Differential pressure rise event for filters of HTTR primary helium gas circulators, 1; Investigation of differential pressure rise event

Nemoto, Takahiro; Arakawa, Ryoki; Kawakami, Satoru; Nagasumi, Satoru; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; Furusawa, Takayuki; Inoi, Hiroyuki; et al.

JAEA-Technology 2023-005, 33 Pages, 2023/05

JAEA-Technology-2023-005.pdf:5.25MB

During shut down of the HTTR (High Temperature engineering Test Reactor) RS-14 cycle, an increasing trend of filter differential pressure for the helium gas circulator was observed. In order to investigate this phenomenon, the blower of the primary helium purification system was disassembled and inspected. As a result, it is clear that the silicon oil mist entered into the primary coolant due to the deterioration of the charcoal filter performance. The replacement and further investigation of the filter are planning to prevent the reoccurrence of the same phenomenon in the future.

Neutron diffraction study of hydrogen-ordered ice XI; Annealing effect and memory effect

Arakawa, Masashi*; Kagi, Hiroyuki; Fernandez-Baca, J. A.*; Chakoumakos, B. C.*; Fukazawa, Hiroshi

Physics and Chemistry of Ice 2010, p.329 - 338, 2011/03

We measured neutron diffraction profiles of KOD, NaOD, LiOD, Ca(OD), and ND-doped ices. Ice XI, which is a hydrogen-ordered phase of normal ice (ice Ih), was observed in the KOD and NaOD-doped ices although Ca(OD) and ND-doped ice did not transformed to ice XI. The mass fraction of ice XI to that of the doped ice () was estimated using Rietveld analysis for each doped ice. The value of the doped ice, which had once experienced being ice XI, was larger than that of the doped ice, which had never experienced being ice XI. The large value of the doped ice indicates that small hydrogen-ordered domains remained above the transition temperature between ice XI and Ih. Our results suggest that large amounts of ice on icy bodies in our solar system can transform to ice XI. In this paper, we discussed the existence of the small hydrogen-ordered domains in space and the evolution of icy grain.

Annealing effects on hydrogen ordering in KOD-doped ice observed using neutron diffraction

Arakawa, Masashi*; Kagi, Hiroyuki; Fukazawa, Hiroshi

Journal of Molecular Structure, 972(1-3), p.111 - 114, 2010/05

https://doi.org/10.1016/j.molstruc.2010.02.016

We measured the neutron powder diffraction of 0.013 M KOD-doped DO ice to investigate the formation process of ice XI, a hydrogen-ordered phase of ice Ih. The doped ice Ih transformed to ice XI after annealing at 57 and subsequently at 68 K. The mass fraction of ice XI to that of the doped ice () was estimated using Rietveld analysis for each sample. The value of the doped ice, which had once experienced being ice XI ( = 0.23), was larger than that of the doped ice, which had never experienced being ice XI ( = 0.14). Results indicate that small hydrogen-ordered domains remained in the ice Ih, which had once trans- formed to ice XI, and accelerated the phase transition from ice Ih to ice XI. Results further suggest that large amounts of ice on icy bodies in our solar system can transform to ice XI, which might be detectable using infrared telescopes or planetary exploration in the near future.

A Cubic-anvil high-pressure device for pulsed neutron powder diffraction

Abe, Jun; Arakawa, Masashi*; Hattori, Takanori; Arima, Hiroshi; Kagi, Hiroyuki; Komatsu, Kazuki*; Sano, Asami; Uwatoko, Yoshiya*; Matsubayashi, Kazuyuki*; Harjo, S.; et al.

Review of Scientific Instruments, 81(4), p.043910_1 - 043910_5, 2010/04

https://doi.org/10.1063/1.3384238

A compact cubic-anvil high-pressure device was developed for in situ neutron powder diffraction studies. In this device, a cubic shaped pressure medium is compressed by six anvils, and neutron beam pass through gaps between the anvils. The first high-pressure experiment using this device was conducted at J-PARC and clearly showed the neutron diffraction patterns of Pb. Combining the cubic-anvil high-pressure device with a pulsed neutron source will prove to be a useful tool for neutron diffraction experiments.

