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from the more-then-just-a-fission-expedition dept.
Arthur T Knackerbracket has found the following story:
The road to cleaner, meltdown-proof nuclear power has taken a big step forward. Researchers at NRG, a Dutch nuclear materials firm, have begun the first tests of nuclear fission using thorium salts since experiments ended at Oak Ridge National Laboratory in the early 1970s.
Thorium has several advantages over uranium, the fuel that powers most nuclear reactors in service today. First, it's much harder to weaponize. Second, as we pointed out last year in a long read on thorium-salt reactors, designs that call for using it in a liquid form are, essentially, self-regulating and fail-safe.
The team at NRG is testing several reactor designs [javascript required] on a small scale at first. The first experiment is on a setup called a molten-salt fast reactor, which burns thorium salt and in theory should also be able to consume spent nuclear fuel from typical uranium fission reactions.
The tests come amid renewed global interest in thorium. While updated models of uranium-fueled power plants are struggling mightily to get off the ground in the U.S., several startup companies are exploring molten-salt reactors. China, meanwhile, is charging ahead with big plans for its nuclear industry, including a heavy bet on thorium-based reactors. The country plans to have the first such power plants hooked up to the grid inside 15 years. If they pull it off, it might just help usher in a safer future for nuclear power.
-- submitted from IRC
(Score: 3, Disagree) by zeigerpuppy on Saturday August 26 2017, @01:36AM (7 children)
Liquid fluorine salt reactors are an interesting concept but beware of the misinformation about them.
First, let's start with the positives: they can burn low enriched fuel and have fast neutrons capable of 'burning' (splitting) some long lived transuranics. This is potentially useful for processing spent nuclear fuel. They also have a negative temperature coefficient meaning that if they get too hot the reaction slows. The fuel is the coolant which makes heat exchange relatively simple.
However, they also have some really difficult limitations. Fission poisons (fission products that build up and prevent further reactions) need to be removed from the working fluid. Thus means that they need an external loop and constant chemical separation. This drops efficiency and also results in a very difficult chemical separation problem. Handling hot, heavy, radioactive fluids is very hazardous. And the fluid in a fluoride salt reactor is very corrosive too. So we've effectively turned some nuclear safety benefits into some major chemical management headaches that also happen to be radioactive. It'll be hugely expensive if it works and probably not very efficient for power generation. It can also be used to generate plutonium quite easily, just feed in uranium instead of thorium. In fact it needs plutonium to kick start the reaction.
These reactors may prove useful for consuming spent fuel but we should have learnt our lesson by now; renewables like solar thermal and large scale wind and wave are cheaper, require less ongoing transport of materials, can be built by people with existing skills and don't cause a large part of a state to be unusable in perpetuity when they fail. The current challenge for the nuclear industry is safely decommissioning all the reactors that are past their safe lifetime, there are more than 20 Mark 1 GE boiling water reactors in the US with the same known failure modes as the Fukushima reactors. But you wait, Westinghouse already went bankrupt, these companies will leave the multi-billion dollar bills for cleanups to the government. Nuclear was a nice dream but it's dead and not soon enough. Ps. I wholeheartedly support the other nuclear technology: fusion. But for now build as many solar thermal plants as possible. . They also use molten salts if it makes you happy...
(Score: 2, Disagree) by PocketSizeSUn on Saturday August 26 2017, @04:30AM (3 children)
Yes .. and if the earth only had 4x the surface area it does ... we could cover it with solar panels and actually meet the current energy demand.
Or are you planning to reduce demand by 3/4 or maybe 7/8th ... or realistically by 19/20th? We could theoretically meet demand 1/20th if the world energy demand using only renewable sources.
(Score: 2, Touché) by khallow on Saturday August 26 2017, @06:15AM (2 children)
We'd have to increase current demand by three or four orders of magnitude to consume that much electricity. Do the math.
