Computational modeling of hydrogen behavior and thermo-pressure dynamics for safety assessment in nuclear power plants

Abstract

Following the Three Mile Island Nuclear Generating Station incident 1979, extensive research has focused on preventing hydrogen accumulation and explosions during nuclear power plant emergencies. We used advanced computational fluid dynamics (CFD) simulations to analyze hydrogen distribution, pressure dynamics, and the efficacy of safety measures across various containment structures under accident scenarios. Results indicate that smaller containment structures experience rapid hydrogen accumulation, reaching a peak pressure of 2.5 bars and a temperature of 120 °C within the first 30 s. Structural integrity is compromised at pressures around 3.8 bars, leading to failure within 10 min under sustained high pressure. In contrast, larger containment structures exhibit delayed pressure buildup, peaking at 2.3 bars with a corresponding temperature of 110 °C, and maintain integrity for up to 30 min. Fire scenarios demonstrate that smaller containment structures reach peak temperatures of 500 °C, which resulted in partial structural failure, whereas larger containments withstand up to 450 °C for 40 min without compromise. When hydrogen concentrations exceed 35%, and temperatures surpass 1430 °C, explosion risks increase substantially, which reduces the effectiveness of passive mitigation systems.