Radioactive rare gas captured in solid powder by fission recoil was successfully used as tracer for emanation method studies to observe continuously the monoclinic-tetragonal transformation of zirconia, the stabilization of zirconia with calcia, the formation of a solid solution of calcia-stabilized zirconia with uranium dioxide, and the oxidation behavior of solid solutions formed between uranium dioxide and 15 15mol/O calcia-stabilized zirconia. The observed results of this experiment clearly confirm the information so far reported.

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An experiment to predict the amount of fission gas release from U heated in CO₂ was made in connection with the safety evaluation of the Tokai Atomic Power Reactor. Fission gas release from slightly irradiated U pieces was measured as a function of percent oxidation, and it was found that the percent release was proportional to the percent oxidation. The fission gas released before the U was completely oxidized was 11%, 23% and 48% at 500°, 600° and 700°C, respectively. The form of temperature dependence of the fission gas release was of the Arrhenius type, with an activation energy of 5.1 kcal/mol.

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The surface area of vibratory compacted UO2 fuel specimens was measured from the low temperature adsorption of krypton gas.
Main results are as follows :
(1) The n-layer B.E.T. equation, with n-value in the range 2.0-3.5, was found to be best suited for adsorption isotherms of vibratory compacts.
(2) For approximate calculation, Hiittig's equation is better than either ∞-layer B.E.T., L.G.D. or H.J. equations.
(3) Specific surface areas of dense UO2 vibratory compacts (over 85%T.D.) were found in the range 0.340-0.450m2/g.

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The ²⁴⁰Pu content in Pu samples was determined by spontaneous fission measurement with a p-n junction silicon detector. Prolonged continuous measurements were run, extending over several hundred hours, using a transistorized counting system to obtain the required stability during such long periods. The results indicated that this method is applicable to the determination of ²⁴⁰Pu/²³⁹Pu ratio.

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From neutron-irradiated uranium cooled for about 2 days, ¹⁴³Pr was separated indirectly by solvent extraction. After removing uranium and some extractable nuclides with bis(2-ethyl hexyl) rthophosphoric acid from 10 M nitric acid solution, ¹⁴³Co was extracted with his (2-ethyl hexyl)orthophosphoric acid (n-heptane diluent) from a 10 M nitric acid solution containing potassium bromate. Then, ¹⁴³Pr was purified after most of the ¹⁴³Ce had decayed off. Detailed measurements indicated a half-life of 13.55 ±0.02 days and maximum β-ray energy of 0.93±0.05 MeV.

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The radiation detector is by nature a current generator of high output impedance.
A current sensitive amplifier of low input and high output impedance can be devised for incorporation in a nuclear electronic system, providing a matched impedance at the terminal of the detector cable.
The amplifier output is given by i×Ai (i: detector current output pulse, Ai: current amp. gain), when the amplifier rise time (t_γ) is faster than the current pulse rise time. Meanwhile, when t_γ is longer than the current pulse width, the output should be defined by Q/t_γ×Ai (Q: detector output charge) in amp/coulomb units.
The rise time of fission counters, BF3 counters, PR gas-flow proportional counters and inorganic scintillators with conventional photomultipliers is short and is even shorter in the case of fast photomultipliers combined with organic scintillators and semi-conductor detectors.
Thus marked improvement in signal-to-noise ratio can be expected from a current-sensitive system, and this has been proved even with a slow amplifier (t_γ ?? 200 ns), not to mention what can be expected with a faster amplifier (tγ<20 ns).
G-M tubes are inherently, slow, and combination with slow amplifiers does not distort the current pulse shape.
Current pulse transmission via. cable is more rational and easier than the conventional voltage pulse transmission. In the present study, G-M tube current pulses were successfully sent over a distance of 1 km without any preamplifier or pulse transformer.

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For reactors without feed-back, the space-time correlation function in neutron distridutions is obtained in a continuous phase space. The stationary process is investigated in detail. The applicability of the Langevin equation is also examined.

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