VISAKHAPATNAM: In a focused effort to address long-term durability and safety concerns in nuclear infrastructure, the Visakhapatnam-based Institute of Solid Waste Research and Ecological Balance (INSWAREB) has proposed the development and application of advanced concrete materials for use in nuclear power plants.
The research centres on irradiated complementary cement materials (ICCMs) and nano concrete, which are expected to perform better than conventional concrete under prolonged radiation exposure.
INSWAREB founders and scientist-technocrat couple N Kalidas and N Bhanumathi explained that concrete is the most widely used construction material globally after water, with annual consumption estimated at nearly 14 billion cubic metres.
Since its constituents are derived from natural mineral resources, they emphasised that extending the service life of concrete structures is critical to reducing resource depletion and supporting sustainable development.
They noted that many modern concrete structures suffer early deterioration due to changes in cement manufacturing practices over the past several decades. “Prior to the Second World War, cement released heat and lime slowly, allowing concrete to gain strength over extended periods. Post-war demand for rapid construction led to the widespread use of high early-strength cements, where heat and lime are released quickly, often resulting in early-age damage and reduced long-term durability,” they explained.
According to INSWAREB, complementary cement materials such as fly ash, silica fume, metakaolin, slag and rice husk ash help mitigate these issues. When blended with ordinary cement, these materials react with excess lime during hydration, leading to denser microstructures and improved strength and durability over time.
Concrete used in nuclear power plants faces additional challenges due to radiation exposure. INSWAREB pointed out that international studies have shown radiation can alter the crystalline structure of quartz present in aggregates, causing expansion, cracking and loss of strength. This phenomenon has been confirmed by recent experimental research, including studies conducted by the University of Tokyo.
Drawing on its long-standing work on fly ash-based products and advanced concrete technologies, INSWAREB has submitted detailed proposals to the Prime Minister’s Office and the Department of Atomic Energy. The proposals seek to examine whether irradiation can be used to convert materials such as quartz, fly ash and rice husk ash into ICCMs capable of enhancing concrete performance in nuclear environments.
Initial discussions with the Bhabha Atomic Research Centre (BARC) and the Nuclear Power Corporation of India Limited (NPCIL) have paved the way for preliminary studies. However, since existing reactors can generate only limited quantities of irradiated material, INSWAREB is exploring collaborations with overseas universities and facilities such as the Advanced Test Reactor in the US to obtain larger samples for testing.
The institute has proposed the use of nano concrete for radiation-resistant shield walls, citing its compact microstructure and high fly ash content. Further validation studies are proposed.