Search

The first nuclear power station in Japan (Advanced Calder Hall type, 166 MW electric) is now under construction at Tokaimura.Construction of several new nuclear power stations will begin within a few years and also building project of the first nuclear powered ship (6500 G.T.) has been started in 1963.Al-killed steel plates 8094 mm thick were manually welded for Tokai reactor pressure vessel and its steam raising units were constructed with 5474 mm thick boiler plates using both submerged arc and manual welding. JPDR is a small BWR (12.5 MW electric), and the inner surface of its pressure vessel was stainless steel cladded by submerged arc process.Researches on the welding of the nuclear reactor have been extensively carried out by Japan Welding Engineering Society and also each industrial plant is doing its own researches. The study on the effect of irradiation on the properties of materials has been just started.

In order to analyze gases included in the porosity of welds of aluminium alloy, we formerly constructed an apparatus of gas analysis and investigated the relation between several welding conditions and results of gas analysis on the welds.In this paper, we report on a comparison of the results of several porosity inspections with the results of gas analysis on the welds. For porosity inspections, we have made codes of micrographic inspection and X-ray inspection. These codes are convenient for comparison of the results of gas analysis.We have obtained experimental results as following :1) In precise inspection, it is necessary to use micrographic inspection together with X-ray inspection.2) Gas contents mainly hydrogen included in welds of aluminium alloy (NP 5/6) are about 1-3ml/100g at 0 percentage void.3) According to the observation of the distribution of pores of each size, microporosities (