Analysis of the causes of failure in the rubber lining of the concentrated hydrochloric acid storage tank at a nuclear power plant

Abstract The rubber lining in a condensate polishing system of a nuclear power plant exhibited significant blistering and cracking shortly after the operation, posing a safety risk to the chlorine storage tank. Extensive analysis, including thermal gravimetric analysis, infrared spectroscopy, mechanical testing, and scanning electron microscopy, was conducted to assess the rubber lining thoroughly. Subsequently, the lining underwent a 72-hour immersion test in 31 % hydrochloric acid at 50°C to evaluate its performance. The results revealed that the rubber content of the lining was 55.7 %, with natural rubber as the material type. Although there was minimal change in mass following hydrochloric acid exposure, both tensile strength and hardness were compromised. Macroscopic and microscopic observations suggested that improper operation during mixing or curing processes led to uneven distribution of components within the lining, allowing for hydrochloric acid penetration through defects and subsequent blistering.