A burnup calculation was performed to analyze the Apr`es ORIENT process, which aims to create highlyvaluable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmut...A burnup calculation was performed to analyze the Apr`es ORIENT process, which aims to create highlyvaluable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmutation induced by a neutron capture reaction followed by a β-decay, thus changing the atomic number Z of a target element in fission products by 1 unit. LWR(PWR) and FBR(MONJU) were considered as the transmutation devices. High rates of creation were obtained in some cases of platinum group metals(44Ru by FBR,46 Pd by LWR) and rare earth(64Gd by LWR,66 Dy by FBR). Therefore, systems based on LWR and FBR have their own advantages depending on target elements. Furthermore, it was found that creation rates of even Z(= Z + 1) elements from odd Z ones were higher than the opposite cases. This creation rate of an element was interpreted in terms of "average 1-group neutron capture cross section of the corresponding target element σc Z defined in this work. General trends of the creation rate of an even(odd) Z element from the corresponding odd(even) Z one were found to be proportional to the 0.78th(0.63th) power of σc Z, however with noticeable dispersion. The difference in the powers in the above analysis was explained by the difference in the number of stable isotopes caused by the even-odd effect of Z.展开更多
A supercritical CO2 gas turbine cycle can produce power at high efficiency and the gas turbine is compact compared with the steam turbine. Therefore, it is very advantageous power cycle for the medium temperature rang...A supercritical CO2 gas turbine cycle can produce power at high efficiency and the gas turbine is compact compared with the steam turbine. Therefore, it is very advantageous power cycle for the medium temperature range less than 650 ℃. The purpose of this paper is to show how it can be effectively applied not only to the nuclear power but also to the fossil fired power plant. A design of 300 MWe plant has been carried out, where thermal energy of flue gas leaving a CO2 heater is utilized effectively by means of economizer and a high cycle thermal efficiency of 43.4 % has been achieved. Since the temperature and the pressure difference of the CO2 heater are very high, the structural design becomes very difficult. It is revealed that this problem can be effectively solved by introducing a double expansion turbine cycle. The component designs of the CO2 heater, the economizer, supercritical CO2 turbines, compressors and the recuperators are given and it is shown that these components have good performances and compact sizes.展开更多
We have performed sequential studies on new types of soft rubber for their application as artificial skin in robots and haptic sensors. Based on a proposed electrolytic polymerization method and novel adhesion techniq...We have performed sequential studies on new types of soft rubber for their application as artificial skin in robots and haptic sensors. Based on a proposed electrolytic polymerization method and novel adhesion technique for rubber and a metal that utilizes a metal complex hydrate, we have developed an MCF rubber sensor. This sensor uses a magnetic compound fluid (MCF), natural rubber (NR-latex) or chloroprene rubber latex (CR-latex), and requires the application of a magnetic field. The potential application of the developed sensor in various engineering scenarios and our daily lives is significant. In this regard, we investigated the effects of γ-irradiation, infrared radiation, microwaves, and a thermal source on the MCF rubber sensor. We established that the MCF rubber is effective enough to be used for power generation of broadband electro-magnetic waves from γ-rays to microwaves, including the range of the solar spectrum, which is the typical characteristic obtained in the present investigation. The remarkable attribute is that the MCF rubber sensor dose is not degraded by γ-irradiation. We also demonstrated the effectiveness of the MCF rubber sensor in energy harvesting.展开更多
Processing of alumina fiber-reinforced alumina matrix composites by hot-pressing was described. The mechanical properties of the composites fabricated by different sintering conditions including temperature and pressu...Processing of alumina fiber-reinforced alumina matrix composites by hot-pressing was described. The mechanical properties of the composites fabricated by different sintering conditions including temperature and pressure have been investigated. The results indicated that the higher sintering temperature and pressure corresponded to the higher bulk density and higher maximum strength of the composite, whereas the pseudo-ductility of the composite was lower. The preliminary results of the composite with monazite-coated fibers showed that maximum strength could be improved up to 35% compared with the noncoated fiber composite in the same sintering condition. Moreover, the fracture behavior of the composite changed from completely brittle fracture to non-brittle fracture under the suitable sintering conditions. SEM observation of the fracture surface indicated that the coating worked as a protective barrier and avoided sintering of the fibers together even at high temperature and pressure during densification process.展开更多
