Microstructural characterization of reactor cavity concrete

摘要

Reactor cavity concrete, a major component of LightWater Reactors (LWRs), serves as a biological shield andas a structural support. The most important agingmechanisms that affect the structural integrity of reactorcavity concrete are neutron irradiation, alkali-silicareaction (ASR), and loss of moisture. All thesephenomena reduce the strength and can generate cracks inthe cavity concrete structures. Neutron irradiation canlead to the gradual amorphization of the minerals thatform the aggregates. With time the amorphization ofminerals induces the expansion of mineral phase resultingin radiation-induced volumetric expansion (RIVE) . Ina similar fashion, ASR induces swelling in the concrete.In this manuscript, the authors will present results from aseries of complimentary microscopy techniques that canbe used to characterize the RIVE and ASR effects todevelop a more coherent understanding of how theseeffects degrade the integrity of the concrete. Thesetechniques include x-ray computed tomography (XCT),transmission electron microscopy (TEM), x-rayfluorescence (XRF) and electron backscatter diffraction(EBSD). Using these techniques in combination isnecessary to develop an understanding of the fundamentalmechanisms that lead to concrete degradation.