Abstract
The Three Mile Island Unit-2 accident was examined from the view point of chemical engineering. It was concluded that preventive measures for the TMI atomic power plant were insufficient compared with those of a chemical plant. Zirconium alloy cladding reacts with steam and generates a hydrogen and zirconium oxide, which loses mechanical strength. As a result, the fuel element melted. At the temperature of 871°C, zirconium alloy starts to react with steam.
Zr + 2H2O → ZrO2 + 2H2 + 141 Kcal (1)
The reaction rate was observed by Pawel et al., and they presented a rate equation called the Cathcart-Pawel equation. According to the Cathcart-Pawel equation , zirconium alloy cladding was oxidized for 40 minutes at 1649°C (Schneider, 1980). This paper will state that the simulation of a hydrogen explosion at a higher temperature results in a significantly shorter reaction time. For example, at 1000°C the time is 100 hours, whereas at 1500°C it is two hours.
