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

Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

spectrum.ieee.org

Post reply on HN
Print view View original

331–340 of 357 posts

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#331

Post by dredmorbius »

WalterBright wrote: post #330
dredmorbius wrote: post #287

Earlier quoted context omitted.

I suspect that's not the only SPOF in play. Nukes, as with rockets, are complex. Many things have to go right and keep going right for them to operate as intended. (See Rickover's "Paper Reactors" paper for a similar take on this.) Another factor that contributed not only to Fukushima but other inundations following the Tohoku earthquake was that in response to the megathrust-fault slip, the east coast of Japan sank…

There are a number of cheap-as-dirt things that could have been done to prevent the disaster. Putting the generators on a platform was one. Venting the hydrogen outside instead of inside, another. Having emergency repair parts on site is a third. Having a gravity-fed way to cool the reactors with external water, a fourth. And so on.

Every programming problem boils down to a binary choice of having a 1 or 0 in a given memory / binary code address.

Pile up enough binary choices, each individually cheap as dirt, and you've got a large problem.

Even dirt in quantity gets expensive to manage: dams (earthen), mines, levees, landslides, etc.

Nukes are complex with variance conditions that are extreme to the extreme.

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#332

Post by slt2021 »

natmaka wrote: post #307
slt2021 wrote: post #305

Earlier quoted context omitted.

this is not an issue at all, Ukraine is at war with Russia, yet Russia continues to pump natural gas through Ukraine to Europe and even pays $$$ to Ukraine for transit (!!!!) When it comes to commodity trading - $$$ trumps everything. uranium reserves are plentiful, given that you dont need a lot of Uranium to recharge the plant https://www.visualcapitalist.com/charted-global-uranium-rese... the most importantly: for…

> Ukraine is at war with Russia This single fact shows, according to you, that no embargo can ever happen in the future. I abandon this "conclusion" to you. Uranium reserves are to be considered in current conditions, all reserves are not immediately available nor equivalent (ore grade...). > there is zero reason to withhold uranium There will be more and more reasons to do so if it becomes scarce and needed by super…

Uranium has been strategic mineral for nuclear weapons and yet still is traded free on the global market.

Every country that has nuclear weapons does have nuclear reactors, and supply is basically not an issue. The technology is the main moat (uranium enrichment & reactor tech & turbine tech & missile tech)

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#333

Post by chpatrick »

zettabomb wrote: post #324
natmaka wrote: post #311

Earlier quoted context omitted.

> Fukushima could have been easily predicted After such an accident some armchair experts are quite sure that it "could have been easily predicted". Before the accident (to "easily" prevent it) or during it they are nowhere to be found. https://news.ycombinator.com/item?id=41774144

I won't try to summarize here, but long story short, the conditions which led to the Fukushima disaster were well known and TEPCO was warned as early as 2000, but they did nothing to prevent it. There a number of good sources on the Wikipedia page ( https://en.wikipedia.org/wiki/Fukushima_nuclear_accident#Pri... ).

How do we know the next time a similar situation arises it will be dealt with in time?

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#334

Post by bamboozled »

littlestymaar wrote: post #308
bamboozled wrote: post #284

Earlier quoted context omitted.

Japanese wages are notorious for being lower that a lot of the developed world and there is a problem with stagnant wage growth. I don't think there is any need to try justify a screw up on this level as being good. Fukushima was a disaster, economically and for the image of nuclear globally.

Nobody said otherwise, you are desperately moving the goalpost here.

“Desperately”, you’re a funny guy. I live in Japan, no tax payer here is sitting around going, “how wonderful the nuclear disaster was, now we’ll get all this new tech to boot”.

Sometimes you need to call a spade a spade. This was a disaster, politically, economically and environmentally. Yes some good will come from it, but ultimately, it was better off not happening. All that money could’ve and should’ve went on new and safer power plants.

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#335

Post by natmaka »

slt2021 wrote: post #332
natmaka wrote: post #307

Earlier quoted context omitted.

> Ukraine is at war with Russia This single fact shows, according to you, that no embargo can ever happen in the future. I abandon this "conclusion" to you. Uranium reserves are to be considered in current conditions, all reserves are not immediately available nor equivalent (ore grade...). > there is zero reason to withhold uranium There will be more and more reasons to do so if it becomes scarce and needed by super…

Uranium has been strategic mineral for nuclear weapons and yet still is traded free on the global market. Every country that has nuclear weapons does have nuclear reactors, and supply is basically not an issue. The technology is the main moat (uranium enrichment & reactor tech & turbine tech & missile tech)

No, it never was as all pertinent nations could easily obtain enough uranium to 'cook' it for weapons. Even the most eager to build huge amounts of weapons (USSR and USA) never had any problem related to the amount of uranium needed.

Short version: the amount of uranium needed to build an impressive arsenal of nuclear weapons is way, way lower than the amount needed to produce a fair part of gridpower for years.

> Every country that has nuclear weapons does have nuclear reactors

Yes, because a reactor is needed to 'cook' uranium (in order to obtain high-grade Pu-239) for weapons. This very need was what led nations to build reactors, electricity-generating nuclear plants were at best an aftermath and in some cases an excuse (hiding the real objective).

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#336

Post by natmaka »

Moldoteck wrote: post #315
natmaka wrote: post #293

Earlier quoted context omitted.

> Uranium supply is not an issue I disagree: https://news.ycombinator.com/item?id=41783584 > you need to replenish uranium fuel like once in 5 years At best. Then, if you cannot obtain uranium, your reactor is just a pile of hot waste.

