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Volume 16, Issue 10
Displaying 1-9 of 9 articles from this issue
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Makio OHKUBO, Yuuki KAWARASAKI1979 Volume 16 Issue 10 Pages 701-710
Published: October 25, 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSAn experiment of neutron resonances in 159Tb was carried out using the Japan Atomic Energy Research Institute linac time-of-flight facility. Transmission and capture measurements were made on terbium samples of two thicknesses, using 6Li-glass and Moxon-Rae detectors at the 47 m station ; the neutron flux was monitored with a 6Li-glass transmission type flux monitor. Transmission data were analyzed with an area program up to 1.2 keV, and capture data with Monte-Carlo program CAFIT, to obtain 2gΓ0n, Γ and Γγ. Resonance parameters of 209 levels below 1.2 keV are obtained, and 52 levels between 754 eV and 1.2 keV are new ones. The results are ; average level spacing <D> = 4.4 ± 0.4 eV below 600 eV, s-wave strength function S0 = (1.55 ± 0.15)10-4 below 1.2 keV, and average radiation width <Γγ> = 107 ± 7 meV for lower 25 levels. Average capture cross section <σc> were obtained from 50 eV to 30 keV.View full abstractDownload PDF (560K) -
Motoharu MIZUMOTO, Akira ASAMI, Yutaka NAKAJIMA, Yuuki KAWARASAKI, Toy ...1979 Volume 16 Issue 10 Pages 711-719
Published: October 25, 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSNeutron capture cross sections of europium isotopes 151Eu and 153Eu were measured in the neutron energy range of 3100 keV. Experiments were carried out with the time-of-flight facility at the 52 m station of the JAERI Electron Linear Accelerator. Prompt capture γ-rays were detected by a large liquid scintillation detector and the neutron flux shape was determined with a 6Li glass scintillation detector. The average capture cross sections were examined in terms of energy independent strength functions for 151Eu and 153Eu.View full abstractDownload PDF (535K) -
Hidetoshi KONNO, Keiichi SAITO1979 Volume 16 Issue 10 Pages 720-731
Published: October 25, 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe irreversible circulation of fluctuation a for a coupled-core nuclear reactors is derived. Neutrons in this system are transported from a certain core to another one with a finite time lag and their fluctuations are generally described by a set of non-Markoffian Langevin equations.
This system cannot accept Tomita's original theory based on the Markoffian stochastic process. When the system has the exp(-t/τ)-type memory kernel, we can, however, build up an equivalent Markoffian model-4-points model-by introducing "transit zones", and we can evaluate the irreversible circulation of fluctuation α. The a for symmetrically coupled-cores takes null-value, while for an asymmetrical case the α becomes finite and turns out to be a new information from which the coupling parameters between the cores can be extracted.View full abstractDownload PDF (596K) -
Nobuhiko MATSUMOTO, Kiyoshi TOKIEDA, Yoshizo OKAMOTO, Ryozo ECHIGO, Ke ...1979 Volume 16 Issue 10 Pages 732-740
Published: October 25, 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThermal insulation systems are often used to high-temperature gas cooled reactors. In this paper, transient behavior of the gas flow in thermal insulation media was systematically analyzed in the case of sudden decrease in a coolant pressure. The structure of these systems is capable of substituting for the simplified model that the gas in a containment filled with porous insulation media exhausts from a balancing hole to main flow duct. In the case of rapid depressurization, these behaviors were calculated by using equations of continuity and motion based on the Darcy flow model with area ratio of a balancing hole and permeability of porous insulation media as parameters. The transient pressure difference of a hot liner wall between the main flow helium and the insulation layer induced at depressurization was numerically analyzed. It was revealed from analytical results that transient behaviors were strongly influenced by prescribed parameters, and experimental results can be explained by using the analytical model.View full abstractDownload PDF (520K) -
Hirozumi IZAWA, Shohei ISOMURA, Ryohei NAKANE1979 Volume 16 Issue 10 Pages 741-749
Published: October 25, 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe deuterium exchange reaction between hydrogen and water in the gas phase where the fed hydrogen gas is saturated with water vapor is studied experimentally by use of the proper hydrophobic catalysts supporting platinum. It is found that the activities of those catalysts for this reaction system are very high compared with the other known ones for the systems in which gas and liquid should coexist on catalyst surfaces, and that the apparent catalytic activity becomes larger as the amount of platimun supported on a catalyst particle increases. By analyses of the data the following informations are obtained. The exchange reaction can be expressed by a first order reversible reaction kinetics. The pore diffusion in the catalyst particles has significant effect on the overall reaction mechanisms.View full abstractDownload PDF (517K) -
Yoshiaki FUTAMURA, Hiroshi KAMATA1979 Volume 16 Issue 10 Pages 750-763
Published: October 25, 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSBoth from the mechanics of fracture and from actual instances of defects observed in reactor pressure vessels, it is indicated that greater importance should be attached to surface than to internal defects in the in-service inspection of these components.
In the JPDR, the reactor pressure vessel has undergone ISI three times since 1968, with emphasis placed on surface inspection, and using both remote bore scope and remote Smeck methods. The two methods gave the same results on all three occasions, so that both methods can be considered effective.
With the remote Smeck method, the lower limit of detectable defect size was found to be less than ±1 mm, and the reproducibility of defect position, measured on a mock-up nozzle was better than ±3 mm. For the bore scope a newly devised "shadowing technique" is described, which appreciably enhances its ability to detect and to accurately observe surface defects.
The results of ISI in JPDR indicate that significant improvements in detection ability and accuracy could be expected by systematic application of ISI methods.View full abstractDownload PDF (6635K) -
Kazutaka KANDA, Mamoru BABA, Naohiro HIRAKAWA1979 Volume 16 Issue 10 Pages 764-776
Published: October 25, 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA new form of 6Li sandwich counter has been developed for use in measurements of neutron spectra in fast critical assemblies. The counters have two large surface area diodes approached very close to each other, on one of which is evaporated the target 6Li. This arrangement proves to provide a ten-fold increase of detection efficiency, while the resolution is improved by approximately 1/2 compared with currently used counters. The new counters were first tested on mono-energetic neutrons, after which neutron spectrum measurements were performed on natural uranium blocks, in the fast source reactor "YAYOI", in the FCA IV-1-P and in the FCA V-3 core. The resulting spectra are compared with the measurements made with other types of counter and with calculated data. Proof was obtained that the new counter can serve practically and usefully for in-core measurements of fast neutron energy spectrum between 0.8 and 5 MeV.View full abstractDownload PDF (795K) -
Akira WADAMOTO, Tetsu YAMASA, Tadashi YANAGI1979 Volume 16 Issue 10 Pages 777-778
Published: October 25, 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (136K) -
1979 Volume 16 Issue 10 Pages 778
Published: 1979
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (50K)
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