Physicstoday.scitation.org. The report also calls for a national strategic fusion plan to resolve issues that won’t be addressed by the mammoth undertaking in France.

Shaky participation in a major experimental reactor threatens the US’s progress in developing commercially viable fusion energy technology, according to a new report from the National Academies of Sciences, Engineering, and Medicine. The report warns that the US risks being left behind in the high-risk, high-reward pursuit of bountiful emissions-free energy.

For years Congress has been haggling over funding for ITER, the international effort to build an experimental fusion reactor in southern France. In 2017 the Senate Appropriations Committee repeated previous years’ calls for the US to end its participation in ITER. But a House-passed omnibus appropriations bill for fiscal year 2018 includes $63 million for the US contribution to the project, the same amount requested by the Trump administration. Last year, the US provided $50 million after the House’s position prevailed over the Senate’s. It remains to be seen whether that pattern will be repeated when the House and Senate versions of the appropriations bill are reconciled prior to signing by the president.

The National Academies report notes that the $22 billion ITER project is the only one capable of studying burning plasmas on the scale of a commercial power plant. Without the knowledge it will gain from ITER participation, the US fusion program would have to design, license, and construct a new facility capable of performing that research. The US fusion budget for FY 2017 was $437 million. President Trump’s budget proposes to cut that by 29% in 2018.

Since rejoining ITER in 2003, the US has never come close to providing annual contribution levels commensurate with its 9% ownership share. Through FY 2017, it has contributed a total of $1.1 billion. ITER spokesperson Laban Coblentz says the US made no cash contribution to support operations at the French site in FY 2016 or 2017, and the unpaid balance for the two years stands at $65 million. In addition, the US in-kind contribution in 2017 fell short by about $50 million.

Five member nations—China, India, Japan, South Korea, and Russia—have the same ownership share as the US, and Coblentz says those countries are pulling their weight. As the host, the European Union is paying nearly half of ITER’s cost.

More than 80% of ITER’s estimated cost will be in the form of components provided by the partners. In December, project officials in Saint-Paul-lès-Durance declared ITER construction to be halfway finished. Completion of a machine capable of operating with deuterium is scheduled for 2025. Operations with deuterium–tritium that will produce a burning plasma will begin in 2035 at the soonest.

Ned Sauthoff, director of the US ITER office, said in an email that 17 subcontractors there were laid off in response to the FY 2017 funding shortfall. That leaves a project staff of 55 employees and 42 on-site subcontractors at the office, which is located at Oak Ridge National Laboratory in Tennessee.

So far, the US ITER office has managed to reprioritize work to avoid component delivery delays that would impact the reactor construction schedule. Should the US funding shortfalls be corrected in 2018, the overall ITER schedule shouldn’t be impacted, according to Coblentz. Reassigning components from the US to other ITER members isn’t feasible, he says, since years are often required to qualify companies to build them to exacting specifications.

Coblentz says he is hopeful that the US will meet its commitments this year. Yet the most optimistic likely outcome is for lawmakers to provide little more than last year’s relatively small amount. A 2016 DOE report to Congress estimated the US requirement at $275 million this year, with annual amounts in excess of $200 million through FY 2024. Overall, $2.1 billion will be required through 2025 to meet the US commitment. Another $1.6 billion will be expected from the US from FY 2026–35 for the upgrade to deuterium–tritium operations.

Participation in ITER alone isn’t sufficient to advance to commercial fusion energy, according to the report. Unlike the other ITER partners, the US has not composed a national strategic plan for the additional R&D needed for a commercial power reactor. Strategic plans “guide national research and innovation programs, help to engage industrial partners, and set the national priorities of our partners, enabling them to develop key areas of unique expertise,” the report states.

The lack of a US plan inhibits long-term planning by universities, national laboratories, and industry participants in fusion R&D. And there is plenty of R&D to be done: Unmet requirements for a working fusion power plant include methods for more efficient coupling of RF waves to the plasma, new materials that can withstand the intense neutron flux, and consistent breeding and safe handling of tritium inside the reactor chamber.

Editor’s note, 9 January: The article has been updated to correct the amount of funding that the US provided to ITER in fiscal year 2017.

Written by David Cramer

Photo: ITER