Effects of alloying elements on the stress corrosion cracking resistance

During exposure to a radiation environment, the mechanical and microstructural properties of a material will change. The materials become harder and more brittle and the microstructure evolves in such a way as to make the material potentially more susceptible to cracking.

A series of studies being conducted in the Halden reactor are aimed at gaining a better understanding of the benefits of specific alloying elements in improving the stress corrosion cracking resistance of the stainless steels that are used for nuclear power plant structural components. A number of materials, specially prepared in a laboratory to enable systematic variation of the alloy contents, are being irradiated for different lengths of time in the Halden reactor.

After irradiation, the materials are tested in international hot cell facilities and the results are compared with similar tests conducted on specimens prepared from components taken directly from commercial reactors. By comparing the laboratory and the reactor materials behaviour, a better understanding can be gained which alloying elements are either beneficial or detrimental for improving resistance to stress corrosion cracking.

The irradiation programme has been on-going with international laboratories since 1992 and will be continued in a new series of tests this year.

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