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Journal Articles

Layered structure in the crystalline adsorption layer and the leaching process of poly(vinyl alcohol) revealed by neutron reflectivity

Miyazaki, Tsukasa*; Miyata, Noboru*; Arima, Hiroshi*; Kira, Hiroshi*; Ouchi, Keiichi*; Kasai, Satoshi*; Tsumura, Yoshihiro*; Aoki, Hiroyuki

Langmuir, 37(32), p.9873 - 9882, 2021/08

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

Journal Articles

Position-encoded automatic cell elevator for BL02, J-PARC MLF

Tominaga, Taiki*; Kobayashi, Makoto*; Yamada, Takeshi*; Matsuura, Masato*; Kawakita, Yukinobu; Kasai, Satoshi*

JPS Conference Proceedings (Internet), 33, p.011095_1 - 011095_5, 2021/03

A vertical movement type of sample changer for the neutron spectrometer BL02, J-PARC MLF was developed for our top-loading type cryostat. The sample changer, termed as "PEACE", can control reproducibility of the irradiated position using guides made of polyether ether ketone. The variation between the background scattering profiles of three sample positions was found to be less than plus minus 1.6%. This result is reasonable, considering the deviation of sample position of less than plus minus 0.3 mm from the vertical axis.

Journal Articles

Morphological reproductive characteristics of testes and fertilization capacity of cryopreserved sperm after the Fukushima accident in raccoon (${it Procyon lotor}$)

Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.

Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03

We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.

Journal Articles

Fine-structure analysis of perhydropolysilazane-derived nano layers in deep-buried condition using polarized neutron reflectometry

Akutsu, Kazuhiro*; Kira, Hiroshi*; Miyata, Noboru*; Hanashima, Takayasu*; Miyazaki, Tsukasa*; Kasai, Satoshi*; Yamazaki, Dai; Soyama, Kazuhiko; Aoki, Hiroyuki

Polymers (Internet), 12(10), p.2180_1 - 2180_10, 2020/10

 Times Cited Count:0 Percentile:0(Polymer Science)

Journal Articles

Development of alternative $$^3$$He NDA detector system

Koizumi, Mitsuo; Sakasai, Kaoru; Kureta, Masatoshi; Nakamura, Hironobu

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 58(11), p.642 - 646, 2016/11

no abstracts in English

Journal Articles

Numerical evaluation of the light transport properties of alternative He-3 neutron detectors using ceramic scintillators

Ozu, Akira; Takase, Misao*; Haruyama, Mitsuo; Kurata, Noritaka*; Kobayashi, Nozomi*; Kureta, Masatoshi; Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; et al.

Nuclear Instruments and Methods in Physics Research A, 798, p.62 - 69, 2015/10

 Times Cited Count:2 Percentile:22.25(Instruments & Instrumentation)

The light transport properties of scintillator light inside alternative He-3 neutron detector modules using scintillator sheets have been investigated by a ray-tracing simulation code. The detector module consists of a light-reflecting tube, a thin rectangular ceramic scintillator sheet laminated on a glass plate, and two photo-multiplier tubes (PMTs) mounted at both ends of the detector tube. The light induced on the surface of the scintillator sheet via nuclear interaction between the scintillator and neutrons are detected by the two PMTs. The light output of various detector modules in which the scintillator sheets are installed with several different arrangements were examined and evaluated in comparison with experimental results. The results derived from the simulation reveal that the light transport property is strongly dependent on the arrangement of the scintillator sheet inside the tube and the shape of the tube.

Journal Articles

Development and demonstration of a Pu NDA system using ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator detectors

Nakamura, Hironobu; Ozu, Akira; Kobayashi, Nozomi*; Mukai, Yasunobu; Sakasai, Kaoru; Nakamura, Tatsuya; Soyama, Kazuhiko; Kureta, Masatoshi; Kurita, Tsutomu; Seya, Michio

Proceedings of INMM 55th Annual Meeting (Internet), 9 Pages, 2014/07

To establish an alternative technique of He-3 neutron detector that is used for nuclear material accountancy and safeguards, we have started an R&D project to develop a new type of neutron detector (Pu NDA system) using ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator with support of Japanese government. The design of the alternative system (ASAS: Alternative Sample Assay System) is basically referenced from INVS (INVentory Sample assay system) which is passive neutron assay system of plutonium and has total 18 He-3 tubes (about 42% of counting efficiency), and the small amount of Pu in the MOX powder or Pu nitrate solution in a vial can be measured. In order to establish the technology and performance after the fabrication of the new detector progresses, we are planning to conduct demonstration activity in the early 2015 experimentally. The demonstration activity implements the confirmation of reproducibility about sample positioning, optimization of detector parameters, counting statistical uncertainty, stability (temperature and $$gamma$$-ray change) check and figure of merit (FOM) using check source and actual MOX powder. In addition to that, performance comparison between current INVS and the ASAS are also conducted. In this paper, we present some analytical study results using a Monte-Carlo simulation code (MCNP), entire ASAS design and demonstration plan to prove technology and performance.

