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New records on Wendelstein 7-X

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Re: New records on Wendelstein 7-X

#61

Post by api »

sheepscreek wrote: post #53
StevenWaterman wrote: post #7

Earlier quoted context omitted.

Your question reminds me of the image showing how SpaceX raptor motors evolved https://imgur.com/a/4w3q3lS

Wow - beautiful. So there is hope! As someone unfamiliar with the challenges of mechanical engineering, I’ve often wondered at the complexity of fusion reactors. This picture puts a lot into perspective. Thanks for sharing!

Current fusion reactors are also studded with a ton of sensors and adjustments and injection ports and such that might not be present in a production reactor. They are experimental platforms, more like scientific instruments for studying the problem domain than production systems.

Re: New records on Wendelstein 7-X

#62

Post by riffraff »

smallerize wrote: post #49
Analemma_ wrote: post #42

Earlier quoted context omitted.

I thought the expectation was that actually-operating fusion plants would operate in pulses rather than continuously, but I could be misremembering.

Toroidal reactors have to operate in pulses. Stellarators can be operated in steady-state (although sometimes they are pulsed to achieve higher energy).

But don't you need to "refuel" now and then?

Re: New records on Wendelstein 7-X

#63

Post by tetha »

riffraff wrote: post #62
smallerize wrote: post #49

Earlier quoted context omitted.

Toroidal reactors have to operate in pulses. Stellarators can be operated in steady-state (although sometimes they are pulsed to achieve higher energy).

But don't you need to "refuel" now and then?

W7x has a pellet injection system now.

This is shared in the better article here: https://www.ipp.mpg.de/5532945/w7x

> During the record-setting experiment, about 90 frozen hydrogen pellets, each about a millimeter in size, were injected over 43 seconds, while powerful microwaves simultaneously heated the plasma. Precise coordination between heating and pellet injection was crucial to achieve the optimal balance between heating power and fuel supply.

Re: New records on Wendelstein 7-X

#64

Post by Retric »

pama wrote: post #22
bradleyy wrote: post #12

In any future fusion power plant, a plasma with a high triple product must be maintained for long periods. I love vague terms like "long periods". Long compared to the Planck length? Geological time? Is the advertised 43 seconds almost there or "off by 17 orders of magnitude?"

I agree vague language in popular press is sometimes annoying. “Off by 17 orders of magnitude” would be off by 136 billion years, so not that much for sure. Assuming you want to be able to test the plant and or maintain it once per year, 43 seconds is less than 6 orders of magnitude off. The jump was more than a full order of magnitude compared to past records, so another handful such developments and we are there.

Even 1 hour of stability with a relatively short restart period (under 5 minutes) would be fine with a battery system assuming the rest of the power plant was cheap enough to build and operate.

Nuclear already gets taken offline for several weeks for refueling, but redundancy covers such issues.

Re: New records on Wendelstein 7-X

#65

Post by Cthulhu_ »

IlikeKitties wrote: post #14
ortusdux wrote: post #8

Earlier quoted context omitted.

I'm not keen on the idea of applying a 'keep subtracting things until it blows up' mentality to fusion reactors.

I mean, it's expensive but there's nothing that can happen, they just stop working the nanosecond the environment isn't just right.

It'll be expensive, but will it be more expensive than the costliest disaster ever, Chernobyl, which apparently cost (is costing) $700 billion to contain / clean up?

Re: New records on Wendelstein 7-X

#66

Post by IlikeKitties »

Cthulhu_ wrote: post #65
IlikeKitties wrote: post #14

Earlier quoted context omitted.

I mean, it's expensive but there's nothing that can happen, they just stop working the nanosecond the environment isn't just right.

It'll be expensive, but will it be more expensive than the costliest disaster ever, Chernobyl, which apparently cost (is costing) $700 billion to contain / clean up?

No,... so?

Re: New records on Wendelstein 7-X

#67

Post by grumbelbart »

ars wrote: post #59
HarHarVeryFunny wrote: post #37

Earlier quoted context omitted.

I think gravitational confinement is the way to go - it's the only operationally proven design! Gotta think big!

It has density issues though. If you had a piece of the sun the size of a huge power plant - like enormous, the power output would be too low to be useful.

Mandatory: We should build it in space and beam the electricity back to earth using electromagnetic waves. We could collect those using solar cells. And then get rid of the plant and use the sun instead.

Re: New records on Wendelstein 7-X

#68

Post by JumpCrisscross »

empath75 wrote: post #23
apples_oranges wrote: post #3

Looking at the picture, I wonder if complexity of these devices will significantly be reduced once it finally works. I assume a lot of the bells and whistles are needed to find the way, but once it's found..

The real problem with fusion power is that even if they figure it out, it still won't be cost competitive with solar and wind. Economically all the cost of building a "boil some water and turn some turbines" plant is _already_ in the "boiling some water and turning some turbines" part of the generation, and even if the heat part of it was _free_, the rest of it would be too expensive to bother building a plant for it…

> real problem with fusion power is that even if they figure it out, it still won't be cost competitive with solar and wind

This is difficult to say when comparing an emerging technology with an established technology in an emerging economy.

Based on every historical prior, it would be surprising if there weren't diminishing returns to solar and wind. And I wouldn't underestimate the degree to which power is, in part, fashion. Today we value emissions. Tomorrow it may be preserving and expanding wild spaces.

On a practical level, fusion research doesn't compete with solar and wind deployment. Pursuing both is optimal.

Re: New records on Wendelstein 7-X

#69

Post by perihelions »

chris_va wrote: post #48

A better link: https://www.ipp.mpg.de/5532945/w7x?c=5481737 (there is some irony in using the iter.org link for a stellarator announcement) 1.8GJ over 360 seconds, beta of 0.03

> "1.8GJ over 360 seconds"

Not sure if this is contextually obvious to practitioners, but that figure is the "Energy turnover" / "is calculated as the product of injected heating power and plasma duration".

Re: New records on Wendelstein 7-X

#70

Post by perihelions »

philipkglass wrote: post #38
soperj wrote: post #24

Earlier quoted context omitted.

they have fission reactors that have done that since the 60s (CANDU Reactor). They just don't help you produce nuclear bombs...

CANDU has low intrinsic nuclear proliferation resistance. It can run on natural uranium, so it's easier to fuel than light water reactors which need enriched uranium, and its online fuel-swapping design means that it's easy to switch to low-burnup operation for generating weapons grade plutonium. Current CANDU power reactors have extensive monitoring to confirm that they are used peacefully, but if e.g. South Korea h…

It's topical that India's nuclear weapons program was started up with a Canadian-supplied heavy water reactor (though not CANDU; a not-power-generating type).

https://en.wikipedia.org/wiki/CIRUS_reactor

> "Canada stipulated, and the U.S. supply contract for the heavy water explicitly specified, that it only be used for peaceful purposes. Nonetheless, CIRUS produced some of India's initial weapons-grade plutonium stockpile,[6] as well as the plutonium for India's 1974 Pokhran-I (Codename Smiling Buddha) nuclear test, the country's first nuclear test.[7]"

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