Showing papers in "Journal of Nuclear Science and Technology in 2001"
TL;DR: In this paper, a two-dimensional numerical analysis of jet breakup is performed using the MPS method (Moving Particle Semi-implicit Method) which is a particle method for incompressible flows.
Abstract: A continuous jet changes to droplets where jet breakup occurs. In this study, two-dimensional numerical analysis of jet breakup is performed using the MPS method (Moving Particle Semi-implicit Method) which is a particle method for incompressible flows. The continuous fluid surrounding the jet is neglected. Dependencies of the jet breakup length on the Weber number and the Froude number agree with the experiment. The size distribution of droplets is in agreement with the Nukiyama-Tanasawa distribution that has been widely used as an experimental correlation. Effects of the Weber number and the Froude number on the size distribution are also obtained.
171 citations
TL;DR: In this paper, the lattice Boltzmann method (LBM) was applied to the simulation of bubble motion under gravity by using a self-organizing self-assembly of mesoscopic fluid particles.
Abstract: We describe the numerical simulation results of bubble motion under gravity by the lattice Boltzmann method(LBM), which assumes that a fluid consists of mesoscopic fluid particles repeating collision and translation and a multiphase interface is reproduced in a self-organizing way by repulsive interaction between different kinds of particles. The purposes in this study are to examine the applicability of LBM to the numerical analysis of bubble motions, and to develop a three-dimensional version of the binary fluid model that introduces a free energy function. We included the buoyancy terms due to the density difference in the lattice Boltzmann equations, and simulated single- and two-bubble motions, setting flow conditions according to the Eotvos and Morton numbers. The two-dimensional results by LBM agree with those by the Volume of Fluid method based on the Navier-Stokes equations. The three-dimensional model possesses the surface tension satisfying the Laplace's law, and reproduces the motion of single...
88 citations
TL;DR: In this article, the authors used the Moving Particle Semi-Implicit (MPS) method based on moving particles and their interactions to understand the behavior of jet penetration, water jet injection into a pool of a denser fluid under non-boiling and isothermal conditions.
Abstract: The numerical method used in this study is Moving Particle Semi-implicit (MPS) method which is based on moving particles and their interactions. Grids are not necessary, so that large deformation of fluids can be calculated without grid tangling. Particles move in fully Lagrangian description. Thus, convection terms are not necessary to discretize and numerical diffusion does not arise. To understand the behavior of jet penetration, water jet injection into a pool of a denser fluid under non-boiling and isothermal conditions is analyzed using the MPS method. The density ratio of the denser fluid (Fluorinert) to water is 1.88. This is categorized to the coolant injection (CI) mode where the coolant is assumed to be injected into the melt pool. The calculation results are compared with experiments which were conducted by Park et al. in Japan Atomic Energy Research Institute (JAERI) for visualization of basic processes in fuel-coolant interaction (FCI). The jet penetration behavior of the three-dimensional c...
87 citations
TL;DR: In this paper, the performance of small bending radius helical coil-pipe used in HTR-10 steam generator experimental facility was investigated and it was confirmed that the critical Reynolds number is much greater than in a straight pipe and is a function of De.
Abstract: Helical steam generator or helical heat exchanger is extensively used in high-temperature gas cooling reactor, fast breeder reactor, pressurized water reactor using in ship propulsion and areas of electro-power, chemical industry and petroleum industry. The purpose of this paper is to research the hydraulic performance of small bending radius helical coil-pipe used in HTR-10. Research for hydraulic performance of small bending radius helical pipe was carried out on the HTR-10 steam generator experimental facility. Based on the experimental results, it was confirmed that for helical pipe the critical Reynolds number (Re) is much greater than in a straight pipe and is a function of De. Formulas for Re of single-phase flow structure transition, friction coefficient of single-phase flow, and two-phase flow friction factor are obtained. Experience formulas of small bending radius helical pipe are recommended for design and research.
