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EPISODE: The Engineering Physics Department Newsletter


Fall / Winter 2006-2007
Featured articles

University of Wisconsin Energy Institute engages stakeholders in creative solutions

Designing ways to help ITER operate safely

Learning why fusion plasmas sometimes act unpredictably

GOOD HEAVENS: Space telescopes may have steadier view

EP alum honored on Engineers' Day

A "hot" idea for insulating tiny batteries

Regular Features

Message from the chair

Department News

Alumni News with Alumni Profile: John Parkyn


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Graphic showing a 40-degree slice, in volume, of ITER.

Graphic showing a 40-degree slice, in volume, of ITER. (View larger image)

Designing ways to help ITER operate safely

Decorative initial cap Fusion Technology Institute (FTI) researchers are playing a key role in ITER (the International Thermonuclear Experimental Reactor), a multi-national project designed to demonstrate the scientific and technological feasibility of fusion power. It will take nearly a decade to build; construction will begin in Cadarache, France, in 2007.

Each participating entity—the United States, China, the European Union, India, Japan, the Republic of Korea and the Russian Federation—will design, analyze and build certain components of ITER. “There are still a lot of design issues that need to be tackled,” says Research Professor Mohamed Sawan.

Sawan is leading the FTI team, which includes Assistant Professor Paul Wilson, Adjunct Professor and Argonne National Laboratory Scientist Tim Tautges, and Researcher Greg Sviatoslavsky.

FTI researchers are leading the U.S. portion of the ITER neutronics analysis. In a reactor such as ITER, the fusion reaction that occurs in the plasma produces neutrons with much higher energy than those produced in fission reactions.

“High-energy neutrons can produce more damage to structural materials, to sensitive components,” says Sawan. “Nuclear analysis essentially is looking at what these neutrons will do to the components of the reactor.”

From left: Assistant Professor Paul Wilson, Mohamed Sawan, Adjunct Professor Tim Tautges and Researcher Greg Sviatoslavsky.

From left: Assistant Professor Paul Wilson, Mohamed Sawan, Adjunct Professor Tim Tautges and Researcher Greg Sviatoslavsky. (View larger image)

In addition, it helps designers provide adequate shielding and assess what might happen when streaming—neutrons flying out of tiny holes in the shield—occurs. Knowing what level to expect, says Sawan, is important both in licensing and for maintenance access.

To achieve a quicker, more accurate neutronics analysis, the group is integrating the neutronics code—the “tool” that conducts the analysis—with a CAD modeling engine that draws on an external library of CAD-created geometries.

In the past, says Sawan, the neutronics code was separate from the CAD model and researchers had to feed the code geometric descriptions of every surface in whatever it was they were studying. Modeling that geometry was a primitive, error-prone process in which they had to identify each surface and write the corresponding geometric equation to describe it. If the design changed, they had to generate every surface again. “Now, we take the CAD model itself and do neutron transport in the CAD model,” he says. “We don’t have to redefine these surfaces for the code.”

If there’s a design change, the change is only in the CAD model, so the researchers just point the neutronics code to the updated model. “This cuts down the turnaround time to accommodate the changes and do iterations,” says Sawan.

FTI researchers also are helping design and analyze tritium breeding test blanket modules. Because the tritium fuel is not a naturally occurring isotope, a fusion power reactor should be self-sufficient, producing at least as much tritium as it burns, says Sawan. Tritium breeding blankets generate, or “breed,” additional tritium as the reactor operates and researchers currently are studying a number of designs.

Working with ITER designers, FTI researchers are modeling the reactor’s diagnostic ports to assess whether components such as cables, fiber optics, transducers and detectors can withstand radiation damage. “These are all very sensitive components, but particularly when we operate in the severe nuclear environment,” says Sawan.

Likewise, the “first wall,” or the wall that faces the plasma, receives very high doses of radiation from neutrons and large surface heat flux from radiation emanating from the plasma. FTI researchers are collaborating with colleagues at Sandia to ensure the three U.S. first-wall shield modules have adequate cooling and can handle the experiment’s highest heat flux and radiation levels. “These should survive for the life of the machine and should be designed carefully,” says Sawan.

Directed by Grainger Professor Gerald Kulcinski, the FTI has received approximately $600,000 in 2006 Department of Energy funding for these ITER initiatives.


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Date last modified: Friday, 22-Dec-2006 11:49:00 CDT
Date created: 22-Dec-2006