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Japan Pictures Likely Show Melted Fukushima Fuel for First Time

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Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#111

Post by WalterBright »

mikeash wrote: post #110
WalterBright wrote: post #105

Earlier quoted context omitted.

All that shows is people are spectacularly bad at assessing risks. Many people, for example, are terrified that what happened in today's headline will happen to them. But the reason it is a headline is it is rare. The mundane deadly things that are very likely to happen to you are not reported in the paper.

The thing that always fascinates me is how people constantly bring up the long lifespan of nuclear waste, while ignoring the essentially infinite lifespan of many forms of toxic chemical pollution. Tell people that the mercury that comes out of a coal plant will outlast the Earth itself, and you get a shrug. Tell them that nuclear waste will remain dangerous for 10,000 years and suddenly it's a Big Problem that needs…

The other thing about a half-life of 10,000 years is it means the actual radiation is very, very small. If it was large, it wouldn't last 10,000 years.

The way to make nuclear waste safe is not to concentrate it and bury it. It's to disperse it in such low concentrations that it doesn't make any difference.

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#112

Post by marze »

nate_meurer wrote: post #100
marze wrote: post #94

Earlier quoted context omitted.

You don't need cladding on a simple light pipe. Did they consider non-electronics solutions? Who knows. It may be the sooner they discover where the fuel went, the sooner they need to start spending the $80B to dig it out. So slow is a feature.

Where'd you get that idea? :) You absolutely would need cladding on a light pipe, and lots of it. All kinds of optical materials are subject to darkening, clouding, and embrittlement by much lower levels of ionizing radiation than exist in the reactor [0]. Again, here we're talking about tremendous amounts of radiation over much of the pipe's length, so even small amounts of damage per unit length are going to quickl…

I see the problem, you are misunderstanding the proposal. I suggested using optics for imaging, and fiber to bring in illumination. You'd have a telescope-like camera at the far end. No image transmission through a fiber bundle. You would need refractive elements that would work in the high radiation environment.

As for the illumination, collimated light down a polish steel tube would obviously work, but a rod of glass should work as well.

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#113

Post by [deleted] »

nate_meurer wrote: post #100
marze wrote: post #94

Earlier quoted context omitted.

You don't need cladding on a simple light pipe. Did they consider non-electronics solutions? Who knows. It may be the sooner they discover where the fuel went, the sooner they need to start spending the $80B to dig it out. So slow is a feature.

Where'd you get that idea? :) You absolutely would need cladding on a light pipe, and lots of it. All kinds of optical materials are subject to darkening, clouding, and embrittlement by much lower levels of ionizing radiation than exist in the reactor [0]. Again, here we're talking about tremendous amounts of radiation over much of the pipe's length, so even small amounts of damage per unit length are going to quickl…

[deleted]

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#114

Post by fit2rule »

Boothroid wrote: post #43

A common response from defenders of nuclear when concerns are raised is to point to the impact of other energy sources, and say that nuclear is better in those terms. But I just cannot get away from the thought that whilst in aggregate those other forms of energy (fossil fuels, etc) might be provably worse than well managed nuclear within a particular analysis, humanity does not seem capable of this good management o…

> fossil fuels they don't have the same potential to go quite so spectacularly bad

No, that's not quite right. In fact with all oil-based energy consumption, we get harmful particles. And its worse, because: oil-based consumption is massively distributed, and it is therefore harder to turn off.

Apropros management of energy, we humans are surrounded by free energy we haven't yet learned to manage. If we will perish because of oil-greed, then the lesson learned in all of this is that we must continue to go "local" in production and consumption.

(Myself, I'd be happy to transition to 100% solar-power, and I de-incentivize my own personal oil consumption, i.e. I ride a bicycle to work.)

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#115

Post by ohyes »

Boothroid wrote: post #43

A common response from defenders of nuclear when concerns are raised is to point to the impact of other energy sources, and say that nuclear is better in those terms. But I just cannot get away from the thought that whilst in aggregate those other forms of energy (fossil fuels, etc) might be provably worse than well managed nuclear within a particular analysis, humanity does not seem capable of this good management o…

See: global warming. Things are about to go very wrong with fossil fuels / you might say they already have.

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#116

Post by mikeash »

WalterBright wrote: post #111
mikeash wrote: post #110

Earlier quoted context omitted.

The thing that always fascinates me is how people constantly bring up the long lifespan of nuclear waste, while ignoring the essentially infinite lifespan of many forms of toxic chemical pollution. Tell people that the mercury that comes out of a coal plant will outlast the Earth itself, and you get a shrug. Tell them that nuclear waste will remain dangerous for 10,000 years and suddenly it's a Big Problem that needs…

The other thing about a half-life of 10,000 years is it means the actual radiation is very, very small. If it was large, it wouldn't last 10,000 years. The way to make nuclear waste safe is not to concentrate it and bury it. It's to disperse it in such low concentrations that it doesn't make any difference.

