Concrete structures in light water reactors (LWRs) are exposed to varied in-service environmental conditions (e.g., irradiation, moisture ingress, temperature). In conjunction with the specific chemical composition of the concrete constituents, several degradation modes can be triggered, including radiation-induced volumetric expansion, alkali-silica reaction (ASR), and corrosion. For about a decade,
the US Department of Energy’s Light Water Reactor Sustainability (LWRS) program has been comprehensively addressing research needs regarding the effects of concrete irradiation and the structural significance of ASR. Despite some remaining knowledge gaps (e.g., comparing possible rate effects caused by accelerated experimental conditions with in-service degradation that requires characterizing harvested materials), the existing corpus of knowledge favorably supports the second
license renewal’s application of operating LWRs. The possibility of operation beyond 80 years is governed by endogenous (e.g., aging management, operation costs) and exogenous (e.g., natural gas, deployment of advanced nuclear reactors) economic factors but also by technical issues associated with doubling the original 40-year license period. Over such an extended time, the possibility of degradation to mechanism synergies must be studied to ensure that concrete structures will satisfy
their desired performance up to 100 years of operation. This article highlights the varied coupling mechanisms among irradiation, ASR, corrosion, and microcracking in concrete and discusses existing knowledge gaps.