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Author

Masaki Saito

Other affiliations: Japan Atomic Energy Agency
Bio: Masaki Saito is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Nuclear transmutation & Plutonium. The author has an hindex of 15, co-authored 100 publications receiving 719 citations. Previous affiliations of Masaki Saito include Japan Atomic Energy Agency.


Papers
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TL;DR: In this article, the gamma spectra were processed by the GENIE-2000 code and the ITEP-developed SIGMA code was used together with the PCNUDAT nuclear decay database to identify the gamma lines and to determine the cross sections.
Abstract: 114 cross sections for nuclide production in a 1.0 GeV proton-irradiated thin 208Pb target have been measured by the direct gamma spectrometry method using a high-resolution Ge detector. The gamma spectra were processed by the GENIE-2000 code. The ITEP-developed SIGMA code was used together with the PCNUDAT nuclear decay database to identify the gamma lines and to determine the cross sections. The 27Al(p,x)22Na reaction was used to monitor the proton flux. Results of a feasibility study of the auxiliary 27Al(p,x)24Na and 27Al(p,x)7Be monitor reactions in the 0.07-2.6 GeV proton-energy range are presented as well. Most of the experimental data have been analyzed by the LAHET (with ISABEL and Bertini options), CEM95, CEM2k, INUCL, CASCADE, CASCADE/INPE, and YIELDX codes that simulate hadron-nucleus interactions.

53 citations

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TL;DR: In this article, the effects of reduced gravity on the flow regime and the heat transfer characteristics of a boiling two-phase horizontal flow were studied by using an aircraft in parabolic flight experiments.

40 citations

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TL;DR: In this paper, an assessment of passive measure against nuclear material proliferation by focusing on improving the inherent proliferation barrier of discharged Pu from an FBR is presented. But, the work in this paper is limited to the assumption of protected Pu whose 238Pu isotopic fraction is more th...
Abstract: The improvement of proliferation resistance properties of Pu and the burnup characteristics of fast breeder reactor (FBR) had been studied by utilizing minor actinides (MAs) to produce more 238Pu from 237Np and 241Am through neutron capture reaction. The higher the 238Pu content in the fuel, the higher the proliferation resistance of the fuel would be owing to the natural characteristics of 238Pu with high decay heat and high neutron production. The present paper deals with the assessment of passive measure against nuclear material proliferation by focusing on improving the inherent proliferation barrier of discharged Pu from an FBR. Results showed that 5% MA doping to the blanket of an FBR gives as high as 17–19% 238Pu, which could be seen as a significant improvement of the proliferation properties of Pu. Moreover, additional 5% ZrH2, togather with 5% MA doping to the blanket, could enhance the 238Pu fraction much more (22–24%). With an assumption of protected Pu whose 238Pu isotopic fraction is more th...

33 citations

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TL;DR: In this article, the heat transfer of the inversely stratified molten corium in the lower vessel, which was experimentally demonstrated in the MASCA project, was analyzed, and it was shown that the peak heat flux from the corium does not exceed the critical heat flux of the flooded vessel.
Abstract: The heat transfer of the inversely stratified molten corium in the lower vessel, which was experimentally demonstrated in the MASCA project, was analyzed. For the oxide layer, turbulent models of the k-e and the large eddy simulation were examined through the CEA BALI test analysis, and the Mason-Derbyshire Smagorinsky large eddy simulation, which models the anisotropic buoyancy effect, was selected. A melt-solidification model was incorporated for the metal layer analysis since our preliminary analysis shows that the vessel boundary change due to its melting is important. An analysis under an inversely stratified configuration of a lower power density condition shows that the peak heat flux from the corium does not exceed the critical heat flux of the flooded vessel. However, the heat flux focuses at the top of the lower metal layer because it is under the thermally stable condition, and this focusing would be a new challenge for the in-vessel retention.

29 citations

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TL;DR: In this paper, external non-fission based neutron sources into fission energy system would open the possibility of approaching the Multi-Component Self-Consistent Nuclear Energy System (MC-SCNES) with unlimited fuel resources and zero radioactivity release.

28 citations


Cited by
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Journal ArticleDOI
01 Jun 2008-Energy
TL;DR: The impact of rapidly growing economies of the highly populated countries, as well as of the concern about global warming, are presented and assessed in this paper, where a brief discussion of the status and prospects of fossil, nuclear and renewable energy use, and of power generation (including hydrogen, fuel cells, micro power systems, and the futuristic concept of generating power in space for terrestrial use, is given.

