I’m in Wyoming to celebrate the next nuclear breakthrough | Hacker News Reader

I’m in Wyoming to celebrate the next nuclear breakthrough

gatesnotes.com

302 pointserentz233 comments

"liquid sodium, whose boiling point is more than 8 times higher than water’s"

Ew, multiplicative temperature comparisons in unspecified units.

Sodium's boiling point is 882'C.

"so it can absorb all the extra heat"

Confusion of temperature and heat? Sodium's specific heat capacity is ~1/3 of water, so sodium's higher boiling point doesn't by itself mean that it can absorb more heat, though ofc the combination is still in sodium's favour.

Sodium is such a nightmarish coolant. Yes, there are advantages in building and engineering a sodium cooled reactor, but from an operating point of view... oh boy.

Sodium catches fire when exposed to air.

Sodium reacts violently with water (used in some designs as secondary cooling cycle).

Sodium absorbing a neutron creates a strong gamma emitter with a low half time.

Sodium reactors have always had low availability times, caused by constant technical problems.

However unlike lead as coolant, no advances in material sciences are required to get an operational Gen 4 reactor. On the upside, you can pretty much use Sodium (fast) reactors right now... but maybe you shouldn't?

All of these are true.

Sodium catches fire when exposed to air. That's why you don't expose it to air. Generally you fill the reactor with argon, which is an inert gas, and very heavy (dense) compared to air. Leaks can still happen, and the few sodium cooled plants around the world have all experienced them. But the fire the sodium catches when in contact with air is a very mild one. It's nothing like the violent reaction sodium has with water.

Which brings up your next point, that sodium reacts with water. For some reason you said "in some designs [water is used] as secondary cooling cycle". Which makes me think you are fully aware that this particular design does not actually use water in its secondary cooling cycle, but rather molten salt (point mentioned by Gates in the article). It's a bit disingenuous of you to bring up this point (arguably the greatest negative point about sodium) when it is actually irrelevant in the reactor discussed here.

Sodium absorbs a neutron and becomes a strong gamma emitter with a low half time. To be more precise, the half life of Na-24 is 15 days [1]. It decays in a stable isotope of Magnesium, which is not radioactive. Any leak will result in radioactivity that will naturally completely disappear after about one year.

As for the "strong gamma rays" (all gamma rays are strong, by the way), they are contained in the containment vessel.

Edit: the half life of Na24 is 15 hours, not 15 days. Even better.

[1] https://en.wikipedia.org/wiki/Isotopes_of_sodium#Sodium-24

It sounds like you’re expecting ideal operating conditions indefinitely?

No. But I have a hope that the US engineers can do at least as well as the Russian ones. Russia has been running BN-600 for more than 4 decades now, and BN-800 for 8 years. There were incidents but not huge. Here's what wikipedia has to say [1]

  In the first 15 years of operation, there have been 12 incidents involving sodium/water interactions from tube breaks in the steam generators, a sodium-air oxidation/"fire" from a leak in an auxiliary system, and a sodium "fire" from a leak in a secondary coolant loop while shut down. All these incidents were classified at the lowest level on the International Nuclear Event Scale, and none of the events prevented restarting operation of the facility after repairs. As of 1997, there had been 27 sodium leaks, 14 of which resulted in sodium-air oxidations/"fires". The steam generators are separated in modules so they can be repaired without shutting down the reactor. As of 2020, the cumulative "energy Availability factor" calculated up to year 2019 and recorded by the IAEA was 75.6%.

[1] https://en.wikipedia.org/wiki/BN-600_reactor

It sounds like you don’t understand that engineering is compromises.

As soon as you involve radiation, you have some severe compromises to make, and the choices of elements you can use are limited.

Sodium is not chosen because of its dangers. Sodium was chosen despite the dangers, because the engineers very very carefully looked at other options and the other options were worse for the needs of their design. https://xkcd.com/793/ and http://johnsalvatier.org/blog/2017/reality-has-a-surprising-... seem relevant.