80 citations
TL;DR: In this paper, the authors developed new reactor concepts for the innovation of light water reactors (LWR) and fast reactors and developed a once-through coolant cycle, supercritical-pressure light water cooled reactor was developed.
Abstract: The purpose of the study is to develop new reactor concepts for the innovation of light water reactors (LWR) and fast reactors. Concept of the once-through coolant cycle, supercritical-pressure light water cooled reactor was developed. Major aspects of reactor design and safety were analysed by the computer codes which were developed by ourselves. It includes core design of thermal and fast reactors, plant system, safety criteria, accident and transient analysis, LOCA, PSA, plant control, start up and stability. High enthalpy rise as supercritical boiler was achieved by evaluating the cladding temperature directly during transients. Fundamental safety principle of the reactor is monitoring coolant flow rate instead of water level of LWR. The reactor system is compact and simple because of high specific enthalpy of supercritical water and the once-through cycle. The major components are similar to those of LWR and supercritical thermal plant. Their temperature are within the experiences in spite of the hig...
77 citations
TL;DR: In this paper, coal fly ash was used to synthesize K-H zeolite (K2Al2Si4O12-nH2O) under optimum conditions of 160°C, 3 d, 1 M (=mol/dm3) KOH and liquid-solid ratio of 15cm3/g.
Abstract: Zeolites were synthesized from coal fly ash by hydrothermal treatment with KOH solutions. K-H zeolite (K2Al2Si4O12-nH2O) was produced under optimum conditions of 160°C, 3 d, 1 M (=mol/dm3) KOH and liquid-solid ratio of 15cm3/g. The uptake behavior of radioactive cesium for the products was investigated by batch and column methods. The uptake equilibrium of Cs+ for the above product was attained within 2h yielding the distribution coefficient of above 104 cm3/g. The uptake of Cs+ was followed by a Langmuir adsorption isotherm and the maximum uptake capacity was estimated to be 3.34 mmol/g. The successive removal of Cs+ was accomplished through the column packed with granular composites of product-alginate gel polymer.
70 citations
TL;DR: In this article, the dissolution behavior of U3O8 and UO2 using supercritical CO2 medium containing HNO3-TBP complex as a reactant was studied.
Abstract: Dissolution behavior of U3O8 and UO2 using supercritical CO2 medium containing HNO3-TBP complex as a reactant was studied. The dissolution rate of the oxides increased with increasing the HNO3/TBP ratio of the HNO3-TBP complex and the concentration of the HNO3-TBP complex in the supercritical CO2 phase. A remarkable increase of the dissolution rate was observed in the dissolution of U3O8 when the HNO3/TBP ratio of the reactant was higher than ca. 1, which indicates that the 2:1 complex, (HNO3)2TBP, plays a role in facilitating the dissolution of the oxides. Half-dissolution time (t½ ) as an indication of the dissolution kinetic was determined from the relationship between the amount of uranium dissolved and the dissolution time (dissolution curve). A logarithmic value of a reciprocal of the t½ was proportional to the logarithmic concentration of HNO3, CHNO3, in the supercritical CO2. The slopes of the (l/t½ ) vs. ln CHNO3 plots for U3O8 and UO2 were different from each other, indicating that the reaction ...
60 citations
TL;DR: In this paper, the free energy of ammonium molybdophosphate (AMP) and its composite with alginate gel polymer have been studied by the batch and column methods.
