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Volume 25, Issue 5
Displaying 1-10 of 10 articles from this issue
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Yukio OYAMA, Seiya YAMAGUCHI, Hiroshi MAEKAWA1988 Volume 25 Issue 5 Pages 419-428
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSAngular neutron fluxes leaking from the surface of lithium-oxide and graphite slab assemblies have been measured with irradiation of D-T neutrons. The spectrum measurement was performed using the time-of-flight technique with an NE213 scintillation detector. The thicknesses of the slabs were 0.6 to 5 mean free path for 14.8 MeV neutrons, and the measured leaking angles of the angular fluxes were 0.0°, 12.2°, 24.9°, 41.8° and 66.8°. The experimental results have been compared with the results calculated by the continuous energy Monte Carlo transport code MCNP, using the data in the JENDL-3PR1, -3PR2, and ENDF/B-V nuclear data files. The comparisons between the experimental and calculated results show that the data of 7Li in JENDL-3PR2 is improved for the secondary emission spectra of the 4.63 MeV level and (n, 2n) reactions; the angular distributions of 3rd- and 4th-level inelastic reactions of C in the JENDLs are questionable. The thickness dependences for high energy neutrons also suggest that the total cross section of 7Li and the elastic cross sections of C are slightly inadequate.View full abstractDownload PDF (674K) -
Ichiro YAMAMOTO, Tadahiko YAMASHITA, Akira KANAGAWA1988 Volume 25 Issue 5 Pages 429-440
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA laminar free convection of heat generating fluid in a horizontal square container with 10 cm × 10 cm cross section and infinite length was analyzed through the Newton iterative numerical solution of the equations of change without the Boussinesq approximation. Computations were performed for Kr gas in the case of charging pressure of 0.216, 0.540 and 1.081 MPa at 295 K. As the Newton iterating procedure requires initial values not far away from the true solution, the solution of slightly lower percentage of 85Kr was used for the initial values. The percentage of 85Kr (and, hence heat generating rate) was thus increased gradually untill the concentration of 85Kr was so high (13% at 0.216 MPa) that convergent solution could not be obtained. With increasing the concentration of 85Kr, flow pattern is changed from "ordinary" free convection like one generated when heated from below to a complexed pattern with several vortices in the upper part of the container. Similarity of flow fields was shown among various sets of charging pressure and concentration of 85Kr. Reason of an onset of the vortical flows was also discussed based on the temperature distribution within the cavity.View full abstractDownload PDF (878K) -
Taisuke YONOMOTO, Kanji TASAKA1988 Volume 25 Issue 5 Pages 441-455
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA theoretical and experimental study was conducted to understand two-phase flow discharged from a stratified two-phase region through a small break. This problem is important for an analysis of a small break loss-of-coolant accident (LOCA) in a light water reactor (LWR). The present theoretical results show that a break quality is a function of h/hb, where h is the elevation difference between a bulk water level in the upstream region and the break and b the suffix for entrainment initiation. This result is consistent with existing experimental results in literature. An air-water experiment was also conducted changing a break orientation as an experimental parameter to develop and assess the model. Comparisons between the model and the experimental results show that the present model can satisfactorily predict the flow rate and the quality at the break without using any adjusting constant when liquid entrainment occurs in a stratified two-phase region. When gas entrainment occurs, the experimental data are correlated well by using a single empirical constant.View full abstractDownload PDF (974K) -
Takashi IWAI, Ichiro TAKAHASHI, Muneo HANDA1988 Volume 25 Issue 5 Pages 456-463
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe release of the occluded gases in uranium-plutonium mixed carbide and uranium carbide pellets for irradiation tests were measured successfully using a multipurpose high temperature apparatus. A new type of gas line filter was set up in the gas exhausting line, where the filter could be exchanged easily without plutonium contamination and degassed by heating.
The release of the occluded gases in the carbide fuels was measured at 1, 473, 1, 673 and 1, 873 K. At 1, 473 K, most of the gases evolved was H2 gas and above this temperature, the oxygen contained in the fuel was released continuously in the form of CO gas. It was shown that the H2 gas was generated by the reaction of the fuel with moisture adsorbed at the fuel surface during storage and the CO gas was released in proportion to its equilibrium pressure of the oxycarbide solid solution.
