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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

#111

Post by samstave »

izend wrote: post #81
samstave wrote: post #59

Earlier quoted context omitted.

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…

The accurate number of deaths appears to be very controversial.

Most certainly - I'd expect its way higher.

They were referred to bio-robots.

There are a few documentaries about them. A lot of elderly volunteered to be a bio-robot.

There was one doc that showed them throwing lead bricks into the pit - and they were only capable of being exposed up to like ~2 minutes maximum of something.

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

#112

Post by saagarjha »

petschge wrote: post #107
saagarjha wrote: post #103

Earlier quoted context omitted.

What parts are we missing?

Regulatory capture and "understandings" between supervising authorities and commercial operators that boarder on corruption, unsolved waste problem, very slow ramp-ups and ramp-downs which are annoying for the grid and a lot of things I don't understand well as an astrophysicist either. But both friends I have in the nuclear energy field have become very anti nuclear power and would rather see it shut down tomorrow i…

> there is a rather pro-nuclear crowd on HN here that does not understand enough of the physics and the systems engineering of the large scale electrical grid

Regulatory capture and what's essentially corruption is not "physics and systems engineering", and they should be considered independently of nuclear power's inherent technical merit. And regarding ramp-ups and ramp-downs, I have never heard of anyone suggesting nuclear power for anything other than base load, so I don't see how this would be an issue?

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

#113

Post by acidburnNSA »

Intermernet wrote: post #109
cm2187 wrote: post #104

Earlier quoted context omitted.

Also we should keep in mind that the major incidents involed reactors designed in the 60s/early 70s, when nuclear energy was still very new. It's like wanting to ban planes because of the safety records of planes from the 1930s. It is because plane designs iterated, learning from our mistakes over time, that it became an extremely safe technology.

When were the majority of reactors operating today designed? Serious question. I actually want to know.

1960s and 1970s mostly. Chernobyl was designed earlier. Fukushima was a super early design. The real flaw there was they put the backup generator fuel supply in the basement in a flood zone. The reactor was designed for the US midwest, with tornados in mind as the biggest threat. Moving to Japan, they should have put at least some of the backup fuel above ground level and it would have been fine.

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

#114

Post by vpribish »

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…

10% of an adult population dying over the course of 20 years doesn't seem inherently crazy? The WHO says no more than 4k died due to the accident.

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

#115

Post by eXpl0it3r »

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…

The sad part is that the whole anti-nuclear politics often prevent building new and way safer reactors, yet they also don't manage to force shutdown all the dangers ones.

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

#116

Post by rabidrat »

mimixco wrote: post #98
rabidrat wrote: post #89

Earlier quoted context omitted.

If climate change truly is incompatible with global civilization, I would rather have some defunct coal plants laying around than spent nuclear fuel. Nuclear maybe would have helped us avoid the worst of climate change if we had adopted it at a broader scale sooner, but at this point I think we have to be planning for post-civilization scenarios.

You might want to read "The Moral Case for Fossil Fuels" for a slightly less dire perspective.

Thanks, I'll check it out. I've been watching the shitshow for a few decades now though, and to be honest the only surprising thing is that it hasn't already fallen apart. In my mind it's inevitable, and not just due to fossil fuel usage. We won't change course until it's demonstrably catastrophic and then it will be "too late" for a majority of humans. The only question is, will it happen within 20 years or 50 or 100? Malthus was right in principle, only wrong in timeline.

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

#117

Post by Erwin »

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…

The effects of the Chernobyl radiation are apparently common, that when I left my luggage in the Belorusskaya train station in Moscow I encountered a very large plaque describing exactly what categories of people were allowed to get in front of the queue when retrieving your stored luggage -- with "People suffering from radiation as consequence of Chernobyl" on the list.

If you served in the military for at least 6 months 1941-1945, you were higher on the priority list, which included around 17 different very detailed categories, all translated to English too.

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

#118

Post by notablyconfused »

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…

> 100,000 Bq per square meter

What is the Sievert dose one receives from being permanently exposed to such radiation (ideally expressed as bananas eaten per time)? To the lay person such numbers are useless without some comparison.

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

#119

Post by mempko »

What strikes me is just how inept the Japanese are in handling Fukushima compared to the USSR during the much worse Chernobyl disaster. The USSR responded quickly and it took just 8 months to entomb the reactor. Over 600k people worked to handle Chernobyl. Fukushima, on the other hand, is still at risk of another disaster, 10 years later. The Japanese government and power company under-handled the situation and lied for years about it's severity. For example that 300 tons of polluted water was going into the pacific every day for 5 years.

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

#120

Post by Pharmakon »

meenzu wrote: post #64
roywiggins wrote: post #57

Earlier quoted context omitted.

Gamma radiation goes through everything. The only thing that stops it is mass and distance. You can only wear a certain amount of lead before you collapse. The amount of radiation is just too high.

Thanks for the answer, just curious would the lead sheet have holes thorough it if you put it up to that radiation? I'm picturing a sheet of paper with bullet holes through it. Or is there a better analogy of what is going on?

A lead apron, when exposed to a strong enough source of gamma rays, will be unable to sufficiently attenuate the radioactive flux. It will absorb gamma photons, and then emit a bunch of of them right into you. Radiation shielding has to take into account the total flux, and then it has to be built in layers to a given thickness and overall density. It doesn’t do you any good if the incident radiation is all absorbed, only for 99.9% of the original flux to be re-emitted by the shield!

You can think of it as roughly analogous to the excitation of atoms leading to emission of a photon in the visible range. It doesn’t help to wear a pair of goggles that will absorb all of the light you’re hoping to block, only to have your goggles glow brightly as a result. You’d rightly conclude that you need much thicker goggles, and the same is true here.

No holes needed, and a lot of the original gamma radiation is being absorbed and subsequently emitted, which defeats the point. There are also complications of a substance being exposed to some forms of radiation (primarily neutron) becoming radioactive themselves. It wouldn’t be visible, but it wouldn’t be good either.

A note that shielding, in addition to considering total flux, has to consider the type of radiation. Gamma (very high energy photon) is very penetrating, beta (high energy electron) is less so, and alpha (a helium nucleus) hardly penetrates at all. You also have to consider, in the case of a molten core, other contaminants and radionuclides actually getting on you or in you. Alpha emitters are pretty harmless outside of you, where your skin stops them cold. If you eat or breath them in however, they’re deveststing. So your concern with alpha emitters tends to be covering yourself and wearing a respirator, while that won’t even help a little with gamma.

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