Journal of Nuclear Science and Technology

Neutron Behavior in Cluster-Type Fuel Lattices, (I)

Experimental Method and Results

Yuuki HACHIYA, Haruo HATAKENAKA

1972 Volume 9 Issue 11 Pages 629-641
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.629

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Lattice parameters δ²⁸, δ²⁵, ρ²⁸ and C^* were measured on cluster-type fuel lattices of the ATR (Advanced Thermal Reactor) by using a two region critical facility (D₂O-cluster test and H₂O-rod driver regions). Their dependence on lattice pitch, coolant-void ratio and fuel composition (whether UO₂ or PuO₂-UO₂) have been made clear by this experiment.
A foil handling technique has been developed for determining the lattice parameters of the PuO₂-UO₂ fuel pins, and the resulting measurement errors are almost as small as those obtained on the UO₂ fuel pins.
The effects of the Cd-filter and of the presence of UO₂ buttons in the measurement of ρ²⁸ and δ²⁵ were studied experimentally and correction factors have been determined.
A method of observing the spatial distribution of the γ-ray source in an activated foil has been developed, and the relation between the spatial distribution and the coincidence counting efficiency of the foil has been examined.

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Adjustment of Group Cross Sections by Means of Integral Data, (II)

Numerical Study

Hiroshi MITANI, Hideo KUROI

1972 Volume 9 Issue 11 Pages 642-657
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.642

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Adjustment of the ABBN set is performed using various integral data obtained from fast critical experiments; through this adjustment, some practical properties are also examined in detail. The correlation coefficient between group cross sections is numerically obtained by assuming that the compound nucleus formation cross section can be described by a statistical model. The effect brought by this correlation to the adjustment of group cross sections is also studied. When the differential and integral data used in the adjustment contain a systematic error, the normalized sum of squares of residuals has a non-central Chi-square distribution. This is numerically examined by generating artificial differential and integral data with the aid of random numbers. The ABBN set collapsed into 15 energy groups is adjusted, and the principal results are compared with the measurements. The reliability of the adjusted integral data and group cross sections is also studied.

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Half-Life and Gamma-Ray Energies of Lanthanum-144

Akira OHYOSHI, Emiko OHYOSHI, Tadaharu TAMAI, Hirokatsu TAKEMI, Mutsua ...

1972 Volume 9 Issue 11 Pages 658-661
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.658

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A procedure using a complexing agent (NTA) in paper electromigration has been devised to achieve rapid separation of fission product lanthanum. This technique permits direct observation of the decay of the 42sec ¹⁴⁴La without interference from the radiation of other fission products. The γ-ray spectrum of ¹⁴⁴La has been measured with a high-resolution Ge(Li) detector, and the following γ-transitions were observed: 397, 434, 541, 586, 704, 734, 845, 951 and 1, 292keV. Their relative intensities were also determined. From the decay plots of the two strong photopeaks at 397 and 541keV, the half-life of the ¹⁴⁴La was determined as 42.4±0.6sec which is more accurate than that of 41±3sec previously reported.
It is concluded that the separation procedure used in the present study can be adapted to the isolation of other short-lived fission products as well whenever their metal ions from the complexes by different values of the equilibrium constant.

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New Continuous Slowing-Down Theory for Fast Reactor Spectra

Hisashi YAMAMOTO, Shin-ichi ITO

1972 Volume 9 Issue 11 Pages 662-669
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.662

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A new analytic representation for fast neutron spectra is described, based on the continuous slowing-dawn theory using generalized slowing-down parameters ξ(u), γ(u) in order to taking account of inelastic scattering.
The theory is basically formulated for neutrons moderated from monoenergetic source. For fast reactor spectra calculations, the fission source is generated by means of fictitious inelastic scattering. Examples of calculation show good agreement with multigroup calculations.

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Continuous Boiling Phenomena of Sodium under Forced Convection by Direct Heating

Katsuro TAKAHASHI, Yoichi FUJII-E, Tokuo SUITA

1972 Volume 9 Issue 11 Pages 670-679
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.670

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The results of an experimental study on the continuous boiling behavior of sodium with upward forced convection loop are reported. The sodium was passed through a vertical tube of 14.9mm I. D., where it was heated by d. c. power (∼4V, ∼5, 000A) directly applied through the flowing sodium, The experiments were carried out in the following range of conditions:
Input power: 6∼12kw
Pressure at the condenser: 0.9∼1.1kg/cm²
Flow rate: 1.0∼3.0l/min
Inlet temperature: 750°∼830°C.
Under certain conditions, steady boiling occurred, but boiling generally had a tendency to become unstable, and flow patterns representing violently pulsating boiling were observed. These latter flow patterns were either of single bubble ejection type with expulsion and subsequent re-filling of sections of the tube mainly by liquid sodium falling back from above, or else of slug type with periodical expulsions, without fall-back of liquid. For these patterns of pulsating boiling, the frequencies of oscillation ranged from 0.5 to 1.0Hz. The film thickness remaining on the channel wall was also measured.

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Some Remarks on the Greuling Goertzel Approximation for the Higher P_L Equation

Yasunori YAMAMURA, Tamotsu SEKIYA

1972 Volume 9 Issue 11 Pages 680-682
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.680

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Comparison of the Anisotropic Diffusion Coefficients Based on the Benoist and Deniz Formulas

Toshikazu TAKEDA, Tamotsu SEKIYA

1972 Volume 9 Issue 11 Pages 682-685
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.682

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Correlation between the Integral Data Obtained in Partial and Full Mock-Up Systems

Hideo KUROI, Kinji KOYAMA, Hiroshi MITANI

1972 Volume 9 Issue 11 Pages 685-688
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.685

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Neutron Active Assay Techniques for Nuclear Reactor Fuel

Yasuhiko MATSUDA, Tohru MURATA, Toshiyuki TAMURA, Nawoyuki KAWAI

1972 Volume 9 Issue 11 Pages 688-690
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.688

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Noise Measurements in the MOATA Reactor

Leslie G. KEMENY

1972 Volume 9 Issue 11 Pages 691-693
Published: November 25, 1972
Released on J-STAGE: December 19, 2008

DOIhttps://doi.org/10.3327/jnst.9.691

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Errata (Vol. 9, No. 9, 1972)

1972 Volume 9 Issue 11 Pages 693
Published: 1972
Released on J-STAGE: December 19, 2008

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