Twin vortices flow behavior with out-of-plane angle effect in double bent pipe system is studied numerically and experimentally. Double bent pipe system generates very complicated flow behavior including twin vortices...Twin vortices flow behavior with out-of-plane angle effect in double bent pipe system is studied numerically and experimentally. Double bent pipe system generates very complicated flow behavior including twin vortices in the downstream of the double bent. Moreover, angle from the plane of the double bent forms more complicated flow behavior due to the flow twist by out-of-plane angle. In this study, numerical analysis is examined for this double bent system using three-dimensional CFD code, FLUENT, to reproduce those complicated flow behaviors with twin vortices. Numerical results are compared with experimental results obtained by Ultrasonic Velocity Profiler (UVP). Discrepancy between numerical and experimental result is discussed changing out-of- plane angle, α. Velocity profiles obtained by numerical results are converted into UVP profiles, and they are compared with the experimental results by UVP. Consequently, velocity behavior especially around the pipe wall obtained by numerical results is agreed with experimental results.展开更多
For the purpose of the replacement of Magnetic Fluid (MF) which is effective in the production of an artificial soft and tactile skin for the robot, etc. by utilizing a rubber solidification method with electrolytic p...For the purpose of the replacement of Magnetic Fluid (MF) which is effective in the production of an artificial soft and tactile skin for the robot, etc. by utilizing a rubber solidification method with electrolytic polymerization, we proposed a novel magnetic responsive intelligent fluid, Hybrid Fluid (HF). HF is structured with water, kerosene, silicon oil having Polydimethylsiloxane (PDMS) and Polyvinyl Alcohol (PVA) as well as magnetic particles and surfactant. The state of HF changes as jelly or fluid by their rates of the constituents and motion style. In the present paper, we presented the characteristics of HF: the viscosity and the magnetization are respectively equivalent to those of other magnetic responsive fluids, MF and their solvents. For the structure, HF is soluble simultaneously with both diene and non-diene rubbers. The diene rubber such as Natural Rubber (NR) or Chloroprene (CR) has a role in the feasibility of electrolytic polymerization and the non-diene rubber such as silicon oil rubber (Q) has a role in defense against deterioration. Therefore, the electrolytically polymerized HF rubber by mixing NR, CR as well as Q is effective for the artificial soft and tactile skin. It is responsive to pressure and has optimal property on piezoelectricity in the case of the mixture of Ni particles as filler. HF is effective in the production of the artificial soft and tactile skin made of rubber.展开更多
The feasibility of rhenium （Re） production by irradiating tungsten （W） metal in a medium size fast reactor was evaluated by using a Monte Carlo code. The fast reactor can produce about 50 kilograms of Re per every...The feasibility of rhenium （Re） production by irradiating tungsten （W） metal in a medium size fast reactor was evaluated by using a Monte Carlo code. The fast reactor can produce about 50 kilograms of Re per every 3 years, which corresponds 10% of Japanese domestic production. The specific activity of Re can be reduced below the exemption level or even the natural Re level if W and osmium is separated after the irradiation. The use of ZrD1.7 moderator reduces the specific activity by half compared to that of ZrH1.7 case, and even the no moderator case is permissible to produce the production of Re which has lower specific reactivity than that of natural Re.展开更多
Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） ...Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） and three kinds of interaction zones （solidification, deformation and fragmentation） were observed during LBE droplet/water interaction and lead droplet/water interaction, respectively. The fragmentation zone （FZ） could be identified exactly by two border lines： spontaneous nucleation temperature and minimum film boiling temperature. Within fragmentation zone, 10% to 35% tiny debris （diameter 〈 1 mm） of LBE and 5 to 8 kPa peak pressure generated with increasing the LBE temperature and no effect with increasing the subcooling of water. Only 2%-4% tiny debris （diameter 〈 1 mm） of lead and 2 kPa peak pressure generated regardless of lead and water temperature.展开更多
The chemical compositions of atmospheric deposits collected in Fukuoka, Japan, in 1964 and 2000, which are known to have high 235U/238U uranium isotope ratio were determined. High uranium contents relative to that of ...The chemical compositions of atmospheric deposits collected in Fukuoka, Japan, in 1964 and 2000, which are known to have high 235U/238U uranium isotope ratio were determined. High uranium contents relative to that of continental crust were observed for the deposition samples in 1964 together with the high 235U/238U ratios, which indicated that the origin of uranium is fallout materials due to the large-scale 1961- 1962 nuclear explosions conducted by US and former USSR. The deposits in 2000 were mainly composed of dusts from the East Asia. This suggested that uranium with a high 235U/238U ratio in the deposits in 2000 has been transported as a component of mineral dust particles contaminated with nuclear debris from nuclear test sites from the East Asian deserts and arid regions by the prevailing wind.展开更多
