Development plan for coupling technology between high temperature gas-cooled reactor HTTR and hydrogen production facility, 1; Overview of the HTTR heat application test plan to establish high safety coupling technology

Nomoto, Yasunobu; Mizuta, Naoki; Morita, Keisuke; Aoki, Takeshi; Okita, Shoichiro; Ishii, Katsunori; Kurahayashi, Kaoru; Yasuda, Takanori; Tanaka, Masato; Isaka, Kazuyoshi; et al.

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 7 Pages, 2023/05

Structural change by phosphorus addition to borosilicate glass containing simulated waste components

Okamoto, Yoshihiro; Shiwaku, Hideaki; Shimamura, Keisuke*; Kobayashi, Hidekazu; Nagai, Takayuki; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*

Journal of Nuclear Materials, 570, p.153962_1 - 153962_13, 2022/11

https://doi.org/10.1016/j.jnucmat.2022.153962

Simulated nuclear waste glass samples containing phosphorus, which increase the solubility of molybdenum, were prepared and analyzed using synchrotron X-ray Absorption Fine Structure (XAFS) analysis for some constituent elements and Raman spectroscopic analysis of their complex structure. Changes in local structure and chemical state due to different phosphorus additions and waste loading rates were systematically studied. Consequently, no crystalline phase due to the molybdate compound was observed even at a maximum waste content of 30 wt% (corresponding to 1.87 mol% MoO). Oxidation proceeded when the waste-loading rate was increased, whereas the reduction proceeded when phosphorus was added. In some cases, the effects of oxidation and reduction were offset. The local structure around specific elements can be classified as follows; Zn that is affected mainly by the waste-loading rate, Ce that is affected by both the waste-loading rate and phosphorus addition, and Zr element that is not affected by either of them. From the comparison between the analytical results of Mo and other elements, it was considered that the added phosphorus exists as a free PO structural unit and may deprive the alkali metal coordinated to the molybdate ion.

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.

Field test around Fukushima Daiichi Nuclear Power Plant site using improved Ce:Gd(Al,Ga)O scintillator Compton camera mounted on an unmanned helicopter

Shikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.

Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12

https://doi.org/10.1080/00223131.2016.1185980

The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 44 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the -ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10).

Space radiation dosimetry to evaluate the effect of polyethylene shielding in the Russian segment of the International Space Station

Nagamatsu, Aiko*; Casolino, M.*; Larsson, O.*; Ito, Tsuyoshi*; Yasuda, Nakahiro*; Kitajo, Keiichi*; Shimada, Ken*; Takeda, Kazuo*; Tsuda, Shuichi; Sato, Tatsuhiko

Physics Procedia, 80, p.25 - 35, 2015/12

https://doi.org/10.1016/j.phpro.2015.11.083

JAXA has been investigated the effect of the shielding material for dosimeters in the ISS Russian segment under the ALTCRISS project. The PADLES package is a passive dosimeters which usually consists of two types of passive and integrating dosimeters, a CR-39 plastic nuclear track detector and a thermoluminescence dosimeter. In the ALTCRISS experiments, both tissue-equivalent material CR-39 PNTDs and NAN-JAERI were enclosed in the PADLES packages as radiators for CR-39 to precisely measure a personal exposed doses. We compared the doses obtained by PADLESs with or without the PEs, and with or difference of the two tissue-equivalent materials. The results of space radiation measurements of the ALTCRISS project Phase 1 to 4 using the PADLES system will be reported in this time: Phase 1 experiments was from December 2005 to April 2006, Phase 2 was from April to September 2006, phase 3 was from Sep 2006 to April 2007, and Phase 4 was conducted from May to October 2007.

Current status of electrostatic accelerators at TIARA

Usui, Aya; Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Kitano, Toshihiko*; Takayama, Terumitsu*; Orimo, Takao*; Kanai, Shinji*; Aoki, Yuki*; et al.

