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.

Structure of nitride layer formed on titanium alloy surface by N-gas exposure at high temperatures

Takeda, Yusuke; Iida, Kiyoshi*; Sato, Shinji*; Matsuo, Tadatoshi*; Nagashima, Yasuyuki*; Okubo, Nariaki; Kondo, Keietsu; Hirade, Tetsuya

Journal of Physics; Conference Series, 791(1), p.012022_1 - 012022_4, 2017/02

https://doi.org/10.1088/1742-6596/791/1/012022

Titanium alloy is widely used for applications such as golf club heads and structural materials for aircrafts. The surface can be exceedingly hardened by nitriding treatment that initiates defects, but there are some difficulties on use of titanium nitride because the layer can be exfoliated by stress. Therefore, we prepared samples in two different treatment conditions, (1) 810C 600 min and (2) 850C 720 min and performed depth profile analysis of Doppler broadening of positron annihilation -rays (DB) for these samples. According to a calculation of nitrogen diffusion depth, the nitride layer should be only about 0.05-0.1m. However, the depth profile analysis of the DB measurement indicated that the defects introduced by nitriding treatment extended to a depth of 0.5m.

Photoneutron cross sections for Sn and the -ray strength function method

Utsunomiya, Hiroaki*; Goriely, S.*; Kamata, Masaki*; Akimune, Hidetoshi*; Kondo, Takeo*; Ito, Osamu*; Iwamoto, Chihiro*; Yamagata, Tamio*; Toyokawa, Hiroyuki*; Lui, Y.-W.*; et al.

Physical Review C, 84(5), p.055805_1 - 055805_6, 2011/11

https://doi.org/10.1103/PhysRevC.84.055805

Photoneutron cross sections were measured for Sn, Sn, Sn, Sn, and Sn near neutron threshold with quasi-monochromatic laser-Compton scattering -rays. A systematic analysis of the present photoneutron data and existing neutron-capture data is made using the -ray strength function on the basis of the HFB+QRPA model of E1 strength supplemented with a pygmy dipole resonance, which was deduced from a previous study on Sn and Sn. Radiative neutron capture cross sections for two radioactive nuclei, Sn and Sn, are deduced through the -ray strength function method.

Photoneutron cross sections for Au

Ito, Osamu*; Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Yamagata, Tamio*; Kondo, Takeo*; Kamata, Masaki*; Toyokawa, Hiroyuki*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; et al.

AIP Conference Proceedings 1377, p.362 - 364, 2011/10

https://doi.org/10.1063/1.3628413

Photoneutron cross sections for Au revisited; Measurements with laser Compton scattering -rays and data reduction by a least-squares method

Ito, Osamu*; Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Kondo, Takeo*; Kamata, Masaki*; Yamagata, Tamio*; Toyokawa, Hiroyuki*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; et al.

Journal of Nuclear Science and Technology, 48(5), p.834 - 840, 2011/05

https://doi.org/10.3327/jnst.48.834

Photoneutron cross section measurements were made for Au in the entire energy range of the (,n) channel based on a direct neutron-counting technique with quasi-monochromatic -rays produced in inverse Compton-scattering of laser photons with relativistic electrons. The data were analyzed with a least-squares method to deduce photoneutron cross sections. The analysis significantly reduced experimental uncertainties compared with those resulted from the photon difference method. The result is compared with the previous data by direct neutron-counting with -rays produced in positron annihilation in flight and by photoactivation with bremsstrahlung. The present data are in good agreement with the previous data near neutron threshold, while there remain some discrepancies between the present and the previous data above 10 MeV.

-ray strength function method and its application to Pd

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; Kondo, Takeo*; Ito, Osamu*; et al.

Physical Review C, 82(6), p.064610_1 - 064610_5, 2010/12

https://doi.org/10.1103/PhysRevC.82.064610

The -ray strength function method (SF method) is devised to indirectly determine radiative neutron capture cross sections for radioactive nuclei. This method is applied here to the Pd case. Photoneutron cross sections were measured for Pd near neutron threshold with quasi-monochromatic laser-Compton-scattering -ray beams. These photoneutron cross sections as well as the reverse radiative neutron capture cross sections for Pd are used to provide constraints on the Pd(n,) Pd cross section.

