Yoshio Ando

NEUTRON IRRADIATION BRITTLENESS OF STRUCTURAL STEELS IN REACTORS

As a recently results of the irradiation test, it has been found that the brittleductile transition temperature shifts to higher temperature for the structural steels when these are irradiated. Therefore, the problem of the brittle fracture of the reactor pressure vessel is now emphasized from the standpoint of the safety of reactor operation.This paper describes the theoretical and experimental studies on the neutron irradiation brittleness both in Japan and other countries. The paper also points out the some problems encountered in the irradiation tests.

Studies on the Porosity in Welding Joints (Roport 1)

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 (<0.1mm pore dia.) seem to be an important factor of the deterioration of mechanical properties of the welds.