Abstract: The uptake properties of Cs+ for ammonium molybdophosphate (AMP, (NH4)3PMo12O40.3H2O) and its composite with alginate gel polymer have been studied by the batch and column methods. The free energy for the ion exchange ([NH+ 4]ad+Cs+NH+ 4+[Cs+]ad) was found to have a relatively low value of -9.7 kJ/mol compared to other inorganic ion exchangers, indicating high selectivity of AMP for Cs+ ions. The fine crystals of AMP exchanger were granulated with calcium alginate (CaALG) gel polymer as an immobilization matrices. The uptake rate of Cs+ for AMP-CaALG composite was fairly fast and the uptake attained equilibrium within 3 h; the uptake was above 96% even in the presence of 5M (=mol/dm3) NaNO3. The distribution coefficient of Cs+, Kd-Cs, decreased in the order of coexisting ions, H+>Na+>K+>NH+. In a wide HNO3 concentration region of 10-2-5M, the Kd,cs value for the composite was around 104cm3/g, while those for other elements, Na+, Sr2+, Co2+, Eu3+ and Am3+, were less than 102cm3/g. The uptake of Cs+ followe...
56 citations
TL;DR: In this article, the effect of hydration on the reduced partition function ratio (RPFR) of the monoborate anion (B(OH) 4 - ) is evaluated in order to better understand boron isotope fractionation observed in aqueous systems.
Abstract: Based on the ab initio molecular orbital theory at the HF/6-31G(d) level, the effect of hydration on the reduced partition function ratio (RPFR) of the monoborate anion (B(OH) 4 - ) is evaluated in order to better understand boron isotope fractionation observed in aqueous systems. Aquoborate anions up to decaaquoborate anion, B(OH) 4 - (H 2 O) 10 , were considered and their geometry optimization and RPFR calculations were carried out. It was induced that hydration decreased the ln(RPFR) value of B(OH) 4 - by ca. 1.2%.
49 citations
TL;DR: In this article, the authors developed underwater YAG laser repair technology and implemented 0.3MPa underwater laser welding in both downward and horizontal direction repairs, even in a U groove work piece.
Abstract: In May 2000 JSME issued Rules on fitness-for-service for nuclear power plants, which define allowable flaw sizes at operating nuclear power plants, and based on evaluation against these rules, rational repairs were to be realized. According to results, rational in-situ repairs were urgently needed on aged nuclear power plants, and since underwater laser repairs met utilities requirements, the authors developed underwater YAG laser repair technology. Hitachi installed the equipment at JAPEIC (Japan Power Engineering and Inspection Corporation) in 1998 and implemented 0.3MPa underwater YAG laser welding in both downward and horizontal direction repairs, even in a U groove work piece. Metallurgical studies are ongoing.
48 citations
TL;DR: In this paper, the authors focused on modeling the interfacial area transport mechanism of vertical adiabatic air-water bubbly flows in a relatively small diameter pipe where the bubble size-to-pipe diameter ratio was relatively high and the radial motion of bubbles was restricted by the presence of the pipe wall.
Abstract: In relation to the development of the interfacial area transport equation, this study focused on modeling of the interfacial area transport mechanism of vertical adiabatic air-water bubbly flows in a relatively small diameter pipe where the bubble size-to-pipe diameter ratio was relatively high and the radial motion of bubbles was restricted by the presence of the pipe wall. The sink term of the interfacial area concentration was modeled by considering wake en-trainment as a possible bubble coalescence mechanism, whereas the source term was neglected by assuming negligibly small bubble breakup for low liquid velocity conditions based on visual observation. One-dimensional interfacial area transport equation with the derived sink term was evaluated by using five datasets of vertical adiabatic air-water bubbly flows measured in a 9.0mm-diameter pipe (superficial gas velocity: 0.013–0.052 m/s, superficial liquid velocity: 0.58–1.0m/s). The modeled interfacial area transport equation could reproduce the prope...
TL;DR: In this article, an extractant having a strong affinity for palladium, bis(2,4,4-trimethylpentyl) monothiophosphinic acid (Cyanex 302, HA), was enclosed into microcapsules by utilizing highly immobilizing ability of biopolymer (alginate and alginic acid gel polymers).
