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Nuclear fusion has encountered a shortage of tritium

wired.co.uk

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Re: Nuclear fusion has encountered a shortage of tritium

#21

Post by areoform »

fffobar wrote: post #14
areoform wrote: post #12

Just a quick reminder, we already have practical fusion with tens of thousands of years of runway available to us today. We choose not to do it because it sounds dangerous and it’s not politically expedient. For those unfamiliar, I am talking about Project PACER. The fusion reactor proposed by Teller after the creation of the thermonuclear weapon. It may sound fanciful but it’s based on a simple precept. We can alrea…

Isn't the problem that the fuse for a fusion bomb is a fission bomb, and a fission bomb very violently disperses lots of radioactive material? What am I not getting?

It’s a sealed chamber underground. And the amount of fallout can be controlled. Some fusion designs are “cleaner” than others w.r.t. fallout.

From the wiki,

> A typical design called for a 4 m thick steel alloy blast-chamber, 30 m (100 ft) in diameter and 100 m (300 ft) tall,[9] to be embedded in a cavity dug into bedrock in Nevada. Hundreds of 15 m (45 ft) long bolts were to be driven into the surrounding rock to support the cavity. The space between the blast-chamber and the rock cavity walls was to be filled with concrete; then the bolts were to be put under enormous tension to pre-stress the rock, concrete, and blast-chamber. The blast-chamber was then to be partially filled with molten fluoride salts to a depth of 30 m (100 ft), a "waterfall" would be initiated by pumping the salt to the top of the chamber and letting it fall to the bottom. While surrounded by this falling coolant, a 1-kiloton fission bomb would be detonated; this would be repeated every 45 minutes. The fluid would also absorb neutrons to avoid damage to the walls of the cavity.

You can see the general design here, https://nextbigfuture.s3.amazonaws.com/uploads/2016/01/zyrEF...

Re: Nuclear fusion has encountered a shortage of tritium

#22

Post by howenterprisey »

If anyone was wondering if SPARC and ARC care about this, SPARC onsite tritium inventory is planned to be fairly low: just 10 grams (not kg) in this 2018 SPARC paper[0]. I would also speculate that 200 kg/year sounds a little bit too high, although I can't find an ARC paper to corroborate (the magic words you want are "total on-site tritium inventory").

[0] https://www1.psfc.mit.edu/research/alcator/pubs/APS/APS2018/...

Re: Nuclear fusion has encountered a shortage of tritium

#23

Post by jandrese »

areoform wrote: post #12

Just a quick reminder, we already have practical fusion with tens of thousands of years of runway available to us today. We choose not to do it because it sounds dangerous and it’s not politically expedient. For those unfamiliar, I am talking about Project PACER. The fusion reactor proposed by Teller after the creation of the thermonuclear weapon. It may sound fanciful but it’s based on a simple precept. We can alrea…

Some of the heartburn about PACER is that there are failure modes that can only be described as catastrophic.

Re: Nuclear fusion has encountered a shortage of tritium

#24

Post by [deleted] »

areoform wrote: post #12

Just a quick reminder, we already have practical fusion with tens of thousands of years of runway available to us today. We choose not to do it because it sounds dangerous and it’s not politically expedient. For those unfamiliar, I am talking about Project PACER. The fusion reactor proposed by Teller after the creation of the thermonuclear weapon. It may sound fanciful but it’s based on a simple precept. We can alrea…

[deleted]

Re: Nuclear fusion has encountered a shortage of tritium

#25

Post by cogman10 »

jandrese wrote: post #23
areoform wrote: post #12

Just a quick reminder, we already have practical fusion with tens of thousands of years of runway available to us today. We choose not to do it because it sounds dangerous and it’s not politically expedient. For those unfamiliar, I am talking about Project PACER. The fusion reactor proposed by Teller after the creation of the thermonuclear weapon. It may sound fanciful but it’s based on a simple precept. We can alrea…

Some of the heartburn about PACER is that there are failure modes that can only be described as catastrophic.

No shit.

Turns out a daily detonation of a fusion bomb tends to wear on things and when those things fail... you've just detonated a fusion bomb.

