WASHINGTON – Along with participation in the International Thermonuclear Experimental Reactor (ITER) project – a large, international burning plasma experiment – the U.S. Department of Energy (DOE) should start a national program of accompanying research and technology to build a compact pilot plant that produces electricity from fusion at the lowest possible capital cost, says a new report from the National Academies of Sciences, Engineering, and Medicine.  The report provides a strategic plan to guide implementation of the main recommendations.

“We are seeing tremendous progress being made in the path to achieving fusion energy around the world,” said Michael Mauel, professor of applied physics at Columbia University and co-chair of the committee that authored the report.  “Now is the right time for the U.S. to benefit from the investments in burning plasma research and take leadership in fusion energy.”

Burning plasma – an ionized gas heated to extremely high temperatures by fusion reactions, similar to processes that power the sun and stars – is a key requirement to make fusion energy. A magnetic fusion reactor can be thought of as a miniature sun confined inside a vessel.  As an energy source, fusion has environmental advantages, as it produces abundant energy from heavy hydrogen found in water and lithium. Burning plasma research is interdisciplinary and results in technological and scientific achievements that lead to new insights in related fields, like fluid mechanics and astrophysics, and advances our industrial capability for large superconducting magnets, vacuum technologies, complex cryogenic systems, ultra-precise construction, and robotic systems to handle materials.

In its interim report, the committee said that withdrawal from ITER could isolate scientists from the international effort and recommended adopting a national strategic plan for fusion energy.  ITER plays a central role in U.S. burning plasma research activities and is the only existing project that is expected to create and study a burning plasma. It is the next critical step in the development of fusion energy, says the report.

As a partner in ITER, the U.S. receives full benefit from the technologies developed for ITER while providing only a fraction of the financial resources.  If the U.S. is to profit from its share, the nation’s strategic plan for fusion should combine its ITER experience with additional science and engineering research needed to develop reliable and economical fusion electricity, the report says.

“There is a critical need for research in addition to our participation in ITER, or else the U.S. risks being overtaken by other countries that are ramping up their science and technology to achieve fusion energy,” said Melvyn Shochet, professor of physics at University of Chicago and co-chair of the committee. 

By starting a national research program toward building a compact pilot plant, important results can be achieved in a time frame such that, combined with knowledge learned from ITER operation, we may be able to demonstrate electricity production by midcentury.  The strategic value of a new national focus on developing this plant will help set research priorities for the near- and mid-term fusion program, including –

• Increasing the fusion power density beyond that obtainable in ITER
• Learning how to operate without interruption while handling escaping heat from the plasma
• Developing very high-field superconducting magnets for fusion
• Developing materials and technologies needed to extract heat and recirculate tritium – the heavy isotope of hydrogen in fusion fuel

The committee envisions a compact pilot plant that could produce power similar to that expected in ITER but in a device much smaller in size and cost and employing design improvements that would allow net electricity production. As a pilot plant, its purpose will be learning, and the knowledge obtained would be sufficient to design the first commercial fusion power systems, the report says. 

The committee expects the implementation of its recommendations, including both continued partnership in ITER and the start of a national research program for a pilot plant, will require additional funding of nearly $200 million annually for several decades.

For this final report, the committee was also asked to provide strategic guidance on the next steps if the U.S. were to withdraw from ITER.  Without ITER, the committee noted, the U.S. would need to design, license, and construct an alternative means to gain experience creating and controlling an energy-producing burning plasma. As a result, the scale of research facilities domestically would be more costly, and producing electricity from fusion would be delayed.  Nevertheless, if the U.S. does decide to withdraw from ITER, DOE should initiate a plan to continue research that will lead toward the construction of a compact fusion plant, the report concludes.

The study was sponsored by the U.S. Department of Energy.  The National Academies of Sciences, Engineering, and Medicine are private, nonprofit institutions that provide independent, objective analysis and advice to the nation to solve complex problems and inform public policy decisions related to science, technology, and medicine.  The National Academies operate under an 1863 congressional charter to the National Academy of Sciences, signed by President Lincoln.

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