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Volume 6, Issue 12
Displaying 1-8 of 8 articles from this issue
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Shigeyasu SAKAMOTO, Yoshihiko KANEKO, Fujiyoshi AKINO1969 Volume 6 Issue 12 Pages 671-677
Published: December 25, 1969
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSMeasurements of the neutron slowing down times in light water, ice, paraffin and santowax have been made by pulsed neutron technique. Bursts of D-T neutrons of 0.1 μsec width were generated in moderator cubes of 40×40×40 cm3. The slowing down neutrons were detected by bare as well as energy-selective filter-covered BF3 counters, and analyzed with a 256-channel time analyzer. Slowing down times in the moderator were determined by interpreting the in-crement of the difference of events between the two counters as attributable to the fraction of the neutrons slowing down at the time of measurement below the cut-off energy of the filter.
The measured slowing down times below 0.63 and 0.43 eV agreed well with theoretical values on the 0°K free gas model. On the other hand, the measured values below 0.20 eV were found to be appreciably greater than the theoretical, which would appear to indicate that he effect of thermal agitation and chemical binding come into play at this range of energy.View full abstractDownload PDF (418K) -
Mikio YAMASHITA, Taichi MICHIKAWA1969 Volume 6 Issue 12 Pages 678-688
Published: December 25, 1969
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA systematic approach has been made to theoretical estimation of the basic parameters characterizing the different types of spectrum stabilizers, as also of their control performance.
The transient responses to regular disturbances, and the mean square errors due to random disturbance and statistical fluctuations in the counting rates have been treated analytically with use made of linear approximation of the transfer functions.
The results obtained are valid only in the limit of small gain shifts in comparison with the half width of the reference peak, but nevertheless they still provide a measure for predicting the requirements for optimum control as well as an indication of the limitations to their range of applicability.View full abstractDownload PDF (792K) -
Fumio AMANO1969 Volume 6 Issue 12 Pages 689-697
Published: December 25, 1969
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSBy expanding the static flux into kinetic fluxes containing the fundamental and higher modes, we derive a kind of inhour equation which can express kinetic distortion, and can relate the static reactivity to prompt decay constants and to kinetic and adjoint fluxes. The equation is developed using the time-dependent, multigroup diffusion approximation, and is applied to the interpretation of pulsed-neutron-source experiments in a multiregion reactor. It is shown from this application that the Simmons-King formula can express the dynamic reactivity only under conditions of constant generation time and no kinetic distortion, and that the conventional in-hour equation derived by the perturbation method cannot distinguish between the static and dynamic reactivities differing from each other on account of kinetic distortion.View full abstractDownload PDF (711K) -
Enrichment of Lithium-7Yoshinobu YAMAMURA1969 Volume 6 Issue 12 Pages 698-702
Published: December 25, 1969
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSLithium-7 was enriched by electromigration at 500°C in fused LiBr-KBr mixture.
The migration cell was made of Pyrex glass; zircon sand (100200 mesh) was used for packing material, and graphite rods as electrodes.
The electromigration was carried out for 13.4 days at a constant electric current of 165 mA. The distribution of the abundance ratio of the Li isotopes and of the composition of the salt in the migration cell were investigated. The abundance ratio of the Li isotopes (7Li/6Li) in the anode compartment was found to change from the original value of 12.20 to 46.9. The com-position (Li/K in chemical equivalent ratio) of the salt reached roughly constant at 1.41 through-out the migration cell except in the vicinity of the cathode, and the value was not affected by the composition of the feed salt. It is the selective transport of salt of this composition toward the anode compartment by capillary action in the migration cell that is considered the mechanism that makes sustained electromigration possible. The mechanism of the accumulation of the iso-tope effect is also discussed.View full abstractDownload PDF (349K) -
Carl CHIARELLA1969 Volume 6 Issue 12 Pages 703-706
Published: December 25, 1969
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSAn equivalence relation which extends, and incorporates into the rational approximation, the basic ideas of some Russian workers is derived. This equivalence relation takes accurate account of the dependence on the Dancoff correction. The narrow resonance approximation is assumed throughout.View full abstractDownload PDF (244K) -
Yorio GOTOH, Kinji KOYAMA1969 Volume 6 Issue 12 Pages 707-710
Published: December 25, 1969
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (271K) -
Yoshiko HARIMA, Yasushi NISHIWAKI1969 Volume 6 Issue 12 Pages 711-714
Published: December 25, 1969
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (313K) -
Tadahiro OHNISHI, Yasuyuki UEDA1969 Volume 6 Issue 12 Pages 715-717
Published: December 25, 1969
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (245K)
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