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

Small nuclear reactors: tiny NuScale reactor gets safety approval

popularmechanics.com

Post reply on HN
Print view View original

471–480 of 554 posts

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#471

Post by mayama »

freeopinion wrote: post #241
RhodesianHunter wrote: post #58

Earlier quoted context omitted.

This is IMO a positive for nuclear, not a negative. You're forced to confront the cleanup as opposed to fossil fuels, where you just blow your waste out into the atmosphere and make it the commons' problem.

We don't have a good track record of confronting the cleanup of nuclear waste. The US federal government recently shipped a secret load of waste into Nevada. Nevada was very unhappy about that and claimed it was done in secrecy because it was illegal. After a bit of a fight, the feds caved and have agreed to remove the waste. There is no plan for this stuff. The repository that was built in Nevada was never actually…

How can a multi million dollar construction start without necessary approvals?

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#472

Post by runarberg »

selectodude wrote: post #354
runarberg wrote: post #285

Earlier quoted context omitted.

I’m not sure anything you say here is true: * I really doubt GMO has raised the standard of living for the average person. * I really doubt people in less then stable economy have any less salt towards the rich, the government, or polluters. * I really doubt there is a correlation between the standard of living caring about your neighbors. So to answer your question. No. I have never noticed that countries where peop…

>I really doubt GMO has raised the standard of living for the average person. Then you are absolutely not paying attention at all whatsoever. In fact, the majority of the impact of GMO crops has been felt in countries where there was literally not enough food to go around. You’re welcome to your organics in a country as food secure as in the west but starving poor and middle income countries is not okay. https://www.…

Thank you for this correction. I guess there are in fact evidence for greater crop yield and more farmer profits with GMO crops.

However this doesn’t really take away from my point that GMO didn’t fix world hunger. Farmers can save money by using less pesticide and have better crop yield all they want but that still doesn’t fix food not going to where it is needed.

This—on its own—doesn’t even take away from my weaker claim that „I doubt GMO has raised the standard of living for the average person“. Sure it has raised the standard of living for the farmers that have the option of swapping to GMO crops that previously needed a lot of pesticide. But unless you believe in some trickle down economic theory that will not automatically raise the standard of living to anyone else.

That all said I do find it a little handy that the quoted study only talks about maize, soy, and cotton. One of these is not even a food crop. And the two food crops here are notorious for giant industrial scale farms where much of the yield isn’t even for human consumption, but turned into feed for the meat industry. See it’s a problem of distribution. The profits of more maize and soy yield grown with less pesticide will most likely stay with the farmer, and even if they reduce the price of their price product, the profit from the cheaper crops will more likely go to the cattle farmer up stream with the cheaper feed. The standard of living for the average person will just remain the same, or—at best—marginally improve.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#473

Post by DanBC »

runarberg wrote: post #472
selectodude wrote: post #354

Earlier quoted context omitted.

>I really doubt GMO has raised the standard of living for the average person. Then you are absolutely not paying attention at all whatsoever. In fact, the majority of the impact of GMO crops has been felt in countries where there was literally not enough food to go around. You’re welcome to your organics in a country as food secure as in the west but starving poor and middle income countries is not okay. https://www.…

Thank you for this correction. I guess there are in fact evidence for greater crop yield and more farmer profits with GMO crops. However this doesn’t really take away from my point that GMO didn’t fix world hunger. Farmers can save money by using less pesticide and have better crop yield all they want but that still doesn’t fix food not going to where it is needed. This—on its own—doesn’t even take away from my weake…

How do you feel about golden rice?

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#474

Post by Krasnol »

gambiting wrote: post #421
Krasnol wrote: post #222

Earlier quoted context omitted.

And than there is Asse: https://en.wikipedia.org/wiki/Asse_II_mine You just don't know. The time frame is too long. It's too long for natural causes and far too long for human civilisation. The earlier we stop producing this crap, the better.

Sure, but that's why I suggested deep borehole storage - there is no known geological process that can bring up material stored at 5km+ depth into the surface on any sort of human timescale. A mine, even at 700m depth, is just too shallow for long term storage.

But there are many human processes which can.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#475

Post by valuearb »

revax wrote: post #460
valuearb wrote: post #353

Earlier quoted context omitted.

Humans aren’t at risk from climate change, it’s all the other species without our powers of quick adaption.

Even for Humans, some regions of the world will be simply to hot to be continuated habited.

I doubt that because technology is so powerful and adaptable. Dikes can protect lowlands. Air conditioning can make hot summers tolerable. Food can be grown in more northern climes.

But coral can’t adapt to warmer more acidic waters overnight. Polar bears can’t darken their fur in a couple generations to hunt in perpetual summer tundra.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#476

Post by nemosaltat »

crowbahr wrote: post #448
sandworm101 wrote: post #446

Earlier quoted context omitted.

So it requires gravity. It may seem trivial, but how would this thing react if suddenly not mounted vertically, say if it got knocked onto its side while running? Would coolant still flow as planned?

