ORNL’s stainless steel attracts global interest

Wednesday, Nov 12, 2008

A super-strong form of stainless steel developed at Oak Ridge National Laboratory is attracting worldwide interest, and maybe that’s fitting because the steel could be used in an international project — the International Thermonuclear Experimental Reactor.

Lead researcher Jeremy Busby, a 36-year-old nuclear engineer, said all the attention caught him by surprise.

“U.S. Beats Britain to Fusion Super Steel,” was among the headlines streaming around the World Wide Web in recent days. Busby found some humor in that one because he and other members of his research team, which includes a couple of Brits, didn’t realize there was a competition.

Researchers in ORNL’s Materials Science and Technology Division were approached a couple of years ago by the U.S. ITER team, which is based in Oak Ridge, and were asked to work on better materials for the high-priority fusion project. Among the U.S. responsibilities is the shielding blanket that goes around the magnetically confined fusion chamber, where the plasma fuel may reach 100 million degrees Celsius.

The components won’t need to survive that kind of inferno, but their location would be 200 to 300 degrees Celsius (or somewhere around 500 degrees Fahrenheit), so heat is still an issue, Busby said. So would radiation levels and water corrosion, he said.

ORNL’s cast stainless steel is reported to be 70 percent stronger than comparable steels, and further testing will determine if, indeed, it’s the right material for the international project. Busby said the fusion reactor will need about 100 of the steel components, each weighing 3 or 4 tons.

“We’re hopeful and optimistic,” he said earlier this week. “The only downside at this point is it’s just so new. So we need more information (to qualify the material for use in ITER).”

How to proceed will be a topic of discussion between the U.S. team and leaders of the international project, which is being built near Cadarache, France. In addition to the United States, other partners on ITER are the European Union, India, China, Japan, South Korea and Russia.

Busby, who came to ORNL four years ago from the University of Michigan, said the super steel doesn’t have a name yet. “We’ve been calling it the improved cast steel,” he said.

Actually, it’s not a new steel, but a variation or subgrade of Stainless Steel 316. “We’ve tightened the specifications to get better performance,” Busby said.