First contact made with melted nuclear fuel at Fukushima plant • Hacker News Board

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

#101

Post by ChuckMcM » Fri, Feb 15, 2019, 10:38 PM UTC

transistor-man wrote: post #83

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…

@ 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.

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

#102

Post by petschge » Fri, Feb 15, 2019, 10:38 PM UTC

pfdietz wrote: post #99

petschge wrote: post #45

Earlier quoted context omitted.

Boron actually mostly acts as a neutron poison, i.e. it absorbs neutrons. That way further (stimulated) decay of other nucleii that were hit by a neutron is eliminated and the chain reaction stops, reducing the production of thermal energy. A moderator on the other hand inelastically scatters neutrons, converting some of the kinetic energy of the neutrons to heat and leaving a slower neutron. Moderators are used in r…

> A moderator on the other hand inelastically scatters neutrons, Most moderators elastically scatter neutrons. What other kind of collision could there be with a hydrogen nucleus?

You are of course right. The scattering conserved total energy, but not the energy of the neutron.

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

#103

Post by saagarjha » Fri, Feb 15, 2019, 10:39 PM UTC

petschge wrote: post #84

lucb1e wrote: post #73

Earlier quoted context omitted.

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 th…

The thing is that 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 that goes into making this trade-off in a rational way.

What parts are we missing?

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

#104

Post by cm2187 » Fri, Feb 15, 2019, 10:43 PM UTC

acidburnNSA wrote: post #21

mimixco wrote: post #15

It took 10 years to even get a robot that could get close to the fuel... and people still ask if nuclear might not be as bad as coal! The truth is that accidents like this can never be cleaned up or salvaged. It's time to move away from nuclear, as other countries have already figured out. Fortunately for us in the US, the last nuclear plant under construction today will likely be cancelled, as the last two were. The…

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…

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.

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

#105

Post by aldoushuxley001 » Fri, Feb 15, 2019, 10:46 PM UTC

ChuckMcM wrote: post #79

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…

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…

What are you using to organize your nuclear effects library?

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

#106

Post by zkms » Fri, Feb 15, 2019, 10:50 PM UTC

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.

> 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.

With adequate transuranic/actinide burning and breeding/reprocessing capacity the time constants for waste disposal won't be anywhere that long. Discounting nuclear energy because of stupid once-through fuel cycles seems a bit unfair.

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

#107

Post by petschge » Fri, Feb 15, 2019, 10:53 PM UTC

saagarjha wrote: post #103

petschge wrote: post #84

Earlier quoted context omitted.

The thing is that 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 that goes into making this trade-off in a rational way.

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 instead of next year.

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

#108

Post by bdamm » Fri, Feb 15, 2019, 10:56 PM UTC

sixothree wrote: post #94

ctoth wrote: post #55

I suspect I am not the only person who saw "First contact made" at the top of HN and for one brief, shining moment lived in a far more interesting Universe.

I don't want to die not knowing.

I hope an alien friend visits me at my deathbed.

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

#109

Post by Intermernet » Fri, Feb 15, 2019, 10:57 PM UTC

cm2187 wrote: post #104

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…

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.

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

#110

Post by zkms » Fri, Feb 15, 2019, 10:59 PM UTC

tomatotomato37 wrote: post #56

mikro2nd wrote: post #41

Earlier quoted context omitted.

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.

Uranium mining is a tiny operation due to it's absurd energy density. I wouldn't be surprised if the mining cost of rare Earth's used to maintain broken solar units surpasses it it's so insignificant. Besides most countries with a nuclear weapons program end up with a lot of reactor-grade uranium lying about anyway, and those countries also happen to be the biggest polluters in energy

> I wouldn't be surprised if the mining cost of rare Earth's used to maintain broken solar units surpasses it it's so insignificant.

Yeah, there's plenty of very unpleasant chemistry involved in making PV panels and I strongly doubt that the wastes involved in the associated mining/manufacturing/disposal processes are treated anywhere nearly as carefully as nuclear waste (not to speak of the fact that due to sheer energy density difference, PV panels will produce far more waste than nuclear fuel/reactors).