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Research could take the steam out of vapor explosions

Cold water and molten metal can be pure dynamite in industrial settings. Their inadvertent contact produces vapor explosions, a powerful expulsion of steam that disperses metal in hazardous fragments.

But a University of Wisconsin-Madison engineering research team is setting them off deliberately to find the thresholds where these damaging explosions occur.

Vapor explosion experiment

Researchers perform a vapor explosion experiment. (large image)

Nuclear engineering professors Michael L. Corradini and Riccardo Bonazza have two research projects underway to measure the energy and core causes of vapor explosions. "They result from an interesting piece of physics that nobody really understands completely, so industry has just tried to live with them," Corradini says.

They have been the nemesis of the steel, paper and aluminum industries. The explosions have caused on-the-job fatalities, and the aluminum industry cites them as the cause of 80 percent of accident-related equipment losses. They are also of concern to the nuclear industry, where a vapor explosion could result from worst-case scenarios during a reactor core meltdown.

The first project is funded by the Nuclear Regulatory Commission, which wants to quantify the risks associated with such an event. Corradini says their odds of occurring is extremely remote -- the meltdowns at Three Mile Island and Chernobyl were contained long before radioactive material became hot enough to pose a risk. Nonetheless, such an explosion was documented 30 years ago at a small U.S. Army reactor, he says.

The second project is being done for a Boston company with a patent to use molten metal in the disposal of hazardous wastes. Waste such as PCBs and low-level radioactive material can be injected into the metal and burned into less noxious, harmless elements. Corradini and Bonazza will investigate the fluid dynamics of this process to rule out any potential for vapor explosions and improve their injection process.