U.K. and Chinese national fusion programs can take the heat

June 3, 2021, 7:02AMNuclear News
Plasma in MAST. (Photo: UKAEA/EUROfusion)

As governments around the world cooperate on the ITER tokamak and, in parallel, race each other and private companies to develop commercial fusion power concepts, it seems that “game-changing” developments are proclaimed almost weekly. Recently, the United Kingdom and China announced new fusion program results.

Super-X is on the job: The U.K. Atomic Energy Authority announced on May 26 that its MAST Upgrade experiment at the Culham Centre for Fusion Energy has demonstrated the effectiveness of an exhaust system, dubbed the “Super-X” divertor, that is intended to make compact fusion power plants commercially viable.

The UKAEA plans to build a prototype fusion power plant, known as STEP, by the early 2040s, using a spherical tokamak design. To pave the way, the agency recently took on the challenge of removing excess heat produced by fusion reactions. According to the UKAEA, “Without an exhaust system that can handle this intense heat, materials will have to be regularly replaced—significantly affecting the amount of time a power plant could operate for.”

Tokamak fusion devices feature a divertor region that acts as an exhaust system, steering excess heat and particles from the fuel out of the plasma chamber. The Super-X divertor that is being tested at the MAST Upgrade experiment would, according to the UKAEA, increase the power plant’s availability, improve its economic viability, and reduce the cost of fusion electricity.

A video released by the UKAEA compares the divertor in a tokamak to an exhaust pipe on a conventional car, explaining that the Super-X divertor essentially gives a fusion tokamak a longer exhaust pipe to remove heat and prevent heat damage to plasma-facing components. Testing at the MAST Upgrade, which began operating in October 2020, found that Super-X can reduce the heat on materials by at least 10 times, according to the UKAEA.

“We built MAST Upgrade to solve the exhaust problem for compact fusion power plants, and the signs are that we’ve succeeded,” said Andrew Kirk, the UKAEA’s lead scientist at the MAST Upgrade. “Super-X reduces the heat on the exhaust system from a blowtorch level down to more like you’d find in a car engine. This could mean it would only have to be replaced once during the lifetime of a power plant. It’s a pivotal development for the U.K.’s plan to put a fusion power plant on the grid by the early 2040s—and for bringing low-carbon energy from fusion to the world.”

In this April 2021 photo, staff members perform an upgrade to China’s Experimental Advanced Superconducting Tokamak (EAST). (Photo: Xinhua)

Fusion heat record in China: Chinese news agency Xinhua announced on May 28 that researchers at the Institute of Plasma Physics of the Chinese Academy of Sciences’ Experimental Advanced Superconducting Tokamak (EAST) have set a new world record, achieving a plasma temperature of 120 million degrees Celsius for a period of 101 seconds. The EAST tokamak, which is located in Hefei, the capital of east China’s Anhui Province, also achieved a plasma temperature of 160 million degrees Celsius, lasting for 20 seconds, according to Xinhua. In 2020, EAST claimed a plasma temperature of 100 million degrees Celsius lasting for 20 seconds.

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