back

by ortusdux·1y ago·view on hn ↗
I'm not keen on the idea of applying a 'keep subtracting things until it blows up' mentality to fusion reactors.
7 comments
I wouldn't be concerned about this, personally, for the precise reason that it is a fusion device - not fission!

Fusion is incredibly difficult just to start, let alone keep burning - unlike fission, which is only too happy to enter runaway conditions if not very carefully regulated. Fusion is like a little ember in your fireplace you have to carefully blow on to keep alight; fission is like keeping a fireplace lit by pouring gasoline into it.

I'd say (older-generation) fission is more like having an indoor swimming pool filled with burning gasoline, but keeping the windows shut so there's only enough air for it to burn at the rate you want to heat the house.
Or a swimming pool full of those spicy rocket propellents discussed in the book Ignition! which have combustion products like hydrogen fluoride.
Neither of the hypergolics described in Command and Control seem chill either: the fuel reacts with atmospheric water and oxygen, the oxidizer is in the highest category of poison (https://www.penguinrandomhouse.co.za/extracts/command-and-co...).

Indeed there's no such thing as a free launch, and that is rocket science.

"Things I will not work with" - "at this point hydrogen fluoride loses its gentle nature".
Would love to take a look at your library.
Not the poster above, but as someone who also has a copy of Ignition! in their library, I think you might enjoy the pdf version:

https://library.sciencemadness.org/library/books/ignition.pd...

You could probably summarize the history of bridge-building as "keep subtracting things until they don't stand up anymore."

Building bridges (and large structures in general) has always been about the tension between over-engineering (for safety) and under-engineering (for cost/aesthetics).

The Brooklyn Bridge is massive; they'd never built a bridge like that so they over-engineered it. But once they saw that it was more than strong enough to stand up, the next bridge was lighter. And the next one after that was even lighter. And so on, until a bridge collapses because some new factor came into play (e.g., harmonic resonance).

Source: To Engineer Is Human by Henry Petroski--one of my favorite engineering books.

When I was an engineering summer intern at HP, they had all the interns do a side project of building a bridge (model sized). The designs would be judged by stacking bricks on the bridges and then dividing the max count of bricks before failure by the weight of the bridge. Most interns, myself included, over engineered our designs. One intern “got it” and submitted a bridge that was built out of just a few pieces of balsa wood. It only held one or two bricks before snapping, but it was ultra-light and won the competition. That exercise always stayed with me. Engineers always need to focus on the correct priorities and understand when “enough is enough.”
Not read the book but I thought the Brooklyn Bridge was over specified on the wire strength because they knew the corrupt supplier would circumvent quality control to supply them with substandard material.
That's not what they're doing though. Reducing manifolds actually improves the durability.
The nice thing about fusion reactors is that they don’t blow up but just don’t work anymore.
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 had a security crisis and decided to pursue a crash nuclear weapons program, world opinion be damned, its CANDU based reactors at Wolseong could be quickly reconfigured for weapons purposes:

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

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]"

I dunno dude, if you fuse tritium and deuterium it does make neutrons.
You should be keen on that idea. Simpler designs are usually more reliable. And a fusion reactor doesn't really blow up. It's hard enough to make it do something.
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?
Fusion is incredibly safe with none of the risks of runaway reactions like in fission.