Imo I find such statements like 100-150 years of supply similar to the statements about petroleum supply that was about to end and suddenly with demand, new supply was found, just like with other materials like lithium

This is a billion dollar bet, who wants to take it?

No such risk with renewables.

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#337

Post by natmaka »

Moldoteck wrote: post #314
natmaka wrote: post #294

Earlier quoted context omitted.

Most materials used by renewables are eternally (at human scale) reusable. In France recycling 95% of the sheer mass of a wind turbine is now mandatory ( https://www.lemoniteur.fr/article/demantelement-des-eolienne... ) > France does have several years worth of fuel Indeed, 'le stock stratégique', about 9 years at best (counting the average amount of uranium already present in reactors). 9 years at best for an overal…

I mean... france really doesn't have a problem with n fuel... It's not just classic stockpiles but the reprocessed ones. Needless to say that imports are pretty diversified - even if one country will ban exports to France, they'll not face total ban from all partners, so in this regard they are indeed lucky.

France already encountered challenges: for 5 decades some there pretended that Niger will provide, then it abruptly became tricky ( https://www.bbc.com/news/articles/c0kked7ydqyo ).

Some recycling operations (past contracts) involving Russia also had to be maintained during the current embargo.

No major problem for now, indeed.

However a war or a nuclear renaissance may abruptly lead to challenging conditions, if superpowers need more uranium.

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#338

Post by defrost »

natmaka wrote: post #335
slt2021 wrote: post #332

Earlier quoted context omitted.

Uranium has been strategic mineral for nuclear weapons and yet still is traded free on the global market. Every country that has nuclear weapons does have nuclear reactors, and supply is basically not an issue. The technology is the main moat (uranium enrichment & reactor tech & turbine tech & missile tech)

No, it never was as all pertinent nations could easily obtain enough uranium to 'cook' it for weapons. Even the most eager to build huge amounts of weapons (USSR and USA) never had any problem related to the amount of uranium needed. Short version: the amount of uranium needed to build an impressive arsenal of nuclear weapons is way, way lower than the amount needed to produce a fair part of gridpower for years. > Ev…

Sure, once the Cold War started ...

> This very need was what led nations to build reactors, electricity-generating nuclear plants were at best an aftermath

In absolute history, though, this is arse backwards.

The UK and the US both had piles and generation plans before they even thought building nuclear weapons was at all possible.

The US, in particular, had a nuclear science body that were pretty damn sure weapons weren't feasible and had a major focus on atomic power to generate energy.

They ignored the letter by Einstein that highlighted the dangers of a German nuclear program suspected of chasing weapons and only paid heed after several approaches by Tube Alloys (the UK nuclear weapons group) when the Australian nuclear scientist Mark Oliphant visited the US and laid out in detail a method by which a bomb could be feasibly constructed.

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#339

Post by natmaka »

Moldoteck wrote: post #318
Krasnol wrote: post #272

Earlier quoted context omitted.

The fact which is missing here is how much money Germany made with those trades. As the other commenter wrote: trading, transfers, etc. is normal in the EU grid. You buy cheap, you sell expensive. Just because Germany imports electricity, doesn't mean it has to. The German grid, even in its unfinished state, allows turning off power generation where it doesn't make sense financially, and they can do that fast because…

nuclear can be turned modulated pretty fast too, look at France. We indeed should look at final year balance. Edf indeed needs to sell as much as they can, because of arenh. Afaik it'll end in the end of 2025. "In France, alternative retailers (i.e. those who aren’t EDF) can currently secure regulated access to energy produced by EDF’s existing nuclear fleet under the ARENH mechanism. It places an obligation on EDF t…

> nuclear can be turned modulated pretty fast too, look at France

Nope. Albeit being shock-full of nuclear reactors... France always maintains fossil fuel active in order to load-follow. Add 'peakers' (needed during peak-demand) and here is the result: https://ourworldindata.org/explorers/energy?Metric=Share+of+...

Details: there are safety-related limits (power modulation proportion, duration of a pause needed after each modulation, modulations frequency...) to nuclear load-following capacity, and the very combustible status is a major parameter.

Pertinent document (French ahead!): https://www.sfen.org/rgn/expertise-nucleaire-francaise-suivi...

« un réacteur peut varier de 100 % à 20 % de puissance en une demi-heure, et remonter aussi vite après un palier d’au moins deux heures, et ce deux fois par jour »

Proposed translation: "a reactor power output can vary from 100% to 20% in 30 minutes, then after 2 hours can go back to 100% at the same speed, and can cycle this way 2 times per day".

This is quite a good performance when it comes to load-following (French engineers are very good at this), however it is insufficient in the real world (save any ridiculously expensive over-provision of nuclear reactor, most idling) and very weak compared to gas turbines performances.

> Edf indeed needs to sell as much as they can

No. EDF always needed to sell as much as they can, even before AREHN, because maintaining a high load factor for their nuclear reactors is financially key. An idle industrial reactor is a financial disaster.

Re: Fukushima Reactor: TEPCO robot aims to extract nuclear fuel

#340

Post by natmaka »

Dalewyn wrote: post #312
natmaka wrote: post #310

Earlier quoted context omitted.

No, because we have ne replacement for kitchen knives. We have a replacement for nuclear: renewables.

Sincerely, please stop talking nonsense. Renewables can be a complement to other power sources, but to even suggest they can be a "replacement" for nuclear power indicates either naivety or ignorance.

Quantitatively this replacement is already done (renewables produce way more than nuclear) and is running (nuclear produces less and less), right now, nearly everywhere (explore using 'Change country or region'): https://ourworldindata.org/grapher/electricity-fossil-renewa...
Post reply on HN