For cases in which a robot with installed solar cells and a sensor operates in a nuclear reactor building or in space for extravehicular activity, we require elastic and extensible solar cells. More than two different...For cases in which a robot with installed solar cells and a sensor operates in a nuclear reactor building or in space for extravehicular activity, we require elastic and extensible solar cells. More than two different types of sensing are also required, minimally with photovoltaics and built-in electricity. Magnetic compound fluid (MCF) rubber solar cells are made of rubber, so they are elastic and extensible as well as sensitive. To achieve flexibility and an effective photovoltaic effect, MCF rubber solar cells must include both soluble and insoluble rubbers, Fe<sub>3</sub>O<sub>4</sub>, TiO<sub>2</sub>, Na<sub>2</sub>WO<sub>4</sub>∙2H<sub>2</sub>O, etc. On the basis of this constitution, we propose a consummate fabrication process for MCF rubber solar cells. The characteristics of these cells result from the semiconductor-like role of the molecules of TiO<sub>2</sub>, Fe<sub>3</sub>O<sub>4</sub>, Ni, Na<sub>2</sub>WO<sub>4</sub>∙2H<sub>2</sub>O, polydimethylsiloxane (PDMS), natural rubber (NR), oleic acid, polyvinyl alcohol (PVA), water and magnetic cluster involved in the MCF rubber. Their tendencies can be deduced by synthesizing knowledge about the enhancement of the reverse-bias saturation current <em>I</em><sub><em>S</em></sub> and the diode ideality factor <em>N</em>, with conventional knowledge about the semiconductor affected by <em>γ</em>-irradiation and the attenuation of the photon energy of <em>γ</em>-rays.展开更多
A burnup calculation has been performed to evaluate heavy rare earth （terbium--Tb, dysprosium--Dy） production in spent gadolinium oxide （Gd203） installed as a BP （burnable poison）. Each amount of Tb and Dy produ...A burnup calculation has been performed to evaluate heavy rare earth （terbium--Tb, dysprosium--Dy） production in spent gadolinium oxide （Gd203） installed as a BP （burnable poison）. Each amount of Tb and Dy production derived from the BP has been about 30-40 times larger than those created in FP （fission products）. Required cooling time to achieve exemption level on radioactivity concentration produced Tb and Dy derived from the BP are much shorter （BP-Tb： 7.9y, BP-Dy： 〈 0.1y） than those created in FP （FP-Tb： 3,616y, FP-Dy： 6.9y）. However, the BP is mixed homogeneously with UO2 pellet in current nuclear fuel system of LWRs （light water reactors）, and hence mixing of FP cannot be not avoided. In such a mixture case, the required cooling time of recovered Tb will become 2,653y and that of recovered Dy be 4.8y. For this reason, recovered Tb is unlikely to be resource for utilization, while recovered Dy must be the resource provided the precise separation from the other FP.展开更多
Measurements of the keV-neutron capture cross sections and radiative γ-ray spectrum of 56Fe and 57Fe are performed based on a 7 Li（p,n）7 Be reaction neutron source. The incident neutron spectrum on a capture sample...Measurements of the keV-neutron capture cross sections and radiative γ-ray spectrum of 56Fe and 57Fe are performed based on a 7 Li（p,n）7 Be reaction neutron source. The incident neutron spectrum on a capture sample is measured by means of a time-of-flight （TOF） method with a 6Li-glass detector. The radiative capture 7-rays emitted from an iron CS Fe or 57 Fe） or standard gold （197Au） sample are detected by a large anti-Compton NaI（TI） spectrometer covered with a heavy shield. The capture yields of samples are obtained by applying a pulse-height weighting technique to the corresponding capture γ-ray pulse-height spectrum. The Maxwellian averaged neutron capture cross sections of 56Fe and 5T Fe are derived according to the present capture cross section results.展开更多
A resourceability on nuclear fuel cycle by transmutation of fission products in the spent fuel of nuclear reactors is discussed in this paper to investigate the feasibility of ＂creation and utilization＂ of Apr6s ORI...A resourceability on nuclear fuel cycle by transmutation of fission products in the spent fuel of nuclear reactors is discussed in this paper to investigate the feasibility of ＂creation and utilization＂ of Apr6s ORIENT from Adv.-ORIENT cycle, in which chemical ＂separation and utilization＂ of nuclear rare metals （platinum group metals, Mo, Tc, rare earth, etc.） has been proposed since FY2006. Apr6s ORIENT research program was newly initiated in FY2011 for nuclear transmutation of fission products into stable or short-lived highly-valuable elements. In the resourceability of rare earth metals from fission products, non-radioactive Nd and Dy can be created from Pr and Tb, respectively, by transmutation. Especially, the Dy creation has relatively high feasibility of about 10-20 %/y in creation rate. A proper moderation of neutrons in blanket of fast reactors may be required to provide a high creation rate of La from Ba. In light platinum group metals, non-radioactive Ru can be created from Tc by transmutation, of which creation rate is about 4-5 %/y in blanket of fast reactors. Pd created from Rh is almost non-radioactively depending on the isotope fraction of 107pd. Rh creation from Ru is not feasible under the neutron irradiation of typical nuclear reactors.展开更多