Something as seemingly safe as water can be as dangerous as molten Sodium. The following is an explanation of the Chernobyl accident, which in part was due to using water as a coolant:

  Efforts to increase the power to the level originally planned for the test were frustrated by a combination of xenon poisoning, reduced coolant void and graphite cooldown. Many of the control rods were withdrawn to compensate for these effects, resulting in a violation of the minimum operating reactivity margin (ORM, see Positive void coefficient section in the information page on RBMK Reactors) by 01:00 – although the operators may not have known this. At 01:03, the reactor was stabilised at about 200 MWt and it was decided that the test would be carried out at this power level. Calculations performed after the accident showed that the ORM at 01:22:30 was equal to eight manual control rods. The minimum permissible ORM stipulated in the operating procedures was 15 rods. The test commenced at 01:23:04; the turbine stop valves were closed and the four pumps powered by the slowing turbine started to run down. The slower flowrate, together with the entry to the core of slightly warmer feedwater, may have caused boiling (void formation) at the bottom of the core. This, along with xenon burnout, could have resulted in a runaway increase in power. An alternative view is that the power excursion was triggered by the insertion of the control rods after the scram button was pressed (at 01:23:40). At 01:23:43, the power excursion rate emergency protection system signals came on and power exceeded 530 MWt and continued to rise. Fuel elements ruptured, leading to increased steam generation, which in turn further increased power owing to the large positive void coefficient. Damage to even three or four fuel assemblies would have been enough to lead to the destruction of the reactor. The rupture of several fuel channels increased the pressure in the reactor to the extent that the 1000t reactor support plate became detached, consequently jamming the control rods, which were only halfway down by that time. As the channel pipes began to rupture, mass steam generation occurred as a result of depressurisation of the reactor cooling circuit. Two explosions were reported, the first being the initial steam explosion, followed two or three seconds later by a second explosion, possibly from the build-up of hydrogen due to zirconium-steam reactions.

https://world-nuclear.org/information-library/safety-and-sec...

I'd be curious to know how that radioactive coolant is processed to filter out magnesium that is bound to accumulate over time.

Sodium has a melting point slightly below 100 degrees Celsius. Magnesium has a melting point of 650 Celsius. I don't know the exact temperature that sodium will have in the Natrium reactor, but in the French Phenix reactor it was about 560 Celsius. But that's the highest one. The temperature at the bottom of the sodium pool is most likely much lower. In any case, much, much lower than the "freezing" point of magnesium, which will particulate. So, I imagine it can be filtered by a sieve made of steel, not much different than the sieve in my kitchen to filter my tea.

Won't the magnesium just dissolve in the sodium? I'd expect distilling the sodium or chemically processing it being a requirement for removing accumulated magnesium from the sodium coolant.

this process (neutron capture and decay) contributes to only a small amount of magnesium in the reactor coolant, as the probability of neutron capture by sodium-23 is relatively low compared to other reactions involving the reactor's fuel, coolant, and/or structural materials.

>But the fire the sodium catches when in contact with air is a very mild one. It's nothing like the violent reaction sodium has with water.

Yep, and then someone will go and build the reactor beside the ocean and a tsunami will swap it, or by a river for its cooling waters, and oopsie a flood.

Not many tsunamis in Wyoming.

Or Arizona, Texas and New Mexico with an even more dry climate than Wyoming. Although, water is becoming a much more serious issue in these regions given the influx of migration from other states over time. I still think that Nuclear + Water for Hydrogen as a general fuel storage for transportation is a better option than battery packs... Though would require more investment in water infrastructure and transport as well as desalinization.

> Sodium absorbing a neutron creates a strong gamma emitter with a low half time.

Isn't that a feature? Is it 24Na that decays to 24Mg in 14 hours? In case of an accident, you can run away for a week and it will magically disappear. You don't need a long term storage of the waste.

Actually this might be sodium's biggest advantage.

Everyone knows that Uranium (or Plutonium) can sustain a chain reaction: when hit with a neutron, they split in 2 or 3 lighter atoms, and 2 or 3 new (and fast) neutrons. That can be used to produce a bomb, because the fission events grow exponentially. But it's not all that useful for a reactor, where you want the number of fission events per second to stay constant in time. Which means, on average, each out of the 2 or 3 neutrons produced in a fission event, exactly one will trigger another fission event, and the remaining 1 or 2 neutrons have to find some way to disappear. Roughly speaking they can be absorbed by: 1. by some heavy nucleus like uranium 2. some control rods 3. some neutron poison introduced in the reactor on purpose, such as boron, gadolinium or hafnium, 4. the moderator, like water, or sodium in this case, 5. the walls of the containment vessel.

If you think of it, it's such a waste. Many of these options result in radioactive elements. Some result in material embrittlement.

Given that, it may very well be that sodium could be the best option out there.

There’s an argument to be made that we should do a much better job of directing those neutrons to make tritium, since fission isn’t even something to discuss until we know how to make abundant tritium.

Yes. But fusion is not quite here yet. It's a difficult business proposition to store large quantities of tritium in the hope that you'll be able to sell to an operator of a fusion reactor three decades down the road (after about 80% of it has decayed).