The release of the gases from the fuels scarcely affects the increase of the inner gas pressure of fuel pins since the amount of H2 gas is small, about 100μl•atm/g-fuel corrected at 273 K and CO gas pressure equilibrated with carbided fuel is only several hundred Pascal.View full abstractDownload PDF (490K) -
Haruo FUJIMORI, Yamato ASAKURA, Kazumichi SUZUKI, Shunsuke UCHIDA1988 Volume 25 Issue 5 Pages 464-471
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSNickel ion deposit was produced on a heated rod surface in high pressure boiling water (150285°C, 0.47.0 MPa). The deposit under the same temperature and pressure conditions as those for BWR reactor water (285°C, 7.0 MPa) was identified as NiO by spectrum profile analysis of the NiLα, NiLβ and 9th-order NiKα1 lines. Deposition rate was obtained from in situ measurements of deposit thickness, by a photoacoustic method, and from chemical analysis of deposit amount. The deposition rate coefficients obtained in temperature and pressure ranges of 150250°C and 0.44.0 MPa were 2×10-35×10-2, which were 0.154.45 times as large as those of iron crud. This was attributed to a dissolution effect of Ni ion from NiO. The deposition rate coefficient at 285°C, 7.0 MPa was estimated to be 4.4×10-24.3×10-1.View full abstractDownload PDF (569K) -
Akira SASAHIRA, Fumio KAWAMURA1988 Volume 25 Issue 5 Pages 472-478
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe formation rate of ruthenium tetroxide (RuO4) from nitrosyl ruthenium trinitrate (RuNO(NO3)3) was measured at temperatures of 70115°C in 39 mol•dm-3 nitric acid solutions. The gas-liquid equilibrium ratio was measured at temperatures of 4080°C in 0.19 mol•dm-3 nitric acid solutions. The gas-liquid equilibrium ratio of RuO4 ranged about 60260 under the experimental conditions. The reaction rate increased greatly with acid concentrations above 6 mol•dm-3. The activation energy of the reaction was about 130 kJ•mol-1 in 9 mol•dm-3 nitric acid solution. It was concluded that the rate of RuO4 formation dominated the distill-out phenomena of Ru in an evaporator as used in nuclear fuel reprocessing plants.View full abstractDownload PDF (437K) -
Satoshi FUKADA, Nobuo MITSUISHI1988 Volume 25 Issue 5 Pages 479-488
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA tritium permeation window is an effective separation method for recovering hydrogen isotopes in the fuel cycle of a D-T fusion reactor. Hydrogen permeation through a plate type metal window has been analyzed numerically for laminar flow. The results obtained were summarized by a correlation between the local or mean Sherwood number and the reciprocal of the Graetz number. Longitudinal diffusion in the flow direction was also taken into account in the calculations. The contributions of the permeation parameter of walls and longitudinal diffusion in the flow direction to the Sherwood number was discussed. A set of equations which correlate the numerical results were proposed.
Numerical calculations were performed for the selective permeation of tritium from tritium-helium mixtures in the D-T fuel cycle and from liquid Li blanket fluid. It was pointed out that both the diffusion resistances through the metallic wall and in the fluid in the vicinity of walls must be taken into consideration.View full abstractDownload PDF (638K) -
Kazuo TAKEUCHI, Sakae SATOOKA1988 Volume 25 Issue 5 Pages 489-494
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSOptimum irradiation conditions in laser isotope separation of tritium were investigated experimentally by using trifluoromethane from the viewpoint of the energy efficiency in product formation. The absorbed energy εabs and the fractional conversion of CTF3 per pulse qγ. were measured as the functions of irradiation wavenumber, laser pulse duration, laser fluence, gas pressure and temperature. The results of optimization were shown in contour maps, where the ratio of the fractional conversion of CTF3 per pulse to the absorbed energy qγ/εabs was adopted as the objective function. The value of the objective function at the optimum condition was related to the maximum flow rate of the working substance attainable for given laser power.View full abstractDownload PDF (403K) -
Kazuo WATARI, Kiyoko IMAI, Yoichiro OHMOMO, Yasuyuki MURAMATSU, Yoshik ...1988 Volume 25 Issue 5 Pages 495-499
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESS"Metal ferrocyanide-anion exchange resin", which is made by precipitating the metal ferrocyanide in an anion exchange resin matrix, has been used for selective adsorption of Cs ion in a variety of aqueous solutions.
The "resin" has both properties of metal ferrocyanide and anion exchange resin. Therefore, we tried simultaneous adsorption of radiocesium and radioiodine from water and milk on the "resin".
Results showed that "metal ferrocyanide-anion exchange resin" such as Cu, Fe and Ni ferrocyanide can be used for a rapid and simple concentration of radiocesium and radioiodine quantitatively from a large volume of sample solutions.
This paper also touches upon the removal of 137Cs and 131I in rain water and milk collected in Japan after the Chernobyl accident.View full abstractDownload PDF (325K) -
Kazuaki YANAGISAWA, Hideo SASAJIMA, Hiroyuki KANAZAWA1988 Volume 25 Issue 5 Pages 500-506
Published: May 25, 1988
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSAfter a short irradiation of UO2 fuels with and without SiO2+ AI2O3 additive in NSRR, a comparative study of the fission products (FP) dissolved in nitric acid and undissolved materials was performed. Results of the study were : (1) The additive fuel behaved similarly to non-additive fuel. (2) In both types of fuels, the undissolved materials in dried out solution were not FP but metals existing from the fuel fabrication stage. (3) The NSRR short irradiation had great influence on the shape of the undissolved components without changing the as-fabricated compositions.View full abstractDownload PDF (6508K)
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