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Volume 18, Issue 7
Displaying 1-9 of 9 articles from this issue
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Daijiro TANAKA, Yoshio HATTORI1981 Volume 18 Issue 7 Pages 477-486
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe time-dependent characteristics of a non-equilibrium Faraday-type MHD generator operating under the condition of "fully ionized seed regime" are analyzed, to examine the practical applicability of this regime. Potassium-seeded argon plasma is adopted as the working gas. High electrical efficiencies are known to be realizable with this fully ionized seed regime, but such a regime severely narrows down the range of operating conditions that ensure maintenance of stable plasma, and this introduces the risk of incurring dynamical instabilities like fluctuations of output power occasioned by minor derangements of the plasma state such as small changes affecting the seed density, gas pressure or load current of the generator. Moreover, for a given load resistance, the generator has two operating points-one in the stable region free from ionization instability, and the other in the partially-ionized region of argon. When the operating point is shifted from the former to the latter point, the generator output power diminishes sharply. Some technique for suppressing the dynamical instability would require to be established.View full abstractDownload PDF (580K) -
Yukio SUDO, Peter GRIFFITH1981 Volume 18 Issue 7 Pages 487-500
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSUpper plenum dump during reflood in a large break loss-of-coolant accident of PWR is studied with the emergency core coolant injection into the upper plenum in addition to the cold leg. Transient experiments were carried out by injecting water into the upper plenum and the simple analysis based on a one-dimensional model was done using the drift flux model in order to investigate the conditions under which water dump through the core occurs during reflood.
The most significant result is an upper plenum dump occurs when the pressure (hydrostatic head) in the upper plenum is greater than that in the lower plenum. Under those circumstances the flow regime isco-current down flow in which the upper plenum is rapidly emptied. On the other hand, when the upper plenum pressure (hydrostatic head) is less than the lower plenum pressure (hydrostatic head), the co-current down flow is not realized but a counter-current flow occurs. With subcooled water injection to the upper plenum, co-current down flow is realized even when the upper plenum hydrostatic head is less than the lower plenum hydrostatic head. The importance of this effect varies according to the magnitude of water subcooling.View full abstractDownload PDF (875K) -
Muneo KIDA, Yoshihiro KIKUCHI, Osamu TAKAHASHI, Itaru MICHIYOSHI1981 Volume 18 Issue 7 Pages 501-513
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSAn experimental study was conducted on pool-boiling heat transfer from an electrically heated horizontal wire to saturated liquid nitrogen at atmospheric pressure. Experimental results of heat transfer characteristics in both nucleate- and film-boiling regimes, critical heat flux and minimum heat flux were analyzed and compared with various correlations. In addition, photography was used to obtain information concerning the vapor-bubble and vapor-film behaviors around the heating wire. These data of microcharacteristics were utilized for evaluating theoretical models of nucleate-boiling mechanism proposed by other investigators. Transient conduction to the relatively cold (saturated) liquid, which came into the space vacated by the departing bubble and contacted with the heating surface, was found to be important for high heat transfer rates associated with nucleate boiling.View full abstractDownload PDF (2645K) -
Vibration Experiment of Two-Dimensional Vertical Slice Core ModelTakeshi IKUSHIMA, Toshiaki HONMA1981 Volume 18 Issue 7 Pages 514-524
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe resistance against earthquakes of high-temperature gas cooled reactors (HTGR) with block-type fuel, is not fully ascertained yet. Seismic studies must be made if such a reactor plant is to be installed in area with frequent earthquakes.
In this paper experimental results of seismic behaviour of a half scale two-dimentional vertical slice model are presented. The following results were obtained : (1) with soft spring support of the side reflector structure the relative column displacement is larger than that for hard support but the impact force is smaller, (2) in the case of hard spring support the dowel force is smaller than for soft support, (3) the relative column displacement and impact force are smaller with the gas pressure simulation spring than without.View full abstractDownload PDF (2212K) -
Masahiro KINOSHITA, Yuji MATSUDA, Yuji NARUSE, Kichizo TANAKA1981 Volume 18 Issue 7 Pages 525-539
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA computer code is developed for effective and exact simulation of cryogenic distillation columns. The simulation model incorporates the differences of latent heat of vaporization among the six molecular species, pressure drop, decay heat of tritium, heat transfer through the column wall, Raoult's law deviation of the solutions of hydrogen isotopes, multiple feeds and multiple sidestreams. The calculational procedure developed by Tomich for general equilibrium stage processes is further modified to match this complicated simulation model.
A computer simulation study is performed for the typical cryogenic distillation column cascade and separation characteristics of each column are clarified. The effects of pressure drop are found not significant. If the tritium concentration in the column is considerably high, the lower performance caused by decay heat effects cannot be neglected any longer. Increase of the reflux ratio or refrigeration of the stripping section, is required for improvement.
The present study provides a great help to development of exact simulation models and simulation procedures of cryogenic distillation columns.View full abstractDownload PDF (839K) -
Seichi SATO, Yuji NISHINO, Hidetsugu NISHIKAWA, Hirotaka FURUYA1981 Volume 18 Issue 7 Pages 540-544
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe enthalpies of two kinds of simulated radioactive waste glasses have been measured with an ice isothermal calorimeter at temperatures of 424875 K by means of drop calorimetry. The fitting functions for the enthalpies per gram have been determined by the least squares fitting. Specific heat and average molar heat capacity have been obtained. It is likely that heat capacity of waste glass remarkably depends on its composition especially above its glass transition temperature.View full abstractDownload PDF (331K) -
Hiroaki WAKABAYASHI, Isao SAITO, Takaaki TAMURA, Shigehiro AN1981 Volume 18 Issue 7 Pages 545-557
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSUniversity of Tokyo research reactor "YAYOI" is intended to be operated as a dynamic fast neutron source reactor as well as a stationary one. It is equipped with reactivity adding devices with both slow and quick action, and a LINAC PNS (Pulsed Neutron Source) to be operated with the devices mentioned above. The unique idea of fly-through type pulse reactivity addition into the core lends itself to minimizing thermal shock problems pertaining to fast burst reactors thereby increasing safety of a single shot type burst reactor.
Operational experiences of YAYOI obtained during the dynamic testing of super critical state are described here with some explanation of design aspects of YAYOI as a fast pulsed reactor.
Throughout present experiments, the super prompt critical state reactivity of about up to 29 cents was realized for YAYOI core, and it was confirmed that the sizes of pulse power were well controllable with this reactivity pulser (R-P) mode pulse operation.View full abstractDownload PDF (2591K) -
Hidematsu IKEDA, Ryohei KIYOSE1981 Volume 18 Issue 7 Pages 558-560
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (165K) -
James D. NAVRATIL1981 Volume 18 Issue 7 Pages 561-562
Published: July 25, 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (177K)
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