Journal of Nuclear Science and Technology

A Matrix Operator Method for Reactor Calculation

Yoichi FUJIIE, Akira OYAMA

1964 Volume 1 Issue 9 Pages 325-334
Published: 1964
Released on J-STAGE: February 28, 2008

DOIhttps://doi.org/10.3327/jnst.1.325

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As a means of numerically computing neutron flux distribution, a matrix operator method is considered. In this method time, space and neutron energy are discretized, i, e., considered as discrete variables, and the operators describing the neutron motion are defined in each interval of the discrete variables. The operators consist of space and energy operators, which describe the spatial and the energy distribution of the neutron flux respectively. The operation of these matrix operators on the collision density and the pseudo neutron flux vectors yields the neutron flux distribution of the entire system.
This method may be considered an extension to space of the conventional multi-energy treatment, and eliminates tedious procedures to take account of boundary and initial conditions. It eases moreover the selection of time interval from the computational point of view.

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Adsorption of Fission Products on Alumina in Organic Solutions

Noboru OI

1964 Volume 1 Issue 9 Pages 335-338
Published: 1964
Released on J-STAGE: February 28, 2008

DOIhttps://doi.org/10.3327/jnst.1.335

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Metal nitrates are readily adsorbed on alumina in organic solutions such as acetone and n-butylacetate. Adsorption isotherms for such compounds as uranyl nitrate, thorium nitrate and cerium nitrate (III) were examined, and the adsorption was found to have occured monomolecularlly on the surface of the alumina.
The weakest adsorption strength on alumina was found to be that of uranyl nitrate, and the adsorbed uranyl nitrate could be substituted very easily by other nitrates such as of fission products.
The logarithmic decrease of the Kd values of fission products on alumina with increase of uranyl nitrate concentration in n-butylacetate was found to correspond to the increase of the solubility of nitrates of fission products (Ce, Sr and Zr) with increase of uranyl nitrate concentration.

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On the Statistical Nature of Backgrounds of Low Background Counters

Eiichi TANAKA, Takashi MARUYAMA

1964 Volume 1 Issue 9 Pages 339-342
Published: 1964
Released on J-STAGE: February 28, 2008

DOIhttps://doi.org/10.3327/jnst.1.339

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The statistical nature of the background counting rates of low background β-ray counting systems was studied. Chi-squared tests were applied to the background data obtained by several counting systems routinely used in various laboratories. The counting systems tested were four windowless G-M counters, five thin window G-M counters and one CO₂ proportional tube in conventional anti-coincidence shielding and one coincidence type β-ray scintillation spectrometer. The result shows that standard deviations of the background obtained with many of the anti-coincidence type G-M counters were considerably higher than expected from theory.

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Analysis of Outputs from Gas Flow Counter with Respect to Plateau Curves

Shuji YAMADA, Munemaro IMAI IMAI

1964 Volume 1 Issue 9 Pages 343-349
Published: 1964
Released on J-STAGE: February 28, 2008

DOIhttps://doi.org/10.3327/jnst.1.343

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The plateau characteristics of proportional counters depend on the internal structure of the counters as well as on the specifications of the amplifiers used. Experiments were performed with gas flow counters to investigate such items as overload characteristics of the amplifiers, position of the center loop of the counter, and pulse height distribution. The results show that a plateau stretch of 600 V is obtained with gas flow counter using PR gas, and a stretch of 500 V with BF₃ proportional counter. It was determined from current-voltage curves that the maximum voltage of the proportional region was 2, 600 V.

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Automatic Start-Up of a Research Reactor, (II)

Design of a Logarithmic Counting-rate and Period Meter, and Automatic Start-up Experiments

Takeo FUJISAWA, Kenji SUMITA, Koichi WATANABE

1964 Volume 1 Issue 9 Pages 350-361
Published: 1964
Released on J-STAGE: February 28, 2008

DOIhttps://doi.org/10.3327/jnst.1.350

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As a step toward putting into practice full range automatic start-up of a research reactor, this paper describes first the design problem of a logarithmic counting-rate and period meter (LCRPM) used for period control in the counter range. The design basis is to find the optimum point of compromise between requirements such as smaller period signal fluctuations and faster response of the LCRPM, under the condition that the pulse sequence coming from a fission counter is Poisson-distributed. The LCRPM thus optimized was then applied to automatic start-up experiments with JRR-1, ranging in power level from 3 mW (or 20 cps) up to about 2 kW. The experiments demonstrated the applicability of the design method and the feasibility of full range automatic start-up.

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Separation of Potassium Isotopes by Zirconyl Phosphate in Fused Potassium Nitrate

Mutsuaki SHINAGAWA, Emiko OYOSHI, Akira OYOSHI

1964 Volume 1 Issue 9 Pages 362-364
Published: 1964
Released on J-STAGE: February 28, 2008

DOIhttps://doi.org/10.3327/jnst.1.362

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A Remark on the Integral Measurement of Thermal Neutron Spectra

Keiji KANDA, Akira FURUHASHI

1964 Volume 1 Issue 9 Pages 363-364
Published: 1964
Released on J-STAGE: February 28, 2008

DOIhttps://doi.org/10.3327/jnst.1.363

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