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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

#131

Post by k4l3 »

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…

I agree with your assessment that it's impractical to meltdown reactors just to learn how to clean them up, but apparently the US government didn't: https://en.wikipedia.org/wiki/BORAX_experiments

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

#132

Post by gus_massa »

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…

> the 137Cs concentrations were incredibly high, up to 480,000 Bq per square meter in their deepest samples.

But is that high? I don't know. Let's make some uninformed back of the envelope calculations. The energy of the Cs137 radiation is 662keV, let's assume a normal person with 100lb and a surface of 2m^2 (only half get the radiation). In a day this person will get https://www.wolframalpha.com/input/?i=480000Bq%2Fm%5E2+*+662... 48uSv per day. [If I didn't make a huge mistake.]

It's like 5 times the normal background radiation, a little more than the radiation you get during a flight in a plane, less than the maximum permitted radiation dose for a worked in a nuclear plant (when there is not an emergency). https://xkcd.com/radiation/

I was expecting a much lower value, but this is still on the side of the safe level (if I didn't make a huge mistake).

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

#133

Post by toomuchtodo »

avar wrote: post #123
toomuchtodo wrote: post #24

Earlier quoted context omitted.

Solar, wind, storage. Fusion at a distance. EDIT: "20 years from now" is still faster than any nuclear generator getting built.

Nuclear power plants take at most 5 years to build from the time we break ground until the reactor's hooked up to the grid. Look at how fast the Chinese are building them, or how fast e.g. the French or the US were at building them in the 60s and 70s. That it takes so long now in the west is because we're not building enough of them, thus losing the advantage of experienced workforces and inability to leverage mass-m…

>Look at how fast the Chinese are building them, or how fast e.g. the French or the US were at building them in the 60s and 70s.

"The country [China] has the capacity to build 10 to 12 nuclear reactors a year. But though reactors begun several years ago are still coming online, the industry has not broken ground on a new plant in China since late 2016, according to a recent World Nuclear Industry Status Report.

Officially China still sees nuclear power as a must-have. But unofficially, the technology is on a death watch. Experts, including some with links to the government, see China’s nuclear sector succumbing to the same problems affecting the West: the technology is too expensive, and the public doesn’t want it."

https://www.technologyreview.com/s/612564/chinas-losing-its-... (China’s losing its taste for nuclear power. That’s bad news.)

> That it takes so long now in the west is because we're not building enough of them, thus losing the advantage of experienced workforces and inability to leverage mass-manufacturing of standardized designs.

Can you provide evidence that the cost of nuclear would be comparable to solar and wind if built at scale?

> It's also slow because of onerous safety regulation seeking to make nuclear too safe, when we consider the result of a slowdown in commissioning of new reactors, thus increasing the reliance on coal killing way more people than if we were to hypothetically mass manufacture relatively unsafe reactor designs from the 60s today.

I'm unsure you can sell nuclear to the public or politicians as "it's expensive because it's too safe". It's unlikely we're going to relax safety regulations when cheaper alternatives already exist (solar, wind, natural gas, storage). We're not increasing our reliance on coal, we're temporarily increasing our reliance on natural gas (which is driving coal and nuclear out of business).

EDIT:

"but pointed out that it taking anywhere near 20 years to build a nuclear power plant is clearly off by an order of 4x at the very least."

I’d prefer nuclear reactors not be built in the developed world to Chinese standards.

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

#134

Post by yongjik »

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…

For comparison:

According to Wikipedia, granite contains 1-20 ppm of uranium [1]. One gram of natural uranium is about 25,280 Bq. Hence, one ton of granite is somewhere between 25,280 - 505,600 Bq.

In other words, if a beach is made of eroded granite, its radioactivity will be between 25,000-500,000 Bq/t: assuming the sand is more than a feet deep, I think it's safe to assume > 25,000 Bq/m^2.

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

> Some granites contain around 10 to 20 parts per million (ppm) of uranium. By contrast, more mafic rocks, such as tonalite, gabbro and diorite, have 1 to 5 ppm uranium, and limestones and sedimentary rocks usually have equally low amounts.

[2] http://www.wise-uranium.org/rup.html

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

#135

Post by avar »

toomuchtodo wrote: post #133
avar wrote: post #123

Earlier quoted context omitted.