(Score: 2) by PocketSizeSUn on Saturday August 26 2017, @10:20AM (1 child)
https://en.wikipedia.org/wiki/World_energy_consumption [wikipedia.org]
-> 109,613 TWh / year or 12.5 TWh/h is the 2014 world energy usage.
https://en.wikipedia.org/wiki/Solar_energy#Electricity_production [wikipedia.org]
-> 3.5 to 7 kWh/m2 per day. [Using 5kWh for a world wide avg, which is optimistic]
Earth land area: 510.1 million km2
earth * 5 / 24 -> kWh of solar radiation (per h).
kWh/h 106270833333333 of solar -> 106.3 TWh/h
Decent PV@20% efficient -> 21.3 TWh convertible to grid.
So every m2 of the entire land area of the earth is just a little bit over current demand.
I don't think that's going to work. YMMV.
(Score: 1) by khallow on Saturday August 26 2017, @03:12PM
The sanity check here is that while a modest fraction of global generation of power is done via solar or wind (like a few percent), the surface area of Earth devoted to these means of power is extremely small in comparison. That indicates solar power, which drives both, is a lot bigger than our production of relevant energy.
(Score: 5, Interesting) by Aiwendil on Saturday August 26 2017, @08:50AM (2 children)
Since you already have a hot online processing plant you could also use the 22 day window to separate out the Pa233 and wait for it to decay to U233.
U233 is in many regards quite similar to Pu239 including being the other commonly suggested initial-load (and is the intended driver fuel) for Th reactors (you could also use HEU as initial load).
(Or one could just use a design that has better neutron economy)
There are quite a few reactor designs that can be safely built by people able to build ships, quite frankly all but the most pushing-the-envelope reactors can be built like this (however - most countries requires a few magnitudes more safety than is needed). Some reactors (CANDU, maybe PIUS) even was designed with this in mind.
TIL that perpetuity is 3-60 years. Just a quick FYI, they are considering _partially_ lifting the madatory evacuation order for Futaba (the town neighbouring the Fukushima-I plant to the north, and yes, that is the "ghost town" used in most scary-media-stuff).
Not really a challange; get permits [ok, this is hard] and then just defuel it, hire a few guards and you're done (Ågesta is currently used as a (non-nuclear) training area for the fire department, the reactor is still there but they don't have access to it).
If you also want dismantling wait 20-120 years (, maybe send in a robotic unit to wash the insides), and then send in a robotic cutter (kinda like how they are doing at Sellafield right now) and later dismantle it like any other chemical plant.The issues are impatient people that also insist on dismantling (never heard/seen why they do that)
Also, the reactors are still within their safe lifetime - most of then are safer today than when they're were built. (We havn't found the upper safe or technical lifetime for reactors yet, we just know it is _at_least_ 25 years if you don't do any upgrades or more than basic maintenance. Pretty much all powerreactors have had extensive upgrades).
Add a release-filter and the releases are cut to some 3% (the swedes tried to sell such to the japanese in the 90s, the japanese didn't buy, now those filters are a requirement for BWR restarts in japan), have nearby portable generators and/or change the main pressure valves (to modern design) to non-electric to really lower the risk of entering the same failure mode.
(Score: 2) by zeigerpuppy on Saturday August 26 2017, @04:32PM (1 child)
I would challenge the assertion that they're safer today. Embrittlement of the reactor vessels which raises the transition temperature (from ductile to brittle) is a significant issue. There have been some reports that this played a part in the meldown/through of Fukushima 1 as the cooling was too fast initially.
(Score: 2) by Aiwendil on Saturday August 26 2017, @05:43PM
The Fukushima I 1-4 (1&2 in particular) was severly neglected in terms if upgrades and inspections - to the point where they wouldn't have passed inspection in some countries.
But yeah, I agree that a fast cooldown (or ramp-up) probably would be a potential issue, but newer instrumentation and control (outside of japan that tends to be upgraded every 20-30 years, with the new policies japan will be in line with the rest of the world) would assert better control on the cooldown and thereby increase margins. (They are less safe than what a newly built Mark 1 with modern control would; be but yet safer than what a 1960s/early 70s reactor with that era's control was).
(Fun thing here btw - older reactor pressure vessels[RPV] actually had a lot bigger margin of error than modern RPVs has, mainly due to cruder understanding made the designers err further into the side of caution)