That's too far the other way. Material that's safe in 10,000 years (which means the half-life is significantly less) is highly active and not something you want to hang out with unless it's shielded. The longer-lived stuff isn't all that great either when it gets inside you. Being near a bunch of uranium is fine, but breathing it in is considerably less fine.

Several countries tried your approach around the middle of the last century, pulverizing large amounts of radioactive material and dispersing it into the atmosphere. The results weren't catastrophic, but thousands did die from it.

We shouldn't be irrationally fearful of nuclear waste, but we shouldn't be completely blase about it either. The stuff is dangerous... just not dangerous on a level beyond anything else out there, the way many treat it.

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#117

Post by WalterBright »

mikeash wrote: post #116
WalterBright wrote: post #111

Earlier quoted context omitted.

The other thing about a half-life of 10,000 years is it means the actual radiation is very, very small. If it was large, it wouldn't last 10,000 years. The way to make nuclear waste safe is not to concentrate it and bury it. It's to disperse it in such low concentrations that it doesn't make any difference.

That's too far the other way. Material that's safe in 10,000 years (which means the half-life is significantly less) is highly active and not something you want to hang out with unless it's shielded. The longer-lived stuff isn't all that great either when it gets inside you. Being near a bunch of uranium is fine, but breathing it in is considerably less fine. Several countries tried your approach around the middle of…

There's also a considerable difference between the poisonous chemical properties of heavy metals, which will persist, and their radioactive danger.

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#118

Post by frik »

nate_meurer wrote: post #81
marze wrote: post #6

I still don't see why they are spending years trying to make rad hard robots. A long steel tube with fiber optics to pipe in light, mirrors and optics to transmit an image down the tube would be infinitely easier. They'd need to burn a few holes, but none of the reactor vessels are intact so that wouldn't allow additional radioactive material to escape. I'm surprised the Japanese decision to dump the all the tritium…

Honest question: do you really think they haven't thought of this? You think that none of these engineers and scientists have yet thought of your shielded fiber optics idea? I'm not trying to be mean, I'm really curious. Radiation shielding is a hard problem. For meaningful reduction of xray and gamma radiation in this environment, we're talking inches of lead cladding [0]. And even that won't ensure a useful lifespa…

* Fiber cables (that OP and I wrote) means a cable made out of glass - no problem at all for radiation. (face palm #1)

* You can transfer light through such cables. This means you use one cable to send light into the scene and another cable to see to the scene. Please just look up how endoscopy works for many many many decades, long before computers were a thing. (face palm #2) You probably have a SPDIF connector at your home entertainment devices. Have a look at the fiber cable and hold it against a light or look through it, to get the idea. https://en.wikipedia.org/wiki/S/PDIF (it's about a single fiber cable, not a multi-fiber cable that is nowadays more common)

* Endoscopes are operated with wires, mechanical wires operated by a human (or could be by low tech remote pneumatic construct many feets away from the scene) - just look up endoscop (face palm #3)

So a low tech solution would work in such environments, though it's not as news worthy and not as cool as some robots, but it would be useful for a long time, not die at all.

I am surprised by the lacking education here, unfortunately the site got mainstream and attracted average joes from everywhere - with even basic education like in physics and mechanical engineering we could have a proper conversation here. Even CS and startup topics are now littered by corporate drones and fanboys of minor things. Maybe different tags/channels would help to channel the news.

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#119

Post by kalleboo »

mercurysmessage wrote: post #8
krapp wrote: post #5

Earlier quoted context omitted.

We've seen pictures of the melted core of Chernobyl too (the "Elephant's Foot") havent' we?

Yes, and here is an article and a pretty scary shot from the Elephants foot. http://rarehistoricalphotos.com/the-elephant-foot-of-the-che... I couldn't find if robots were used here, but I'm sure more were later.

Your link says

> From a safe distance, workers – or “liquidators” as they were called – rigged up a crude wheeled camera contraption and pushed it towards the Elephant’s Foot

Re: Japan Pictures Likely Show Melted Fukushima Fuel for First Time

#120

Post by itchy_eyelids »

Boothroid wrote: post #43

A common response from defenders of nuclear when concerns are raised is to point to the impact of other energy sources, and say that nuclear is better in those terms. But I just cannot get away from the thought that whilst in aggregate those other forms of energy (fossil fuels, etc) might be provably worse than well managed nuclear within a particular analysis, humanity does not seem capable of this good management o…

Historically I was a supporter of nuclear power, but as time has gone on, I've been questioning this.

My belief in the technology hasn't changed. It's my belief in humanity that has faltered.

It's not the technology that needs improvement before it can be safely used.

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