On the other hand, when fusion is ready for prime time, one could use liquid lithium in a reactor. Liquid lithium has quite a number of advantages over sodium: in that temperature range it has more specific heat capacity than any metal, higher even than water. It has excellent conductivity.

And if it captures a neutron, it splits in helium and tritium plus energy. It could increase the energy production of a fission reactor by more than 5%. And you get that tritium for free, and ultra-rare helium-3 if you fancy some aneutronic fusion at some point.

A half-life of a few seconds and it will probably decay before it gets near a human.

A half-life of thousands years and it will give out it's energy so slowly you will probably be more worried about it's toxicity (e.g. plutonium).

The most dangerous ones are generally those that have half-lives of days or weeks. That is long enough to get into a human body and give out a lot of it's energy. The is particularly the case for elements that are readily absorbed by the human body (such as strontium which replace calcium IIRC).

On that basis radioctivity from sodium probably isn't too much of a threat. I would be more worried about it's reactivity.

(not an expert on this, but did consultancy for the nuclear industry some time ago)

> The most dangerous ones are generally those that have half-lives of days or weeks. That is long enough to get into a human body and give out a lot of it's energy. The is particularly the case for elements that are readily absorbed by the human body (such as strontium which replace calcium IIRC).

You're mistaken, the most dangerous waste is that with half lives measured in decades, like cesium-137 or strontium-90 which both have half lives of about 30 years. That 30 year half life means that it can take centuries for the waste to decay away to safe levels. More than hot enough to kill, and with the longevity to do so for several generations. Strontium-85 and strontium-89 half half lives measured in tens of days, but after a few years you don't have to worry about those anymore. It's the isotopes like strontium-90 that are the major concern.

for that specific waste, the coolant in a water cooled reactor isn't a huge problem either. The things that are "complicated" are the fuel rods that some people refuse to be convinced we can bury in storage until reprocessing becomes necessary.

Run away where? To the next river basin? Na will dissolve into any moisture and be carried away by any moisture.

The advantage is 24Na's short (14.9 hour) half-life, not the lack of solubility in water. Half of the original radiation will be gone in 15 hours, and close to 90% in two days.

I understand half life. My point moisture currents can spread water soluble things very far very quickly.

Think of it this way, what happens if there's a catastrophic sodium leak? The winds carry it far and the Na gets into everything because it will be diluted into the wind's moisture. Won't you breath the radioactive Na from the air's moisture?

The point is that the leaked material stops being dangerous before it can get very far.

Two days of strong winds and storms and you've just dumped sieverts on most of the central US and Canada.

2 days and ~90% of the original radiation is gone. 3 days and it's ~97%.

10% of the radiation of something with a half life measured in hours in a lot od radiation.

10 tons of radioactive Na leak.

1 ton is left after 2 days.

Thats a lot!

I imagine drinking only bottled water for a week, and perhaps increase the intake of salt for the same time. (Be careful if you have hypertension, it may be more dangerous the additional salt than the radiation.) Beer and salted peanuts looks like a wonderful anti-radiation plan.

If you get enough radioactive sodium salts to get covered in a dust layer, you are probably in trouble anyway. It may help that sodium is soluble an it can be washed easily.

If the small hidden sodium salts leak to water streams, my guess is that the concentration will be smaller than the natural sodium, and eating some additional non-radioactive sodium may help to remove it from inside the body even faster. Something like the potassium iodine pills.

Are you saying they use raw sodium as the coolant? I thought they used a sodium-based salt liquid? In which case, most of the sodium in the mixture is too tied up to react with air or water.

(edit: yes they do, see https://news.ycombinator.com/item?id=35841237)

Water bombarded with neutrons create tritium, which is it’s own nightmare.

The problem is the neutrons, not what they hit.

From a link shared in a thread below:

“High-temperature properties such as the volumetric storage density, viscosity and transparency are similar to water at room temperature. The major advantages of molten salts are low costs, non-toxicity, non-flammability, high thermal stabilities and low vapor pressures. The low vapor pressure results in storage designs without pressurized tanks (Fig. 1). Molten salts are suitable both as heat storage medium and heat transfer fluid (HTF). In general, there is experience with molten salts in a number of industrial applications related to heat treatment, electrochemical treatment and heat transfer for decades.”

I don’t know anything about this but it does seem that things are not as clear cut as your comment made it seem.

ref: https://onlinelibrary.wiley.com/doi/10.1002/cite.202000137

EDIT: From ChatGPT 3.5:

“ One of the most commonly used molten salts in nuclear reactors is a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2), commonly referred to as FLiBe. FLiBe is used as both a coolant and a neutron moderator in some types of nuclear reactors, such as molten salt reactors (MSRs) and some advanced small modular reactors (SMRs).