The previously derived Lane consistent dispersive coupled-channel optical model for nucleon scattering on 232Th and 23Su nuclei is extended to describe scattering on even-even actinides with Z=90-98. A soft-rotator- m...The previously derived Lane consistent dispersive coupled-channel optical model for nucleon scattering on 232Th and 23Su nuclei is extended to describe scattering on even-even actinides with Z=90-98. A soft-rotator- model （SRM） description of the low-lying nuclear structure is used, where the SRM Hamiltonian parameters are adjusted to the observed collective levels of the target nucleus. SRM nuclear wave functions （mixed in K quantum number） have been used to calculate the coupling matrix elements of the generalized optical model. The ＂effective＂ deformations that define inter-band couplings are derived from the SRM Hamiltonian parameters. Conservation of nuclear volume is enforced by introducing a dynamic monopolar term to the deformed potential, leading to additional couplings between rotational bands. The fitted static deformation parameters are in very good agreement with those derived by Wang and collaborators using the Weizs^cker-Skyrme global mass model （WS4）, allowing use of the latter to predict cross sections for nuclei without experimental data. A good description of the scarce ＂optical＇experimental database is achieved. SRM couplings and volume conservation allow a precise calculation of the compound-nucleus formation cross sections, which is significantly different from that calculated with rigid-rotor potentials coupling the ground-state rotational band. The derived parameters can be used to describe both neutron- and proton-induced reactions.展开更多
In order to examine the chemical form of uranyl species in l-ethyl-3-methylimidazolium （EMI） based ionic liquids, UV-visible absorption spectra of solutions prepared by dissolving [EMI]2[UO2CI4] into a mixture of EM...In order to examine the chemical form of uranyl species in l-ethyl-3-methylimidazolium （EMI） based ionic liquids, UV-visible absorption spectra of solutions prepared by dissolving [EMI]2[UO2CI4] into a mixture of EMICI and EMIBF4 （50：50 tool%） were measured. As a result, it was confirmed that uranyl species in the mixture of EMICI and EMIBF4 existed as [UO2C14]2-. Cyclic voltammograms （CVs） of [UO2CI4]2- in the mixture were measured at 25 ~C using a Pt working electrode, a Pt wire counter electrode, and an Ag/Ag＋ reference electrode （0.01 M AgNO3, 0.1 M tetrabutylammonium perchlorate in acetonitrile） in a glove box under an Ar atmosphere. Peaks corresponding to one redox couple were observed around -1.05 V （Epc） and -0.92 V （Epa） vs. ferrocene/ferrocenium ion （Fc/Fc＋）. The potential differences between two peaks （AEp） increased from 101 to 152 mV with an increase in the scan rate from 50 to 300 mV s-1, while the （Epc ＋ Epa）/2 value was constant, -0.989 V vs. Fc/Fc＋ regardless of the scan rate. Furthermore, the diffusion coefficient of [UO2C14]2 and the standard rate constant were es- timated to be 3.7× 10^-8 cm^2 s 1 and （2.7-2,8） × 10^-4 cm s-! at 25 ℃. By using the diffusion coefficient and the standard rate constant, the simulation of CVs was performed based on the reaction, [UO2C14]2- ＋ e- = [UO2C14]3-. The simulated CVs were found to be consistent with the experimental ones. From these results, it is concluded that [UO2C14]2- in the mixture of EMIC1 and EMIBF4 is reduced to [UO2C14]3- quasi-reversibly at -0.989 V vs. Fc/Fc＋.展开更多
To evaluate the stability of N-alkylated pyrrolidone derivatives （NRPs）, which are supposed to be used as precipitants for U（VI） and Pu（IV, VI） species in HNO3 media, under irradiation environment, some candidat...To evaluate the stability of N-alkylated pyrrolidone derivatives （NRPs）, which are supposed to be used as precipitants for U（VI） and Pu（IV, VI） species in HNO3 media, under irradiation environment, some candidate NRPs were irradiated by γ-ray. Irradia- tion to HNO3 solutions up to 6 mol dm-3 （= M） containing 2 M N-n-butyl-2-pyrrolidone （NBP）, one of NRPs with lower hy- drophobicity, has revealed that the residual ratios of NBP in the samples of HNO3 up to 3 M decreased identically and linearly. Approximately 20% of NBP was found to be degraded after the irradiation at 1 MGy. It was also found that the decrease in the precipitation ratio of UOf＋ （P.R., %） was gentle and that the P.R. values were relatively in accordance with the residual ratios of NBP. On the other hand, the degradation of the samples irradiated in 6 M HNO3 was found more distinguished. It was pro- posed from the analyses of degraded compounds that the degradation of NBP in HNO3 by γ-ray irradiation started from the cleavage of the pyrrolidone ring by the addition of oxygen atom originating from HNO3, followed by the formation of chain compounds by the successive addition of oxygen, leading to the generation of oxalic acid and acetic acid. The stability of other NRPs in 3 M HNO3 was evaluated to be nearly identical with that of NBP except lower P.R. values of the samples containing NRPs with higher hydrophobicity irradiated at more than 0.5 MGy.展开更多
1 Results When a C60 film was irradiated with electron-beam (EB) with an incident energy of 3 kV, a peanut-shaped C60 polymer with metallic properties was formed[1], as shown in Fig.1. To elucidate the origin of the m...1 Results When a C60 film was irradiated with electron-beam (EB) with an incident energy of 3 kV, a peanut-shaped C60 polymer with metallic properties was formed[1], as shown in Fig.1. To elucidate the origin of the metallic properties of the peanut-shaped polymer, we examined the valence photoelectron spectra of the polymer using in situ high-resolution photoelectron spectroscopy and found that the electronic states of the polymer came across the Fermi level (EF)[2]. Interestingly, the spectral shape i...展开更多
