A review is presented on the recent studies on nuclear fission. The influence of the nuclear shell on the potential energy surfaces of the deformed heavy nuclei is discussed. Some results of the two-centre shell model are shown. The stability of the superheavy nuclei, their production using heavy ion reactions, and heavy-ion fission are discussed. The emission of light nuclei in fission is noted as an important phenomenon for the study of nuclear fission.

View full abstract

The system for burnup measurements of spent nuclear fuel adopted in the Japan Atomic Energy Research Institute is outlined, and the procedure of destructive measurement, which is the most important part of this system, is described in detail. In this procedure, various determinations by γ-ray and a-ray spectrometry, coulometry and mass-spectrometry are systematically employed after sequential ion-exchange separation.
Treatment of the data and the method of analysis for burnup evaluation are also discussed. A description is also given of the present status of installations of the Burnup Measurement Cell, and some results obtained from test runs are presented.

View full abstract

Corrosion experiments on zircaloy-2 have been performed with corrosion loop and autoclave, under the conditions of saturated water, water vapor mixture, saturated steam and superheated steam in the temperature range of 310°-320°C.
The results of the experiments are summarized as follows:
(1) Adhesion of the cladding increases with the content of dissolved oxygen and the flow rate of water. After declading the weight increase by corrosion is not affected by the flow rate of water, nor also by any factor determining the conditions of the water.
(2) The weight of zirconium transfered into water can be determined by oxygen analysis on the exposed specimen.
(3) 80% of the oxygen content introduced by corrosion reaction dissolves into the metallic zirconium, and only 20% of the remainder oxygen into the oxide film.

View full abstract