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Volume 26, Issue 7
Displaying 1-10 of 10 articles from this issue
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Yukinori HIROSE, Peng Hong LIEM, Eiichi SUETOMI, Tohru OBARA, Hiroshi ...1989 Volume 26 Issue 7 Pages 647-654
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSAnalysis was performed on the effects of fuel loading schemes and fuel materials on the inherent (passive) safety characteristic of the modular pebble-bed type high-temperature reactor against depressurization accident involving loss of He forced circulation Two extreme fuel loading schemes, the infinite-velocity multipass and Once-Through-Then-Out (OTTO), were evaluated for both U and Th fuel cycles. The results of the analysis show that the maximum core temperatures attained following the accident were much lower for the infinite-velocity multipass scheme than for the OTTO scheme. For both schemes, the Th cycle showed slightly higher maximum peak temperatures, compared to U cycle.View full abstractDownload PDF (588K) -
Knowledge-Based Operation Guidance System for Nuclear Power Plants Based on Generic Task MethodologyNaoyuki YAMADA, B. CHANDRASEKARAN, Rajiv BHATNAGER1989 Volume 26 Issue 7 Pages 655-669
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSA knowledge-based system for operation guidance of nuclear power plants is proposed The Dynamic Procedure Management System (DPMS) is designed and developed to assist human operators interactively by selecting and modifying predefined operation procedures in a dynamic situation. Unlike most operation guidance systems, DPMS has been built based on Generic Task Methodology, which makes the overall framework of the system perspicuous and also lets domain knowledge be represented in a natural way. This paper describes the organization of the system, the definition of each task, and the form and organization of knowledge, followed by an application example.View full abstractDownload PDF (1070K) -
Void Distribution and Average Void FractionKensuke USUI, Kazuo SATO1989 Volume 26 Issue 7 Pages 670-680
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSFully developed vertically downward two-phase flow of air-water mixture was investigated on void distribution and average void fraction among the three basic flow regimes; bubbly, slug and annular flows. The annular flow further was divided into two regimes of falling film flow and annular drop flow. Test channel is in form of inverted U-tube and tests were carried out at 100 tube diameters downstream from the curved part. Distributions of local void fraction were measured by means of a conductance needle probe method and the average void fraction was obtained from numerical integration of the measured local void fraction According to the results, profiles of local void fraction in bubby and slug flows showed characteristic natures with a peak in the middle region between the center and the wall of tube. The average void fraction in downward flow depended greatly on the flow regimes. Accordingly correlation for each flow regime was developed to predict the average void fraction, based on flow mechanisms and experiments. The correlations were compared with experimental results for atmospheric air-water flow and showed satisfactory agreement.View full abstractDownload PDF (4553K) -
Mohammad Reza ANSARI, Hideki NARIAI1989 Volume 26 Issue 7 Pages 681-688
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSTwo-phase air-water flow was studied experimentally under atmospheric conditions. Wave growth and slugging from stratified flow regime in a horizontal duct were analyzed by using a video camera. The result for slug initiation was compared with the instability criteria based on linear analysis and the empirical correlations of other researchers. The required instability criteria is in good agreement. The reason for the necessary lower gas velocity in comparison with Kelvin-Helmholtz relation and growth of short wavelength waves which create slugs were discussed and presented by some pictures. The result of this kind of careful experimentation was aimed in verification of inherent problems which are contained in two fluid models.View full abstractDownload PDF (7090K) -
Hideo KIMURA1989 Volume 26 Issue 7 Pages 689-697
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSA computer code of groundwater flow in two-dimensional porous media based on the mixed finite element method was developed for accurate approximations of Darcy velocities in safety evaluation of radioactive waste disposal. The mixed finite element procedure solves for both the Darcy velocities and pressure heads simultaneously in the Darcy equation and continuity equation. Numerical results of a single well pumping at a constant rate in a uniform flow field showed that the mixed finite element method gives more accurate Darcy velocities nearly 50% on average error than standard finite element methodView full abstractDownload PDF (543K) -
Influence of Monoisodecyl Phosphoric Acid on Extraction of Neptunium with Diisodecyl Phosphoric AcidYasuji MORITA, Masumitsu KUBOTA, Masahiro YONEYA, Osamu TOCHIYAMA, Yas ...1989 Volume 26 Issue 7 Pages 698-704
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSThe influence of monoisodecyl phosphoric acid (MIDPA) on the separation of Np with diisodecyl phosphoric acid (DIDPA) was studied from the aspects of the extraction rate and the back-extraction with H2C2O4 solution. This study is important for the development of the partitioning method for high-level waste because MIDPA is one of the radiolysis products of DIDPA
The increase in the MIDPA concentration was found to accelerate the extraction of Np initially in the pentavalent oxidation state. When the MIDPA concentration was 0.1 M, the extraction rate was ten times faster in the absence of H2O2 and twice faster in the presence of 0.5 M H2O2. It was also found that the extraction mechanism in the aspect of Np redox reactions did not change even in the presence of MIDPA
On the other hand, Np became less back-extracted with increasing MIDPA concentration. However, the tolerable concentration of MIDPA, determined by the required distribution ratio for the Np back-extraction, is higher than the estimated concentration of MIDPA produced radiolytically in the partitioning process.View full abstractDownload PDF (493K) -
Tsunetaka BANBA, Kiyoshi NUKAGA, Tamio SAGAWA1989 Volume 26 Issue 7 Pages 705-711
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSThe two kinds of nuclear waste glass with similar composition, a 238Pu-doped and non-radioactive waste glass, were leached under the ISO-test conditions at temperature between 23 and 90°C. An activation energy of 22±10 kJ/mole was obtained from the initial leach rates of Pu, which was much lower than the 78±9 kJ/mole obtained from those of Si, Na, Sr and Cs. It is suggested that in the initial stages of leaching, Pu is not released from the waste glass with the same mechanisms as the releases of Si, Na, Sr and Cs, but the dissolution of hydrous plutonium dioxide PuO2•xH2O formed on the glass surface becomes predominant. In the long duration tests (>32 d), the release of Pu appears to be affected by the solubility of PuO2•xH2O remaining in the leached surface layers.View full abstractDownload PDF (537K) -
Suresh Moses LEE, Shigeaki AOKI, Toshikazu TAKEDA1989 Volume 26 Issue 7 Pages 712-720
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSA study is made of the use of modified diffusion theory to calculate the negative reactivity worth of recently proposed flow activated reactor shutdown devices, in which sodium is voided from purely sodium filled channels located at the boundary between the core and the radial blanket in a Liquid Metal cooled Fast Breeder Reactor (LMFBR). Three-dimensional diffusion theory calculations using various definitions of modified diffusion coefficients in the channels are compared with each other and with three-dimensional transport theory computations. While normal diffusion coefficient is found to be inadequate for these reactivity worth calculations, the various modified diffusion coefficients appear adequate for the considered case. Modelling method of the small thickness of steel wall and interstitial sodium layer of the modules are also studied.View full abstractDownload PDF (598K) -
Simulation of Plasma DisruptionMasuro OGAWA, Masanori ARAKI, Kiyoshi FUKAYA, Kenji YOKOYAMA, Kouichi ...1989 Volume 26 Issue 7 Pages 721-724
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSDownload PDF (1769K) -
Akira SASAHIRA, Fumio KAWAMURA, Hideo YUSA1989 Volume 26 Issue 7 Pages 725-728
Published: July 25, 1989
Released on J-STAGE: May 14, 2008
JOURNAL FREE ACCESSDownload PDF (273K)
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