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Coordinating America's participation in an international fusion energy experiment.
An international project that seeks to demonstrate one of humankind's few abundant clean energy options will be both a scientific and cultural experiment. Oak Ridge National Laboratory is playing key roles in the U.S. contribution to the International Thermonuclear Experimental Reactor (ITER) fusion energy project through ORNL's expertise and experience in fusion technology and management of large projects. Assigned the leadership role by the Department of Energy, ORNL is guiding the U.S. participation in the international partnership to design and build ITER, a multi-billion-dollar fusion research device too large and complex for any single nation to develop. The six other partners are China, India, Japan, Russia, South Korea and the European Union. ORNL is joined by DOE partners Princeton Plasma Physics Laboratory and Savannah River National Laboratory in working on ITER, a top priority of DOE's Office of Science. ITER will be built in Cadarache, France, with scheduled completion in 2016. Plans call for ITER to operate 20 years to demonstrate the scientific and technical feasibility of magnetically confined burning plasmas on a large scale. ITER represents a meeting of nuclear particles as well as a meeting of the minds. In a burning plasma, two types of fast-moving hydrogen nuclei—deuterium and tritium—bounce off each other and occasionally fuse after overcoming their natural repulsion. The result is the production of helium nuclei and neutrons. The electrically charged helium nuclei slow down in the plasma, keeping the plasma hot. ITER will not produce electricity but will provide considerable heat that can be converted to electricity. Ned Sauthoff, manager of the U.S. ITER Project Office in Oak Ridge, says that DOE Undersecretary for Science Raymond Orbach's decision in 2005 to locate the U.S. ITER project office in Oak Ridge, "had a lot to do with ORNL's success in coordinating the construction of the $1.4 billion Spallation Neutron Source. Oak Ridge was recognized for its capability of delivering large projects on cost and on schedule. One of Oak Ridge's core competencies is the management of large-scale scientific projects. "The ITER team includes many of the people who were working in the same positions for the SNS. Carl Strawbridge, who had been deputy manager of SNS, is now deputy manager of the U.S. ITER Project Office." Many ORNL employees, as well as current staff in DOE's headquarters and Oak Ridge Office, proved with the sevenyear SNS project their leadership capabilities and the ability of their management tools to control costs and schedules and manage risks. "I am most proud of our team members," Sauthoff says. "They are experts in their technical or management field, they have experience that is directly relevant and they work together well as an integrated team." ORNL, which hosts one of the world's broadest fusion energy research programs, has also contributed leaders in fusion science and technology to help guide the design and construction of ITER. Their expertise will be required for a facility 10 times larger than the world's current largest fusion research device, the Joint European Torus in the United Kingdom. "Our signature is the integration of research across the spectrum of science and technology issues facing the development of fusion energy as an economical, commercial source of electricity," says Stan Milora, leader of ORNL's fusion energy researchers. For the U.S. ITER Project Office, Milora is director of the Virtual Laboratory for Technology and chief technologist. "ORNL's fusion core competencies are atomic physics, plasma theory and simulation, experimental plasma physics, integrated fusion systems, technology and materials research and concept innovation, such as the Quasi-Poloidal Stellarator, or QPS, that we hope to build and operate at ORNL later this decade. We collaborate with major fusion laboratories around the world, especially those engaged in research on tokamaks, stellarators and spherical tori." The U.S. labs—Oak Ridge, Princeton and Savannah River—will build hardware for ITER and ship it overseas to France. The United States through ORNL will provide magnets including materials from Japan, superconductors for the large magnets, radiofrequency heating components to heat the plasma, plasma-facing materials that remove heat, vacuum components, power supplies, cooling water systems and pellet injectors for refueling the plasma (a technology that was pioneered by Milora). Princeton will provide instrumentation for diagnostics and electrical power systems. Savannah River will deliver ITER's tritium processing systems.
If ITER proves viable, fusion power plants built in 40 to 50 years will provide electricity without producing high-level radioactive waste or carbon dioxide, a greenhouse gas that contributes to global warming. A fusion plasma consists of super-hot gases of deuterium and tritium. The sun is powered by fusion, with gravity confining its plasma. In ITER, superconducting magnets will confine the plasma, which will be heated to more than 100 million degrees by shooting in radio waves and neutral particle beams (using technologies developed at ORNL) and by fusion reactions themselves. "What we are trying to do at ITER is move from an externally heated system to a self-heated regime," Sauthoff says, explaining that commercial fusion power plants must be self-heated to be efficient. ITER will demonstrate plasma "burns" lasting from minutes to an hour in which deuterium from seawater and tritium nuclei combine to form helium nuclei, or alpha particles (two protons and two neutrons), which deposit energy in the plasma as they slow down. The helium "exhaust" is extracted from the plasma vessel, and deuterium and tritium recovered from the exhaust are recycled back to refuel the plasma. Another significant scientific difference is the size of ITER's plasma vessel, which is at least 10 times as large as today's largest fusion research device. Just as coffee retains its heat longer in a big pot than in a small cup, the plasma in ITER is expected to stay hot longer than the plasma in smaller fusion devices, helping sustain fusion reactions. A third difference is the influence on plasma stability of energetic particles sailing through the plasma and stirring up waves. DOE Undersecretary for Science Orbach is the leader of the U.S. delegation on the 28-member ITER Council. The four-person U.S. delegation includes a member from the State Department. Sauthoff says the State Department views ITER as a major positive activity in foreign relations, a successful cultural experiment in which countries are working together for a common goal. To make ITER a truly successful scientific experiment, researchers must produce a stable, self-heating plasma, the long-term key to abundant and affordable clean energy. —Carolyn Krause Contact: Ned R. Sauthoff Contact: Stanley L. Milora
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