Development of high-resolution imaging camera for alpha dust (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*

JAEA-Review 2020-039, 59 Pages, 2021/01

JAEA-Review-2020-039.pdf:4.18MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of high-resolution imaging camera for alpha dust" conducted in FY2019. We have developed an imaging camera with a position resolution of less than approximately 10 m to monitor alpha dust in the nuclear plant during the decommissioning process, because the operators avoid to drawing in such dusts. Moreover, we have developed real-time monitor system with optical fiber and scintillator under high dose-rate condition.

Development of imaging system with ultra-high spatial resolution aiming to detect alpha-dust (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*

JAEA-Review 2019-038, 57 Pages, 2020/03

JAEA-Review-2019-038.pdf:4.6MB

JAEA/CLADS, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of Imaging System with Ultra-high Spatial Resolution Aiming to Detect Alpha-dust". In the present study, we have developed a prototype of a system aiming to elucidate the behavior of alpha-dust generated at the time of debris retrieval. In this system, alpha-ray is first converted to visible light by novel scintillator. Then, imaging with ultra-high resolution will be possible using a lens and an Si-semiconductor camera (CMOS camera). Also, it will be possible to identify the species of alpha-ray emitting nuclides by unfolding of the spectra. The demonstration tests of the system will be conducted for dust samplers at the Plutonium Fuel Development Center, JAEA. In the development of the present system, it is important to use scintillator whose emission wavelength is sensitive to the CMOS camera as well as high emission scintillator. Considering these conditions, the key technology will be the improvement of the purity of crystals and optimization of the shapes of the materials including powers.

Local-scale high-resolution atmospheric dispersion model using large-eddy simulation; LOHDIM-LES

Nakayama, Hiromasa; Nagai, Haruyasu

JAEA-Data/Code 2015-026, 37 Pages, 2016/03

JAEA-Data-Code-2015-026.pdf:2.48MB

We developed LOcal-scale High-resolution atmospheric DIspersion Model using Large-Eddy Simulation (LOHDIM-LES). This dispersion model is designed based on LES which is effective to reproduce unsteady behaviors of turbulent flows and plume dispersion. The basic equations are the continuity equation, the Navier-Stokes equation, and the scalar conservation equation. Buildings and local terrain variability are resolved by high-resolution grids with of a few meters and these turbulent effects are represented by immersed boundary method. In simulating atmospheric turbulence, boundary layer flows are generated by a recycling turbulent inflow technique in a driver region set up at the upstream of the main analysis region. This turbulent inflow data are imposed at the inlet of the main analysis region. By this approach, the LOHDIM-LES can provide detailed information on wind velocities and plume concentration in the investigated area.

Development of a neutron-imaging detector based on pulse-height correlation between two superconducting tunnel junctions on a LiBO crystal

Nakamura, Tatsuya; Katagiri, Masaki; Chen, Y. E.*; Ukibe, Masahiro*; Okubo, Masataka*

Nuclear Instruments and Methods in Physics Research A, 559(2), p.766 - 768, 2006/04

https://doi.org/10.1016/j.nima.2005.12.131

We have been developing a position-sensitive neutron detector, which exhibits a high spatial resolution of the order of 10 microns and high detection efficiency. The analysis on the pulse-heights or on the time-delay between the STJs gives incident positions of the neutrons. In this paper, the response of the STJs/LBO neutron detector measured using a cold neutron beam is presented. The two STJs have the same size of 50 50 m and their distance is 1.3 mm. The count intensity in the correlation map varied depending on the incident position of the neutron beam which gives an evidence for the position-sensitivity of the detector. These experimental results were qualitatively understood by a simple solid-angle model.

High-pressure induced structural changes in metastable GeSbTe thin films; An X-ray absorption study

Fons, P.*; Kolobov, A.*; Tominaga, Junji*; Katayama, Yoshinori

Nuclear Instruments and Methods in Physics Research B, 238(1-4), p.160 - 162, 2005/08

https://doi.org/10.1016/j.nimb.2005.06.039

Super-resolution (SR) media offer up to a factor of ten increase in areal storage density over conventional DVD media. Although SR has been realized, there is a strong need for a deeper understanding of structural and electronic changes in GeSbTe (GST), a principal optical memory component, with external perturbations. Recording of SR disks leads to the formation of gas-phase bubbles that in turn lead to the development of large stresses on the underlying GST layer. In this paper we report on XAFS of nominally hydrostatic (0-10 GPa) compressive stress-induced structural changes of the metastable crystalline phase of GST. An analysis showed that the initial splitting of Ge Te bond lengths of the room-temperature distorted rocksalt structure decreased to a small but finite splitting for 6 GPa. The implications of this upon the proposed ferroelectric catastrophe super-RENS readout mechanism are discussed.