Anything that knocks a fully functional multiple thousands of tonnes of concrete, steel, water and fissile material onto it's side was already going to fuck up your day. As far as I'm aware we've never had a nuclear reactor go sideways, and it's kinda ludicrous to even ask. It's one of the most massive structures, built on bedrock because it's too heavy to be built on anything else, and even these "small" reactors wi…

As other Nuke submariners in this thread can attest, there are definitely PWRs designed to tolerate massive rolls and “angles and dangles.” I guess it depends on your definition of sideways.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#477

Post by torpfactory »

sandworm101 wrote: post #453
crowbahr wrote: post #448

Earlier quoted context omitted.

Anything that knocks a fully functional multiple thousands of tonnes of concrete, steel, water and fissile material onto it's side was already going to fuck up your day. As far as I'm aware we've never had a nuclear reactor go sideways, and it's kinda ludicrous to even ask. It's one of the most massive structures, built on bedrock because it's too heavy to be built on anything else, and even these "small" reactors wi…

They are vertical cylinders to be suspended vertically in a pool of water, not massive squat objects sitting on bedrock. They are thin and relatively top-heavy. It is not ludicrous to ask what could happen should they not remain as vertical as designed. From a planning perspective, if verticality is a requirement then that verticality has to be protected as strongly as any other aspect. Any attachment or mounting poi…

I think they are not trivial but relatively easy parts of the design. I’m sure they can design support structure to withstand whatever arbitrarily large earthquake you throw at it. The structure doesn’t need to be particularly light or compact so there shouldn’t be any design constraints getting in the way of strength. The heat transfer problem is much much harder and they’ve already solved that apparently.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#478

Post by godelski »

revax wrote: post #459
godelski wrote: post #331

Earlier quoted context omitted.

I'm unsure what you are suggesting here, so I want to be extra clear about the French policy and current state of affairs. As in stands, France has one of the lowest CO2 emissions per capita[0][1]. No one is saying that we should _only_ use nuclear. Not diversifying your energy portfolio is a terrible idea. France is trying to reduce its dependence upon nuclear (which is a good idea) and replace its fossil fuel infra…

>Nuclear serves as a baseload and backbone Not in France, the nuclear plants here can do some load following (to some extent). >You will not find pro-nuclear supporters upset with France's decision to reduce their dependence on nuclear. In fact you will often find support. I cannot agree here, there is a growing movement mainly lead by Jean-Marc Jancovici deploring the shutdown of safe and profitable nuclear power pl…

> Not in France, the nuclear plants here can do some load following (to some extent).

They can in do but the economics makes more sense to run high for long periods. The nuclear output of France doesn't typically vary much throughout the day, but yes they do have the capacity to.

But yeah, all we are fighting for is that nuclear is __part__ of the solution (not __the__ solution. Big difference).

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#479

Post by i_am_proteus »

sandworm101 wrote: post #446
i_am_proteus wrote: post #356

Earlier quoted context omitted.

Nuclear engineer here. I've read through a good portion of the regulatory submission to the NRC and have a few takeaways that oppose some of the less-well-informed takes in this thread: - The reactor differs substantially from existing PWRs by encasing the primary in double containment, using natural circulation flow for both normal operation and emergency cooling. There are no pumps needed (or installed) to move coo…

So it requires gravity. It may seem trivial, but how would this thing react if suddenly not mounted vertically, say if it got knocked onto its side while running? Would coolant still flow as planned?

This is a great question!

From reading the NRC submission, the support structure for the modules is Seismic Category 1 (rated for design basis earthquake). This includes the entire Reactor Building, its foundation, and requirements for the site on which it is built. The reactor building is also designed to withstand an impact from a large commercial aircraft. Note that conjecture that the modules are top-heavy appears to be unfounded given the configuration described in the NRC submission.

Elsewhere in the probabilistic risk assessment, they address a module tipping over if it is dropped in the operating area-- the most probable scenario for a horizontal module.

In the case where the drop causes the containment to be breached and does not permit inflow of water from the pool (ostensibly due to pressure difference) the result is core damage and a release of radioactive contamination to the pool.

I encourage interested readers to look at Chapter 19 of the NRC submission. Much of the document is at a level where a lay engineer can understand it. NB: I am not affiliated with NuScale or the NRC.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#480

Post by revax »

valuearb wrote: post #475
revax wrote: post #460

Earlier quoted context omitted.

Even for Humans, some regions of the world will be simply to hot to be continuated habited.

I doubt that because technology is so powerful and adaptable. Dikes can protect lowlands. Air conditioning can make hot summers tolerable. Food can be grown in more northern climes. But coral can’t adapt to warmer more acidic waters overnight. Polar bears can’t darken their fur in a couple generations to hunt in perpetual summer tundra.

The technology you talked about is only available in developed countries. What about the people in parts in Africa who already have problem in terms of food insecurities?
Post reply on HN