Journal Articles

Neutron-sensitive ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator detector as an alternative to a $$^{3}$$He-gas-based detector for a plutonium canister assay system

Nakamura, Tatsuya; Ozu, Akira; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; Honda, Katsunori; Birumachi, Atsushi; Ebine, Masumi; Yamagishi, Hideshi*; Takase, Misao; et al.

Nuclear Instruments and Methods in Physics Research A, 763, p.340 - 346, 2014/05

 Times Cited Count:3 Percentile:30.04(Instruments & Instrumentation)

A neutron-sensitive ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator detector was developed as an alternative to a $$^{3}$$He-gas-based detector for use in a plutonium canister assay system. The detector has a modular structure, with a flat ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ceramic scintillator strip that is installed diagonally inside a light-reflecting aluminium case with a square cross section. The prototype detectors, which have a neutron-sensitive area of 30 mm $$times$$ 250 mm, exhibited a sensitivity of 21.7-23.4 $$pm$$ 0.1 cps$$/$$nv for thermal neutrons, a $$^{137}$$Cs $$gamma$$-ray sensitivity of 1.1-1.9 $$pm $$0.2 $$times$$ 10$$^{-7}$$ and a count variation of less than 6% over the detector length. A trial experiment revealed a temperature coefficient of less than -0.24$$pm$$ 0.05% / $$^{circ}$$C over the temperature range of 20-50$$^{circ}$$C.

Journal Articles

Evaluation of light transport property in alternative He-3 neutron detectors using ceramic scintillators by a ray-tracing simulation

Ozu, Akira; Takase, Misao*; Kurata, Noritaka*; Kobayashi, Nozomi*; Tobita, Hiroshi; Haruyama, Mitsuo; Kureta, Masatoshi; Nakamura, Tatsuya; Suzuki, Hiroyuki; To, Kentaro; et al.

Proceedings of 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference; 21st International Symposium on Room-Temperature Semiconductor X-ray and $$gamma$$-ray detectors (NSS/MIC 2014), 5 Pages, 2014/00

In Japan Atomic Energy Agency, the helium-3 alternative neutron detector using ceramic scintillators for nuclear safeguards is under development with the support of the government. The alternative detector module consists of four components: an aluminum regular square tube, a light reflecting foil put on the inner surface of the square tube, a rectangular scintillator sheet sintered on a glass plate, and two PMTs provided at both ends of the tube. The scintillator sheet is fit on the diagonal inside the square tube. The light transport property of scintillator lights inside the tube influences on the fundamental performance of the alternative detector. Therefore, the properties of the lights emitted on the surface of the scintillator sheet and scintillation lights passing through the glass plate to the PMTs in several arrangements of the scintillator in the tubes were investigated with a ray-tracing simulation. The results are described in comparison with the experimental results.

Journal Articles

Development of an alternative plutonium canister assay system (APCA) using He-3 alternative neutron detector

Ozu, Akira; Kureta, Masatoshi; Haruyama, Mitsuo; Takase, Misao; Kurata, Noritaka; Kobayashi, Nozomi; Soyama, Kazuhiko; Nakamura, Tatsuya; Sakasai, Kaoru; To, Kentaro; et al.

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-34-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2013/10

no abstracts in English

Journal Articles

Development plan of Pu NDA system using ZnS ceramic scintillator

Kureta, Masatoshi; Soyama, Kazuhiko; Seya, Michio; Ozu, Akira; Haruyama, Mitsuo; Takase, Misao; Sakasai, Kaoru; Nakamura, Tatsuya; To, Kentaro

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-33-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2012/10

Alternative techniques to neutron detection by helium-3 for nuclear security and safeguards systems are necessary to be developed since helium-3 shortage is serious. With support of Japanese government (the Ministry of Education, Culture, Sports, Science and Technology), we have started an R&D project of Pu NDA system using ZnS ceramic scintillator. Here we present development plan, production of a new type of ZnS ceramic scintillator experimentally and basic design of a PCAS alternative Pu NDA system. We are planning the demonstration tests using the alternative NDA system comparing with the current PCAS in which the helium-3 counters are installed.