Re: Nuclear fusion has encountered a shortage of tritium

#26

Post by GuB-42 »

api wrote: post #4
ceejayoz wrote: post #3

Earlier quoted context omitted.

The article covers that. > Tritium breeding was originally going to be tested as part of ITER, but as costs ballooned from an initial $6 billion to more than $25 billion it was quietly dropped. Willms’ job at ITER is to manage smaller-scale tests. Instead of a full blanket of lithium surrounding the fusion reaction, ITER will use suitcase-sized samples of differently presented lithium inserted into “ports” around the…

Oops missed that. ITER is not necessarily the best approach to fusion, although it's the best funded. In any case if we can't breed tritium than we either need to shoot for higher energy D-D fusion or some other reaction or fusion will never be cost-competitive.

Is there any other approach to fusion than ITER?

I mean fusion capable of practical power generation.

D-T fusion is the easiest, and yet super hard. Tokamaks are the only design that we know how to build in order to meet the goal, with maybe stellerators in second position. Inertial fusion work for scientific and military experiments, but are far from being a usable power source. Things like fusors and its derivative are great hobby projects with a few limited practical applications, but we are not even sure if it is physically possible to produce more energy than we put in. As for LENR (aka. cold fusion) we are essentially at the "thought experiment" stage, when it is not a scam.

One other idea that may work with current tech is to dig a large cave, line it with really thick material and detonate hydrogen bombs inside it, extracting energy from the heat of the explosion. I don't think I need to tell you that even if we can do that (unsure), we certainly shouldn't (absolutely sure).

Or, take, advantage of that really big fusion reactor we already have and makes us go around in circles.

Re: Nuclear fusion has encountered a shortage of tritium

#27

Post by ceejayoz »

Victerius wrote: post #6

"Precious tritium is what makes this project go. There's only 25 pounds of it on the whole planet."

> There's only 25 pounds of it on the whole planet.

"Because we haven't needed more until now, and it's mostly man-made."

There wasn't any plutonium on Earth, either, until we decided we needed some.

Re: Nuclear fusion has encountered a shortage of tritium

#28

Post by gfodor »

nh23423fefe wrote: post #18
photochemsyn wrote: post #7

Tell that to the Sun. We already have a fusion reactor sufficient to meet all of humanity's energy needs, it's a gravitationally contained fusion reactor with a projected lifetime of at least one billion years, so why not just rely on that? Seems to have done wonders for the biosphere for the last one billion years, hasn't it?

Instead of asking oblique rhetorical questions, you could actually make a meaningful statement.

It seems like every fusion post is bound to have at least one commenter point out that the sun is a working fusion reactor, as if literally anyone in these threads will learn something from this observation.

Re: Nuclear fusion has encountered a shortage of tritium

#29

Post by marcosdumay »

jszymborski wrote: post #17

I'm not sure about the scale here, but is it really as crazy as the article says to use tritium that is formed from fission? What's the ratio of fusion:fission energy you'd need? I can't imagine even if it was 50% or 25% that it wouldn't be worth doing seeing as you'd just be fuelling a clean energy source from the waste stream of another energy source that doesn't produce CO2.

The reaction is supposed to be self-sustaining. The reactor walls are supposed to emit more than enough tritium to satisfy your needs.

Whatever you bring from outside is just to bootstrap it once you turn it on. (I imagine they are not collecting the tritium between runs, but it's something you are expected to do.)

Re: Nuclear fusion has encountered a shortage of tritium

#30

Post by adgjlsfhk1 »

BurningFrog wrote: post #16
ceejayoz wrote: post #3

Earlier quoted context omitted.

The article covers that. > Tritium breeding was originally going to be tested as part of ITER, but as costs ballooned from an initial $6 billion to more than $25 billion it was quietly dropped. Willms’ job at ITER is to manage smaller-scale tests. Instead of a full blanket of lithium surrounding the fusion reaction, ITER will use suitcase-sized samples of differently presented lithium inserted into “ports” around the…

I'm very unimpressed by the "we must only consider short term solutions to global warming" idea. We don't know the future, and we keep being surprised by it!

if we want to significantly curb global warming, long term solutions aren't where we need to focus effort
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