FLiBe has several advantages as a coolant in nuclear reactors, including its good heat transfer properties and its ability to operate at high temperatures without evaporating. Additionally, FLiBe is not highly corrosive to many materials commonly used in reactor components, which can help reduce maintenance and replacement costs.

However, FLiBe does have some potential disadvantages, such as its relatively high viscosity, which can make it more difficult to pump and circulate, and its high melting point, which can increase startup times for reactor systems. Additionally, FLiBe can be corrosive to some materials, such as aluminum and some types of steels, so care must be taken in selecting materials that are compatible with FLiBe.”

The reactor that Gates talks about (Natrium) uses sodium as moderator and coolant. In other words, the uranium fuel is submerged in a pool (literally, a pool) of liquid sodium. There are some pipes that circulate the liquid (and very hot) sodium to a separate place, where it heats up a secondary circuit of molten salt. That molten salt then goes on to heat some water and make it steam, which then drives some turbines and generate electricity. Or that molten salt can be left molten for a number of hours, as some form of energy storage solution.

So, the molten salt does not get in contact with the nuclear fuel in any way in this design.

There are other designs where this happens, and especially, there are designs where the uranium (or thorium) is itself part of the molten salt. Even Gates's company, Terrapower, has such a design in the works. But the Natrium reactor is not that.

> Sodium reactors have always had low availability times, caused by constant technical problems

BN-800 has between 70 and 80%, looks good to me

"Sodium reacts violently with water (used in some designs as secondary cooling cycle)."

Wow. This statement is ludicrous. It's like me saying this wind-turbine is dangerous because of solar-panel hazardous waste...Seemed pretty obvious (guy in the article goes on for a while talking about why water was a bad choice) that the design for this reactor is using some variation of molten-salt as a coolant (not pressurized water).

This seems overly harsh - is there not water involved at the plant to drive the steam turbines?

That the design of the plant does not directly heat water from sodium is great, but it still is useful to know the plant becomes sensitive to water issues like flooding.

So tell us how this will make the Natrium plant fail? since you are knowledgeable about this area.

Here is a read on the horror of building a sodium cooled reactor. Makes Vogtle look like a walk in the park.

https://en.wikipedia.org/wiki/Monju_Nuclear_Power_Plant

After bout 60 years and many heavily-financed large projects there isn't a single one industrial breeder reactor ready for deployment.

https://en.wikipedia.org/wiki/Breeder_reactor#Development_an...

>As of June 2011, the reactor had only generated electricity for one hour since its first testing two decades prior.

It would be hilarious if not for the wasting of a trillion Yen on this.

His understanding appears worse than that. Heat capacity is important, but as a second order. Absolute temperatures is the real deal since it sets the Carnot efficiency.

Another way to look at it, if I were doing a back of the envelop calculation (the most important calculations), I wouldn't look up the Cp of Na. Id only look up its boiling T

High Cp, low Cp... that can be remedied to some extent by running the pump faster or slower.

The text also kind of blanks the part where 2/3rd of world's nuclear reactors are PWRs, with typical water boiling temperature around 275°c.

Overall, the piece is a very flattering take on the technology, where all drawbacks are forgotten, and the comparison with competitors is not really honest.

A higher boiling point means that the coolant can absorb more heat without turning into a gas, which is crucial for efficient heat transfer in the reactor.

The statement about the boiling point being "8 times higher" refers to the boiling point comparison, not the specific heat capacity (which is +/- 3.4 times higher).

I don’t think the specific heat matters so much. The key is the boiling point is so high, the thermal flux will cool the system before pressurizing it. IIRC, thermal flux is proportional to the temperature differential.

But sodium's reactive, fire-starting, go-boom, good pair of running shoes temperature is considerable lower than water's.

> Ew, multiplicative temperature comparisons in unspecified units

In the previous paragraph he's said that water boils at 100 C

I'd expect a multiplicative temperature comparison to refer to Kelvin, not Celsius.

Or Rankine for a US reactor, surely? ;0)

Ah, TIL that Celsius is "non-multiplicative". From ChatGPT:

"When using Celsius as the unit for temperature, it is not meaningful to say that one temperature is a certain number of times higher than another. The Celsius scale is based on the freezing point (0°C) and boiling point (100°C) of water, which are not absolute values. Thus, the Celsius scale has negative values, and simply multiplying temperatures does not provide an accurate representation of relative differences.

