International Noble Gas joint measurement at Mutsu City, Aomori for CTBT verification

Kijima, Yuichi; Yamamoto, Yoichi; Oda, Tetsuzo

JAEA-Technology 2017-028, 33 Pages, 2018/01

JAEA-Technology-2017-028.pdf:38.85MB

The International Noble Gas Experiment related to monitoring network for radioactive noble gas (xenon) has been carried out all over the world, as part of the International Monitoring System (IMS) of CTBT. Thirty IMS radionuclide stations including the Takasaki station in Japan are monitoring radioxenon. The past measurement results show that several stations often detect radioxenon and the major emission source of these radioxenon is medical radioisotope production facilities. And nuclear power plants and medical institutions used radioxenon for nuclear medicine diagnosis, and so on are also considered as the possible sources of radioxenon, and it is therefore important to understand the background behavior of radioxenon originated from above facilities for enhancement of monitoring capability for nuclear tests. The international joint measurement was conducted in 2012 by the Preparatory Commission for the CTBT Organization, US Pacific Northwest National Laboratory, Japan Chemical Analysis Center and JAEA at the Ohminato site of JAEA Aomori Research and Development Center in Mutsu city, Aomori, as part of investigation on radioxenon background in East Asia region. In 2014, the additional measurement was carried out at the same place for further investigation. A high sensitive Transportable Xenon Laboratory developed by PNNL was used for this measurement. This paper describes the outline and the results of the joint measurement conducted in 2012 and 2014.

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.

Monitoring of radionuclide related to CTBT

Kijima, Yuichi; Yamamoto, Yoichi

Nihon Genshiryoku Gakkai-Shi ATOMO, 58(3), p.156 - 160, 2016/03

JAEA has built and operated two radionuclide stations and a certified laboratory for monitoring of radionuclide out of facilities of the International Monitoring System (IMS) under the CTBT National Operation System of Japan. JAEA also has developed and operated the National Data Center for analysis and evaluation of radionuclide observation data obtained from the IMS station. In this paper, we explain the outline of the CTBT and the CTBT activities of JAEA, and introduce two examples of detection of some anthropogenic radionuclides including the monitoring case for the DPRK's 3rd nuclear test in February 2013 from all observational results obtained from the CTBT radionuclide stations in Japan.

Noble gas monitoring at the Takasaki radionuclide station of JAEA; Certification by the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Organization

Yamamoto, Yoichi

Isotope News, (736), p.31 - 33, 2015/08

https://www.jrias.or.jp/books/pdf/201508_TRACER_YAMAMOTO.pdf

The Takasaki radionuclide (RN) station for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) has been in operation for monitoring of radioactive noble gases (radioxenon) by the Japan Atomic Energy Agency (JAEA) since 2007, first as a test run prior to receiving the certification. The noble gas system in the station was certified by the CTBT Organization (CTBTO) on December 19, 2014. Monitoring of radioxenon is expected to have a particularly valuable role in detection of an underground nuclear test. The Takasaki RN station detected radioxenon isotopes simultaneously with radioactive concentration exceeding normal background range in April, 2013. This abnormal event was identified as being associated with the nuclear test declared by North Korea in February, 2013. Since the Takasaki RN station is located at the east end of Asia, it is receiving widespread international attention as the station for radionuclides dispersed by the westerlies.

Developing the soil moisture sensor using optical fiber technique (Joint research)

Komatsu, Mitsuru*; Nishigaki, Makoto*; Seno, Shoji*; Hirata, Yoichi*; Takenobu, Kazuyoshi*; Tagishi, Hirotaka*; Kunimaru, Takanori; Maekawa, Keisuke; Yamamoto, Yoichi; Toida, Masaru*; et al.

JAEA-Research 2012-001, 77 Pages, 2012/09

JAEA-Research-2012-001.pdf:4.85MB

This research focused on methods of estimating the amounts of groundwater recharge, which are normally required as upper boundary conditions in groundwater flow analyses, based on measurements of infiltrating water in the ground, to systematize the methods and establish systems which are stable and measurable on site over a long time. Regarding developing measurement systems, fiber-optic strain measurement methods that enable multiple-point and long-distance measurement were used for measuring three quantities: suction pressure, soil moisture and volumetric water content rate obtained by applying water absorption swelling material, and each measurement was discussed. The results showed that the fiber-optic soil aquameter has two types of practical application: one for measuring suction pressure (Type I), and the other for measuring volumetric water content rate obtained by applying water absorption swelling material (Type III). Furthermore, by using measurement instruments in actual fields, the validity of the two methods for estimating the rainfall infiltration capacities of shallow-layer soils, that is, estimating the capacities either directly by measurements of soil water or from unsaturated hydraulic conductivities, was confirmed.

