Behavior of materials in the core of PWRs

As in all industrial installations, the materials used in pressurized water reactors (PWRs) are subjected to mechanical, thermal and chemical stress during operation, for particularly long periods of time: 40 years, even 60 years. More specifically, the materials closest to the nuclear fuel are subjected to intense particle bombardment (mainly neutrons) from nuclear reactions in the core.

The damage likely to result is many and varied: irradiation ageing (due to neutron bombardment), thermal ageing (due to operating temperatures of around 300°C), thinning due to wear (due to friction) or general corrosion (due to the chemical environment), stress corrosion, and so on.

Understanding the behavior of reactor core materials during operation in sometimes aggressive conditions, particularly due to irradiation phenomena, is therefore a major concern for the nuclear industry, and forecasting their behavior over very long periods is a necessity.

The main non-irradiation and irradiation degradation modes of these materials will be described in the remainder of the text, along with ways of predicting their behavior using physics-based models.