Showing papers in "Journal of Nuclear Science and Technology in 1980"
TL;DR: In this paper, the average void fraction in the curved test section was determined, and empirically correlated to the pressure drop, by means of a series of nondimensional numbers, and the combined action of gravity and centrifugal force acting on two-phase flow was expressed in terms of a modified Froude number representing the balance of radial forces between those acting on the liquid and the gaseous phases of the flow passing through the reclined vertical U- bend.
Abstract: Experimental results are presented on the flow behavior, average void fraction and pressure drop in air-water two-phase flow mixture flowing upward through a C-shaped bend curved in vertical plane The curved test section of transparent acrylic resin tubing was varied in four versions of (a) 90 mm, (b) 1325 mm and (c) 180 mm radii of curvature with 16 mm inside diameter tube, and (d) 135 radius with 24 mm diameter tube The combined action of gravity and centrifugal force acting on the two-phase flow is expressed in terms of a modified Froude number representing the balance of radial forces between those acting on the liquid and the gaseous phases of the flow passing through the reclined vertical U- bend The average void fraction in the curved test section was determined, and empirically correlated to the pressure drop, by means of a series of nondimensional numbers
70 citations
TL;DR: In this paper, the authors measured pressure and fluid oscillation in vent tubes and a header induced by steam condensation with a test apparatus, and the theoretical analysis was conducted by considering the header as one volume and by modeling chugging as one-dimensional.
Abstract: Pressure and fluid oscillation in vent tubes and a header induced by steam condensation were measured with a test apparatus Pressure oscillation consists of low-, middle- and high-frequency components The frequencies measured in the present apparatus are around 2–8Hz, 15 Hz and 100–150 Hz for low, middle and high frequency respectively The chugging phenomenon occurs in a certain range of steam flow rate When the amplitude of fluid oscillation becomes maximum, the amplitude of pressure oscillation in the header also becomes maximum High frequency component is predominant in the pressure oscillation in vent tubes When the temperature of pool water becomes lower, the amplitude becomes larger As the temperature of pool water gets higher, high-frequency component of pressure oscillation disappears, and middle, low frequency in order Based on the experimental facts mentioned above, the theoretical analysis was conducted by considering the header as one volume and by modeling chugging as one-dimensional
55 citations
TL;DR: In this article, two new release models are proposed, the Preferential-Release model and the Exponential-release model, where both of nuclide-specific release rate and time-dependence of leach are taken into account.
Abstract: In safety evaluation of nuclear waste repository systems, the analysis on migration of radionuclides in geologic media is important. In previous analytical models called Band- Release, Step-Release and Impulse-Release for decay chains, nuclide-specific release rate and time-dependence of release rate can not be taken into consideration. In this paper, two new release models are proposed. In Preferential-Release model, both of nuclide-specific release rate and time-dependence of leach are taken into account. Exponential-Release model is a special case of Preferential-Release model, in which no preferentiality in leach is assumed. The obtained analytical solutions for these new models are applicable even to four or more member decay chains and are as simple as those for the previous models. As an example of the application of the new models, the discharge rates of the four nuclides in the decay chain of 238Pu→234U→ 230Th→236Ra→ into a surface water body are calculated as a function of time after the start o...
49 citations
TL;DR: In this article, the stability of high-level liquid waste (HLW) from nuclear fuel reprocessing was studied by using a simulated HLW in 2 mol/lHNO3 solution.
Abstract: Stability of high-level liquid waste (HLW) from nuclear fuel reprocessing was studied by using a simulated HLW. Fundamental works disclosed that precipitates formed during aging at ambient temperature or refluxing the simulated HLW in 2 mol/lHNO3 solution consist mainly of Mo, Zr and Te contributing significantly to the formation of precipitate. When the simulated HLW was denitrated with formic acid or deacidified with NaOH, fractions of precipitated Mo, Zr and Te increased with pH and amounted to over 85% at pH 0.5, where the fraction of precipitated La was below 0.1%. For further treatment of HLW such as partitioning, denitration of HLW to pH 0.5 might be useful for removing Mo, Zr and Te from the solution without significant contamination with rare earths, Am and Cm.
38 citations
33 citations
TL;DR: In this paper, the effect of a magnetic field on laminar natural convection of liquid metal was studied experimentally using NaK as conducting fluid, and the magnetic field was imposed horizontally and parallel to a uniformly heated vertical plate, to act perpendicularly across the convective flow.