316 citations

Journal ArticleDOI
TL;DR: The present review presents the first comprehensive report of current knowledge (including synthesis aspects not discussed before) regarding the related giant metal-oxide clusters mainly of the type {Mo(57)M'(6)} (M' = Fe(III), V(IV)) (torus structure),
Abstract: Following Nature's lessons, today chemists can cross the boundary of the small molecule world to construct multifunctional and highly complex molecular nano-objects up to protein size and even cell-like nanosystems showing responsive sensing. Impressive examples emerge from studies of the solutions of some oxoanions of the early transition metals especially under reducing conditions which enable the controlled linking of metal-oxide building blocks. The latter are available from constitutional dynamic libraries, thus providing the option to generate multifunctional unique nanoscale molecular systems with exquisite architectures, which even opens the way towards adaptive and evolutive (Darwinian) chemistry. The present review presents the first comprehensive report of current knowledge (including synthesis aspects not discussed before) regarding the related giant metal-oxide clusters mainly of the type {Mo57M′6} (M′ = FeIII, VIV) (torus structure), {M72M′30} (M = Mo, M′ = VIV, CrIII, FeIII, MoV), {M72Mo60} (M = Mo, W) (Keplerates), {Mo154}, {Mo176}, {Mo248} (“big wheels”), and {Mo368} (“blue lemon”) – all having the important transferable pentagonal {(M)M5} groups in common. These discoveries expanded the frontiers of inorganic chemistry to the mesoscopic world, while there is probably no collection of discrete inorganic compounds which offers such a versatile chemistry and the option to study new phenomena of interdisciplinary interest. The variety of different properties of the sphere- and wheel-type metal-oxide-based clusters can directly be related to their unique architectures: The spherical Keplerate-type capsules having 20 crown-ether-type pores and tunable internal functionalities allow the investigation of confined matter as well as that of sphere-surface-supramolecular and encapsulation chemistry – including related new aspects of the biologically important hydrophobic effects – but also of nanoscale ion transport and separation. The wheel-type molybdenum-oxide clusters exhibiting complex landscapes do not only have well-defined reaction sites but also show unprecedented adaptability regarding the integration of various kinds of matter. Applications in different fields, e.g. in materials science and catalysis including those in small spaces, investigated by several groups, are discussed while possible directions for future work are outlined.

303 citations

Journal ArticleDOI
Issam Mudawar1
TL;DR: In this paper, the performance of two-phase micro-channel heat sinks has been investigated in a wide range of applications, such as computer, fusion, and rocket nozzles.
Abstract: Boiling water in small channels that are formed along turbine blades has been examined since the 1970s as a means to dissipating large amounts of heat. Later, similar geometries could be found in cooling systems for computers, fusion reactors, rocket nozzles, avionics, hybrid vehicle power electronics, and space systems. This paper addresses (a) the implementation of two-phase microchannel heat sinks in these applications, (b) the fluid physics and limitations of boiling in small passages, and effective tools for predicting the thermal performance of heat sinks, and (c) means to enhance this performance. It is shown that despite many hundreds of publications attempting to predict the performance of two-phase microchannel heat sinks, there are only a handful of predictive tools that can tackle broad ranges of geometrical and operating parameters or different fluids. Development of these tools is complicated by a lack of reliable databases and the drastic differences in boiling behavior of different fluids in small passages. For example, flow boiling of certain fluids in very small diameter channels may be no different than in macrochannels. Conversely, other fluids may exhibit considerable “confinement” even in seemingly large diameter channels. It is shown that cutting-edge heat transfer enhancement techniques, such as the use of nanofluids and carbon nanotube coatings, with proven merits to single-phase macrosystems, may not offer similar advantages to microchannel heat sinks. Better performance may be achieved by careful optimization of the heat sink’s geometrical parameters and by adapting a new class of hybrid cooling schemes that combine the benefits of microchannel flow with those of jet impingement. [DOI: 10.1115/1.4005300]

248 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the literature concerning two-phase flow and heat transfer in reduced gravity is presented, where different methods and platforms dedicated to exploring the influence of reduced gravity, including ground flow boiling experiments performed at different orientations relative to Earth gravity.

127 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined flow boiling CHF in microgravity that was achieved in parabolic flight experiments with FC-72 onboard NASA's KC-135 turbojet and showed that at low velocities CHF is significantly smaller than in horizontal flow on earth.

98 citations