If you want to compare temperatures in a more meaningful way, you should use the Kelvin scale. The Kelvin scale is an absolute temperature scale, with its zero point (0 K) representing absolute zero. In this scale, it is appropriate to say that one temperature is a certain number of times higher than another because the scale starts at an absolute zero point. To convert Celsius temperatures to Kelvin, add 273.15 to the Celsius value. Once the temperatures are in Kelvin, you can then make meaningful comparisons using multiplication or division."

Yeah, kelvin strictly speaking, but for reactors on earth (not in 3 kelvin outer space) with a baseline earth-ambient temperature, perhaps multiplicative C is valid, very approximately? I don't know, I guess I'm asking.

Temperature, especially in this context, relates to energy. The relative energy isn't 8x.

> boiling point is more than 8 times higher than water’s, so it can absorb all the extra heat

This is a bit like saying that a skyscraper is 8 times as tall as an apartment building, so the gravity is much weaker up there. Obviously not as extreme a mistake, but that's why people are jumping on it.

Specifying "times" in Celsius is fine... as long as you stay either positive or negative.

Implying that you can only specify multiples in Kelvin is being pedantic.

The Celsius scale is an "interval scale" while the Kelvin scale is a "ratio scale". One cannot take ratios of Celsius values as ratios are not even defined for that. https://en.wikipedia.org/wiki/Level_of_measurement

But not really.

100°C times two is not 200°C.

100°C times two is 473°C

Howso? If the conversion to Kelvin is additive (as opposed to something more complicated), and multiplying in Kelvin is fine, then how is multiplying effectively-unsigned in Celsius not fine?

Ok, another example.

Is 10°C 10 times as hot as 1°C?

No.

Multiplying kelvin is fine because kelvin is an absolute scale.

> No.

For a given baseline, perhaps yes?. Kelvin has its baseline inherent, for C you can pick what you like if you're clear about it. Perhaps. (Edit: and using only positive or negative temps as pointed out above)

Yes.

Parent's spaghetti examples weren't the most illustrative.

What I believe they're griping about is that "10°C does not have 10x as much heat as 1°C."

In actuality, "10°C has 10x the difference in heat that 1°C has relative to the freezing point of water."

So it's a comparison definition quirk, not a numerical one.

    c = k + 273
    x * c = x * k + x * 273

This leaves multiplied celsius off by a delta of (x - 1) * 273.

That's showing multiplied Celsius in terms of Kelvin, no?

  1 Celsius = 274.15 Kelvin
  10 Celsius = 283.15 Kelvin

Obviously 283.15 K != 10 * 274.15 K.

But that's not what's being said, per my lower comment -- it's 10x the difference relative to the freezing point of water, compared to 1°C.

The original upthread comments I were taking issue with were saying that multiplication has no meaning / is invalid in Celsius.

It does have a meaning, and it's mathematically consistent.

It may not mean what's being assumed, but nuance doesn't mandate "thou shalt never," IMHO.

When I say multiply by n, what I'm really doing is applying a delta of (n - 1) times my distance to the origin.

The origin with celsius isn't at zero, so you're prevented from doing what you were pretending was multiplication (at least in the most natural way of doing it).

Obviously you can negate your offset, multiply and reapply your delta.

It's a bit damned awkward though.

It's a bit the same as with time, multiplication of the time of the day don't make much sense.

I started the work at 1:20 pm, but my colleague started three times later, at 4pm.

> Specifying "times" in Celsius is fine... as long as you stay either positive or negative

127C is twice as hot as -73C though

<pedant>C is a measure of temperature, not heat.</pedant>

I still believe it is safer than water cooled plants, but Mr. Gates doesn't seem to have touched the downsides of using sodium [1]:

> A disadvantage of sodium is its chemical reactivity, which requires special precautions to prevent and suppress fires. If sodium comes into contact with water it reacts to produce sodium hydroxide and hydrogen, and the hydrogen burns in contact with air. This was the case at the Monju Nuclear Power Plant in a 1995 accident. In addition, neutron capture causes it to become radioactive; albeit with a half-life of only 15 hours.

> Another problem is leaks. Sodium at high temperatures ignites in contact with oxygen. Such sodium fires can be extinguished by powder, or by replacing the air with nitrogen. A Russian breeder reactor, the BN-600, reported 27 sodium leaks in a 17-year period, 14 of which led to sodium fires.

[1] https://en.wikipedia.org/wiki/Sodium-cooled_fast_reactor#Dis...

Is the heat transfer fluid for these nuclear plants considered radioactive? I honestly don’t know.

If so, then if a leak happens I’m guessing you have bigger problems than its chemical reactivity. Any leak is a major nuclear cleanup whether it’s water or sodium. Maybe the chemical hazard is just a drop in the bucket compared to the nuclear hazard, in which case why wouldn’t they use sodium?