The ratio ofγtransition-intensities from the initial capture state to low-lying states may represent the model-independentγ-strength function,which reflects the effects of different neutron-capture reaction mechanis...The ratio ofγtransition-intensities from the initial capture state to low-lying states may represent the model-independentγ-strength function,which reflects the effects of different neutron-capture reaction mechanisms.The extraordinary quenching of theγ0 transition from the p-wave neutron radiative capture in 57Fe is observed,for the first time,from the pronounced enhancement of theγ-strength function ratios fγ1/fγ0 and fγ2/fγ0.The 2p-1h doorway excitation leads to suppression of theγ0 transition to the ground state and the enhancement of theγ1 andγ2 transitions to the first and second excited states,respectively.The fp sub-shells supply the exact number of spaces required for the 2p-1h configuration,which features the neutron capture mechanism in the vicinity of A=55.展开更多
文摘A burnup calculation was performed to analyze the Apr`es ORIENT process, which aims to create highlyvaluable elements from fission products separated from spent nuclear fuels. The basic idea is to use nuclear transmutation induced by a neutron capture reaction followed by a β-decay, thus changing the atomic number Z of a target element in fission products by 1 unit. LWR(PWR) and FBR(MONJU) were considered as the transmutation devices. High rates of creation were obtained in some cases of platinum group metals(44Ru by FBR,46 Pd by LWR) and rare earth(64Gd by LWR,66 Dy by FBR). Therefore, systems based on LWR and FBR have their own advantages depending on target elements. Furthermore, it was found that creation rates of even Z(= Z + 1) elements from odd Z ones were higher than the opposite cases. This creation rate of an element was interpreted in terms of "average 1-group neutron capture cross section of the corresponding target element σc Z defined in this work. General trends of the creation rate of an even(odd) Z element from the corresponding odd(even) Z one were found to be proportional to the 0.78th(0.63th) power of σc Z, however with noticeable dispersion. The difference in the powers in the above analysis was explained by the difference in the number of stable isotopes caused by the even-odd effect of Z.
文摘A supercritical CO2 gas turbine cycle can produce power at high efficiency and the gas turbine is compact compared with the steam turbine. Therefore, it is very advantageous power cycle for the medium temperature range less than 650 ℃. The purpose of this paper is to show how it can be effectively applied not only to the nuclear power but also to the fossil fired power plant. A design of 300 MWe plant has been carried out, where thermal energy of flue gas leaving a CO2 heater is utilized effectively by means of economizer and a high cycle thermal efficiency of 43.4 % has been achieved. Since the temperature and the pressure difference of the CO2 heater are very high, the structural design becomes very difficult. It is revealed that this problem can be effectively solved by introducing a double expansion turbine cycle. The component designs of the CO2 heater, the economizer, supercritical CO2 turbines, compressors and the recuperators are given and it is shown that these components have good performances and compact sizes.
文摘We have performed sequential studies on new types of soft rubber for their application as artificial skin in robots and haptic sensors. Based on a proposed electrolytic polymerization method and novel adhesion technique for rubber and a metal that utilizes a metal complex hydrate, we have developed an MCF rubber sensor. This sensor uses a magnetic compound fluid (MCF), natural rubber (NR-latex) or chloroprene rubber latex (CR-latex), and requires the application of a magnetic field. The potential application of the developed sensor in various engineering scenarios and our daily lives is significant. In this regard, we investigated the effects of γ-irradiation, infrared radiation, microwaves, and a thermal source on the MCF rubber sensor. We established that the MCF rubber is effective enough to be used for power generation of broadband electro-magnetic waves from γ-rays to microwaves, including the range of the solar spectrum, which is the typical characteristic obtained in the present investigation. The remarkable attribute is that the MCF rubber sensor dose is not degraded by γ-irradiation. We also demonstrated the effectiveness of the MCF rubber sensor in energy harvesting.
文摘Processing of alumina fiber-reinforced alumina matrix composites by hot-pressing was described. The mechanical properties of the composites fabricated by different sintering conditions including temperature and pressure have been investigated. The results indicated that the higher sintering temperature and pressure corresponded to the higher bulk density and higher maximum strength of the composite, whereas the pseudo-ductility of the composite was lower. The preliminary results of the composite with monazite-coated fibers showed that maximum strength could be improved up to 35% compared with the noncoated fiber composite in the same sintering condition. Moreover, the fracture behavior of the composite changed from completely brittle fracture to non-brittle fracture under the suitable sintering conditions. SEM observation of the fracture surface indicated that the coating worked as a protective barrier and avoided sintering of the fibers together even at high temperature and pressure during densification process.