Nuclear power plants take at most 5 years to build from the time we break ground until the reactor's hooked up to the grid. Look at how fast the Chinese are building them, or how fast e.g. the French or the US were at building them in the 60s and 70s. That it takes so long now in the west is because we're not building enough of them, thus losing the advantage of experienced workforces and inability to leverage mass-m…

>Look at how fast the Chinese are building them, or how fast e.g. the French or the US were at building them in the 60s and 70s. "The country [China] has the capacity to build 10 to 12 nuclear reactors a year. But though reactors begun several years ago are still coming online, the industry has not broken ground on a new plant in China since late 2016, according to a recent World Nuclear Industry Status Report. Offic…

I made no claims about overall cost, but pointed out that it taking anywhere near 20 years to build a nuclear power plant is clearly off by an order of 4x at the very least.

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

#136

Post by randomsearch »

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…

> realize it was likely impractical to meltdown reactors just to develop the technology to clean them up

That's a great insight.

Maybe if some technologist approaches you and says "this is a great tech but we can't possibly recreate the worst case scenario, even in an expensive simulation" then that tells you that this is a straight "no".

Fukushima is evidence that the worst case cannot be sufficiently modelled and mitigated, at least in a commercial market.

Not saying "don't build nuclear", just that pro-nuclear lobbies should have been able to predict this situation (with a small chance of occurrence) and model it. If not, don't build. If you can predict it, but govt doesn't care about the risks, publicly document it, and that's OK.

OT, but at this point the nuclear debate looks irrelevant - direction of travel is that renewables win.

[ further OT ...moment of wild speculation: the idea that energy will be scarce will, within the 21st century, become as crazy as the idea that food could be scarce in rich nations right now. The race to renewables will look irrelevant as solar costs hit rock bottom, and no-one will remember why coal/nuclear plants were ever a thing. Within our lifetimes. I genuinely think that scenario is more likely than not. ]

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

#137

Post by pvaldes »

gus_massa wrote: post #132
pvaldes wrote: post #46

Earlier quoted context omitted.

> 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…

> the 137Cs concentrations were incredibly high, up to 480,000 Bq per square meter in their deepest samples. But is that high? I don't know. Let's make some uninformed back of the envelope calculations. The energy of the Cs137 radiation is 662keV, let's assume a normal person with 100lb and a surface of 2m^2 (only half get the radiation). In a day this person will get https://www.wolframalpha.com/input/?i=480000Bq%2F…

You are missing there an important factor: Life and dynamics of marine ecosystems. One of the problems is that 137Cs is being accumulated by sea currents, therefore even if we have a safe level in eight years, we could have, lets say, the "double" of the safe level in 16 years, rising to "four" times in the next 30 years (of expected half life of 137Cs). Minus the Cs released again to the water, but...

The other potentially big problem is that Caesium is bioaccumulative. Clams and other animals could take it from the water again.

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

#138

Post by pvaldes »

yongjik wrote: post #134
pvaldes wrote: post #46

Earlier quoted context omitted.

> 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…

For comparison: According to Wikipedia, granite contains 1-20 ppm of uranium [1]. One gram of natural uranium is about 25,280 Bq. Hence, one ton of granite is somewhere between 25,280 - 505,600 Bq. In other words, if a beach is made of eroded granite, its radioactivity will be between 25,000-500,000 Bq/t: assuming the sand is more than a feet deep, I think it's safe to assume > 25,000 Bq/m^2. [1] https://en.wikipedia…

But sand is not normally made of eroded granite, or it does not contains only granite. A lot of sand is made of shells or coral. Most beaches should have much lower levels of radioactivity.

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

#139

Post by ww520 »

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…

> [2] Speculation that a blob of melted core material would just keep melting into the ground until it "got to china"

Are people seriously considered that's a possibility? Even if the melted core went through the earth unstopped, a little bit of physic would conclude that Earth's gravity would pull the melted core toward the Earth's Core, and passing that, it would just be pulled back in the opposite direction, oscillating back and forth until stopping at the Core.

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

#140

Post by robotresearcher »

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…

> [1] It is too radioactive for that to be literally true

They walked up to it anyway

https://rarehistoricalphotos.com/the-elephant-foot-of-the-ch...

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