Sodium-cooled Fast Reactors

Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.

Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07

https://shop.elsevier.com/books/sodium-cooled-fast-reactors/morishita/978-0-12-824076-2

This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

https://doi.org/10.1126/science.aav7432

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

New precise measurements of muonium hyperfine structure at J-PARC MUSE

Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.

EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01

https://doi.org/10.1051/epjconf/201919800003

Structure analysis and derivation of deformed electron density distribution of polydiacetylene giant single crystal by the combination of X-ray and neutron diffraction data

Tashiro, Koji*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; Ohara, Takashi; Hanesaka, Makoto*; Yoshizawa, Yoshinori*; Yamamoto, Hiroko*; Niimura, Nobuo*; Tanaka, Ichiro*; Kurihara, Kazuo*; et al.

Macromolecules, 51(11), p.3911 - 3922, 2018/06

https://doi.org/10.1021/acs.macromol.8b00650

Status of J-PARC accelerators

Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Yamamoto, Kazami; Hayashi, Naoki; Yamazaki, Yoshio; Naito, Fujio*; Hori, Yoichiro*; Yamamoto, Noboru*; Koseki, Tadashi*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1317 - 1321, 2017/12

After the summer shutdown in 2016, the J-PARC restarted user operation late in October for the neutrino experiments (NU) and early in November for the materials and life science experimental facility (MLF). The beam power for the NU was 420 kW in May 2016, but increased to 470 kW in February 2017 thanks to the change and optimization of operation parameters. For the hadron experimental facility (HD), we started beam tuning in April, but suspended by a failure of the electro static septum. After the treatment, we delivered beam at the power of 37 kW. We delivered beam at 150kW for the MLF. In the fiscal year of 2016, the linac, the 3 GeV synchrotron (RCS) and the MLF were stable and the availability was high at 93%. On the contrary, the main ring has several failures and the availabilities were 77% and 84% for NU and HD, respectively.

Performance and status of the J-PARC accelerators

Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio*; Koseki, Tadashi*; Yamamoto, Noboru*; Hori, Yoichiro*

Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2290 - 2293, 2017/06

https://doi.org/10.18429/JACoW-IPAC2017-TUPVA090

The J-PARC is a high intensity proton facility and the accelerator consists of a 400 MeV linac, a 3 GeV Rapid Cycling Synchrotron (RCS) and a 30 GeV Main Ring Synchrotron (MR). We have taken many hardware upgrades such as front end replacement and energy upgrade at the linac, vacuum improvement, collimator upgrade, etc. The beam powers for the neutrino experiment and hadron experiment from the MR have been steadily increased by tuning and reducing beam losses. The designed 1 MW equivalent beam was demonstrated and user program was performed at 500 kW from the RCS to the neutron and muon experiments. We have experienced many failures and troubles, however, to impede full potential and high availability. In this report, operational performance and status of the J-PARC accelerators are presented.

Status of J-PARC accelerators

Hasegawa, Kazuo; Kinsho, Michikazu; Oguri, Hidetomo; Yamamoto, Kazami; Naito, Fujio*

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1409 - 1412, 2016/11

After the summer maintenance in 2015, user operation for the hadron experimental facility (HD) and the life science experimental facility (MLF) was resumed in the middle of October after the tuning of accelerator at J-PARC. In December, we reduced the repetition cycle from 6.0 seconds to the 5.52 seconds at the main ring (MR) and therefore, we have improved beam power to 42 kW, while it was 24 kW in April. The peak beam current at the linac by December 2015 was 30 mA, but we have increased to 40 mA in January, and the tuning was followed by the 3 GeV synchrotron (RCS) and the MR for user operation condition. As a result we improved a beam power to the neutrino experimental facility (NU) to 390 kW by the tuning while it was ranged 300 to 330 kW at 30 mA. User program was performed at 500 kW at the MLF, but it was suspended by a defect of a target in November. It was replaced for a spare one and resumed at 200 kW in February. We have several faults to stop beam operations: ventilation system at the linac by a short circuit, a vacuum leak at the RCS collimator, a breakdown of bending magnet of the MR, etc.

Accurate structure analyses of polymer crystals on the basis of wide-angle X-ray and neutron diffractions

Tashiro, Koji*; Hanesaka, Makoto*; Yamamoto, Hiroko*; Wasanasuk, K.*; Jayaratri, P.*; Yoshizawa, Yoshinori*; Tanaka, Ichiro*; Niimura, Nobuo*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; et al.

Kobunshi Rombunshu, 71(11), p.508 - 526, 2014/11

https://doi.org/10.1295/koron.71.508

The crystal structure analysis of various polymer substances has been reviewed on the basis of wide-angle high-energy X-ray and neutron diffraction data. The progress in structural analytical techniques of polymer crystals have been reviewed at first. The structural models proposed so far were reinvestigated and new models have been proposed for various kinds of polymer crystals including polyethylene, poly(vinyl alcohol), poly(lactic acid) and its stereocomplex etc. The hydrogen atomic positions were also clarified by the quantitative analysis of wide-angle neutron diffraction data, from which the physical properties of polymer crystals have been evaluated theoretically. The bonded electron density distribution has been estimated for a polydiacetylene single crystal on the basis of the so-called X-N method or by the combination of structural information derived from X-ray and neutron diffraction data analysis. Some comments have been added about future developments in the field of structure-property relationship determination.

Design evaluation method of steel-plate reinforced concrete structure containment vessel for sodium-cooled fast reactor

Yamamoto, Tomohiko; Kato, Atsushi; Chikazawa, Yoshitaka; Negishi, Kazuo

Journal of Disaster Research, 7(5), p.645 - 655, 2012/10

http://www.fujipress.jp/finder/xslt.php?mode=present&inputfile=DSSTR000700050016.xml

Japan Sodium-cooled Fast Reactor (JSFR) adopts a new concept of a containment vessel called steel plate reinforced concrete containment vessel (SCCV). The SCCV is considered to be effective to shorten construction period thanks for elimination of rebar work at a site compared with applying a reinforced concrete CV. An SFR CV is lower pressure environment than the LWR CV, although environmental temperature of the SFR is much higher than that of LWR in the accident of coolant leakage. Therefore it is important to investigate its characteristics under high temperature to adopt the SC structure to the JSFR CV because the CV shall keep their containment function in the accidents to be assumed in design. This paper describes the construction of design evaluation method from design, experimental and analytical point of view.