文摘Twin vortices flow behavior with out-of-plane angle effect in double bent pipe system is studied numerically and experimentally. Double bent pipe system generates very complicated flow behavior including twin vortices in the downstream of the double bent. Moreover, angle from the plane of the double bent forms more complicated flow behavior due to the flow twist by out-of-plane angle. In this study, numerical analysis is examined for this double bent system using three-dimensional CFD code, FLUENT, to reproduce those complicated flow behaviors with twin vortices. Numerical results are compared with experimental results obtained by Ultrasonic Velocity Profiler (UVP). Discrepancy between numerical and experimental result is discussed changing out-of- plane angle, α. Velocity profiles obtained by numerical results are converted into UVP profiles, and they are compared with the experimental results by UVP. Consequently, velocity behavior especially around the pipe wall obtained by numerical results is agreed with experimental results.
文摘For the purpose of the replacement of Magnetic Fluid (MF) which is effective in the production of an artificial soft and tactile skin for the robot, etc. by utilizing a rubber solidification method with electrolytic polymerization, we proposed a novel magnetic responsive intelligent fluid, Hybrid Fluid (HF). HF is structured with water, kerosene, silicon oil having Polydimethylsiloxane (PDMS) and Polyvinyl Alcohol (PVA) as well as magnetic particles and surfactant. The state of HF changes as jelly or fluid by their rates of the constituents and motion style. In the present paper, we presented the characteristics of HF: the viscosity and the magnetization are respectively equivalent to those of other magnetic responsive fluids, MF and their solvents. For the structure, HF is soluble simultaneously with both diene and non-diene rubbers. The diene rubber such as Natural Rubber (NR) or Chloroprene (CR) has a role in the feasibility of electrolytic polymerization and the non-diene rubber such as silicon oil rubber (Q) has a role in defense against deterioration. Therefore, the electrolytically polymerized HF rubber by mixing NR, CR as well as Q is effective for the artificial soft and tactile skin. It is responsive to pressure and has optimal property on piezoelectricity in the case of the mixture of Ni particles as filler. HF is effective in the production of the artificial soft and tactile skin made of rubber.
文摘The feasibility of rhenium （Re） production by irradiating tungsten （W） metal in a medium size fast reactor was evaluated by using a Monte Carlo code. The fast reactor can produce about 50 kilograms of Re per every 3 years, which corresponds 10% of Japanese domestic production. The specific activity of Re can be reduced below the exemption level or even the natural Re level if W and osmium is separated after the irradiation. The use of ZrD1.7 moderator reduces the specific activity by half compared to that of ZrH1.7 case, and even the no moderator case is permissible to produce the production of Re which has lower specific reactivity than that of natural Re.
文摘Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） and three kinds of interaction zones （solidification, deformation and fragmentation） were observed during LBE droplet/water interaction and lead droplet/water interaction, respectively. The fragmentation zone （FZ） could be identified exactly by two border lines： spontaneous nucleation temperature and minimum film boiling temperature. Within fragmentation zone, 10% to 35% tiny debris （diameter 〈 1 mm） of LBE and 5 to 8 kPa peak pressure generated with increasing the LBE temperature and no effect with increasing the subcooling of water. Only 2%-4% tiny debris （diameter 〈 1 mm） of lead and 2 kPa peak pressure generated regardless of lead and water temperature.
文摘The chemical compositions of atmospheric deposits collected in Fukuoka, Japan, in 1964 and 2000, which are known to have high 235U/238U uranium isotope ratio were determined. High uranium contents relative to that of continental crust were observed for the deposition samples in 1964 together with the high 235U/238U ratios, which indicated that the origin of uranium is fallout materials due to the large-scale 1961- 1962 nuclear explosions conducted by US and former USSR. The deposits in 2000 were mainly composed of dusts from the East Asia. This suggested that uranium with a high 235U/238U ratio in the deposits in 2000 has been transported as a component of mineral dust particles contaminated with nuclear debris from nuclear test sites from the East Asian deserts and arid regions by the prevailing wind.
