Development of a cooperative operation robot system for radiation source exploration (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tohoku University*

JAEA-Review 2022-041, 76 Pages, 2023/01

JAEA-Review-2022-041.pdf:3.27MB

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 FY2021. 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 FY2021, this report summarizes the research results of the "Development of a cooperative operation robot system for radiation source exploration" conducted in FY2021. The present study aims to develop a Cooperative Operation Robot system for RAdiation Source Exploration (CORRASE). The multiple robot system provides radiation source exploration with wide field of view, rapidity, and low cost. The radiation source exploration is realized with multiple robots carrying directional gamma-ray detectors determining the incident direction of the incoming gamma-rays. We will develop the system by the final year of this proposal aiming for application in the Fukushima Daiichi Nuclear Power Station.

A Two-dimensional scintillation neutron detector for TAKUMI diffractometer in J-PARC MLF

Nakamura, Tatsuya; Kawasaki, Takuro; To, Kentaro; Harjo, S.; Sakasai, Kaoru; Aizawa, Kazuya

JPS Conference Proceedings (Internet), 33, p.011097_1 - 011097_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011097

A large area, two-dimensional scintillation neutron detector was developed for Takumi diffractometer in the J-PARC MLF. The detector is made based on a scintillator/wavelength shifting fiber technology. The detector has a neutron-sensitive area of 32 32 cm with a pixel size of 5 5 mm, which is about 1.5-fold larger than the SENJU detector TAKUMI is one of the neutron diffractometers in the MLF dedicated to use for engineering material research. The developed detector array adds new capabilities to the instrument to measure two-dimensional data collection at the back-scattering angles with a better time-of-flight resolution.

A Large area position-sensitive scintillation neutron detector for upgrading SENJU diffractometer

Nakamura, Tatsuya; To, Kentaro; Ebine, Masumi; Birumachi, Atsushi; Sakasai, Kaoru

Proceedings of 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2019), Vol.1, p.735 - 736, 2020/08

https://doi.org/10.1109/NSS/MIC42101.2019.9059981

A large area, position-sensitive scintillation neutron detector was developed for upgrading the SENJU, time-of-flight Laue single crystal neutron diffractometer, in J-PARC MLF. The detector has a neutron-sensitive area of 512 512 mm with a pixel size of 4 4 mm. The detector was developed for upgrading of the SENJU instrument. The large area detector is to be installed below the vacuum tank to enlarge a covering solid angle. A Li:ZnS (Ag) scintillator and wavelength-shifting fiber technologies are employed. Each fiber channel is read out individually with photon counting mode. The electronics boards are implemented at the backside of the detector, enabling the detector depth as short as 20 cm. The detector exhibited a detection efficiency of 45% for thermal neutron. No degradation in fiber position and in neutron sensitivity has been observed over one year after production. In this paper, detector design and detector performances are presented.

Measurement of ambient dose equivalent rates by walk survey around Fukushima Dai-ichi Nuclear Power Plant using KURAMA-II until 2016

Ando, Masaki; Yamamoto, Hideaki*; Kanno, Takashi*; Saito, Kimiaki

Journal of Environmental Radioactivity, 190-191, p.111 - 121, 2018/10

https://doi.org/10.1016/j.jenvrad.2018.04.025

Ambient dose equivalent rates in various environments related to human lives were measured by walk surveys using the KURAMA-II systems from 2013 to 2016 around the Fukushima Dai-ichi Nuclear Power Plant. The dose rate of the locations where the walk survey was performed decreased to about 38% of its initial value in the 42 months, which was beyond that attributable to the physical decay. The air dose rates decreased depending on the level of the evacuation areas, and the decrease was slightly larger in populated areas where humans are active. The comparison of walk survey data with car-borne survey data indicated that the air dose rate varies largely even within a 100 m square area. The dose rates measured by the walk surveys were estimated to be medial of those along roads and those of undisturbed flat ground. The air dose rates measured by the walk surveys decreased quickly compared with the air dose rate from the flat ground measurement.