Dai-27-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.118 - 121, 2015/03

no abstracts in English

Expansion control for cementation of incinerated ash

Nakayama, Takuya; Suzuki, Shinji; Hanada, Keiji; Tomioka, Osamu; Sato, Junya; Irisawa, Keita; Kato, Jun; Kawato, Yoshimi; Meguro, Yoshihiro

Proceedings of 2nd International Symposium on Cement-based Materials for Nuclear Wastes (NUWCEM 2014) (CD-ROM), 12 Pages, 2014/06

An Investigation for long-term storage of a spent zeolite adsorption vessel; Estimation of washing out salt component in a spent zeolite adsorption vessel, 1

Sato, Hiroyuki; Terada, Atsuhiko; Hayashida, Hitoshi; Kamiji, Yu; Kobayashi, Jun; Yamagishi, Isao; Morita, Keisuke; Kato, Chiaki

JAEA-Research 2013-042, 25 Pages, 2014/03

JAEA-Research-2013-042.pdf:5.13MB

Spent zeolite adsorption vessels in the Fukushima No.1 nuclear power plant are kept for long-term with washing out with fresh water for prevention of corrosion remaining salt component in vessel. However, corrosion result is concerned by residual concentration of salt component, washing out experiment is carried out using actual and unspent adsorption vessel (KURION). KURION adsorption vessel is filled with 1,650 ppm of sodium chloride (1,000 ppm of chloride ion) and washed out with pure water for estimating washing effect in this experiment. Pure water is streamed with volume flow rate 4.5 m/h, chloride concentration in vessel is measured with drainage sample water. 1,000 ppm of chloride concentration is decreased till 0.5 ppm and below by washing out with about double pure water volume of adsorbing material filling volume in vessel, washing out is more effective in KURION adsorption vessel.

Operation of electrostatic accelerators

Uno, Sadanori; Chiba, Atsuya; Yamada, Keisuke; Yokoyama, Akihito; Usui, Aya; Saito, Yuichi; Ishii, Yasuyuki; Sato, Takahiro; Okubo, Takeru; Nara, Takayuki; et al.

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 179, 2014/03

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2013-059.pdf

Three electrostatic accelerators at TIARA were operated on schedule in fiscal year 2012 except changing its schedule by cancellations of users. The yearly operation time of the 3 MV tandem accelerator, the 400 kV ion implanter and the 3MV single-ended accelerator were in the same levels as the ordinary one, whose operation time totaled to 2,073, 1,847 and 2,389 hours, respectively. The tandem accelerator had no trouble, whereas the ion implanter and the single-ended accelerator stopped by any troubles for one day and four days, respectively. The molecular ion beam of helium hydride was generated by the ion implanter, because the users required irradiation of several cluster ions in order to study the effect of irradiation. As a result, its intensity of beam was 50 nA at 200 kV. The ion beam of tungsten (W) at 15 MeV was accelerated by the tandem accelerator, whose intensity was 20 nA at charge state of 4+, because of the request from a researcher in the field of nuclear fusion.

Safe storage of zeolite adsorbents used for treatment of accident-generated water at Fukushima Daiichi Power Station

Yamagishi, Isao; Nagaishi, Ryuji; Terada, Atsuhiko; Kamiji, Yu; Kato, Chiaki; Morita, Keisuke; Nishihara, Kenji; Tsubata, Yasuhiro; Ji, W.*; Fukushima, Hisashi*; et al.

IAEA-CN-211 (Internet), 5 Pages, 2013/01

http://www-pub.iaea.org/iaeameetings/IEM4/29Jan/Yamagishi.pdf

Since the accident at Fukushima Daiichi Nuclear Power Station, a large amount of radioactive contaminated water has been generated to cool damaged reactor cores. Adsorption of cesium with zeolite-like media was employed for treatment of this contaminated saline water. As spent zeolite media are highly radioactive, their safe storage is a pressing issue. Japan Atomic Energy Agency has extensively conducted R&D on the management of secondary wastes produced by the operation of the treatment system. Subjects on the safe storage of spent zeolites include the analysis of their characteristics and the evaluation of effectiveness of the present safety measures in consideration of decay heat emission and hydrogen generation by water radiolysis as well as durability of vessels exposed to saline. Preliminary results obtained are described in the present paper.