Abstract: The effect of a magnetic field on laminar natural convection of liquid metal was studied experimentally using NaK as conducting fluid. The magnetic field was imposed horizontally and parallel to a uniformly heated vertical plate, to act perpendicularly across the convective flow. In a low magnetic field, the temperature profile across the layer of flowing fluid acquired an η-shaped profile characterized by a valley close to the wall and a peak further away, which had the effect of raising heat transfer rate above that obtained in the absence of magnetic field. When the magnetic field was intensified, its braking effect on the flow approached the temperature profile to the case of pure heat conduction through solid, to result in dwindling heat transfer rate.
32 citations
TL;DR: In this article, a single heater rod PWR reflood heat transfer experiments and analyses of the PWR- Full Length Emergency Core Heat Transfer (PWR-FLECHT) Group I data were carried out.
Abstract: A single heater rod PWR reflood heat transfer experiments and analyses of the PWR- Full Length Emergency Core Heat Transfer (PWR-FLECHT) Group I data were carried out. The objectives of the experiments and the analyses were to evaluate film boiling heat transfer coefficients in the core during reflood phase of a postulated loss-of-coolant accident in pressurized water reactors, and to provide necessary information on heat transfer correlations for development of a safety analysis computer code. The results of these experiments showed that the film boiling heat transfer coefficients are strongly dependent upon the local subcooling at the quench front. It was found that when the subcooling at the quench front was zero, the saturated film boiling heat transfer coefficients could be expressed by a correlation similar to the Bromley correlation by introducing a representative length which is defined as the distance between the quench front and the elevation at which the coefficients are evaluated. When the sub...
29 citations
TL;DR: In this paper, data of variations in natural background γ-radiation flux density obtained from observations near the ground surface made for a period of almost 1 year are given together with data on simultaneous measurements on changes in various environmental influencing factors, such as the degree of soil dryness, atmospheric radon daughter concentration and rainfall rate.
Abstract: Data of variations in natural background γ-radiation flux density obtained from observations near the ground surface made for a period of almost 1 year are given together with data on simultaneous measurements on changes in various environmental influencing factors, such as the degree of soil dryness, atmospheric radon daughter concentration and rainfall rate. Statistical and time series analyses of these data have provided much information on the relationships between the flux density and influencing factors and periodical characteristics of those variations in the natural environment. It is concluded from the results of the analyses that the atmospheric randon daughters and rainfall play an important role in short- and middle-term variations in the background radiation flux, while the change of soil dryness contributes to long-term variations.
26 citations
TL;DR: In this paper, a corrosion product of metallic aluminum immersed in sea water extracts lithium from it selectively, and the effect of the temperature and pH of sea water, and of the initial concentration of lithium in it were examined.
Abstract: Extraction of lithium from sea water was investigated. It was found that a corrosion product of metallic aluminum immersed in sea water extracts lithium from it selectively. Effects of the temperature and the pH of sea water, and of the initial concentration of lithium in it were examined. On the basis of the analysis of the surface deposit on aluminum, which is a corrosion product of aluminum, the selectivity coefficients were calculated. For the extraction of lithium from natural sea water, the values of K Li Na Li MgK Li Ca and Li K were 9.9 × 102, 1.1×10, 4.5×10 and 4.4 × 102, respectively.
23 citations
TL;DR: In this paper, a conversion function (G(E) function) was determined to obtain an exposure rate directly from a γ-rays spectrum measured by an in-situ Ge(Li) spectrometer.
Abstract: A conversion function (G(E) function) was determined to obtain an exposure rate directly from a γ-rays spectrum measured by an in-situ Ge(Li) spectrometer. In order to verify the utility of the G(E) function method, three kinds of detector, namely, a portable Ge(Li) detector, a Nal(Tl) detector and an ionization chamber, were used to measure exposure rate due to environmental γ-rays at the same place, and the measured values of exposure rate were compared with each other. Two exposure rate values were obtained from a γ-ray spectrum measured by the Ge(Li) detector, using two different methods, namely, the G(E) function method and the HASL method. The average of exposure rates obtained by four different methods was 4.15 uR/h, and the deviation was 15% of the average. By applying both the G(E) function method and the HASL method to an environmental γ-ray spectrum, a total exposure rate can be determined directly without information on the distribution of the radionuclides in soil, and individual exposure rat...
16 citations
TL;DR: In this article, the authors used the autoregressive (AR) modeling technique together with spectral and correlation analyses to investigate the driving source, which indicates that it is attributed to the dynamic interference with the reactor of heat exchange process in two parallel connected steam transformers.