With a 15-hour halflife, no matter the initial disaster, any radioactivity problems associated with the sodium coolant would disappear in a few days.

And even in those few days it probably won't affect things that aren't close to the accident.

A sodium 24 atom decays to an excited magnesium 24 atom by emitting a 1.39 MeV electron. That has a penetrating power of about 5 m in air.

The excited magnesium 24 quickly drops to the ground state by emitting two gamma rays, one at 2.76 MeV and one at 1.38 MeV. Those won't get past maybe 150 m of air.

What happens if that contaminates something else? I presume that would have a different half life? Not a physicist, so genuine question.

In general, radiation emitted from a radioactive substance is not itself radioactive, nor is it particularly dangerous once it stops moving. The usual radiation consists of:

Alpha particles: literally just Helium minus the electrons. Only harmful because it moves fast at first. Even then, it’s only really harmful if it gets emitted inside your body. It barely penetrates skin.

Beta: electrons and positron. Electrons will chemically react with something very quickly (except in a vacuum, they don’t stick around as free electrons). Positrons will find a nearby electron and be annihilated.

Gamma: very high frequency light. Can be quite dangerous, but doesn’t persist.

None of these transmute other things into radioactive isotopes. The kind of radiation that makes other things radioactive is neutrons, but those are very unusual outside of a nuclear reactor. Fission and some fusion reactions make neutrons, and a couple of radioactive elements make small amounts, and that’s about it. Neutrons also don’t persist in the environment (and, interestingly, they don’t persist very long in space either).

So a spill of hot radioactive sodium is nasty. It’s hot, and it’s highly reactive. But it’s so reactive that it will all react! Sodium can’t meaningfully contaminate groundwater, because it will just turn into salts. It can mess up soil pH, because the reaction product is lye, but that can be remedied by an acid. (Other than its pH, lye is pretty harmless. You use flush it down your drain to clean your drain, and you can even use it to make pretzels!) The radioactive sodium-23 emits radioactive sodium, but much less than 1 trillionth will remain after a day — what’s left is non-radioactive magnesium, which is harmless.

So I wouldn’t want it be around a sodium leak, but visiting it a day or two later while wearing a good pair of boots (for protection against any remaining lye) seems quite safe.

Could an electron emitted by beta decay of a neutron on the sodium hit the nucleus of something else and combine with a proton their to form a neutron, producing an unstable isotope of that something else?

Electron capture by a nucleus is a thing, but as far as I know, this only happens to any significant extent to unstable nuclei that naturally decay that way. It’s probably possible for a high enough energy electron to hit a stable nucleus and convert a proton to a neutron, but I’ve never heard of it (although I’m not an expert). So I don’t think anyone needs to worry about this.

Someone smarter may correct me but my understanding is that radioactivity doesn’t transfer like that. Contamination means for the isotope to find its way into a system (like a human body) and then stay there, radiating harmful particles from the inside.

If you were to be contaminated by ingesting some radioactive sodium, it would still decay and be gone within days.

The fact that it decays quickly also means that it would be very damaging if it got inside you somehow before it had decayed.

No, the half-life is a property of a nucleus, which does not take part in chemical reactions.

The normal way of dealing with cases of taking in radioactive abd bio-active elements, like iodine, sodium, (and even strontium which tends to take place if calcium), is taking excessive amounts of the same element, but a normal, stable isotope. Taking in some excessive table salt (cheese and chips anyone?) should be pretty easy.

How does molten salt solar plants solve those problems?

Because a salt is an already-reacted substance. Molten sodium and molten sodium chloride are utterly different, for example.

https://onlinelibrary.wiley.com/doi/10.1002/cite.202000137

"In commercial CSP plants, almost exclusively a non-eutectic salt mixture of 60 wt % sodium nitrate and 40 wt % potassium nitrate is utilized. This mixture is commonly referred to as Solar Salt"

I believe they use salts of other metals, not sodium. But in any case, in a salt the metal has already reacted with something and is unlikely to react further with commonly encountered substances.

I've heard that salt has corrosion issues. These may also apply to sodium, though.

The Wikipedia article says that sodium actually protects metals from corroding, but I am unable to see how that works by reading the citation.

Some very reactive substances react with their container vessel to form a non-reactive 'skin' on the inside of the vessel. I don't know if they applies in this case.

https://www.wyomingpublicmedia.org/natural-resources-energy/...

> The start date will likely be pushed back two years to 2030, according to a press release from the nuclear plant developer TerraPower. The main reason is Russia’s war in Ukraine, as Russia is the only commercial supplier of the highly enriched uranium (HALEU) the plant needs to run.