Abstract: Selective uptake and recovery of platinum group metals are an important subject in the high level liquid waste treatment. An extractant having a strong affinity for palladium, bis(2,4,4-trimethylpentyl) monothiophosphinic acid (Cyanex 302, HA), was enclosed into microcapsules by utilizing highly immobilizing ability of biopolymer (alginate and alginic acid gel polymers). The uptake of Pd2plus, Ru(NO)3+ and Rh3+ for granular microcapsules has been studied by batch and column methods. A relatively large distribution coefficient of Pd2plus, Kd,Pd, of above 104 cm3/g was obtained in the presence of 0.2–0.5 M HNO3 and the separation factors of Pd/Ru and Pd/Rh were estimated to be above 102. The uptake of Pd2+ on microcapsules followed a Langmuir-type uptake isotherm and the maximum uptake capacity was estimated to be 0.72–0.96 mmol/g. These metal cations were chromatographically separated through the column packed with HA-alginate microcapsules.
TL;DR: In this paper, an effective technique to accelerate the convergence of a fission source distribution in a Monte Carlo simulation is proposed as an application of the fission matrix, where the number of inactive cycles can be automatically determined and reduced by the acceleration method.
Abstract: The effective technique to accelerate the convergence of a fission source distribution in a Monte Carlo simulation is proposed as an application of a fission matrix. It is found that this acceleration method is especially useful for large core analysis where the fission source distribution is slowly converged in a Monte Carlo simulation by the source iteration method. It is found that the number of inactive cycles can be automatically determined and reduced by the acceleration method in this investigation.
TL;DR: In this article, the verification of open pores, the thermal shock resistivity, the adhesion strength and the deuterium permeability were evaluated and compared with Cr2O3-SiO2 (Type 1) coating and Cr2 O3- SiO2 including CrPO4 (Type 2) coating.
Abstract: In a fusion blanket design, ceramic coating on structural materials has been considered to be used as a tritium permeation barrier. The Chemical Densified Coating (CDC) method has some advantage compared with another coating method. This method is capable to form densified coating on either the outer or the inner surface of a tube or a container. This process temperature is low (450°C). The fabrication technique of Cr2O3-SiO2 coating had been developed using CDC method. However, Cr2O3-SiO2 coating had open pores in the coating. For filling open pores, the densification treatment by CrPO4 was examined. In this study, the verification of open pores, the thermal shock resistivity, the adhesion strength and the deuterium permeability were evaluated and compared with Cr2O3-SiO2 (Type 1) coating and Cr2O3-SiO2 including CrPO4 (Type 2) coating. From these results, it was confirmed that Type 2 coating had a good adhesion property, and permeation reduction factor of SS316 with Cr2O3-SiO2 including CrPO4 coating re...
TL;DR: In this article, the authors investigated the effects of flow path scale on gas-liquid two-phase flow analysis of advanced nuclear systems such as passive safety systems and natural-circulation-type reactors.
Abstract: Multi-dimensional analyses have been expected recently with expanding computation resources for gas-liquid two- phase flow analyses of advanced nuclear systems such as passive safety systems and natural-circulation-type reactors. However, the applicability of previous constitutive equations for multi-dimensional analyses has not been fully investigated especially for the effects of flow path scale because the equations have been assessed for small-scale experiments. In this study, we analyzed the scale effects by the multi-dimensional two-fluid model code using data in 38 mm and 200 mm diameter pipes. We clarified a key-parameter to model the scale effects and developed models for the effects on phase distribution. The scale effects can be classified by the relative relationship between bubble diameter db and turbulent length scale lT . Bubble-induced turbulence is increased under that db is smaller than lT and bubble coalescence is predominated rather than breakup under that lT is about three times large...
TL;DR: In this article, the effects of hydrogen peroxide on electrochemical corrosion potential (ECP) of type 304 stainless steel (SUS304) were measured using a high temperature, high pressure.
Abstract: In order to determine the effects of hydrogen peroxide on electrochemical corrosion potential (ECP) of type 304 stainless steel (SUS304), ECPs were measured using a high temperature, high pressure ...
TL;DR: In this paper, the observation of microstructures of compacted Bentonite by Microfocus X-ray Computerized Tomography (MicroCT) is described, and the authors propose a method to detect the structure of the Bentonite.