Abstract: In the Halden Boiling Water Reactor (HBWR), a resonant power oscillation with a period around 0.04 Hz is observed at power levels higher than about 9.5 MWt. Although this resonant oscillation is not so strong as to affect the normal reactor operation, it is significant, from the viewpoint of reactor diagnosis, to reveal the cause of this oscillation as well as to understand its characteristics. Noise analysis based on the autoregressive (AR) modeling technique together with spectral and correlation analyses is performed to investigate the driving source, which indicates that it is attributed to the dynamic interference with the reactor of heat exchange process in two parallel-connected steam transformers. The present study demonstrates the effectiveness of the technique applied here for determining the so-called noise source inducing variations of quantities in a system together with its applicability to various problems in the field of reactor noise analysis and diagnosis.
TL;DR: In this article, Coupled Markovian Langevin equations are cast into a time series model with the aid of contraction of information, coarse graining in time, and the concept of innovation.
Abstract: Coupled Markovian Langevin equations in the conventional reactor noise theory are cast into a time series model with the aid of contraction of information, coarse graining in time, and the concept of innovation. This makes it possible to physically interpret time series data and to apply them to reactor diagnosis. An evolution equation for the variance of the innovation is found and discussed in connection with the Riccati equation used in prediction theory. The relation with the Markovian representation well-known in control theory is also discussed. A simple example is treated to demonstrate that the time series model has less information than Langevin equations.
TL;DR: In this paper, the authors measured the capture cross sections of 93Nb, 127I, 165Ho, 181Ta and 238U from 3.2 to 80 keV using the time-of-flight method.
Abstract: The neutron capture cross sections of 93Nb, 127I, 165Ho, 181Ta and 238U were measured from 3.2 to 80 keV using the time-of-flight method. The neutron beam was produced by the KURRI 46-MeV linear accelerator and capture γ-rays were detected by a C6F6 or C6D6 liquid scintillation detector. As the result of the use of a direct-coupled operational preamplifier, the detector recovered rapidly from the γ-flash such that data for higher energy neutrons can be obtained in spite of the short flight path of 11.7 m. The neutron sensitivities of both detectors are compared and the superiority of the C6D6 detector is shown. The experimental results of capture cross sections, corrected for resonance self-shield- ing and multiple scattering and normalized to the 24-keV absolute values, are shown numerically and graphically, and compared with other data. The agreement between the data is fairly good for 165Ho and 238U, but not for 93Nb, 127I and 181Ta. The discrepancy between the data may be caused by the difference of t...
TL;DR: In this paper, experiments were performed to study the ratio of permeabilities of protium to tritium through Pd-Ag-Au alloy at the conditions of 350°C≦T≦550°C and p < 1,000 mmHg.
Abstract: Experiments were performed to study the ratio of permeabilities of protium to tritium through Pd-Ag-Au alloy at the conditions of 350°C≦T≦550°C and p<1,000 mmHg. The observed ratio was 2.12±0.03 at 350°C, and it was almost independent of temperature. It is remarkable that the obtained ratio of permeabilities is considerably larger than the square root of the atomic weight ratio✓3. The dependence of separation factor for the hydrogen isotopes on pressure and “cut” is also discussed.
TL;DR: In this article, out-of-pile experiments were performed with Zircaloy-4 rods in sub-cooled water envi-ronment to study the basic phenomena occurring in the transient cooling process undergone by a fuel rod during a reactivity-initiated accident (RIA) affecting a light water reactor (LWR).
Abstract: Out-of-pile experiments were performed with Zircaloy-4 rods in subcooled water envi-ronment to study the basic phenomena occurring in the transient cooling process undergone by a fuel rod during a reactivity-initiated accident (RIA) affecting a light water reactor (LWR). The experimental results show that the cooling process of the fuel rod during an RIA can be divided into three phases separated by the quenching temperature Tq and the rewetting temperature Tr. It is also noted from the experimental results that with increasing degree of subcool-ing, Tq tends to rise to levels far exceeding the maximum liquid superheat temperature of water ; Tr, on the other hand, is little affected by the cooling water temperature, and remains close to that of the maximum superheat temperature. Numerical calculations indicate conclusively that radial heat transfer to coolant water is the dominant factor that governs the transient cooling process in an RIA affecting the cold start-up of a BWR, rather than the axial heat conduction through rod which is con-sidered to be the basic mechanism of cooling that governs the reflooding process during a LOCA.
TL;DR: In this article, the acid digestion of Radioactive Combustible Wastes (RWCW) was investigated. But the results were limited to the case of nuclear power plants.