Beam halo reduction in the J-PARC 3-GeV RCS

Hotchi, Hideaki; Harada, Hiroyuki; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; Yoshimoto, Masahiro; Irie, Yoshiro*; Koseki, Tadashi*; et al.

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3918 - 3920, 2012/05

http://accelconf.web.cern.ch/accelconf/IPAC2012/papers/thppp080.pdf

The RCS beam power ramp-up has well proceeded since the start-up of user program in December 2008. So far the RCS has successfully achieved high intensity beam trials up to 420 kW at a low-level intensity loss of less than 1%, and the output beam power for the routine user program has been increased to 210 kW to date. Recently our effort has also been made to improve the quality of the extraction beam, namely to realize low-halo high-power beams. In this paper, recent effort for beam halo reduction in the RCS will be presented.

Measurement of anthropogenic radionuclides in the atmosphere with a radionuclide monitoring network for nuclear tests

Yonezawa, Chushiro*; Yamamoto, Yoichi

Bunseki, (440), p.451 - 458, 2011/08

https://cir.nii.ac.jp/crid/1570291225088387200

A worldwide radionuclide monitoring network for nuclear tests has detected the anthropogenic radioactive materials released in the atmosphere due to the accident of the Fukushima Daiichi Nuclear Power Plant impacted by the Great East Japan Earthquake on March 11, 2011. After four months have passed since the accident occurred, most overseas stations do not detect the radionuclides of Fukushima origin any more. The Takasaki station in Japan, however, is still detecting them every day. This paper describes radionuclide monitoring stations and the network of them as part of the International Monitoring System (IMS) in the Comprehensive Nuclear Test Ban Treaty (CTBT), as well as the measurement results of radionuclide particulates and radioactive isotopes of xenon released from the Fukushima Daiichi Nuclear Power Plant with the monitoring network.

Application of cathodic protection of stainless steel for components in fuel reprocessing plant

Ueno, Fumiyoshi; Uchiyama, Yohei*; Kato, Chiaki; Yamamoto, Masahiro; Ebina, Tetsunari*; Shimogawara, Shigeru*; Kano, Yoichi*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 9(3), p.279 - 287, 2010/09

https://doi.org/10.3327/taesj.J09.035

An application of cathodic protection method with impressed current system to control corrosion of austenitic stainless steel in boiling nitric acid solution was studied to improve corrosion resistance of components in fuel reprocessing plant. Plate and tube type specimens made of ultra low carbon type 304 stainless steel (SUS304ULC) were immersed in boiling nitric acid solutions using electrochemical test cells, electrochemical potentiostatic tests and cathodic protection tests were performed. Corrosion rates in the solution with and without protection were measured. As the results, corrosion rates of plate type specimens with cathodic protection were decreased from 1/40 to 1/10 against without protection. In the case of tube type specimen, loss of outer surface thickness was decreased about 1/8, and no deviation of the loss was observed. Authors were concluded that cathodic protection method was expectative as one of the maintenance methods of components in fuel reprocessing plant.

Conceptual design of experimental equipment for large-diameter NTD-Si

Yagi, Masahiro; Watanabe, Masanori; Oyama, Koji; Yamamoto, Kazuyoshi; Komeda, Masao; Kashima, Yoichi; Yamashita, Kiyonobu

Applied Radiation and Isotopes, 67(7-8), p.1225 - 1229, 2009/07

https://doi.org/10.1016/j.apradiso.2009.02.018

Formation of isotopically enriched silicon film from fluorosilane produced by isotopically selective infrared multiphoton dissociation

Oba, Hironori; Suzuki, Hiroshi*; Esaka, Fumitaka; Taguchi, Tomitsugu; Yamada, Yoichi; Yamamoto, Hiroyuki; Sasase, Masato*; Yokoyama, Atsushi

Journal of the Vacuum Society of Japan, 52(6), p.292 - 295, 2009/07

no abstracts in English