Journal Articles

Development plan of Pu NDA system using ZnS ceramic scintillator

Kureta, Masatoshi; Soyama, Kazuhiko; Seya, Michio; Ozu, Akira; Haruyama, Mitsuo; Takase, Misao; Sakasai, Kaoru; Nakamura, Tatsuya; To, Kentaro

Proceedings of INMM 53rd Annual Meeting (CD-ROM), 8 Pages, 2012/07

Alternative techniques to neutron detection by helium-3 for nuclear security and safeguards systems are necessary to be developed since helium-3 shortage is serious. With support of Japanese government (the Ministry of Education, Culture, Sports, Science and Technology), we have started an R&D project of Pu NDA system using ZnS ceramic scintillator. Here we present development plan, production of a new type of ZnS ceramic scintillator experimentally and basic design of a PCAS alternative Pu NDA system. We are planning the demonstration tests using the alternative NDA system comparing with the current PCAS in which the helium-3 counters are installed.

Journal Articles

Current status of a new polarized neutron reflectometer at the intense pulsed neutron source of the Materials and Life Science Experimental Facility (MLF) of J-PARC

Takeda, Masayasu; Yamazaki, Dai; Soyama, Kazuhiko; Maruyama, Ryuji; Hayashida, Hirotoshi; Asaoka, Hidehito; Yamazaki, Tatsuya; Kubota, Masato; Aizawa, Kazuya; Arai, Masatoshi; et al.

Chinese Journal of Physics, 50(2), p.161 - 170, 2012/04

Journal Articles

Master plan for the development of ZnS scintillation neutron detectors for NDA

Kureta, Masatoshi; Soyama, Kazuhiko; Seya, Michio; Ozu, Akira; Haruyama, Mitsuo; Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-32-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2011/11

Alternative techniques to neutron detection by He-3 for safeguards and nuclear security systems are necessary to be developed since He-3 gas shortage is serious. With support of Japanese government (MEXT), we have started the project of ZnS ceramic scintillation neutron detectors for non-destructive assay (NDA) of Pu in Fresh MOX fuel and other types of nuclear material for a use of safeguards verification. Here we present master plan of the project and feasibility study on neutron absorption probability in our scintillator by using Monte Carlo code.

Journal Articles

Development of scintillation neutron detectors for non-destructive assay of nuclear fuel, 1; Master plan and feasibility study on nuclear reaction probability by Monte Carlo analysis

Kureta, Masatoshi; Soyama, Kazuhiko; Seya, Michio; Ozu, Akira; Haruyama, Mitsuo; Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru

Proceedings of INMM 52nd Annual Meeting (CD-ROM), 10 Pages, 2011/07

Alternative techniques to neutron detection by $$^{3}$$He for nuclear security and safeguards systems are necessary to be developed since $$^{3}$$He shortage is serious. With support of Japanese government (MEXT), we have started an development project of ZnS ceramic scintillation neutron detectors for non-destructive assay of Pu in Fresh MOX fuel and other types of nuclear material for a use of safeguards verification. Here we present master plan of the project and feasibility study on neutron absorption probability between neutron and Lithium/Boron in our scintillator by using Monte Carlo code, MVP.

Journal Articles

Heat transfer characteristics of the first wall with graphite sheet interlayer

Masaki, Kei; Miyo, Yasuhiko; Sakurai, Shinji; Ezato, Koichiro; Suzuki, Satoshi; Sakasai, Akira

Fusion Engineering and Design, 85(10-12), p.1732 - 1735, 2010/12

 Times Cited Count:1 Percentile:11(Nuclear Science & Technology)