Abstract: (1980). Acid Digestion of Radioactive Combustible Wastes. Journal of Nuclear Science and Technology: Vol. 17, No. 11, pp. 865-868.
TL;DR: In this paper, a discrete ordinates transport code ENSEMBLE in (X, Y, Z) geometry has been developed for the purpose of shielding calculations in three-dimensional geometry.
Abstract: A discrete ordinates transport code ENSEMBLE in (X, Y, Z) geometry has been developed for the purpose of shielding calculations in three-dimensional geometry. The code has some superior features, compared with THREETRAN which is the only code of the same kind so far developed. That is, the code can treat higher order anisotropic scattering and employs a coarse mesh rebalancing method. Moreover it has a negative flux fix-up routine using a variable weight diamond difference equation scheme and has a ray-effect fix-up option using a fictitious source based on SN→PN-1 conversion technique. Formulations for these advanced features in three-dimensional space have been derived. As the demonstration of the capabilities of the code, several numerical analyses and an analysis of an annular duct streaming experiment in JRR-4 at Japan Atomic Energy Research Institute, have been performed. As a result of these analyses, confirmation has been obtained for the prospect of applicability of ENSEMBLE to practical shieldin...
TL;DR: In this paper, the average void fraction in a two-phase flow channel was analyzed for both steam-water and air-water systems in the range of low superficial water velocities.
Abstract: During the reflood phase in a postulated loss-of-coolant accident of a pressurized water reactor, the driving force to feed the emergency core coolant into the core is the effective water head of a two-phase flow in the downcomer surrounding the core in the reactor vessel. The effective water head in the downcomer is dominated by the characteristics of the average void fraction in a vertical two-phase flow channel. This paper makes clear the effects of the physical properties of fluids, the channel diameter and superficial velocities of two phases on the void fraction in a vertical flow system by both carrying out the experiment of an air-water system under 1 atm and investigating the previous experimental results of steam-water and air-water systems. As the results, the presentation of the average void fraction could be obtained within errors of ±15% by dimensional analyses in cases of both steam-water and air-water systems in the range of low superficial water velocities (<30cm/s) including the stagnant...
TL;DR: In this paper, a He-Ne laser mist concentration meter (LCM) and mist traps were used to determine the mass concentration and gravitational settling flux of the sodium aerosol in the argon cover gas space over a sodium pool.
Abstract: Sodium mist behavior in argon cover gas space over sodium pool was investigated experimentally using of a test vessel having cover gas volume of ∼100l. Mass concentration and gravitational settling flux of the mist (i.e. sodium aerosol) were determined between pool temperature range of 290∼520°C. Apparatuses used for the concentration determination were a He-Ne laser mist concentration meter (LCM) and mist traps, which were developed specifically for the present experiment. The mist gravitational settling flux φ was determined by using of collection plates, which were exposed to the mist entrained cover gas over sodium pool. The experimental results revealed that the concentration C was very high from 0.15 to 20g/m3. It increased with pool temperature. The mist particle radii, which were determined from the gravitational settling flux φ and decay curve of the concentration, were from 1.5 to 13 μm in the range of the present experiment. The vapor evaporation rate φe from the pool surface, which were also d...
TL;DR: In this article, the number albedo of backscattered photons for Tin and Lead was measured using the number of scattered photons for each element in order to measure its number.
Abstract: (1980). Measurement of Number Albedo of Backscattered Photons for Tin and Lead. Journal of Nuclear Science and Technology: Vol. 17, No. 7, pp. 559-561.
TL;DR: In this paper, the NO removal by electron beam irradiation was studied in the moist NO-SO2-O2-N2 mixtures containing NH3, and it was shown that NH3 improved NO removal.
Abstract: The NO removal by electron beam irradiation was studied in the moist NO-SO2-O2-N2 mixtures containing NH3. The NO removal was promoted markedly by addition of NH3 and at the same time, SO2 was removed. The formations of NO2, N2O, NH4NO3 and (NH4)2SO4 were observed in the mixtures containing NH3. The NO removal increased with H2O and SO2 concentrations and was hardly affected by the presence of 3–19.5% O2. The degree of the NOx(NO+NO2) removal became larger with decreasing temperature in the range of 80–150°°C. The NO removal was independent of dose rate in the range of 3.1×104–2.4×106 rad/s. The promotion of the NO removal by addition of NH3 is attributable to the effective decomposition of NO by NH2 radical formed by the reaction of NH3 with OH radical. The NO2 yield decreased by addition of NH3 and the N2O yield increased.