Great…

Importing enriched uranium from an adversary leads to

> America’s energy independence

Sure.

> First, water isn’t very good at absorbing heat—it turns to steam and stops absorbing heat at just 100 degrees C.

Umm, this is completely wrong and backwards.

Oh to never have encountered a steam table, some people never do I suppose. Some are born to it..

America's energy independence [from fossil fuels] - yeah indeed it does. Also, what stops America from producing its own?

Uranium mining has significant health risks, and it is pretty much guaranteed to result in significant pollution of the surrounding area. The enrichment phase isn't much better either.

Turns out the US has things like worker protection laws and environmental protection laws. Producing it locally is expensive, it is much cheaper to outsource the problem to a country with a more relaxed view on the issue.

A bit of googling shows there are about 1,000 abandoned uranium mining/prospecting sites in New Mexico. Probably many with uncontained tailings. Yikes. But we can count on extraction projects to clean up after themselves now. Right?

Of course! And they'll also maintain the tailings dam for the thousands of years required.

Why would we even doubt that?

Do you really think the situation in Russia is better?

No. It is very likely worse. Same for other places with less regulation than the US.

So, it'd be preferable to move it to the US where it can have better oversight and there's a potential of regulatory-driven change.

You're pretending option C "don't give the nuclear scammers more public money" doesn't exist.

No, actually.

There is plenty of uranium mining in developed nations and the price of nuclear fuel is not particularly relevant - 90 of the cost is pther stuff

So. Can someone Eli5 to me ? There's a large consensus on climate change (it's caused by humans, it's getting worse, it will increase catastrophes). Only people on the fringe regularly and vocally claim otherwise (there's no climate change, it's natural, it won't have any impact, impacts are good, it's all activist's fault because they scared use and we didn't act).

Reading HN and its heated debates around this topic, I don't see any consensus on nuclear vs renewables. Not even a consensus like "it's the mix, stupid".

Do our scientists have a consensus on how to power our societies in regards to climate change ?

If not, is it because it's too soon to settle on something ? Or there's too much bad science fabricated ? Or do we have have the choice, all things being equal: go full nuclear, or go full renewables or go mix but... as a specie we (or our leaders) collectively choose not to ?

The academic debate is generally dominated by two concerns around nuclear energy. The first one is that nuclear energy is by far the most expensive form by unit of energy produced. New project like to claim the opposite, but that is always before cost overruns and years of delay. In general the final price tag may be 2-3x as much than the estimate. Plant Vogtle in Georgial for instance went for $14B to $34B. Nuclear power plants also need water for cooling, so they are sensitive to both drought and extreme heat. Which is generally when you most desperately need electricity. Meanwhile, the same crowd claims to have economics on its side when railing against renewables, which are the cheapest unit by unit, and a great contingency plan for extreme weather events, like the disasters in Haiti.

But the bigger concern raised is that some calls for nuclear are a "cop-out". Nuclear happens to be great for damming up demands for renewable energy, while buying time for existing production capacity. It is not unusual for projects to run for years before any tangible construction is done, and even then it is not unusual for advanced projects to be cancelled for cost overruns. Meanwhile, you can have a solar panel on your roof in a couple of months. So it has some of the qualities of ExxonMobil calling for a carbon tax because they know it is unlikely to happen.[^1]

So overall, the academic debate over nuclear does not have much to do with its technical characteristics, it mostly has to do with the political dimensions of who the advocates are and what their goals or interests are. And if you are in favor of nuclear, it is still a good idea to look at who is on your side and consider what their motivation for fighting that fight is.

[^1]: https://unearthed.greenpeace.org/2021/06/30/exxon-climate-ch...

Nuclear energy debate suffers from the classic problem of impedance mismatch between the supporters and detractors regarding the unit economics at scale.

Current data we have is based on bespoke plants. Utterly maddening overhead. This is the cost disease plaguing any kind of infrastructure/construction/high-unit-cost projects in the "developed world".

If you build one plant per decade, then there's no incentive to streamline, no economies of scale, no overlapping s-curves of improvement, no real industrialization and standardization.

Lack of scale leads to discontinuities, change aversion, lack of innovation, pork and barrel politics, and so on.

See the Boeing 737 MAX fuckup. The regulatory environment created a cost jump so huge, that Boeing risked too much.

I think it's even worse, because so many plants were built in the 70s and 80s, and then there is a large gap. So we don't even have the routine and economies of scale associated with an s-curve anymore. And new plants promise better safety and new features, so we would really start all over again on the s-curve.

Korea build nuclear at scale and it's barely cheaper, still the most expensive form of electricity.

