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First contact made with melted nuclear fuel at Fukushima plant

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Re: First contact made with melted nuclear fuel at Fukushima plant

#71

Post by m_mueller »

ChuckMcM wrote: post #17

While I realize it was likely impractical to meltdown reactors just to develop the technology to clean them up, I find the process here pretty interesting. A lot of good engineering has gone into the effort, and the engineering challenges (and risks) of post runaway reactors has gotten a lot more data. The Chernobyl folks just entombed everything, which is a one approach, even though they can "walk up to"[1] the rema…

Obviously it couldn’t melt through to China but AFAIK the way Czernobyl played out was that they had to somehow stop it from melting down to a flooded basement due to the fear of a long lasting series of hydrogen explosions that could have been truly disastrous for the region, if not Europe. Thus I think that the true worst case has so far never happened: A reactor without any of the modern safeguards (such as boronic sand pits) melting down to groundwater. Though, I guess subcritical core melts would not lead to hydrogen explosions, rather the creation of a lot of steam - it would be interesting to know how likely such a worst case would be and whether any of the world‘s reactors are configured to make this possible. Incredibly, 10 Chernobyl-type RBMK reactors are still in service.

Re: First contact made with melted nuclear fuel at Fukushima plant

#72

Post by aurailious »

hanniabu wrote: post #43
aurailious wrote: post #25

Earlier quoted context omitted.

So a mixture of unreliable, expensive, and "20 years from now".

With many recent breakthroughs, fusion is now seen as very viable and just needs funding to finish it off. The last of the hard problems are solved and they just need to pull it all together and "adjust for rounding errors", so to speak.

ITER won't become fully operational until 2035 and that is just for conducting experiments. We are still decades from commercial fusion power plants.

Re: First contact made with melted nuclear fuel at Fukushima plant

#73

Post by lucb1e »

petschge wrote: post #62
lucb1e wrote: post #31

Earlier quoted context omitted.

> ... and people still ask if nuclear might not be as bad as coal! That's playing on feelings rather than making a rational argument. Regardless of whether I am for or against widely deploying nuclear energy, this is not the way to talk about it and create informed opinions. The media are already doing their best to play on feelings on this topic, we don't need to replicate that here.

The logical argument is that we still do not have a good way to deal with the radioactive waste and that a lot can still go wrong in the next million years.

And another logical argument could be that this causes us to delay cutting emissions enough to prevent massive ecosystem changes resulting in humanity's death in the next few hundred years.

It's just not that simple. We need to look at both sides, weigh the options, and find a solution which probably involves a mix where we compromise on having X m³ of earth dedicated for a long time to nuclear waste to save us in the short term. I'm not informed enough to give exact figures and make proper arguments, but reiterating known one-liners won't get us anywhere.

Re: First contact made with melted nuclear fuel at Fukushima plant

#74

Post by petschge »

m_mueller wrote: post #71
ChuckMcM wrote: post #17

While I realize it was likely impractical to meltdown reactors just to develop the technology to clean them up, I find the process here pretty interesting. A lot of good engineering has gone into the effort, and the engineering challenges (and risks) of post runaway reactors has gotten a lot more data. The Chernobyl folks just entombed everything, which is a one approach, even though they can "walk up to"[1] the rema…

Obviously it couldn’t melt through to China but AFAIK the way Czernobyl played out was that they had to somehow stop it from melting down to a flooded basement due to the fear of a long lasting series of hydrogen explosions that could have been truly disastrous for the region, if not Europe. Thus I think that the true worst case has so far never happened: A reactor without any of the modern safeguards (such as boroni…

Part of that problem is that water is actually a decent moderator and neutron reflector, so it helps a lot in keeping a chain reaction with lots of energy output going. Some of the energy also goes into splitting water into hydrogen and oxygen. The hydrogen can then collect in some corner of the building until it reaches an concentration where it explodes rather easily. The explosion can then damage the building, ruining containment and scatter radioactive material around. Moral of the story? Keep your box of boronic sand nice and dry.

Re: First contact made with melted nuclear fuel at Fukushima plant

#75

Post by roenxi »

mikro2nd wrote: post #41
acidburnNSA wrote: post #21

Earlier quoted context omitted.

If you look objectively at the numbers, you'll see that nuclear is one of the safest forms of energy production we know. Even considering conservative estimates from Fukushima and Chernobyl, nuclear power has net saved over 2 million lives simply by displacing air-pollution related deaths that would have occurred had the nukes not been built. Coal kills on the order of hundreds of thousands of people per year. Fukush…

I don't know how nuclear can be considered remotely "carbon free" if you take into account the usually-externalised emissions incurred in mining, refining and processing the uranium ores into fuels. Then, too, I've seen no figures on the carbon costs of nuclear waste-management.

Australian mining engineer here. Based on some pretty basic evidence [0] I'd assume uranium mining is several orders of magnitude less damaging than other energy sources, and probably has a decisive "carbon free" advantage over wind and solar once you factor those externalities in.

Australia is a top-3 uranium producer [1], we have 3 mines. That rounds to 0 in Australian mining terms. Olympic Dam is a monster in relative terms, and the production numbers are ... by tonnes Olympic Dam isn't even a uranium mine, it is a copper mine. And Olympic Dam [2] is a world class uranium mine afaik.