Abstract: (2001). Observation of Microstructures of Compacted Bentonite by Microfocus X-Ray Computerized Tomography (Micro-CT) Journal of Nuclear Science and Technology: Vol. 38, No. 8, pp. 697-699.
TL;DR: In this paper, the authors developed a new method of friction surfacing repairs to be processed under the melting point of the substrate after the surface grooving of SCC, and demonstrated its applicability in-situ.
Abstract: Some of Japan's ageing operating nuclear power generators are entering their 30th year, which is close to their designed lifespan. With this in mind, JSME (Japan Society of Mechanical Engineer) issued Rules on fitness-for-service for nuclear power plants in May 2000, in which operating plants' maintenance rules were defined and the urgent need for in-situ repair methods on nuclear power plant flaws stated. Because low heat input repairs are necessary for the aged materials of the plants, the authors developed a new method of friction surfacing repairs to be processed under the melting point of the substrate after the surface grooving of SCC, and demonstrated its applicability in-situ.
TL;DR: In this paper, the decay heat from a fissioning system is expressed as a linear combination of macroscopic measurement data for other fissioned systems with a small residual term.
Abstract: We propose a new “hybrid” method for calculating the aggregate decay heat from fission product nuclides after a fission burst. The decay heat from a given fissioning system is expressed as a linear combination of macroscopicmeasurement data for other fissioning systems with a small residual term. This method is based on the linearity of the decay heat to the fission yield. The coefficients in the linear combination are obtained from fitting the fission yield of the given fissioning system with a linear combination of fission yields of other fissioning systems. To demonstrate usefulness of this method, it is applied to examining the consistency among measured decay heat powers of five fast and three thermal neutron induced fissions. The hybrid-method calculations agree well with the measurements and usual summation calculations at cooling times before 4,000 s, except for a γ component measurement of the 235 U thermal fission at about 2,000 s. These results indicate the consistency and reliability of the decay heat evaluation for these systems with the above exception. Furthermore, they also imply usefulness of the present method in predicting the decay heat of other fissioning systems, for which no measurements have been performed so far.
TL;DR: In this paper, a new nuclear fuel reprocessing method based on the anodic dissolution of spent fuels in aqueous alkaline solutions (Na2CO3-NaHCO3) has been proposed.
Abstract: A new nuclear fuel reprocessing method based on the anodic dissolution of spent fuels in aqueous alkaline solutions (Na2CO3-NaHCO3) has been proposed. Experiments of the anodic dissolution were performed by using a simulated spent fuel in a Na2CO3-NaHCO3 solution. Uranyl ions produced anodically were present in the solution as stable carbonato complexes, and at the same time, most of the simulated fission products (FP) were precipitated as hydroxo or carbonate compounds. Under this condition, Cs of an alkali metal group was dissolved in the solution and precipitated by adding sodium tetraphenylborate. Uranyl ion was recovered as hydroxo compounds by adding NaOH to the solution after removing precipitates of the simulated FP. In view of waste disposal, 99Tc having a long half-life should be removed. Precipitation behavior of Tc(VII) was examined by using Re(VII) as a simulant of Tc(VII). It was found that Re(VII) species are completely removed as a precipitate by adding tetraphenylphosphonium chloride. A l...
TL;DR: In this paper, a theoretical study of the density wave oscillation (DWO) of a natural circulation loop is presented, and the nonlinear analysis based on the drift flux model is performed.
Abstract: A theoretical study of the Density Wave Oscillation (DWO) of a natural circulation loop is presented in this paper. The nonlinear analysis based on the drift flux model is performed. The momentum equation is integrated around a closed loop, and the energy equation is integrated separately for every component. The equations are solved numerically using the Gear method, suitable for solving nonlinear stiff equations, with a newly developed Nonlinear Time Domain Computer Code (NTDCC). The Marginal Stability Boundary (MSB) of DWO of the low Temperature Heating Reactor (THR) designed in China was obtained by NTDCC. The results obtained by NTDCC are in good agreement with the experimental results.
