Review of Research on the High Temperature Resistance of Concrete Structures in Chinese NPP

摘要

In line with the strategic energy goals and sustainable development, considerable investment has been made on nuclear energy, leading to construction of a growing number of nuclear power plants (NPPs) across China. Concrete is the main structural materials applied in many key elements of a typical NPP including reactors. Among other stringent require-ments, resistance to thermal loads both at early ages and during operating life is crucial for the concrete used in nuclear facilities. This paper provides an overview of high temperature resistance of concrete structures in Chinese NPP, including information on construction and operation. Early-age thermal cracking of mass concrete structures due to dif-ferential thermal stresses induced by hydration heat has been highlighted in literature as a major issue. The common approaches to tackling this issue are based on limiting the maximum temperature in the concrete and temperature difference between hotter interior and cooler exterior of the concrete. These approaches include the optimum mix ratio method and the reasonable design of the construction technology. During operation, the temperature control of containment under steady or accidental case is an important prerequisite to ensure the safety of NPP, especially after a loss of coolant accident (LOCA). In addition, various coatings used for thermal insulation in China’s NPP are introduced and compared. Based on the existing literature, further studies involving longtime monitoring of temperature, strain and displacement are found necessary to obtain a better understanding of thermal resistance, long-term performance and safety of concrete containment used in NPP.