Steady-state research is indispensable to establish scientific and technological basis for the next fusion devices. In JT-60, long pulse operation of up to 65s (OH) with a neutral beam heating power of $$sim$$12 MW (30s) was conducted to investigate the plasma behavior in several tens of seconds. However, the structure of the JT-60U first wall, which was composed of bolted graphite tiles and backings, restricted the flexibility of the plasma operation, because the first wall was not actively cooled. To improve the heat transfer characteristics of the first wall taking into account the cost, a candidate is to insert a graphite sheet between the graphite tile and the backing plate. Aiming at a design study for next fusion devices, the heat transfer characteristics of the first wall structure were investigated with a variety of graphite sheets and fixing-bolt torque conditions. The first wall mockup used for the experiment was composed of three CFC tiles (125(L) $$times$$110(W)$$times$$24(T) mm for each tile) and a cupper-alloy heat sink (377(L)$$times$$100(W)$$times$$20(T) mm) with two cooling channels of 10 mm diameter. Four types of the graphite sheets, 0.1-mm thickness PGS (Pyrolytic Graphite Sheet; Panasoic Co., Ltd), 0.2-mm PF (Perma Foil; Toyo Tanso Co., Ltd) 0.38-mm PF, 0.6-mm PF, were examined in the experiment. The heat load tests of the mockup were performed with the heat fluxes of 1 and 3 MW/m$$^{2}$$ on the JAERI electron beam irradiation stand. The experimental results showed that the structure with 0.1-mm thickness $$times$$ 3 PGSs had the highest heat transfer performance in the experiment. The first wall structure with the PGS sheets withstood the heat flux of 1 MW/m$$^{2}$$$$times$$100s. The maximum surface temperature of the CFC tile was 500$$^{circ}$$C. Furthermore, the results indicated that the structure could be used at the steady-state condition with the heat flux of $$sim$$1 MW/m$$^{2}$$. In the paper, detail of the results will be presented and discussed.

Journal Articles

Mock-up test results of monoblock-type CFC divertor armor for JT-60SA

Higashijima, Satoru; Sakurai, Shinji; Suzuki, Satoshi; Yokoyama, Kenji; Kashiwa, Yoshitoshi; Masaki, Kei; Shibama, Yusuke; Takechi, Manabu; Shibanuma, Kiyoshi; Sakasai, Akira; et al.

Fusion Engineering and Design, 84(2-6), p.949 - 952, 2009/06

 Times Cited Count:8 Percentile:53.11(Nuclear Science & Technology)

An upgrading device of JT-60 tokamak with fully superconducting coils (JT-60SA) is constructed under both the Japanese domestic program and the international program "Broader Approach". The maximum heat flux to JT-60SA divertor is estimated to 15 MW/m$$^{2}$$ for 100 s, and a monoblock-type CFC divertor armor is promising. The JT-60SA armor consists of CFC monoblocks, a cooling CuCrZr screw-tube, and a thin OFHC-Cu buffer layer, and the brazed joints are essential for the armor. Metalization inside CFC monoblock is applied for further improvement, and we confirmed again that the mock-up has heat removal capability in excess of ITER requirement. For optimization of the fabrication method and understanding of the production yield, the mock-ups corresponding to quantity produced in one furnace is also produced, and the half of the mock-ups could remove 15 MW/m$$^{2}$$ as required. This summarizes the recent progress of design and mock-up test results for JT-60SA divertor armor.

Journal Articles

Engineering design and R&D of impurity influx monitor (divertor) for ITER

Ogawa, Hiroaki; Sugie, Tatsuo; Kasai, Satoshi*; Katsunuma, Atsushi*; Hara, Hirotsugu*; Takeyama, Norihide*; Kusama, Yoshinori

Fusion Engineering and Design, 83(10-12), p.1405 - 1409, 2008/12

 Times Cited Count:12 Percentile:65.48(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Development of the UV and visible impurity influx monitor (divertor) for ITER

Iwamae, Atsushi; Ogawa, Hiroaki; Sugie, Tatsuo; Kasai, Satoshi*; Kusama, Yoshinori

Proceedings of 18th International Toki Conference on Development of Physics and Technology of Stellarator/Heliotrons en route to Demo (ITC-18) (CD-ROM), p.450 - 453, 2008/12

Journal Articles

Spectroscopic measurement system for ITER divertor plasma; Impurity influx monitor (divertor)

Sugie, Tatsuo; Ogawa, Hiroaki; Kasai, Satoshi*; Kusama, Yoshinori

AIP Conference Proceedings 988, p.218 - 221, 2008/04

The detailed design of the Impurity Influx Monitor (divertor) has been carried out to provide the measurement capability in the harsh environment. The potential damaging effects for the first mirrors mounted close to the plasma are the formations of coatings of impurities and the deposition of the dust. Mitigating measures to minimize the degradation of their performance by these effects, such as changes in the reflectivity, are adopted: for example, the plasma is viewed through a small aperture, and baffle plates are inserted in front of the first mirrors. However, it will not be possible to prevent the degradation completely. It is important to know the change of the sensitivity of the optical systems. It is not feasible to install a light source in the vacuum chamber of ITER during operations and so an alternative method is needed. The in-situ calibration system using a micro retro-reflector array has been developed as a possible method.

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