Photoneutron cross sections for Zr; A Systematic experimental study of photoneutron and radiative neutron capture cross sections for zirconium isotopes

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; Kondo, Takeo*; Ito, Osamu*; et al.

Physical Review C, 81(3), p.035801_1 - 035801_5, 2010/03

https://doi.org/10.1103/PhysRevC.81.035801

This manuscript presents photoneutron cross sections for Zr. Combining the present data with the previously published Zr data, we investigated the -ray strength function for zirconium isotopes systematically. We present a unified picture of the -ray strength function that consists of the HFB + QRPA model of E1 strength accompanied by an extra M1 strength attributable to giant M1 resonance. It is shown that the -ray strength function reproduces both (g,n) and (n,g) cross sections for Zr isotopes consistently.

Power Generation with Fe2 VAI modules using Sodium Heat Source

Yoshikawa, Shinji; YOSHIKAWA JNC, Shinji; Suzuki, Ryosuke*; kondo, koki*; Nakai, Satoshi*; NAKAI, Satoshi*

The 23rd International Conference on Termoelectric, 0 Pages, 2004/12

A prototype system for thermoelectric power generation using the Heusler Fe2 VAI alloy has been studied as a potential heat recovery system from a liquid metal cooled fast breeder reactor. The modules consisting of 180 pairs using Fe2VAi cast alloy were mouted on 1.8 m long of the outer surface of a stainless tube (O.D. 34mm) which is internally heated by flowing liquid sodium (484-670K, 2-8 1/min). The element has a shape of a long cuboid, where one small rectangular end was thermally contacted with the tube surface and the other end was directly cooled by forced air flow to form a counter-type heat exchanger. The internal electric resistances of the modules were nearly same, however, the electromotive force varied widely because of the difference of thermal resistance between the module and tube surface. The output power generated from this prototype system was evaluated to be about 4.2 W/m assuming that all the circumference of the pipe surface is covered by the elements.

Depositional sequence of the Post-LGM incised-valley fill controlled by seismic crustal deformation and large-scale lahars; An Example of SKM core obtained from the Sukumo coastal lowland along the Nankai Trough, Japan

Nanayama, Futoshi*; Yamaguchi, Tatsuhiko*; Nakanishi, Toshimichi; Tsuji, Tomohiro*; Ikeda, Michiharu*; Kondo, Yasuo*; Miwa, Michiko*; Sugiyama, Shinji*; Kimura, Kazunari*

no journal, , 

The characteristics of the post-LGM incised valley fills and the depositional sequence were examined the SKM core collected in the Sukumo coastal lowland, where is expected to huge seismic subsidence due to the Nankai Trough great earthquakes. Our sedimentological, radiocarbon dating and paleoenvironmental results are as bellows. Sediments of the SKM core clearly show a succession influenced by post-glacial sea level change. The Matsuda River incised valley was formed in LGM and filled by fluvial sand and gravels in late Pleistocene. After the postglacial transgression, sea level reached -30 m (a.s.l.) at 9.8 ka and the incised valley changed to an estuary environment. The sea level continued to rise and it became an inner bay mud bottom environment, and reaching a maximum water depth was at 7.5 ka. The 7.3 ka Kikai caldera eruption in southern Kyushu caused heavy K-Ah ash fall in southwestern Shikoku, and then large-scale lahars frequently occurred immediately after the ash fall because of the vicinity of volcanic source. After ash fall, the K-Ah secondary sediments rapidly deposited on the inner bay environment and caused forced regression. After 7.0 ka, the growth of the delta became active ahead of the other regions, which may be due to the large K-Ah ash fall. At 5 ka, the sea level reached + 2.5 m (a.s.l.) estimated by the Sukumo midden and this altitude is recognized as the Holocene marine limit in this area. The information on relative sea level change during the past 10000 years has revealed that the Sukumo Bay area has not subsided due to seismic crustal deformation.