CsI(Tl)/Plastic phoswich detector enhanced in low-energy -ray detection

Yamasoto, Kotaro; Tsutsumi, Masahiro; Oishi, Tetsuya*; Yoshizawa, Michio; Yoshida, Makoto

Nuclear Instruments and Methods in Physics Research A, 550(3), p.609 - 615, 2005/09

https://doi.org/10.1016/j.nima.2005.05.054

A phoswich detector composed of a thin plate CsI(Tl) scintillator and a plastic scintillator (BC-400) has been designed and evaluated to improve the sensitivity in the low-energy region of large-area plastic scintillation detector. Applicability of the CsI(Tl)/Plastic phoswich detector was examined on radioactivity measurement of massive and large-area materials. The rise-time discrimination technique was applied in order to further improve the minimum detectable activity in the low-energy region. On the basis of the estimation of minimum detectable activity, it was made clear that the energy range of large-area plastic scintillation detector can be expanded down to a few tens of keV by adding a thin plate CsI(Tl) scintillator.

Development of Aerial Gamma Radiation Survery System I ; Measuring Instruments of Gamma Radiation and Position Data,and Data Processing Method

; ; ; ;

JAERI-M 86-072, 90 Pages, 1986/05

JAERI-M-86-072.pdf:3.95MB

no abstracts in English

Monte Carlo calculation of accurate response functions of a NaI(Tl) detector for gamma rays

;

Nuclear Instruments and Methods, 185(1), p.299 - 308, 1981/00

no abstracts in English

A Two-dimensional scintillation neutron detector module for a new protein single crystal neutron diffractometer at J-PARC MLF

Nakamura, Tatsuya; To, Kentaro; Tsutsui, Noriaki; Ebine, Masumi; Birumachi, Atsushi

no journal, , 

A position-sensitive scintillation detector module for a new protein neutron diffractometer was developed by using a scintillator / wavelength shifting (WLS) fiber technology. The detector module has a spatial resolution of 2.5 mm with a neutron-sensitive area of 320 320 mm. The WLS fibers are arranged in a regular pitch of 2.5 mm in x and y direction and those arrays are placed diagonally. The light reflecting grid is inserted in between the fibers in order for optical isolation and for mechanical support of the fiber. The detector implemented flat Li/ZnS screens up and downstream of the WLF fiber arrays. The detector exhibited a detection efficiency of 30-50% for thermal neutron (depending on -ray sensitivities) and a count uniformity of ~13%. In this paper detailed detector design and experimental results obtained using a pulsed neutron beam are presented.

Development of position-sensitive scintillation neutron detector using wavelength shifting fiber at J-PARC MLF

Nakamura, Tatsuya; To, Kentaro; Kawasaki, Takuro; Kiyanagi, Ryoji; Ohara, Takashi; Koizumi, Tomokatsu; Ebine, Masumi; Sakasai, Kaoru

no journal, , 

Position-sensitive scintillation neutron detectors developed using wavelength-shifting (WLS) fiber read out in the Materials and Life Science Experimental Facility of the Japanese Proton Accelerator Research Complex (J-PARC MLF) are briefly reviewed. Several tens of two-dimensional scintillator / WLS fiber detectors have been developed for the single crystal diffractometers. They are implemented to the beam lines of BL03 and BL18. The scintillator / WLS fiber read out technology has many advantages over conventional clear fiber coupled detectors, such as its simple detector structure, flexibility to a pixel size design, and manufacturing cost. In this paper, several examples of the WLS fiber detectors developed at J-PARC MLF are presented together with a recent detector development for the additional detector bank of the BL18. Moreover, a possibility to produce a larger area detector with this technology will be discussed.

Detector upgrade for SENJU neutron diffractometer at J-PARC MLF

Nakamura, Tatsuya; To, Kentaro; Kiyanagi, Ryoji; Ohara, Takashi; Hosoya, Takaaki; Tobe, Masahiro; Hishinuma, Yukio*; Ebine, Masumi; Sakasai, Kaoru

no journal, , 

New detector modules have been developed based on a Li:ZnS scintillator and wavelength-shifting fibers technology to upgrade the detectors for SENJU neuron diffractometer at J-PARC MLF. The detector upgrade plan includes (1) Thin-type add-in detectors, (2) High efficiency detectors to replace the original ones, (3) a large area detector for installation under the sample vacuum tank (Large area bottom detector), and (4) One detector-bank detectors. As for (1) and (2) the detector modules have been developed with a 1.5-fold improved detection efficiency with a 50-60% smaller detector depth. 4 add-in detectors and 6 replacement detectors have been manufactured and installed to the diffractometer. The large area bottom detector that has a four-fold larger neutron-sensitive area than the original detector, has also been developed. To increase the light collection efficiency a scintillation light is collected from the both ends of the wavelength-shifting fiber. The prototype detector exhibited an acceptable count uniformity 59% over the detector.