Laboratory measurements of infrared absorption spectra of hydrogen-ordered ice; A Step to the exploration of ice XI in space

Arakawa, Masashi; Kagi, Hiroyuki; Fukazawa, Hiroshi

Astrophysical Journal; Supplement Series, 184(1), p.361 - 365, 2009/09

https://doi.org/10.1088/0067-0049/184/2/361

Infrared absorption spectra of ice were obtained at 4, 60, 100, 140, 160, and 240 K to make spectroscopic observations of hydrogen ordering at low temperatures. A broad peak observed at around 850 cm (11.7-181 m) was derived from libration of water molecules. The peak width was notably narrower at temperatures less than 140 K. A decrease in the peak width occurring in accordance with the formation of ice with ordered arrangements of hydrogen atoms was suggested from incoherent inelastic neutron-scattering studies. These results are consistent with ordering of hydrogen atoms. Existence of hydrogen-ordered ice in space is the subject of continuing astronomical debate. Our results demonstrate that the ordered ice in space is detectable using infrared telescopes and planetary exploration.

A High pressure experiment of neutron diffraction at TAKUMI

Abe, Jun; Hattori, Takanori; Arima, Hiroshi; Harjo, S.; Moriai, Atsushi; Ito, Takayoshi; Aizawa, Kazuya; Arai, Masatoshi; Utsumi, Wataru; Arakawa, Masashi; et al.

no journal, , 

The Engineering Materials Diffractometer TAKUMI designed to solve many problems in materials science and engineering including investigations of stresses and crystallographic structures within engineering components was developed at J-PARC. In addition, TAKUMI is suitable for high pressure experiments. High pressure devices (Paris-Edinburgh press and palm cubic anvil press) were developed for in situ neutron powder diffraction experiments under high pressures. In this presentation, we introduce outline of TAKUMI and High pressure devices.

Powder neutron diffraction study using palm cubic anvil cell at TAKUMI

Abe, Jun; Hattori, Takanori; Arima, Hiroshi; Sano, Asami; Utsumi, Wataru; Komatsu, Kazuki*; Arakawa, Masashi*; Kagi, Hiroyuki

no journal, , 

Cubic-anvil devices are typically large scale and combined with a large hydraulic press. However, our research group have been successful in greatly reducing the size of this device and producing clamp-type "palm cubic anvil cell". The device can be brought to neutron sources. We have performed High-pressure neutron diffraction experiments at TAKUMI in J-PARC using the device. Optimization of materials such as anvil and pressure medium and developments of collimators have made possible reduction of background and contamination noise. Incident and diffracted neutron beams travel through high-pressure device, which causes attenuation of neutron. We have studied the method of attenuation correction and analyzed crystal structure using corrected neutron diffraction pattern.

Neutron powder diffraction under high pressure using the engineering materials diffractometer "TAKUMI"

Abe, Jun; Hattori, Takanori; Sano, Asami; Arima, Hiroshi; Fukazawa, Hiroshi; Harjo, S.; Ito, Takayoshi; Aizawa, Kazuya; Utsumi, Wataru; Komatsu, Kazuki*; et al.

no journal, , 

The Engineering Materials Diffractometer TAKUMI designed to solve many problems in materials science and engineering including investigations of stresses and crystallographic structures within engineering components was developed at J-PARC. In addition, TAKUMI is suitable for high-pressure experiments. High-pressure devices (Paris-Edinburgh press, palm cubic anvil press and Diamond Anvil Cell) were developed for in situ neutron powder diffraction experiments under high pressures. However, to apply a these high-pressure devices to neutron diffraction, research and development is needed. Issues to be resolved selecting materials, modifying the diffraction window and reducing BKG.

Memory of ice observed by neutron diffraction

Fukazawa, Hiroshi; Arakawa, Masashi*; Kagi, Hiroyuki; Chakoumakos, B.*; Fernandez-Baca, J. A.*

no journal, , 

From neutron diffraction experiments, we found that small hydrogen-ordered domains exist at significantly higher temperature and the domains induce the growth of bulk ice XI. The small ordered domain is named memory of hydrogen ordered ice because it is the residual structure of ice XI. Since the memory exists up to about 150 K, most of ices in the solar system are hydrogen ordered and may have ferroelectricity. The small hydrogen-ordered domains govern the cosmochemical properties of ice.

Neutron diffraction and IR absorption studies of ice crystal; An Implication of planetary science

Arakawa, Masashi*; Kagi, Hiroyuki; Fernandez-Baca, J. A.*; Chakoumakos, B.*; Fukazawa, Hiroshi

no journal, , 

The existence of ferroelectric ice XI with ordered hydrogen in the universe becomes of interest in astronomy and physical chemistry because of the strong electric force. However, the influence seemed to be limited because it forms at narrow temperature range. From neutron diffraction experiments, we found that small hydrogen-ordered domains with ferroelectricity exist at higher temperature and the domains induce the growth of bulk ice XI. The small ordered domain is named memory of hydrogen ordered ice because it is the residual structure of ice XI.