SEDL / STP / STP1325-EB / STP13888S

Detection of Radiation Damage in Low Alloy Steel Using a Squid Sensor

Otaka, M
Senior Research Scientist, Mechanical Engineering Research Laboratory, Hitachi Ltd., Ibaraki,

Shimizu, S
Engineer, Hitachi Works, Hitachi Ltd., Ibaraki,

Morinaka, R
Engineer, Hitachi Works, Hitachi Ltd., Ibaraki,

Maeda, N
Director, JAPEIC Research Center, Japan Power Engineering and Inspection Corporation, Yokohama,

Yamaguchi, A
Director, JAPEIC Research Center, Japan Power Engineering and Inspection Corporation, Yokohama,

Pages: 8    Published: Jan 1999

Download this paper for $25 PDF (120K)          View License Agreement
Abstract

The magnetic properties of A533B low alloy steel irradiated up to 3 x 10²³ n/m² in a nuclear reactor were measured using a SQUID sensor. The SQUID sensor used in the test is the type with a first-order axial gradiometer. Test specimens were irradiated to 0.5 x 10²³ and 3.0 x 10²³ n/m², and then magnetized in a 0.2 T field until saturation before measurement. The specimens were put on a scanning table in a hot laboratory and the SQUID output was recorded while each specimen was gradually moved in a horizontal direction under the SQUID sensor. A superconducting magnet was used to put the test specimen under a magnetic field that changed from +0.01 T to -0.01 T to observe the relation between magnetic field intensity and coercive force (B-H curve). The B-H curve shows a definite tendency towards a higher coercive force for test specimens with higher neutron fluence. The test result also shows a good relation between mechanical properties, such as yield strength, tensile strength, and the Charpy impact test result, with SQUID output. This proves that there is a very good chance of developing a non-destructive evaluation system for nuclear reactor structure. This kind of evaluation system would be a great help in making plant life management even more reliable and reasonable.