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

Rolls-Royce plans mini nuclear reactors by 2029

bbc.co.uk

Post reply on HN
Print view View original

91–100 of 353 posts

Re: Rolls-Royce plans mini nuclear reactors by 2029

#91

Post by christophilus »

roenxi wrote: post #72
rusk wrote: post #50

Earlier quoted context omitted.

Forgive me if this is a worn trope, but I've read somewhere that the upper bound on what we can do with nuclear energy is not how much we can produce, but what we can do with the leftovers ... as more and more people use nuclear power we're going to produce more and more nuclear waste, and there isn't really any answer as to what we can do with that. There are plenty of fantastic "ideas" as to what can be done, but i…

If literally all the electricity ever produced by the human waste had been produced by current generation nuclear technologies, there would be a small hill of high-level nuclear waste somewhere. It wouldn't be an issue except locally where it was stored. To believe that is a problem is to not have grappled with just how big the world is and how much of it is uninhabitable to humans already. The human population is co…

Nuclear energy has a PR problem that is very hard to solve. It doesn’t help that movies dramatize it. From what I remember, the only people who died due to Fukushima were those that died of fear. The reality is that nuclear is remarkably safe, clean, etc.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#92

Post by the8472 »

eeZah7Ux wrote: post #65
grabbalacious wrote: post #15

>Environmentalists are divided over nuclear power, with some maintaining it is dangerous and expensive, while others say that to achieve net zero emissions by 2050 all technologies are needed. Yes, a mix of technologies. But there's more to it than that. We're going to need increasing amounts of power in the future to explore the solar system and to solve all kinds of existential problems. Energy usage is not inheren…

> solve all kinds of existential problems ...very few existential problems have anything to do with technology.

Long-term existential problems (was there ever any meaning to life if it just dies on earth?) most likely require technological solutions.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#93

Post by shawabawa3 »

rjsw wrote: post #60
imtringued wrote: post #44

Earlier quoted context omitted.

Rivers tend to have different flow rates over the course of the year. If there is a heat wave the plant may not have enough water for cooling. The ocean is more dependable.

France has some nuclear plants that are on rivers where this problem has been seen.

I believe the problem in France wasn't the flow rate of the river, but the maximum temperature the power plants are allowed to leave the river at

During the heatwave the rivers were so warm the reactors weren't allowed to dump any more heat into them

Re: Rolls-Royce plans mini nuclear reactors by 2029

#94

Post by belorn »

hannob wrote: post #48
chrisco255 wrote: post #39

Earlier quoted context omitted.

Yep, and nuclear is the only near-infinite source of energy.

I'm always baffled by such statements. Can you explain in which way solar is not a "near-infinite source of energy"? I mean... there are without doubt technical challenges and all that (but arguably less technical challenges than to do the same with nuclear), but there really is no relevant limit to the deployment of solar cells if you include things like large-scale installations in the desert.

What I have heard, you do loose energy in transmitting power over large distances. There exist low loss transmission cables, but I don't know how effective that is over very great distance. There is also the question of how to redesign a distributed power grid into a centralized version where all the power comes from a single sources in desert areas.

On top of that there are political challenges. I have a hard time imagine Europe in current climate being happy to rely exclusively on power from the Sahara.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#95

Post by posix_me_less »

rusk wrote: post #50
chrisco255 wrote: post #39

Earlier quoted context omitted.

Yep, and nuclear is the only near-infinite source of energy.

Forgive me if this is a worn trope, but I've read somewhere that the upper bound on what we can do with nuclear energy is not how much we can produce, but what we can do with the leftovers ... as more and more people use nuclear power we're going to produce more and more nuclear waste, and there isn't really any answer as to what we can do with that. There are plenty of fantastic "ideas" as to what can be done, but i…

> we're going to produce more and more nuclear waste, and there isn't really any answer as to what we can do with that.

There are several answers to the question "what we can do with it", such as 1) reprocess it and use it again; 2) keep it in the power plant pools or similar storage facilities; 3) dump it to some deserted place where it isn't a big problem (high depth, stable earth crust). In the past, UK just dumped nuclear waste in barrels into the sea, which seems kind of convenient and irresponsible, but if done right (better isolation from sea creatures), this could work too.

It is true that there is no single universally agreed upon answer. But that is the same as with all other waste. Most of waste gets either burned or dumped at some place. The same will happen to nuclear "waste", until people start reprocessing it.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#96

Post by VLM »

jacobush wrote: post #25
mkl wrote: post #18

Earlier quoted context omitted.

I don't think that would generate enough power for a car. See maximum output of some here: https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...

Sure it would. Couple it with a lion - battery as a buffer. A tiny pellet gives 60 watts of heat. A heat cycle engine could recover maybe 10 watts of that. Put 500 pellets in there and you could get 5kw or so electric charge, all the time. Of course the pellets are insanely toxic in just about every way.

