Re: Fusion reactor safe?!!!!
I didn't forget about it exploding in water, I'm just referring to the accidents which HAVE happened.
"Honestly guys, it won't catch fire this time. Promise"
It took 15+ years to clean up the non-radioactive mess from the secondary cooling loop leak and sodium fire at Monju. It wasn't just the fire and 20+ tons of sodium in the basement, it was that the fire was so hot it destroyed the structural integrity of the building by melting most of the steel girders holding things together
Just because something is a "perfect coolant", doesn't make it a "practical coolant", any more than a solid gold frying pan is the best way to achieve the perfect fried egg, despite its wonderful thermal conductivity
More to the point the failing of the molten metal systems is that they _still_ rely on fuel rods and the intrinsic disadvantages of that method such as neutron poisoning/inability to deep load follow.
Alvin Weinberg knew a thing or two about building nuclear reactors when he built the MSRE experiment at Oak Ridge - after all he's the guy who came up with the ORIGINAL DESIGN used on the Nautilus that had been scaled up to obscene Rube-Goldberg sizes for civil power and speciically came up with a better, safer method because of his concerns at the engineering stresses being imposed on steam vessels and the fact that enriched uranium fuelling _RELIES_ on the weaonsmaking proces (plus is 89% wasteful before the reactor even starts, let along the 98% waste of input fuel on the output side - his better mousetrap method reduces output waste by 99%)
His reason for the Nautilus design: It wasn't the best design. It was what could be done with what was available, was entirely self-contained, had an ocean available for cooling and used boilers/turbines so that it could be safely operated by navy guys who understood boilers & turbines. It was not intended for large scale power generation and he was deeply disturbed when industry scaled it up.
Here's a hint on using water in a nuclear reactor: The engineering stresses increase with the cube of power generation capacity. A 10,000hp (8MW) steam boiler as used on a railway locomotive could (and occasionally _did_) level half a city block when it blew and modern 800MWe nuclear boilers are closer to 3200MWt - that's why the containment buildings are so big/solid/expensive and why steam boilers were dumped across industry in favour of internal combustion engines or electric motors wherever possible.
Getting rid of water from the nuclear loop improves safety by several orders of magnitude because you're reducing the steam generator part to a non-nuclear section which can run at 800C instead of 450C (which means you can superheat your steam and run efficient turbines, but also only generate just enough steam as needed, with just enough water as needed and any steam explosion is just a steam explosion, as seen at any convetnional power station). Water is the common factor in just about every civil nuclear reactor accident and incident (the stuff is corrosive as all hell at high temperature and pressure - Diablo Canyon was a very near miss - then there's things like the Nuclear Ouchi incident - handling processes not needed for a MSR, therefore not able to be abused by inexperienced workers not following the manuals)
Getting rid of enriched uranium adds a couple of safety extra factors because reactor fuel/used fuel is incredibly difficult to weaponise (russians and americans both tried making U233 bombs and failed miserably)
Getting rid of water as dangerous means it makes zero sense to introduce a substitute which is dangerous when exposed to air or water or which may leak and shows a reckless mindset on the part of advocates that justifies antinuclear campainers protests. That's the point of Alvin Weinberg's design - it's walkaway safe.
of course thumbs downing MSRs and screaming about how they _might_ be weaponisable seems to be the order of the day because it looks like China's going to be the country cmmercialising them - never mind that existing civil nuclear technology is a PRODUCT of the nuclear weapons industry and by definition if you can build a conventional civil nuclear reactor, you already have the materials onhand to easily build several dozen nuclear weapons should you choose to do so....
Biting the hand that feeds IT
