Following the previoly published status report (I) on the World Uranium Development in 1980, this article intends to overview and introduce up-dated data as a report (II) on the same subject, mainly based upon the "Urium-Resources, Production, and Demand" Published by OECD in 1983 and others. It includes the previous trend of the statistical data preparations and the latest revised definitions on uranium resources, classification, and uranium concentrates production by countries. It also refers to the outlook of world uranium supply and demand up to the year 2025, recent review on the Uranium Institute activities, as well as recently released uranium mine near Krivoi Rog, Ukmaine.

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The "In-pile tritium-release experimental apparatus" was designed and installed at JRR-4 in order to study tritium release from UO₂ during reactor operation. It mainly consists of three systems: the irradiation rig, the gas-supplying system and the tritium-collecting system. The mixture of Ne and H₂ was used as a sweep gas to avoid the tritium-contamination by the nuclear reaction of the sweep gas and the adsorption of the released tritium on the surface of the irradiation rig. The released tritium was transformed to HT by the isotopic exchange reaction HTO+H₂=HT+H₂O, and collected into the water-bubbler after oxidizing to tritiated water by CuO. The temperature of UO₂ irradiated was controlled by changing either the ratio of H₂/Ne mixture gas or the distance between the irradiation rig and reactor core surface. The experimental temperature was from about 400 to 1, 000°C.

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This paper describes core seismic response characteristic of high temperature gas-cooled reactor (HTGR) using results of seismic experiment of two-dimensional core models. The followings are described: (1) Introduction of similarity laws and prediction method of actual HTGR core seismic response using scale model experiments, (2) Prediction of actual HTGR core seismic response using two-dimensional vertical and horizontal slice core models and (3) Consideration of aseismic structure.

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Improvement of high temperature heat exchanger efficiency by inserted porous material (wire net layers) is investigated. The primary high temperature gas is so designed as to pass through the wire net layers, which receive thermal energy from the primary gas and are highly heated. Then the wire net layers heat the secondary-gas-flowing tube bundle by radiation, and this effect improves the heat exchanger efficiency. Because of the fine structure of the porous material the volumetric heat transfer coefficient, with which the primary gas transports its thermal energy, is very high and the ability to emit radiative energy is expected to be as large as that of the black surface, which assure the above mentioned effect of improving heat exchanger efficiency.
Improvement of heat exchanger efficiency by inserted porous material is experimentally clarified. When the porous material is not inserted, the shell wall plays the same role as the porous material, however heating the shell wall to high temperature should be avoided from the structural designing point of view. With the porous material inserted, the improvement of heat exchanger efficiency is found even when the shell wall is cooled.

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