). However enough high temperature strength are not expected in these steels because the Vickers hardness of these steels after the furnace-cooling(FC) or normalizing and tempering (NT) are apparently low.