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Volume 5, Issue 2
Displaying 1-7 of 7 articles from this issue
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Hiroshi KAI, Masahiro KATSURA, Tadao SANO1968 Volume 5 Issue 2 Pages 43-47
Published: February 25, 1968
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe UC-UN solid solution, UC1-xNx, exists stably in monophase within a certain range of nitro-gen pressure at constant temperature. At the upper limit of this range, UC1-xNx coexists with UC2 or with carbon, and it precipitates metallic uranium at the lower limit which corresponds to the de-composition pressure of UC1-xNx.
In order to measure the decomposition temperature of UC1-xNx with given x under constant nitrogen pressure, it is necessary to heat UC1-xNx without changing its composition, at a constant pressure.
In the present work, preliminary considerations have been given to change in composition. Ex-periments were also performed in which the solid solution was heated at a rate of 200°C/min under different nitrogen pressures.
From the results, it is concluded that there exists a temperature range within which the value of x in UC1-xNx is maintained constant when the nitrogen pressure is fixed.View full abstractDownload PDF (366K) -
Akira FURUHASHI, Akira IZUMI1968 Volume 5 Issue 2 Pages 48-59
Published: February 25, 1968
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe fluctuation in neutron counts occurring in the course of short time intervals has been mathematically formulated up to the third moment. Second and the third order fluctuation param-eters representing the degree of neutron correlation in the system are derived as functions of time interval in a form that is independent of the counter efficiency.
It is suggested that measurement of die effective multiplication factor of the system is possible by comparing the third order parameter with the square of that of the second order.View full abstractDownload PDF (723K) -
Takashi MITAMURA, Masayoshi KANNO, Takashi MUKAIBO1968 Volume 5 Issue 2 Pages 60-64
Published: February 25, 1968
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA study was made of UN preparation by two-step reactions with UCl4, Al and N2 gas.In the first step, an intermediate uranium nitride with an N/U ratio of 1.68 resulted from the reaction ofof UC14 with Al under constant flow of N2 at reaction temperatures higher than 800°C.The X-ray pattern of the intermediate nitride did not correspond to any previously known uranium nitride.A maximum conversion efficiency of about 70% was obtained at temperatures between 800° and 1, 000°C for the first reaction.In the second reaction, the intermediate nitride was heat treated under vacuum. To obtain single phase UN from the intermediate nitride, the heat treatment required a temperature of at least 1, 100°C, at which the minimum holding time was 60 min.View full abstractDownload PDF (362K) -
Fumio AMANO, Katsuhiko SUNAKO1968 Volume 5 Issue 2 Pages 65-73
Published: February 25, 1968
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThis report describes an analytical method of transforming the prompt decay constants αl into the static reactivity ρs. It has been developed through the use of the time-dependent, two-group diffusion theory ignoring delayed neutrons under several assumptions. A generalized characteristic equation which relates the prompt decay constants to the effective multiplication constant can in general be derived by expanding the static fluxes into kinetic fluxes containing the fundamental and higher modes, and several approximated formulas for this equation have been obtained with the ap-plication of certain conditions. In particular, a formula that takes into account the change in the generation time -ρd2, =(βeff/αc){αc-(Gα/Gαc)α}- is proposed as a most useful method for reactiv-ity measurement. Error evaluation has been performed in regard to several approximate formulas, and some problems involved in numerical calculation have been examined.View full abstractDownload PDF (609K) -
Yung-Ho KANG, Hatsumi TATSUTA1968 Volume 5 Issue 2 Pages 74-78
Published: February 25, 1968
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSTwo types of personnel dosimeter are presented:an emulsion containing 10B and a Toshiba glass-covered model embodying natural uranium foil.If a Cd sheet is used to reduce thermal neutrons leaving the human body, measurements of the dose equivalent will be possdle to cover a neutron energy range between thermal and 10 MeV.Experimental results show that the minimum detectable dose equivalent with the dosimeters are 0.15 rem and 10 rem for the emulsion type and the etched pit type, respectively.View full abstractDownload PDF (387K) -
Masao HARA, Hozumi USUI, Yoshio FUJII, Nobuhide SUDA1968 Volume 5 Issue 2 Pages 79-85
Published: February 25, 1968
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe maximum period sequence binary signal has been applied to measurements of the JRR-3 frequency response at 10 MW. Three measurements have been made to cover the frequency range of 0.003 to 10 radians/sec. The measurements were readily made when the reactor temperature was in equilibrium. Even when it was not, and the reactor power was varying slowly, a power drift compensating system made it possible to carry out accurate measurements. The results obtained under equilibrium and non-equilibrium conditions agreed well with each other.
A simple mathematical model has been used to predict the JRR-3 high power dynamics. The frequency response computed with the use of this model also agreed fairly well with the experimental data.View full abstractDownload PDF (419K) -
Yasuyuki KIKUCHI, Shigehiro AN1968 Volume 5 Issue 2 Pages 86-89
Published: February 25, 1968
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (226K)
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