Grant to allow UC Davis researchers to investigate alternate nuclear reactor steel

Published: Monday, Jul. 30, 2012 - 12:00 am | Page 2B
Last Modified: Monday, Jul. 30, 2012 - 9:56 am

Inside a nuclear reactor, flying neutrons constantly slam against steel parts.

Under a grant awarded last week by the Department of Energy, UC Davis and UC Berkeley professors will investigate whether a less-expensive type of steel can handle such bombardment. If it stands up to the tests of radiation that steel currently in use has passed, the material could be used in future reactors.

"It's simply an evolutionary process of investigating materials that we know we're going to need in some way or another," said UC Davis' Niels Grønbech-Jensen, one of the professors awarded the grant.

The research is relevant to components of light-water nuclear reactors, the type in a majority of nuclear power plants including Japan's Fukushima Dai-ichi, which was damaged by the devastating earthquake of March 11, 2011.

Special materials are required to build a nuclear reactor, because the high doses of radiation inside could make its metal parts brittle. Grønbech-Jensen gave the example of a bicycle tire that becomes brittle and cracks after being out in the sun too long.

"That's generally not a good thing," said Scott Burnell, spokesman at the Nuclear Research Council, which develops regulations for the safety of nuclear reactors.

"What matters most is that (the materials are) not changing away from what we think they should be" when exposed to radiation inside a reactor, said Grønbech-Jensen.

Burnell said the materials of current nuclear reactors have been thoroughly tested.

The less-expensive material that Grønbech-Jensen and colleagues plan to research is a particular metal alloy. These steels can withstand high temperatures. They're used in crankshafts, gears and even fencing swords.

"They already show some promise" for use in nuclear reactors, said Grønbech-Jensen.

But "it still remains to be seen whether or not these less-expensive steels meet all of the relevant requirements for use in a reactor," Burnell said.

So with the $750,000 grant, Grønbech-Jensen and UC Berkeley professor Mark Asta will perform theoretical research to study how the new material might respond to radiation at the microscopic level.

Their work will involve calculations and computer simulations, since "the complexity is far beyond what we can do with paper and pencil," he said.

"But then we need to understand … what do we get right, what do we get completely wrong, so that we don't fool ourselves by results that look nice on the computer."

To test their predictions, experiments with the steel will be performed by Peter Hosemann at UC Berkeley and Stuart Maloy and other scientists at Los Alamos National Laboratory in New Mexico."You have to be a group of people to look at an engineering problem … because an applied problem involves everything," said Grønbech-Jensen.

Burnell of the NRC agreed.

"You can show that the basic principles work in a theoretical way using a computer model, but before the NRC would allow (a material) to be used, we would have to make sure that what's showing up on the computer screen is matched by what actually occurs in the real world."

"In the nuclear industry, very little is left to chance," Grønbech-Jensen said.

Ahmet Palazoglu, Chemical Engineering and Materials Science department chairman at UC Davis, explained that "obtaining grants such as this from the DOE … helps us to fulfill one of our key missions in the department" in supporting not only research, but also student training.

"It's inevitable that we don't always get the funding that we ask for," said Grønbech-Jensen. But "building broad collaborations somehow makes it easier because we can learn from each other."

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