Status report of JAEA-AMS-TONO; Research and technical development in the last four years

Kokubu, Yoko; Fujita, Natsuko; Watanabe, Takahiro; Matsubara, Akihiro; Ishizaka, Chika; Miyake, Masayasu*; Nishio, Tomohiro*; Kato, Motohisa*; Ogawa, Yumi*; Ishii, Masahiro*; et al.

Nuclear Instruments and Methods in Physics Research B, 539, p.68 - 72, 2023/06

https://doi.org/10.1016/j.nimb.2023.03.005

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has an accelerator mass spectrometer (JAEA-AMS-TONO-5MV). The spectrometer enabled us to use a multi-nuclide AMS of carbon-14 (C), beryllium-10, aluminium-26 and iodine-129, and we have recently been proceeding test measurement of chlorine-36. In response to an increase of samples, we installed a state-of-the-art multi-nuclide AMS with a 300 kV Tandetron accelerator in 2020. Recently, we are driving the development of techniques of isobar separation in AMS and of sample preparation. Ion channeling is applied to remove isobaric interference and we are building a prototype AMS based on this technique for downsizing of AMS. The small sample graphitization for C has been attempted using an automated graphitization equipment equipped with an elemental analyzer.

Present status of the JAEA-AMS-TONO (2022FY)

Fujita, Natsuko; Miyake, Masayasu; Matsubara, Akihiro*; Ishii, Masahiro*; Watanabe, Takahiro; Jinno, Satoshi; Nishio, Tomohiro*; Ogawa, Yumi; Yamamoto, Yusuke; Kimura, Kenji; et al.

Dai-23-Kai AMS Shimpojiumu Hokokushu, p.1 - 4, 2022/12

The JAEA-AMS-TONO facility at the Tono Geoscience Center, JAEA has three accelerator mass spectrometers. We report the present status of the JAEA-AMS-TONO.

Manufacture of substitutive assemblies for MONJU reactor decommissioning

Sakakibara, Hiroshi; Aoki, Nobuhiro; Muto, Masahiro; Otabe, Jun; Takahashi, Kenji*; Fujita, Naoyuki*; Hiyama, Kazuhiko*; Suzuki, Hirokazu*; Kamogawa, Toshiyuki*; Yokosuka, Toru*; et al.

JAEA-Technology 2020-020, 73 Pages, 2021/03

JAEA-Technology-2020-020.pdf:8.26MB

The decommissioning is currently in progress at the prototype fast breeder reactor Monju. Fuel assemblies will be taken out of its core for the first step of the great task. Fuel assemblies stand on their own spike plugged into a socket on the core support plate and support with adjacent assemblies through their housing pads each other, resulting in steady core structure. For this reason, some substitutive assemblies are necessary for the purpose of discharging the fuel assemblies of the core. Monju side commissioned, therefore, Plutonium Fuel Development Center to manufacture the substitutive assemblies and the Center accepted it. This report gives descriptions of design, manufacture, and shipment in regard to the substitutive assemblies.

Development of MIG2DF Version 2

Takai, Shizuka; Kimura, Hideo*; Uchikoshi, Emiko*; Munakata, Masahiro; Takeda, Seiji

JAEA-Data/Code 2020-007, 174 Pages, 2020/09

JAEA-Data-Code-2020-007.pdf:4.23MB

The MIG2DF computer code is a computer program that simulates groundwater flow and radionuclide transport in porous media for the safety assessment of radioactive waste disposal. The original version of MIG2DF was released in 1992. The original code employs a two-dimensional (vertical or horizontal cross-section, or an axisymmetric configuration) finite-element method to approximate the governing equations for density-dependent saturated-unsaturated groundwater flow and radionuclide transport. Meanwhile, for geological disposal of radioactive wastes, landscape evolution such as uplift and erosion needs to be assessed as a long-term geological and climate events, considering site conditions. In coastal areas, the impact to groundwater flow by change of salinity distribution to sea level change also needs to be considered. To deal with these events in the assessment, we have revised the original version of MIG2DF and developed the external program which enables MIG2DF to consider unsteady landscape evolution. In these developments, this report describes an upgrade of MIG2DF (Version 2) and presents the configuration, equations, methods, and verification. This reports also give the explanation external programs of MIG2DF: PASS-TRAC (the particle tracking code), PASS-PRE (the code for dataset preparation), and PASS-POST (the post-processing visualization system).

Measurement of the angular distribution of -rays after neutron capture by La for a T-violation search

Okudaira, Takuya; Shimizu, Hirohiko*; Kitaguchi, Masaaki*; Hirota, Katsuya*; Haddock, C. C.*; Ito, Ikuya*; Yamamoto, Tomoki*; Endo, Shunsuke*; Ishizaki, Kohei*; Sato, Takumi*; et al.