[0] https://en.wikipedia.org/wiki/Energy_density

[1] https://en.wikipedia.org/wiki/List_of_countries_by_uranium_p...

[2] https://www.bhp.com/-/media/bhp/documents/investors/reports/...

Re: First contact made with melted nuclear fuel at Fukushima plant

#76

Post by __m »

cpeterso wrote: post #26
ChuckMcM wrote: post #17

While I realize it was likely impractical to meltdown reactors just to develop the technology to clean them up, I find the process here pretty interesting. A lot of good engineering has gone into the effort, and the engineering challenges (and risks) of post runaway reactors has gotten a lot more data. The Chernobyl folks just entombed everything, which is a one approach, even though they can "walk up to"[1] the rema…

> melted core material would just keep melting into the ground until it "got to china" aka "China Syndrome", just like the 1979 film: https://en.wikipedia.org/wiki/Nuclear_meltdown#China_syndrom...

Now that convincingly debunks the China syndrome, China is obviously not the antipode to Fukushima

Re: First contact made with melted nuclear fuel at Fukushima plant

#77

Post by vonmoltke »

folkrav wrote: post #66
tonyedgecombe wrote: post #27

Earlier quoted context omitted.

We shouldn’t be burning coal either.

What we have right now are three options : fossil fuels, renewable sources like wind/solar/hydro, or nuclear. Fossil fuels kill millions a year related to pollution, and does make whole areas unlivable. About 16% of all fracking oil in the US gets spilled in nature every year[1], on top of crap like Flint. Coal is responsible for 80% of energy-generated related air pollution, worldwide[2]. They are not a good solutio…

> on top of crap like Flint

Flint's water contamination has absolutely nothing to do with energy production of any kind. It was caused by the city still having lead water pipes.

Edit:

> About 16% of all fracking oil in the US gets spilled in nature every year[1]

> [1] https://www.bbc.com/news/science-environment-39032748

That isn't at all what that article says. It says 16% of wells suffer a spill each year. The industry would never allow 16% of its product to simply go to waste, particularly considering how difficult and expensive those operations are.

Re: First contact made with melted nuclear fuel at Fukushima plant

#79

Post by ChuckMcM »

pvaldes wrote: post #46
ChuckMcM wrote: post #17

While I realize it was likely impractical to meltdown reactors just to develop the technology to clean them up, I find the process here pretty interesting. A lot of good engineering has gone into the effort, and the engineering challenges (and risks) of post runaway reactors has gotten a lot more data. The Chernobyl folks just entombed everything, which is a one approach, even though they can "walk up to"[1] the rema…

> the "China Syndrome" speculation is pretty much completely debunked You would be dissapointed. Cou-cou! surprise! The ocean strikes back!. Unexpected source of Fukushima-derived radiocesium to the coastal ocean of Japan. 2017. Sanial, Buessler, Charette, and Nagao. PNAS. DOI:10.1073/pnas.1708659114 "Sanial, Buessler, Charette and Nagao, scientists from Massachusetts and Japan found a new source of Caesium-137 to th…

That is a great paper[1], thanks for the reference I've added it to my nuclear effects library.

It doesn't involve the China Syndrome speculation though, what it does find is much much more interesting.

The paper reports that beach sand is capable of 99% adsorption of Cs137. And then goes on to discuss how it gets de-adsorbed (up to 11%) when Cs137 free sea water is mixed with it. What this says to me is that you can use really cheap beach sand to filter the discharge water from a nuclear reactor and collect 99% of the Cs137 in the water which will stick to the sand. The sand in your filter can be replaced and the cesium rich sand can be sequestered for the Cs137 to decay over time.

This is an excellent finding that suggests reactors have a reservoir of sand for pumping cooling water through especially during reactor compromise. Knowing this a future even would release significantly less Cs into the ocean, collecting it instead in the sand filter.

[1] The experiments showed that beach sands have an adequate ion exchange capacity for this level of 137Cs, with an average adsorption fraction of 99% regardless of the salinity, sediment grain size, or mineralogy (Table S3). ---https://www.pnas.org/content/early/2017/09/26/1708659114

Re: First contact made with melted nuclear fuel at Fukushima plant

#80

Post by varjag »

samstave wrote: post #59
JosephRedfern wrote: post #23

Forgive the macabre question, but if a human (or other living creatue) were to venture in to the plant and collect this fuel by hand, how long would they survive? I'm in no way suggesting that this is an option, of course -- just curious.

You should watch this documentary on Chernobyl: > According to Vyacheslav Grishin of the Chernobyl Union, the main organization of liquidators, "25,000 of the Russian liquidators are dead and 70,000 disabled, about the same in Ukraine, and 10,000 dead in Belarus and 25,000 disabled", which makes a total of 60,000 dead (10% of the 600,000 liquidators) https://en.m.wikipedia.org/wiki/Chernobyl_liquidators They had guys…

I've met a dying Chernobyl first responder on a commuter train in Belarus, back in early 1990s.

These people never made it to WHO statistic as their deaths protracted over many years can not be directly attributed to the accident. As pro nuclear crowd would be happy to tell you, only couple dozen firemen died on the first day and that was it, making nuclear meltdowns almost benign incidents.

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