It seems the proposed fusion nuclear reactors (using hydrogen as the fuel in Sun-like conditions, at several millions deg C temp.) to generate energy / power will be far more complex and expensive than building, controlling and manipulating the currently used fission nuclear reactors (using uranium fuel bundles inside the reactor in which the exchange of heat to the outside takes place at about 300 deg C).

Consider, for example, the following write-up and Youtube video on a recently proposed new design for a nuclear fusion type reactor vessel ("New nuclear fusion reactor design may be a breakthrough," Hard Science, March 20, 2020, https://bigthink.com/hard-science/nuclear-fusion-reactor/):

"The promise of nuclear fusion is tantalizing: By utilizing the same atomic process that powers our sun, we may someday be able to generate virtually unlimited amounts of clean energy.

"But while fusion reactors have been around since the 1950s, scientists haven’t been able to create designs that can produce energy in a sustainable manner. Standing in the way of nuclear fusion are politics, lack of funding, concerns about the power source, and potentially insurmountable technological problems, to name a few roadblocks. Today, the nuclear fusion reactors we have are stuck at the prototype stage.

"However, researcher Michael Zarnstorff in New Jersey may have recently made a significant breakthrough while helping his son with a science project. In a new paper, Zarnstorff, a chief scientist at the Max Planck Princeton Research Center for Plasma Physics in New Jersey, and his colleagues describe a simpler design for a stellarator, one of the most promising types of nuclear fusion reactors.

"Fusion reactors generate power by smashing together, or fusing, two atomic nuclei to produce one or more heavier nuclei. This process can unleash vast amounts of energy. But achieving fusion is difficult. It requires heating hydrogen plasma to over 100, 000, 000 deg C, until the hydrogen nuclei fuse and generate energy. Unsurprisingly, this super-hot plasma is hard to work with, and it can damage and corrode the expensive hardware of the reactor. ..... (contd.)"

Here, in the following Youtube video, the new design "Wendelstein 7-X-from concept to reality" for controlled nuclear fusion to harness energy / power for peaceful purposes, https://www.youtube.com/watch?v=lyqt6u5_sHA&t=16s


>>> It's a very compact and complex design of chamber / vessel to hold the plasma at 100 million deg C during nuclear fusion while the surrounding areas (coils and magnets etc. as part of stellarators) remain at extremely low (supercooling) temperature. Transferring energy / heat to the outside for use in such extreme conditions (following the fusion of hydrogen atoms inside the chamber / torus / vessel at several millions degrees C) might not be as easy and simple as transferring heat to outside for use (from inside the calandria) in fission type reactors.

Besides debunking the cold fusion research / reactor to generate power a few years ago after much initial hype, there still is a plenty of interest in getting power from the nuclear reactor based on regular ("hot") fusion of hydrogen (creating helium and releasing energy) in the Sun-like conditions (at several million degrees C temp., such as by using the above proposed Wendelstein 7-X design).

The proposed nuclear fusion reactors (where the lightest hydrogen is fused to create helium and energy) are expected to yield more energy and release less harmful radioactivity than in the case of currently used fission type nuclear reactors which utilize uranium (a heavy element which, under neutron bombardment during fission, breaks down into lighter elements, radioactive particles and rays, and yields energy in the form of heat).

However, there are plenty of problems and issues currently, as discussed and demonstrated above, which are impeding the development and progress leading to a workable nuclear fusion reactor.

Another setback in Fusion research --- 'Oops! Fusion Facility Keeps Failing to Recreate Last Year's "Breakthrough" Record,' Earth & Energy (July 26, 2022):

Last year, researchers at the National Ignition Facility (NIF) in California announced they had achieved a major breakthrough: they produced fusion energy by heating up a peppercorn-sized sample of two hydrogen isotopes well past the temperature of the Sun's core using a massive laser, a process known as inertial fusion.

At the time, scientists called it "a huge advance for fusion and for the entire fusion community" and "the most significant advance in inertial fusion since its beginning in 1972."

"To me, this is a Wright Brothers moment," Omar Hurricane, chief scientist of the NIF's inertial fusion program, told CNBC at the time.

Just under a year later, and a sobering reality has set in: follow-up experiments attempting to recreate the landmark achievement are falling far short of expectations, Nature reports, forcing the researchers involved to take a step back and reevaluate the entire thing.

In fact, according to that reporting, their best results since have only managed to get to 50 percent of the energy that last year's landmark experiment produced.

It's an unfortunate setback that goes to show just how far we are from creating a perfectly sustainable and green source of energy by fusing atoms together. And that's despite a series of purported breakthroughs and billions of dollars in funding — the laser device at the NIF itself, for instance, cost an eyewatering $3.5 billion to develop and build.

"The fact that we have done it is kind of existence proof that we can do it," Hurricane told Nature. "Our issue is doing it repeatedly and reliably."

Last year's experiment yielded 1.3 megajoules of energy after 192 laser beams shot 1.9 megajoules of energy at a small pellet of hydrogen isotopes. While that means they only got back roughly two thirds of the energy they put in, the experiment crushed the previous record 1,000-fold.

Other more conventional attempts to turn fusion energy into reality involve heating plasma to millions of degrees inside massive donut-shaped reactors.

Hurricane and his colleagues are now desperately looking for why they aren't able to recreate these numbers. Back in October, trials only yielded anywhere between 400 and 700 kilojoules of energy, according to Nature.

In other words, the technology is still in its infancy and is extremely difficult to predict.

And that doesn't bode well for the future of the NIF's inertial fusion program.

https://futurism.com/fusion-facility-failing-recreate-record