Live data from Hacker News

Compact nuclear fusion reactor is 'very likely to work,' studies suggest

nytimes.com

101–110 of 373 posts

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#101

https://www.youtube.com/watch?v=KkpqA8yG9T4 Here's a video lecture from the MIT Professor (Dennis Whyte) who was leading the research group that provided some of the key designs for the SPARC reactor. As the NYT article explains, that research has been spun out into a startup that raised $200M. The key breakthrough is the advancement of REBCO tape superconductors which allow you to (1) generate record breaking magnet…

Phenomenal talk! I'm still watching - so captivating.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#102

Earlier quoted context omitted.

I couldn't agree more. Once you realize that energy is the fundamental unit which powers everything else in the economy, not only from every movement of ourselves to those of our machines as well, you realize the more we advance in our ability to produce more and more energy at cheaper and cheaper costs in increasingly reliable ways, the more we can accelerate, without exception, every other industry.

Make an efficient fusion reactor the size of a truck, and the solar system becomes your backyard.

I like this. :) I am just amazed how many people fail to see the importance of this. It would _really_ pave the way of the future for humanity if it pans out. Pretty exciting stuff.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#103
post #33

Earlier quoted context omitted.

So in the end it's a glorified boiler!

as far as i am aware, solar power is the only prevalent power source that does not derive from spinning a dynamo. Besides wind (and perhaps there, too) almost all of the force used to spin dynamos includes some kind of boiling (eg: dams happen to use the force of the water after the "boil"/evaporation, nuclear, coal, natural gas, etc are all steam-based thermo-mechanical power plants.)

Note that gas powerplants are combined cycle power plants, they contain both gas turbine and steam turbine, so part of their spinning power (from gas turbine) is not based of boiling.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#104
post #84

Earlier quoted context omitted.

I’m also a layperson and also a fan of the 7-X, almost on purely aesthetic grounds. The plasma shape is a beautiful twisted loop, the magnets resemble a French crueler, and with the shielding and instrumentation it has all the charm of a steampunk time machine

To me it looks like alien technology. Such an organic shape. So many valves an openings. What is their purpose? How deliberate is their placement? Awe-inspiring.

It is a research reactor, so most of the openings are for instrumentation and ease of upgrades. A production design would have fewer ports.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#106

Here's the actual summary: "Although many significant challenges remain, the company said construction would be followed by testing and, if successful, building of a power plant that could use fusion energy to generate electricity, beginning in the next decade." In other words, "very likely" in this case means "if several roadblocks are overcome, it might be a net-positive power generator in a decade". Even so, this…

> this is still exciting given how anemic advancement in the fusion space has been for 50+ years At the top of my list for when I'll be king for a day is - massive, national-scale investments (think: reaching towards one percent of GDP) in fusion research. This is a major roadblock, but things look awesome on the other side. We just need to get our stuff together to hop over this fence somehow.

> massive, national-scale investments

A reminder of what could have been:

https://upload.wikimedia.org/wikipedia/commons/a/ab/U.S._his...

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#107

I never quite understood the math behind power densities in a fusion reactor. In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW? Is the density of the plasma so much higher in a fusion reactor? Also, something else I never grokked, how d…

The density is actually lower than the sun in magnetic confinement fusion (MCF) devices because we can’t squeeze plasma together as hard as the sun’s mass can. Inertial confinement fusion (ICF) can squeeze harder than MCF devices, but has serious unaddressed engineering issues. The trick is in higher temperature plasma. The sun fuses protium (lone protons). We don’t have the confinement necessary on Earth to do this,…

The trick is that deuterium (and tritium) are vastly more reactive than ordinary protons. The fusion of the latter is extremely slow, because it involves the weak nuclear interaction to convert a proton to a neutron.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#108

I never quite understood the math behind power densities in a fusion reactor. In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW? Is the density of the plasma so much higher in a fusion reactor? Also, something else I never grokked, how d…

The sun "burns" ordinary hydrogen. The first step in this proton-proton-chain is the reaction of two protons to a deuteron, which requires conversion of one of them into a neutron. This is an interaction of the weak nuclear force, which has very small range, so it is slow. Reactions considered for terrestrial fusion don't require the weak force, and consequently won't run on pure hydrogen.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#109
post #94
post #88

Earlier quoted context omitted.

How so? Unlimited, non-radioactive fuel and inherent safety of the system alone could tip this scale pretty severely in favor of fusion once it becomes energy-positive. And remember, once that happens, investment is going to be through the roof, which will accelerate progress. Either the "scientific community" (whatever that means) is either too pessimistic about this, or you've just made this up.

It was my understanding that fission and fusion both use the same Nuclear Power Plant sized facility. Fusion just replaces the radioactive bit, you still need steam/electricity conversion/transmission/cooling... it's not like a suitcase you can plug wires into, you still need a massive 'factory' to make electricity, just the one bit is a safer.

Just the little bit responsible for Chernobyl and Fukushima is not a part of the design at all. No big deal. :-)

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#110

I never quite understood the math behind power densities in a fusion reactor. In the sun, isn't energy production occurring at something like 100-1000 W/m3? So, if you want to build a multiple MW fusion plant, shouldn't these plants be ridiculously huge compared to, say, a wind turbine rated at a couple of MW? Is the density of the plasma so much higher in a fusion reactor? Also, something else I never grokked, how d…

>The plasma heats up, but how do you turn that into useful electrical energy? I appreciate that many people are commenting 'you couple the plasma to a working fluid', but I think the original comment was more along the line of how you couple a confined plasma to a working fluid. By definition the plasma is in a hard vacuum, magnetically bottled. What, then, is the coupling method? Thermal photons escaping confinement…

80% of the energy from DT fusion comes out as neutrons, which enter a blanket and deposit energy there by collisions and nuclear interactions.
Post reply on HN