The problem with the related 25 KW of 24x7 waste heat is that'll eventually melt the very heavy several inches of lead unless very carefully cooled or distributed.

Even 20 watts will eventually melt small quantities of metal, think of every soldering iron. The authorities are not going to approve a reactor that melts its own armor if someone accidentally throws a quilt on top or equivalent.

So most designs do some kind of incredibly heavy passive cooling where the required very large surface of the armor only emits a fraction of the heat you'd see from sunlight. Now sunlight as an engineering 1 sig fig estimate is about a kilowatt per sq meter, so your 25 KW of waste heat would require some multiple of 25 square meters of surface area for passive safety cooling. A cube 5 meters on a side of solid copper and lead would have a surface area of 150 square meters, which will be warm to the touch but not as warm as it would get laying in the sun all day.

The problem with a cube of lead and copper 5 meters on a side is that is 125 cubic meters. And metal, again to one sig fig, weighs about ten thousand kilos per cubic meter. So that shielding would weigh quite a lot.

Its the old problem of the ratio of surface area to volume that comes up in so many engineering problems. Yeah I'm strong enough that I could pick up a small space craft RTG and walk around with it, for several reps at the gym anyway, but the scaling factors are such that a car charger would be immensely heavy.

I'm not sure, on a daily basis, what you'd do with 125 kilowatt-hours of car charge anyway. A gallon of gas is about 25 KW-hr (to one sig fig) so that's five gallons of gas. That would be 150 miles of driving per day, around here that would be something like 3 to 5 hours of driving per day, which sounds like a horrible way to live. Unless you're a bus driver, or delivery guy, or similar, LOL of course. Still, I don't think a five meter on a side bus or car is in our future.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#97

Post by zahrc »

chrisco255 wrote: post #39
luspr wrote: post #35

Earlier quoted context omitted.

Agree completely. It's a fallacy to believe we will require less energy in the long run. We need much more, if we want to advance as a species.

Yep, and nuclear is the only near-infinite source of energy.

But where does all the nuclear waste go? We already struggle with plastics and tech waste.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#98

Post by arcturus17 »

eeZah7Ux wrote: post #68
arcturus17 wrote: post #13

Earlier quoted context omitted.

How many attacks with the scale and sophistication needed to pull off something like that have we seen in the last 10 years in the West? I mean, how many successful terrorist attacks on nuclear plants have we really seen?

> I mean, how many successful terrorist attacks on nuclear plants have we really seen? This is the best example of survivor bias I've seen in a while.

From Wiki:

"Survivorship bias or survival bias is the logical error of concentrating on the people or things that made it past some selection process and overlooking those that did not, typically because of their lack of visibility"

Can you point me to an example that is being overlooked?

The probabilities of a successful terrorist attack on a nuclear plant are very thin given the extreme security measures around them, and that's a fact.

Thinking that, despite a basic probability being extremely small, "it's still possible", and thus assigning the event a larger probability than it naturally has, now that's an error.

Re: Rolls-Royce plans mini nuclear reactors by 2029

#99

Post by goalieca »

luspr wrote: post #35
grabbalacious wrote: post #15

>Environmentalists are divided over nuclear power, with some maintaining it is dangerous and expensive, while others say that to achieve net zero emissions by 2050 all technologies are needed. Yes, a mix of technologies. But there's more to it than that. We're going to need increasing amounts of power in the future to explore the solar system and to solve all kinds of existential problems. Energy usage is not inheren…

Agree completely. It's a fallacy to believe we will require less energy in the long run. We need much more, if we want to advance as a species.

Id he happy if we just focused on social issues and happiness. But might is right and every nation state and company and human being needs all the technological might we can muster in order to “win” (win what!?)

Re: Rolls-Royce plans mini nuclear reactors by 2029

#100

Post by dmos62 »

the8472 wrote: post #88
dmos62 wrote: post #54

Earlier quoted context omitted.

> we want to advance as a species I'm somewhat weary of people talking of civilization progress as if its definition is obvious and universal.

As far as humans are concerned overall progress has been linked to climbing up fractions of the kardashev scale since fire was invented. And even before fire, organisms could only become more complex as the energy available to them increased. You can't run a hummingbird or mammalian brains on photosynthesis directly, it's just not energy-dense enough.

> overall progress

This thread is becoming recursive. Is organism complexity progress? Everyone might agree with you, or not. That's because progress is whatever we say it is. It's subjective, in that everyone can have a different view of it, and it's non-constant, in that you can change your mind whenever. Progress is such a loaded word today. I'm hardpressed to find more than a few words with so much cultural baggage. Even someone who agrees that good and evil are in the eyes of the observer, can often say that the definition of Progress is self-evident.

Post reply on HN