TL;DR: In this article, the MHD effects on a heat transfer of liquid lithium flowing in an annular channel were studied, using a newly constructed comparatively large-scale lithium loop, where the data on the heat transfer characteristics were arranged in Nu-St diagrams where St=Ha2/Re.
Abstract: The MHD effects on a heat transfer of liquid lithium flowing in an annular channel were studied, using a newly constructed comparatively large-scale lithium loop. The data on the heat transfer characteristics were arranged in Nu-St diagrams where St=Ha2/Re. The diagrams indicate that Nu decreases as St increases as a whole trend. However, singular peaks of Nu were observed at about St=13, corresponding to the singular increments of temperature fluctuations, whereas the peaks occurred at St=1.5 in the previous experiment with a smaller channel. In considering a predominant MHD effect due to conductive wall duct, the current load factor KP for external circuit was taken into account. And Miyazaki number Mi=KPSt, which means the effective electromagnetic interaction, was adopted in substitution for St and the heater pin diameter was taken as the characteristic length in place of the conventional hydraulic equivalent diameter. Thus, an appreciably good agreement was obtained concerning the peaks at Mi=0.13 in...
TL;DR: In this paper, the authors extended this method to a two-fluid (liquid-liquid and gas-liquid) system and introduced a potential-type surface tension to calculate the two-phase flow without experimental correlation.
Abstract: A particle interaction method called MPS (Moving Particle Semi-Implicit) has been developed in recent years, which formulates the differential operators in Navier-Stokes' equation as interactions between particles characterized by a kernel function and adopts a mesh-free algorithm. This method is suitable especially for treating fluid breakup. We have extended this method to a two-fluid (liquid-liquid and gas-liquid) system and introduced a potential-type surface tension to calculate the two-phase flow without experimental correlation. With this extended method, a several number of two-phase flow experiments were analyzed successfully as reported in our previous paper. Herein, as one of the verification studies, the experiment by Valukina et al. was analyzed to show that our method could reproduce the bubble size effect on the radial void distribution in a circular tube. The experiment showed that the radial void distribution changes drastically as the bubble size changes. Our previous work with SIMMER-IV...
TL;DR: In this article, a method for decontamination of uranium from the solid wastes containing uranium oxides, UO 2 or U 3 O 8, using supercritical CO 2 medium containing HNO 3 -TBP complex (TBP: tri-n-butylphosphate).
Abstract: This study aims at the development of a method for the decontamination of uranium from the solid wastes containing uranium oxides, UO 2 or U 3 O 8 , using supercritical CO 2 medium containing HNO 3 -TBP complex (TBP: tri-n-butylphosphate).
TL;DR: In this paper, the hydrogen gas evolution from water dispersing nanoparticles induced by 60Co γ-ray irradiation was studied, and reactions enhancing the hydrogen evolution proceed on particle's surface.
Abstract: Hydrogen gas evolution from water dispersing nanoparticles induced by 60Co γ-ray irradiation was studied. Nanoparticles of TiO2 and Al2O3 with average sizes of 7–33 nm supplied from several suppliers were examined. It was indicated that reactions enhancing the hydrogen evolution proceed on particle's surface. It was implied that the yield depends on size of agglomerated particle regardless of their primary particle size and chemical species. Reactions that enhance the hydrogen yields were discussed, and radiolysis process was concluded dominant in the total enhancement mechanism.
TL;DR: In this article, the condition for liquefaction at the fuel-cladding interface of U-Pu alloys with Fe has been examined at 923 and 943 K. The test results confirmed that the liquid phase is not formed at any region of the reaction zone when the maximum Pu content in the (U,Pu)6Fe phase is less than the Pu solubility limit in this phase.