Operation of a capillary plate under high-pressure He for neutron detection

Nakamura, Tatsuya; Masaoka, Sei; Yamagishi, Hideshi; Tanaka, Hiroki; Soyama, Kazuhiko; Aizawa, Kazuya

Nuclear Instruments and Methods in Physics Research A, 539(1-2), p.363 - 371, 2005/02

https://doi.org/10.1016/j.nima.2004.10.024

We evaluated the neutron-detection performance of a capillary plate under high-pressure helium-3 in terms of the gas gain and the distribution of pulse heights, with the aim of using the device as a neutron detector and a gas preamplification device. The capillary plate exhibited a gas gain of more than 1000 up to a gas pressure of 6 atm with a 5% mixture of ethane, confirming an adequate gas gain as a neutron detector. It was also found that the rise times of the signal pulses were correlated with the range and the emission angle of the secondary particles, protons and tritons, thereby providing useful information for developing a system with position-sensitive readouts with a high spatial resolution and a low background.

Instrumentation for measurement of beam energy spread

Okumura, Susumu; Miyawaki, Nobumasa; Kurashima, Satoshi; Yoshida, Kenichi; Fukuda, Mitsuhiro; Ishibori, Ikuo; Agematsu, Takashi; Nara, Takayuki; Nakamura, Yoshiteru; Arakawa, Kazuo

Proceedings of 17th International Conference on Cyclotrons and Their Applications (CYCLOTRONS 2004), p.410 - 412, 2005/00

A simple analyzing system has been developed to measure the energy spread of the beam extracted from the JAERI AVF cyclotron with an energy resolution of dE/E = 0.001%. The high analyzing power can be obtained with an existing deflecting magnet system in the transport line by installing three sets of slits with a minimum width of 0.01 mm and a beam intensity monitor with a Faraday cup and semiconductor detectors. These new instruments have been compactly designed to fulfill the geometrical condition of the existing beam diagnostic chambers, which are located at the object and image positions. Installation of the analyzing system was completed and a preliminary test has been carried out. This system will be used for optimization of the flat-top acceleration system to achieve the energy spread of dE/E = 0.02%, required for microbeam production.

Neutron image characteristics of imaging plates using SrBPO:Eu photostimulabe phosphors

Sakasai, Kaoru; Katagiri, Masaki; Nakamura, Tatsuya

JAERI-Research 2004-019, 33 Pages, 2004/12

JAERI-Research-2004-019.pdf:7.99MB

As a new candidate for raw materials of a neutron imaging plate, characteristics of a SrBPO:Eu phosphor that has boron (B) in the base matrix as a neutron converter have been investigated. The phosphor has a strong merit that it generates photostimulated luminescence of 390 nm by illumination of red laser light after neutron irradiation. The emission and excitation wavelengths were the same as those of commercially available neutron imaging plate. Therefore, the authors have fabricated neutron imaging plates by painting the phosphor on Al plates. Neutron imaging experiments using the fabricated imaging plates were carried out with a commercially available image reader. A Li block was used as a camera subject in the experiments. As a result of the experiments, it was confirmed that the neutron image was clearly obtained, though the intensity of the image was not so high. The position resolution of 0.2 mm was obtained when the readout resolution of 50 m in the reader was used.

Preliminary examination of a CCD camera with a scintillator coated fiber optic plate for neutron imaging

Matsubayashi, Masahito; Soyama, Kazuhiko

Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.384 - 388, 2004/08

https://doi.org/10.1016/j.nima.2004.05.016

no abstracts in English

Neutron crystallographic study on rubredoxin from by BIX-3, a single-crystal diffractometer for biomacromolecules

Kurihara, Kazuo; Tanaka, Ichiro*; Chatake, Toshiyuki*; Adams, M. W. W.*; Jenney, F. E. Jr.*; Moiseeva, N.*; Bau, R.*; Niimura, Nobuo

Proceedings of the National Academy of Sciences of the United States of America, 101(31), p.11215 - 11220, 2004/08

https://doi.org/10.1073/pnas.0403807101

The structure of a rubredoxin (Rd) from , an organism that grows optimally at 100 C, was determined using the neutron single-crystal diffractometer for biological macromolecules (BIX-3) at the JRR-3 reactor of JAERI. Data were collected at room temperature up to a resolution of 1.5 , and the completeness of the data set was 81.9 %. The model contains 306 H atoms and 50 D atoms. A total of 37 hydration water molecules were identified. The model has been refined to final agreement factors of = 18.6 % and = 21.7 %. Several orientations of the O-D bonds of side chains, whose assignments from X-ray data were previously ambiguous, were clearly visible in the neutron structure. While most backbone N-H bonds had undergone some degree of H/D exchange throughout the molecule, five H atom positions still had distinctly negative (H) peaks. The neutron Fourier maps clearly showed the details of an extensive set of H bonds involving the ND terminus that may contribute to the unusual thermostability of this molecule.