TL;DR: In this paper, the distribution equilibrium of Tritium between adsorbed water on molecular sieve 5A and environmental water was studied, and the authors proposed a method to obtain the equilibrium.
Abstract: (1980). Distribution Equilibrium of Tritium between Adsorbed Water on Molecular Sieve 5A and Environmental Water. Journal of Nuclear Science and Technology: Vol. 17, No. 9, pp. 721-723.
TL;DR: In this article, a new finite element solution technique for neutron diffusion equations has been developed by adding imaginary nodal points, subdividing each triangular element into three quadrilateral subelements, and approximating the spatial variation of neutron flux within each element by three linear planes.
Abstract: A new, finite element solution technique for neutron diffusion equations has been developed. In this method, calculational accuracy is improved by adding imaginary nodal points, subdividing each triangular element into three quadrilateral subelements, and approximating the spatial variation of neutron flux within each element by three linear planes. In the process of solving the algebraic equations, the additional unknown variables are eliminated so that the number of unknowns remains the same as that in the usual finite element method. This technique has been applied to two types of one-group neutron diffusion equations to test its accuracy. It has been shown that the method yields the same degree of accuracy, in eigenvalues and neutron flux distributions, as the usual finite element method when four times as many elements are used. Under the same degree of accuracy, the computing time of the new method is about 1/4 that of the usual method.
TL;DR: In this paper, angular dependent flux spectra from slab assemblies (lithium and graphite) were measured to test nuclear data and calculational methods for D-T fusion reactor neutronics.
Abstract: Angular dependent flux spectra from slab assemblies (lithium and graphite) were measured to test nuclear data and calculational methods for D-T fusion reactor neutronics. The collimated 14 MeV neutron source could be applied by the use of an associated particle method and the neutron spectra from 14 to 2 MeV were observed with TOF technique. The measured spectral pattern was dependent on the anisotropy of secondary neutrons emitted from both the elastic and the non-elastic scattering for 14 MeV neutrons. As for the numerical calculations, one-dimensional discrete ordinates transport codes (ANISN and NITRAN) were used. The multigroup cross sections processed with SPTG4Z from ENDF/B-IV were used as common nuclear data base. The problems of calculational methods and nuclear data were discussed in comparison with the experimental data and it was clarified that sufficient nuclear data of angular dependent cross sections for the non-elastic scattering have not been available in ENDF/B-IV and that the anisotropy...
TL;DR: In this paper, a He-Ne laser mist concentration meter (LCM) and mist traps were developed specifically for the present experiment to determine mass concentration and gravitational settling flux of the mist (i.e., sodium aerosol) between pool temperature range of 290520°C.
Abstract: Sodium mist behavior in argon cover gas space over sodium pool was investigated ex-perimentally using of a test vessel having cover gas volume of 100l. Mass concentration and gravitational settling flux of the mist (i.e. sodium aerosol) were determined between pool temperature range of 290520°C. Apparatuses used for the concentration determination were a He-Ne laser mist concentration meter (LCM) and mist traps, which were developed specifically for the present experiment. The mist gravitational settling flux φ was determined by using of collection plates, which were exposed to the mist entrained cover gas over sodium pool.The experimental results revealed that the concentration C was very high from 0.15 to 20 g/m3. It increased with pool temperature. The mist particle radii, which were determined from the gravitational settling flux ψ and decay curve of the concentration, were from 1.5 to 13 μm in the range of the present experiment. The vapor evaporation rate φe from the pool surface, which were also determined from the experimental ψ data, were found to increase with saturated vapor pressure Ps at pool surface. This rate did not depend so strongly on experimental geometries and cover gas flow convection pattern over sodium pool. Evaluations of transient C changing and steady state C fluctuation indicated that the mist formation was occurred near the pool surface.
TL;DR: In this article, the synthesis of UN from UO2 through carbide by oxide-carbide-nitride process has been studied in an NH3 stream and a mixed H2 and N2 stream at temperatures 1,400-1,750° C.
Abstract: The synthesis of UN from UO2 through carbide by oxide-carbide-nitride process has been studied in an NH3 stream and a mixed H2 and N2 stream at temperatures 1,400-1,750° C. Uranium mononitride is produced from the carbide by the following four stages: (1) deposition of free carbon, (2) deposition and removal of free carbon in the two-phase field (C+UN1-xCx), (3) removal of free carbon in the three-phase field (UN1-xCx+C+N2), and (4) removal of combined carbon in the two-phase field (UN1-xCx+N2). The total amount of impurities (carbon + oxygen) in the UN obtained by the present method is in the range of 0.05-0.10w/0.