JT-60SA will also help ITER, the giant international fusion reactor that is being built in France, to demonstrate that fusion can produce more energy than it consumes.
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T-60SA after completion of assembly of related components. |
Japan's new fusion reactor, JT-60SA, which confines a hot
plasma in a doughnut-shaped chamber using superconducting magnets, has been
successfully turned on. The largest and most sophisticated reactor in the
world, it supports the international Thermonuclear Experimental Reactor (ITER)
project in France and studies the physics of fusion energy.
On October 26, 2023, the first plasma was produced following
over 15 years of development and testing. "This demonstrates to the world
that the apparatus performs its intended function," stated Fusion for
Energy project manager Sam Davis. Regarding JT-60SA and related programmes,
this EU organisation works with the National Institutes for Quantum Science and
Technology (QST) in Japan.
What is JT-60SA?
Unlike earlier large tokamaks, the reactor is intended to
heat the plasma to 200 million degrees Celsius and hold it there for roughly
100 seconds. This will enable scientists to look into ways to regulate and
enhance the performance and stability of the plasma, which are essential for
producing fusion power.
Additionally, JT-60SA will support ITER, the massive
international fusion reactor under construction in France, in proving that
fusion energy can generate more energy than it consumes. ITER will be dependent
on operational expertise and technologies that JT-60SA will verify and test.
Japan was granted permission to construct JT-60SA and two
additional smaller fusion facilities in exchange for France being allowed to
host ITER, the largest fusion experiment in history. This was a component of a
2007 deal between the EU and Japan, which also included modernising Japan's
outdated JT-60 reactor, which has been operational since the middle of the
1980s. The cost of the reactor's total rebuild, which started from scratch, was
kept a secret.
"Superadvanced" refers to JT-60SA, which is
roughly half the height of ITER. One-sixth of what ITER can hold, or 135 cubic
metres, of plasma can be stored there. Alberto Loarte, head of ITER's science
division, says that information from its plasmas should be useful to ITER.
Delays and using rare isotope deuterium
The reactor took far longer than anticipated to
complete—more than 15 years, according to Science.org. Although it was set to
launch in 2016, it encountered numerous difficulties. Along with dealing with
procurement issues, it needed to be redesigned in order to recover from the
March 2011 Tohoku earthquake. Then, during testing in March 2021, a serious
issue arose. A short circuit in the cable of one of the superconducting
magnetic coils damaged the electrical connections and resulted in a helium leak
that might have impacted the cooling systems.
At that moment, the circuit's current was not very deep.
"If the current had been higher, it could have been much worse," QST
project manager Hiroshi Shirai stated. "We were fortunate." It took
the JT-60SA team 2.5 years to repair the insulation in over 100 electrical
connections. The incident also increased the ITER engineers' prudence when it
came to coil testing.
The incident happened when the circuit's current was at its
lowest. The QST project manager, Hiroshi Shirai, stated that "severe
damage to the coil could have occurred if the current had been higher."
"We were in luck." It took the JT-60SA team 2.5 years to rework the
insulation in over 100 electrical connections for safety. The mishap has also
forced ITER engineers to schedule more meticulous testing of their coils.
The disadvantage of JT-60SA is that it will only use
hydrogen and its isotope deuterium—rather than tritium, which is a more potent
but also more expensive, rare, and radioactive form of hydrogen. Since tritium
is the preferred fuel for generating energy, deuterium-tritium will be used by
ITER starting in 2035.
Additionally, Japan plans to construct DEMO by 2050, a power
plant that would serve as a link between the commercialization of fusion energy
and JT-60SA and ITER research. Shirai expressed his happiness at the entry of
new, privately funded approaches to fusion energy. He declared that he is open
to collaborating with people who have fresh ideas. Shirai remarked, "It's
wonderful that more people are in this area."