Emerging Research Fronts Comments by Bruce A. Pint

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ESI Special Topics, October 2005
Citing URL: http://www.esi-topics.com/erf/2005/october05-BruceAPint.html

From •>>October 2005

Bruce A. Pint answers a few questions about this month's emerging research front in field of Engineering:

Engineering
Article: Recent progress in the development of electrically insulating coatings for a liquid lithium blanket
Authors: Pint, BA;Tortorelli, PF;Jankowski, A;Hayes, J;Muroga, T;Suzuki, A;Yeliseyeva, OI;Chernov, VM
Journal: J NUCL MATER, 329: 119-124 Part A, AUG 1 2004
Addresses:
Oak Ridge Natl Lab, Div Met & Ceram, POB 2008,1 Bethel Valley Rd, Oak Ridge, TN 37831 USA.
Oak Ridge Natl Lab, Div Met & Ceram, Oak Ridge, TN 37831 USA.
Lawrence Livermore Natl Lab, Livermore, CA 94551 USA.
Natl Inst Fus Sci, Fus Engn Res Ctr, Gifu 5095292, Japan.
NASU, GV Karpenko Physico Mech Inst, UA-79601 Lvov, Ukraine.
SSC RF AA Bochvar Inst Inorgan Mat, Moscow 123060, Russia.

Why do you think your paper is highly cited?

“Pessimists say that fusion energy is always 50 years away. Optimists say it will be ready when the world needs it.”

Several reasons:

This paper represents a paradigm shift in the US program to develop electrically insulating coatings for Li-cooled blankets. Previous work at another US laboratory had emphasized a "self-healing" coating concept with CaO. Our work showed that this concept is unlikely, if not impossible. Lithium dissolves CaO. The new strategy is to develop durable multi-layered coatings where the ceramic (insulating) layer (e.g., Y₂O₃ or Er₂O₃) is no longer in direct contact with the Li and therefore avoids degradation due to Li reacting with the oxide and Li wetting cracks in the oxide. A multi-layer coating or flow-channel insert essentially solves the problem.

With the recent agreement on the construction of the international fusion research project ITER in France—"iter" means "the way" in Latin—there is now more interest in the technology side of fusion. The US fusion research program is focused on fusion science. However, if we are to turn fusion into a viable technology in the next 35 years, more emphasis is needed on the technology issues such as corrosion and compatibility.

From a technology standpoint, a design using a self-cooled Li blanket is extremely attractive because when Li is exposed to high energy (14MeV) neutrons it breeds tritium, which is the fuel for the fusion reactor. So you have one system that is extracting heat from the reactor—that can be used to generate electricity or produce hydrogen—and generating fuel at the same time. The reality is Li represents major compatibility problems and needs an insulating coating to reduce the pressure drop associated with the magnetohydrodynamic force created by the liquid metal crossing the magnetic field lines of the reactor.

Does it describe a new discovery or a new methodology that's useful to others?

It wouldn't be useful unless you are designing or building a fusion reactor.

Could you summarize the significance of your paper in layman's terms?

This research applies to the development of a magnetic confinement fusion reactor that would use high magnetic fields to contain a plasma-burning tritium at approximately 1 million degrees celsius. The blanket surrounds the plasma and extracts useable heat from the reactor. Lithium is attractive to transfer heat to a power (electricity) generation facility and to create tritium when exposed to the high-energy radiation in the reactor. One problem is that lithium is highly reactive and corrodes or dissolves most metals and ceramics that it contacts at high temperature. The other problem is that the magnetic field in the reactor creates a force preventing the flow of a liquid metal. An electrically insulating layer or coating on the inside of a tube carrying lithium would decouple the lithium from the magnetic field and thereby reduce this force allowing lithium to be pumped in and out of the reactor wall. The research is focused on identifying a coating material that is both insulating and resistant to lithium. There are no materials that meet this requirement so we propose a sort of composite coating of a ceramic layer for electrical insulating and a metal (for example, vanadium) which does not react with lithium at 700°C (1300°F).

How did you become involved in this research?

I came to ORNL in 1994 as part of the US Department of Energy’s Distinguished Post-Doctoral Research Program. The previous generation of corrosion scientists working on fusion issues at ORNL, Jack DeVan and Jim DiStefano, were preparing to retire and got me involved in the fusion program. At the time, I knew nothing about this area (as does most of the scientific community!), but over the last 10 years I have learned a great deal from these gentlemen and am now running the program myself. The ORNL coating program began in 1998.

What are the social or political implications of your research?

Ideally, fusion energy would be a limitless power supply that will free the world from the need for fossil fuels (with all of their geopolitical and environmental issues) to power our society. Realistically, it will be tremendously expensive to develop, build, and operate a fusion reactor so it won’t make energy "free" for everyone and it will benefit the developed world long before it benefits the rest of the world. Pessimists say that fusion energy is always 50 years away. Optimists say it will be ready when the world needs it.

Bruce A. Pint
Research Staff
Oak Ridge National Laboratory
Metals & Ceramics Division
Corrosion Science & Technology Group
Oak Ridge, TN, USA

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ESI Special Topics, October 2005
Citing URL: http://www.esi-topics.com/erf/2005/october05-BruceAPint.html