Abstract: In metallic U-Pu-Zr fuel for fast reactors, metallurgical reactions occur between the fuel alloy and the stainless steel cladding, and a liquid phase may be formed in the reaction zone at a higher temperature. In order to clarify the condition for liquefaction at the fuel-cladding interface, the reactions of U-Pu alloys with Fe have been examined at 923 and 943 K. The test results confirmed that the liquid phase is not formed at 923 K in any region of the reaction zone when the maximum Pu content in the (U,Pu)6Fe phase is less than the Pu solubility limit in this phase. Comparison of the present test results with the liquefaction data from the various tests on metallic fuel-cladding compatibility suggested that the liquefaction condition is independent of the Zr content in the fuel alloy and can be expressed as a function of the atom fraction ratio of Pu/(U+Pu) in the fuel alloy and the reaction temperature. At 923 K, liquefaction will occur when the Pu/(U+Pu) ratio is larger than 0.25.
TL;DR: In this article, two kinds of the blanket in-pile mockups with Li2TiO3 pebble bed were developed and the in-situ tritium recovery experiments were carried out in the Japan Materials Testing Reactor (JMTR).
Abstract: Lithium titanate (Li2TiO3) is one of the most attractive tritium breeders for breeding blanket in fusion reactor from view points of low tritium inventory, high chemical stability and so on. The data on the performance of a blanket mockup with pebble bed under neutron irradiation is needed for the design of breeding blanket. To obtain such data, two kinds of the blanket in-pile mockups with Li2TiO3 pebble bed were developed and the in-situ tritium recovery experiments were carried out in the Japan Materials Testing Reactor (JMTR). In these studies, effects of various parameters, i.e., irradiation temperature, sweep gas flow rate, etc., on the tritium recovery behavior from Li2TiO3 pebble bed were evaluated. It was found that the tritium recovery (R) to tritium generation (G) ratio (R/G) increased with increasing the temperature of Li2TiO3 pebble bed and was saturated when the temperature of Li2TiO3 pebble bed at the outside edge exceeded 300°C. Additionally, the sweep gas flow rate in the range of 100 to ...
TL;DR: In this article, the influence of neutron spectrum on characteristics of several equilibrium fuel cycles of PWRs was evaluated and the results showed that the enrichment and the required amount of natural uranium decrease significantly with increasing number of confined heavy nuclides when uranium is discharged from the reactor.
Abstract: This paper evaluated the influence of neutron spectrum on characteristics of several equilibrium fuel cycles of pressurized water reactor (PWR). In this study, five kinds of fuel cycles were investigated. Required uranium enrichment, required natural uranium amount, and toxicity of heavy metals (HMs) in spent fuel were presented for comparison. The results showed that the enrichment and the required amount of natural uranium decrease significantly with increasing number of confined heavy nuclides when uranium is discharged from the reactor. On the other hand, when uranium is totally confined, the enrichment becomes extremely high. The confinement of plutonium and minor actinides (MA) seems effective in reducing radio-toxicity of discharged wastes. By confining all heavy nuclides except uranium those three characteristics could be reduced considerably. For this fuel cycle the toxicity of HMs in spent fuel become nearly equal to or less than that of loaded uranium.
TL;DR: Within a design study of a fusion DEMO reactor aiming at demonstrating technologies of fusion power plant, supercritical water is applied as a coolant of solid breeder blanket to attain high therma as mentioned in this paper.
Abstract: Within a design study of a fusion DEMO reactor aiming at demonstrating technologies of fusion power plant, supercritical water is applied as a coolant of solid breeder blanket to attain high therma
TL;DR: In this paper, the characterisation of Fe-montmorillonite is presented as a Simulant of Buffer Materials Accommodating Overpack Corrosion Product (BOMPC).
Abstract: (2001) Characterization of Fe-montmorillonite: A Simulant of Buffer Materials Accommodating Overpack Corrosion Product Journal of Nuclear Science and Technology: Vol 38, No 12, pp 1141-1143