There were 20 radioactive waste tanks at the complex. As a result of radiation exposure, one of the metal tanks began to gradually corrode, leading to a loss of containment. About five months before the explosion, the tank contained 256 cubic meters of liquid waste. As a result of the loss of containment, the tank's contents began to seep into the cooling water, which intensified the corrosion of the steel. Measuring consoles indicating the state of the tank's contents and its temperature were damaged.