Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

First contact made with melted nuclear fuel at Fukushima plant

asahi.com

Post reply on HN
Print view View original

161–170 of 222 posts

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

#161

Post by nate_meurer »

ChuckMcM wrote: post #101
transistor-man wrote: post #83

Earlier quoted context omitted.

@ Melting down fuel to determine its properties, the US just restarted a facility that does exactly that! The TREAT reactor purposely melts fuel to determine its failure points and to study new cladding materials. https://en.wikipedia.org/wiki/Transient_Reactor_Test_Facilit...

Very cool with a link to a video https://www.youtube.com/watch?v=h0o4P_F4s9s where you can watch a fuel rod actually melt. Glad to hear they restarted it last year for additional research into these topics.

Holy shit, wikipedia says it handles transients of up to 19 GW. They don't say for how long, but the transient control rod actuators take a quarter second to cover their full range, so I'm guessing that means 19 GW for up to a quarter second. That's about 4.5 gigajoules. As it happens, that's roughly the explosive energy of 1 ton of TNT. From a reactor core the size of a small closet. Makes me wonder, in fascinated terror, what power output we're seeing in that video.

Wikipedia says it can simulate six different reactor loop types. This is a seriously impressive facility.

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

#162

Post by adrianN »

tarre wrote: post #160
ChuckMcM wrote: post #79

Earlier quoted context omitted.

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…

Decontamination factor of 100 is rather terrible compared to DF of over 8 million of actual filter materials, which are being used at Fukushima: https://www.fortum.com/sites/g/files/rkxjap146/files/documen... See also: https://www.fortum.com/products-and-services/power-plant-ser...

Adding another factor of 100 with something as cheap as sand still seems worthwhile.

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

#163

Post by Aeolun »

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 think a few years ago, when all their robots kept dying, I suggested just using a big stick, possibly with mirrors, to look inside.

Funny to see that after years they finally reach the fuel with a big stick :P

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

#164

Post by vidarh »

dmurray wrote: post #125
vpribish wrote: post #114

Earlier quoted context omitted.

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.

It sounds far too good to be true. According to the actuarial tables at [0], 10% is the expected 20-year death rate for 40-year old men. This is for Americans in 2014, I'd expect the outcomes to be worse for Soviet citizens in 1986. [0] https://www.finder.com/life-insurance/odds-of-dying

In 1986, the life expectancy for Soviet men (at birth) was 65 years:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2546027/?page=1

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

#165

Post by jobigoud »

anigbrowl wrote: post #130
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 also find it interesting that the "China Syndrome"[2] speculation is pretty much completely debunked. That term was never meant to be taken literally, in the movie where it originates it is presented as a fanciful exaggeration meant to emphasize the seriousness of the risk. The actual plot concerns the risk of groundwater contamination following a nuclear accident, not a planet-piercing tunnel.

But is there a material that humans could build that would sink into Earth like that, for a few kilometers say, either due to melting its way down or gravity or density?

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

#166

Post by vidarh »

mempko wrote: post #119

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…

The reaction to Chernobyl was excessive. What we've learned since is that while a lot of rapid response was needed at the immediate site, at least a portion of the rapid evacuation likely did more harm than good. Large parts of the exclusion zone remained livable (and the Chernobyl plant itself remained operational for many years afterwards - the danger was low enough that several of the reactors were re-started).

We should be thankful the Japanese did not overreact as badly, but in Fukushima too there is reason to believe that more people than needed were evacuated, and that this response may have caused more harm than the accident itself.

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

#167

Post by vidarh »

varjag wrote: post #80
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…

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.

The "never made it to WHO statistics" as the difference in cancer incidence rates and other problems after Chernobyl are so small that they are hard to distinguish from the background noise. A lot of work has gone into trying to document the actual effects, but the reality is that while there were initial large spikes in e.g. thyroid cancer among children, the cancers that spiked are ones with very high survival rates. The WHO estimates were initially very high, but keep being adjusted down because every year that goes is another year without a spike in deaths above expected levels.

The breakup of the Soviet Union caused much larger scale effects on life expectancy.

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

#168

Post by pndy »

jojocool0501 wrote: post #158
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.

This is IMO a must read : https://fr.scribd.com/doc/257062334/Chernobyl-Confessions-of...

I'd recommend Svetlana's Alexievich "Chernobyl Prayer" although is more intimate (as stories told are very personal) prose than historical records: https://thephraser.com/2017/09/07/chernobyl-prayer-a-chronic...

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

#169

Post by mempko »

vidarh wrote: post #166
mempko wrote: post #119

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…

The reaction to Chernobyl was excessive. What we've learned since is that while a lot of rapid response was needed at the immediate site, at least a portion of the rapid evacuation likely did more harm than good. Large parts of the exclusion zone remained livable (and the Chernobyl plant itself remained operational for many years afterwards - the danger was low enough that several of the reactors were re-started). We…

This is an interesting perspective. It's probably unknown if it's too much or too little without some serious scientific investigation. What do you base your opinion on?

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

#170

Post by tarre »

adrianN wrote: post #162
tarre wrote: post #160

Earlier quoted context omitted.

Decontamination factor of 100 is rather terrible compared to DF of over 8 million of actual filter materials, which are being used at Fukushima: https://www.fortum.com/sites/g/files/rkxjap146/files/documen... See also: https://www.fortum.com/products-and-services/power-plant-ser...

Adding another factor of 100 with something as cheap as sand still seems worthwhile.

There are reasons, why not to do that:

1) DF doesn't add up like that at low concentrations. Then it comes down to selectivity of the material. Sodium and cesium have similar chemical characteristics, but CsTreat is very efficient in selecting Cs over Na.

2) Material you are using as filter becomes radioactive waste. You want to keep the volume at minimum.

3) With CsTreat you already reach radioactive Cs levels below measurable limit. There is no reason to try to remove more Cs from that water :)

Post reply on HN