Part 2 of 2 Parts (Please read Part 1 first)
     Ultimately, physicists will use the knowledge acquired from JET’s decommissioning to improve how they incorporate recycling into the design of the Spherical Tokamak for Energy Production (STEP). It is a prototype commercial fusion reactor being planned in Britain. The information will also shape future regulation, according to Buckingham.
     JET and ITER are both ‘tokamak’ design fusion reactors, which confine gas in their doughnut-shaped cavities. JET uses powerful magnets to compress a plasma of hydrogen isotopes, ten times hotter than the Sun, until the nuclei fuse. The last time the fusion community decommissioned a comparable device was in 1997. The Tokamak Fusion Test Reactor at Princeton Plasma Physics Laboratory in New Jersey was shut down. Many parts, such as the equipment for injecting hot beams of gas into the reactor, were reused. The site itself was repurposes. The tokamak had to be filled with concrete, cut up and buried.
     JET scientists hope that the decommissioning will leave little overall waste. Buckingham says that the main challenge is to understand where the tritium is and to remove it from materials, including from metal tiles that line the inside of the tokamak. JET engineers will utilize a refurbished robotic system to remove sample tiles for analysis. They will use remotely operated lasers to measure how much tritium is in samples that remain inside the experimental equipment. Like all hydrogen isotopes tritium is a gas that “penetrates all materials. and we need to know exactly how deep the tritium has penetrated”, says Buckingham.
     Studies at JET this year will remove and study sixty wall tiles. They are the first of more than 4,000 components in the facility. Buckingham adds that “We can use this information to move from lab-scale research to industrial-scale processes, to detritiate the many tons of tiles and components which will be removed from JET over the next few years.”
     In order to extract the tritium from metal parts, engineers will heat the components in a furnace before capturing the released isotope in water. Tritium can be removed from the water and turned back into fuel. The leftover materials become low-level waste, the same classification given to radioactive waste made by universities and hospitals. Variations on this process are being tested for other materials such as resins and plastics.
     JET researchers are exploring how to dispose of low-level waste. They also need to deal with the much smaller amount of intermediate-level radioactive waste in which nuclear decay occurs more frequently. Options for those low and intermediate level wastes remaining include re-treating the waste, removing it to special disposal sites or storing it until it decays to lower levels of radioactivity. Some unaffected parts of JET that are not radioactive, such as diagnostic and test equipment, have already been repurposed in fusion experiments in France, Italy and Canada.
     In its final experiments last December, JET was deliberately damaged. Scientists researched inverting the shape of the confined plasma in a way that might more readily confine heat. They also deliberately damaged the facility by sending a high-energy beam of ‘runaway’ electrons careering into the reactor’s inner wall. This beam is produced when plasma is disrupted.
Joelle Mailloux leads the scientific program at JET. He said, “Analysis of the damage, after the machine is opened up, will provide useful data to test the detailed predictions.”

Part 1 of 2 Parts
     Scientists have started to decommission one of the world’s earliest nuclear-fusion reactors, forty years after it began operations. Researchers will study the seventeen-year process of dismantling the Joint European Torus (JET) near Oxford, UK, in unprecedented detail. They will use the knowledge to make sure future fusion power plants are safe and economically viable.
     Rob Buckingham leads the decommissioning for the U.K. Atomic Energy Authority (UKAEA), which oversees JET. He said, “We are starting to think seriously about a fusion power plant This means thinking about the whole plant life cycle.”
     The nuclear fusion of atoms is the process that powers the Sun. If it can be harnessed, it could provide humans with a near-limitless source of clean energy. Creating the conditions for fusion in power plants and exploiting the resulting energy will require complex engineering that hasn’t yet been developed. Some researchers think that this means that commercial fusion power is still many decades away. However, some of the organizations researching nuclear fusion are estimating commercial nuclear fusion reactors arriving in the next five to ten years.
    Researchers are moving ahead with designs for the first commercial fusion reactors as excitement about fusion power grows. In 2022, JET broke the record for the amount of energy created through fusion. And the U.S. National Ignition Facility (NIF) in Livermore, California now routinely generates more energy from a fusion reaction than was put in. The NIF calculations do not include the entire energy requirements of running the facility. Fusion plants would need to exceed this level of energy expended to truly ‘break even’, but physicists have celebrated the milestones.
     JET is important because the facility is a test bed for ITER which is a twenty-two billion dollar fusion reactor being constructed near Saint-Paul-lez-Durance, France. ITER aims to prove the feasibility of fusion as an energy source in the 2030s. Jet has assisted decisions on what materials to build ITER with and the fuel it will use. JET has been crucial to predicting how the bigger experiment will behave.
     The most difficult part of decommissioning the JET site will be dealing with its radioactive components. The process of nuclear fusion does not generate waste that is radioactive for millennia, unlike nuclear fission which powers today’s nuclear reactors. But JET is among the small number of experimental fusion facilities worldwide that have used significant amounts of tritium which is a radioactive isotope of hydrogen. Tritium, which will be used as a fuel in some future fusion plants including ITER, has a half-life of 12.3 years. Its natural radiation, alongside the high-energy particles it releases during fusion, can leave reactor components radioactive for decades.
     Anne White is a plasma physicist at the Massachusetts Institute of Technology in Cambridge. She says that decommissioning a fusion experimental facility doesn’t mean “bulldozing everything within sight into rubble and not letting anyone near the site for ages”. Instead, engineers’ priorities will be to reuse and recycle parts when possible. This process will include removing tritium where possible, says Buckingham. Removing tritium reduces radioactivity and allows tritium to be reused as fuel. “The sustainable recycling of this scarce resource makes economic sense,” he says.
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