文摘For cases in which a robot with installed solar cells and a sensor operates in a nuclear reactor building or in space for extravehicular activity, we require elastic and extensible solar cells. More than two different types of sensing are also required, minimally with photovoltaics and built-in electricity. Magnetic compound fluid (MCF) rubber solar cells are made of rubber, so they are elastic and extensible as well as sensitive. To achieve flexibility and an effective photovoltaic effect, MCF rubber solar cells must include both soluble and insoluble rubbers, Fe<sub>3</sub>O<sub>4</sub>, TiO<sub>2</sub>, Na<sub>2</sub>WO<sub>4</sub>∙2H<sub>2</sub>O, etc. On the basis of this constitution, we propose a consummate fabrication process for MCF rubber solar cells. The characteristics of these cells result from the semiconductor-like role of the molecules of TiO<sub>2</sub>, Fe<sub>3</sub>O<sub>4</sub>, Ni, Na<sub>2</sub>WO<sub>4</sub>∙2H<sub>2</sub>O, polydimethylsiloxane (PDMS), natural rubber (NR), oleic acid, polyvinyl alcohol (PVA), water and magnetic cluster involved in the MCF rubber. Their tendencies can be deduced by synthesizing knowledge about the enhancement of the reverse-bias saturation current <em>I</em><sub><em>S</em></sub> and the diode ideality factor <em>N</em>, with conventional knowledge about the semiconductor affected by <em>γ</em>-irradiation and the attenuation of the photon energy of <em>γ</em>-rays.
文摘A burnup calculation has been performed to evaluate heavy rare earth （terbium--Tb, dysprosium--Dy） production in spent gadolinium oxide （Gd203） installed as a BP （burnable poison）. Each amount of Tb and Dy production derived from the BP has been about 30-40 times larger than those created in FP （fission products）. Required cooling time to achieve exemption level on radioactivity concentration produced Tb and Dy derived from the BP are much shorter （BP-Tb： 7.9y, BP-Dy： 〈 0.1y） than those created in FP （FP-Tb： 3,616y, FP-Dy： 6.9y）. However, the BP is mixed homogeneously with UO2 pellet in current nuclear fuel system of LWRs （light water reactors）, and hence mixing of FP cannot be not avoided. In such a mixture case, the required cooling time of recovered Tb will become 2,653y and that of recovered Dy be 4.8y. For this reason, recovered Tb is unlikely to be resource for utilization, while recovered Dy must be the resource provided the precise separation from the other FP.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11305007 and 11235002.
文摘Measurements of the keV-neutron capture cross sections and radiative γ-ray spectrum of 56Fe and 57Fe are performed based on a 7 Li（p,n）7 Be reaction neutron source. The incident neutron spectrum on a capture sample is measured by means of a time-of-flight （TOF） method with a 6Li-glass detector. The radiative capture 7-rays emitted from an iron CS Fe or 57 Fe） or standard gold （197Au） sample are detected by a large anti-Compton NaI（TI） spectrometer covered with a heavy shield. The capture yields of samples are obtained by applying a pulse-height weighting technique to the corresponding capture γ-ray pulse-height spectrum. The Maxwellian averaged neutron capture cross sections of 56Fe and 5T Fe are derived according to the present capture cross section results.
文摘A resourceability on nuclear fuel cycle by transmutation of fission products in the spent fuel of nuclear reactors is discussed in this paper to investigate the feasibility of ＂creation and utilization＂ of Apr6s ORIENT from Adv.-ORIENT cycle, in which chemical ＂separation and utilization＂ of nuclear rare metals （platinum group metals, Mo, Tc, rare earth, etc.） has been proposed since FY2006. Apr6s ORIENT research program was newly initiated in FY2011 for nuclear transmutation of fission products into stable or short-lived highly-valuable elements. In the resourceability of rare earth metals from fission products, non-radioactive Nd and Dy can be created from Pr and Tb, respectively, by transmutation. Especially, the Dy creation has relatively high feasibility of about 10-20 %/y in creation rate. A proper moderation of neutrons in blanket of fast reactors may be required to provide a high creation rate of La from Ba. In light platinum group metals, non-radioactive Ru can be created from Tc by transmutation, of which creation rate is about 4-5 %/y in blanket of fast reactors. Pd created from Rh is almost non-radioactively depending on the isotope fraction of 107pd. Rh creation from Ru is not feasible under the neutron irradiation of typical nuclear reactors.
基金Supported by International Atomic Energy Agency,through the IAEA Research Contract 19263the Spanish Ministry of Economy and Competitivity under Contracts FPA2014-53290-C2-2-P and FPA2016-77689-C2-1-R
文摘The previously derived Lane consistent dispersive coupled-channel optical model for nucleon scattering on 232Th and 23Su nuclei is extended to describe scattering on even-even actinides with Z=90-98. A soft-rotator- model （SRM） description of the low-lying nuclear structure is used, where the SRM Hamiltonian parameters are adjusted to the observed collective levels of the target nucleus. SRM nuclear wave functions （mixed in K quantum number） have been used to calculate the coupling matrix elements of the generalized optical model. The ＂effective＂ deformations that define inter-band couplings are derived from the SRM Hamiltonian parameters. Conservation of nuclear volume is enforced by introducing a dynamic monopolar term to the deformed potential, leading to additional couplings between rotational bands. The fitted static deformation parameters are in very good agreement with those derived by Wang and collaborators using the Weizs^cker-Skyrme global mass model （WS4）, allowing use of the latter to predict cross sections for nuclei without experimental data. A good description of the scarce ＂optical＇experimental database is achieved. SRM couplings and volume conservation allow a precise calculation of the compound-nucleus formation cross sections, which is significantly different from that calculated with rigid-rotor potentials coupling the ground-state rotational band. The derived parameters can be used to describe both neutron- and proton-induced reactions.