EPJ Web of Conferences, 219, p.09001_1 - 09001_6, 2019/12

https://doi.org/10.1051/epjconf/201921909001

Parity violating effects enhanced by up to 10 times have been observed in several neutron induced compound nuclei. There is a theoretical prediction that time reversal (T) violating effects can also be enhanced in these nuclei implying that T-violation can be searched for by making very sensitive measurements. However, the enhancement factor has not yet been measured in all nuclei. The angular distribution of the (n,) reaction was measured with La by using a germanium detector assembly at J-PARC, and the enhancement factor was obtained. From the result, the measurement time to achieve the most sensitive T-violation search was estimated as 1.4 days, and a 40% polarized La target and a 70% polarized He spin filter whose thickness is 70 atmcm are needed. Therefore high quality He spin filter is developed in JAEA. The measurement result of the (n,) reaction at J-PARC and the development status of the He spin filter will be presented.

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

https://doi.org/10.3390/qubs1030009

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Survey on evacuation facilities in case of nuclear emergency in Shimane prefecture (Contract research)

Takahara, Shogo; Watanabe, Masatoshi; Oguri, Tomomi; Kimura, Masanori; Hirouchi, Jun; Munakata, Masahiro; Homma, Toshimitsu

JAEA-Data/Code 2016-016, 65 Pages, 2017/02

JAEA-Data-Code-2016-016.pdf:2.32MB

We surveyed on structural and material data on 22 facilities which are listed in local disaster management plan in Matsue city. These facilities can be divided into educational facilities, communal facilities and gymnastic hall. Height and floor-area of rooms, as well as window-area were collected as the structural data. We also collected information on constructional materials, and density of those. In addition, mass-thicknesses of the constructional materials were evaluated based on our surveys, and compared to the previous studies which were made in Japan, U.S., and European countries. Consequently, it was found that there is no significant difference of mass-thickness of constructional materials between the results of our surveys and the previous studies. However, for gymnastic hall, since thin metal plates are used for roofs, we can point out that the mass-thickness of roofs are much lower than those for other concrete facilities and clay tile roofing wooden houses.

Study on evaluation methodology for groundwater flow based on geochemical data, 2; Case study for Horonobe area (Contract research)

Sakai, Ryutaro; Takeda, Seiji; Munakata, Masahiro; Kimura, Hideo

JAEA-Research 2013-006, 18 Pages, 2013/07

JAEA-Research-2013-006.pdf:2.77MB

In the safety assessment for a geological disposal of radioactive waste, it is important to establish validation methods for deep groundwater flow to estimate radionuclide migration to human environment through groundwater flow. Costal sedimentary rocks in our country provide dominant fossil water formed during sub-seabed sedimentation and chemical compositions of the water mixed with meteoric water and fossil water depend on the initial fossil water composition and groundwater flow conditions. Analytical study on the effects of groundwater flow on the mixed water quality as a indicator of its Cl/O ratios was carried out in case of Horonobe district, where geochemical data is now being stored.

Resonant inelastic X-ray scattering study of intraband charge excitations in hole-doped high- cuprates

Wakimoto, Shuichi; Ishii, Kenji; Kimura, Hiroyuki*; Ikeuchi, Kazuhiko*; Yoshida, Masahiro*; Adachi, Tadashi*; Casa, D.*; Fujita, Masaki*; Fukunaga, Yasushi*; Gog, T.*; et al.

Physical Review B, 87(10), p.104511_1 - 104511_7, 2013/03

https://doi.org/10.1103/PhysRevB.87.104511

Investigation on highly alkaline plume spreading over host rock of geological disposal of TRU waste by reactive transport analysis

Takeda, Seiji; Nishimura, Yuki; Munakata, Masahiro; Sawaguchi, Takuma; Kimura, Hideo

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 19(2), p.23 - 38, 2012/12

https://doi.org/10.3327/jnuce.19.23

In safety assessments of the geological disposal of TRU waste, it is important to understand the possibility and extents of influence of hyperalkaline groundwater derived from the degradation of cementitious materials that are used as forms for the containment of waste and as constructional materials in the disposal facilities of TRU waste. In this research, reactive transport analyses of hyperalkaline plume induced by cementitious materials were performed to clarify the extent of the hyperalkaline groundwater spreading and the type of alterations occurring with or without considering the precipitation of zeolite. The effect of the groundwater velocities on the spread of hyperalkaline groundwater was also examined. The analysis results indicate that whether zeolites precipitate or not significantly affect extent of hyperalkaline groundwater and the amount of precipitation of secondary minerals. In the case that groundwater velocity was 10 times higher, hyperalkaline groundwater spread broader than the original groundwater velocity case. It might be due to our kinetic dissolution model of host rock minerals, which limits chemical reactions neutralizing hyperalkaline groundwater.