文摘In order to examine the chemical form of uranyl species in l-ethyl-3-methylimidazolium （EMI） based ionic liquids, UV-visible absorption spectra of solutions prepared by dissolving [EMI]2[UO2CI4] into a mixture of EMICI and EMIBF4 （50：50 tool%） were measured. As a result, it was confirmed that uranyl species in the mixture of EMICI and EMIBF4 existed as [UO2C14]2-. Cyclic voltammograms （CVs） of [UO2CI4]2- in the mixture were measured at 25 ~C using a Pt working electrode, a Pt wire counter electrode, and an Ag/Ag＋ reference electrode （0.01 M AgNO3, 0.1 M tetrabutylammonium perchlorate in acetonitrile） in a glove box under an Ar atmosphere. Peaks corresponding to one redox couple were observed around -1.05 V （Epc） and -0.92 V （Epa） vs. ferrocene/ferrocenium ion （Fc/Fc＋）. The potential differences between two peaks （AEp） increased from 101 to 152 mV with an increase in the scan rate from 50 to 300 mV s-1, while the （Epc ＋ Epa）/2 value was constant, -0.989 V vs. Fc/Fc＋ regardless of the scan rate. Furthermore, the diffusion coefficient of [UO2C14]2 and the standard rate constant were es- timated to be 3.7× 10^-8 cm^2 s 1 and （2.7-2,8） × 10^-4 cm s-! at 25 ℃. By using the diffusion coefficient and the standard rate constant, the simulation of CVs was performed based on the reaction, [UO2C14]2- ＋ e- = [UO2C14]3-. The simulated CVs were found to be consistent with the experimental ones. From these results, it is concluded that [UO2C14]2- in the mixture of EMIC1 and EMIBF4 is reduced to [UO2C14]3- quasi-reversibly at -0.989 V vs. Fc/Fc＋.
文摘To evaluate the stability of N-alkylated pyrrolidone derivatives （NRPs）, which are supposed to be used as precipitants for U（VI） and Pu（IV, VI） species in HNO3 media, under irradiation environment, some candidate NRPs were irradiated by γ-ray. Irradia- tion to HNO3 solutions up to 6 mol dm-3 （= M） containing 2 M N-n-butyl-2-pyrrolidone （NBP）, one of NRPs with lower hy- drophobicity, has revealed that the residual ratios of NBP in the samples of HNO3 up to 3 M decreased identically and linearly. Approximately 20% of NBP was found to be degraded after the irradiation at 1 MGy. It was also found that the decrease in the precipitation ratio of UOf＋ （P.R., %） was gentle and that the P.R. values were relatively in accordance with the residual ratios of NBP. On the other hand, the degradation of the samples irradiated in 6 M HNO3 was found more distinguished. It was pro- posed from the analyses of degraded compounds that the degradation of NBP in HNO3 by γ-ray irradiation started from the cleavage of the pyrrolidone ring by the addition of oxygen atom originating from HNO3, followed by the formation of chain compounds by the successive addition of oxygen, leading to the generation of oxalic acid and acetic acid. The stability of other NRPs in 3 M HNO3 was evaluated to be nearly identical with that of NBP except lower P.R. values of the samples containing NRPs with higher hydrophobicity irradiated at more than 0.5 MGy.
文摘1 Results When a C60 film was irradiated with electron-beam (EB) with an incident energy of 3 kV, a peanut-shaped C60 polymer with metallic properties was formed[1], as shown in Fig.1. To elucidate the origin of the metallic properties of the peanut-shaped polymer, we examined the valence photoelectron spectra of the polymer using in situ high-resolution photoelectron spectroscopy and found that the electronic states of the polymer came across the Fermi level (EF)[2]. Interestingly, the spectral shape i...
基金Supported by the National Natural Science Foundation of China(10175091,11305007)the National Research Foundation of Korea(2018R1A6A06024970)。
文摘The ratio ofγtransition-intensities from the initial capture state to low-lying states may represent the model-independentγ-strength function,which reflects the effects of different neutron-capture reaction mechanisms.The extraordinary quenching of theγ0 transition from the p-wave neutron radiative capture in 57Fe is observed,for the first time,from the pronounced enhancement of theγ-strength function ratios fγ1/fγ0 and fγ2/fγ0.The 2p-1h doorway excitation leads to suppression of theγ0 transition to the ground state and the enhancement of theγ1 andγ2 transitions to the first and second excited states,respectively.The fp sub-shells supply the exact number of spaces required for the 2p-1h configuration,which features the neutron capture mechanism in the vicinity of A=55.