They've started construction on 2 plants in the past decade. That's not really "at scale".

No one is building nuclear at scale currently. Maybe with SMR it will be possible.

That sounds very Chaebol-y

This is just another lie. Costs increased very nearly monotonically during the peak of construction in the late 70s and 80s. And during every other country's peak of construction including china right now.

> The first one is that nuclear energy is by far the most expensive form by unit of energy produced.

Now that the world is waking up to understanding the LCOE is a wholly inappropriate metric for systems cost comparisons, this statement is more clearly no longer true.

With the firming included, nuclear is right there in the mix, cheaper than most 100% ___ with storage options.

https://www.ctvc.co/firming-costs-renewables/

You might have included the wrong link there. And with nuclear, always consider total cost, not operating cost. Not impossible to determine, but less reliable data floating around. You would have to take the cost of all failed projects as well as the cost of decommission and storage. For nuclear, the cost is a little bit funny. You have huge upfront cost, then lower running cost, and then a very long tail obviously.

You're right. Add the cost of storage or overprovision for demand fluctuation, add rapid dispatch, then planned and unplanned downtime to nuclear and the $150-200/MWh balloons even further.

If you're opposed to nuclear, it's also a good idea to look at who is on your side and consider what their motivation for fighting that fight is: https://www.forbes.com/sites/kensilverstein/2016/07/13/are-f...

Touche! I would argue though that the anti (existing) nuclear energy movement is separate from advocacy for investing into renewables over nuclear for new capacity.

I disagree on the separateness, at least to some extent. Solar and wind are less of an existential threat to coal/oil/gas than base-load-capable green energy sources like nuclear, geothermal, and hydroelectric; the fossil fuel industry therefore has a clear vested interest in bankrolling advocacy for solar/wind over others (especially nuclear, since it's less geography-dependent than geothermal or hydroelectric and therefore a greater threat). If/when battery storage proves to be feasible for providing that base load, I suspect we'll see similar pushback from the fossil fuel industry under similar pretexts (cue the videos of African toddlers slaving away in the lithium mines, cue the battery fires, etc.).

Solar for peak, nuclear for base. We need both, and advocacy for one at the expense/exclusion of the other tends to make me suspect ulterior motives.

Oh, I meant separate as in separate sets of people. Two sets of people with different goals. The original anti-nuclear crowd is a social movement that aims to shut down existing nuclear capacity or to blockade new construction. The other is an academic circle of people that advocates in their paper for the allocation of money to renewables this year over nuclear power in 5--10 years. That second set of people is not concerned as much with existing capacity.

There is broad consensus amongs experts.

With recent improvements in renewables, renewable positive people have said "we now think 100% wind, solar, battery is feasible" after a few years of saying 80% renewables is doable and the last 20% is tricky and people less enthusiastic about renewables are saying "we're still thinking that having 10-20% nuclear might work out slightly cheaper".

Even countries like France and Japan which are very nuclear positive, are not talking about 100% nuclear and have aggressive renewable rollouts planned:

https://www.reuters.com/business/energy/frances-renewables-g...

The extreme anti-renewable, pro-nuclear opinions you find on HN are bizarre and nonsensical. They're basically remnants of climate change denial.

edit: for example this is a summary from 2017 where they're nervously optimistic about getting to 100% but are fairly confident about getting to 60%

https://www.vox.com/energy-and-environment/2017/4/7/15159034...

> Again, it’s all about balancing out VRE. The easiest way to do that is with fast, flexible natural gas plants, but you can’t get past around 60 percent decarbonization with a large fleet of gas plants running. Getting to 80 percent or beyond means closing or idling lots of those plants. So you need other balancing options.

Why is it like climate change denial? I don't get it.

Because neither make any sense except as ways to justify continuing burning fossil fuels, but to disguise that fact from themselves, a believer needs to invent the most absurd conspiracy theories.

This is an economics and politics question, not a science question. Science has delivered the tools, it's a question of how we pay for it and who pays for it.

Scientists don't have a good track record providing answers to economics and political questions. OTOH, neither do economists nor political scientists.

The anti-nuclear camp is one of the greatest illiteraces acceptable to mainstream and high society.

That's the unfortunate reason why you don't see more consensus on this issue.

You can tell how well someone understands a topic by their ability to explain the argument of those who they disagree with.

> > I don't see any consensus on nuclear vs renewables. Not even a consensus like "it's the mix, stupid".

What I got is that nuclear (fission v.3/4 and fusion) are the "swing for the fences" technologies, while renewables are the "stuff largely remains what is today but without CO2 so people 80 years from now won't be living in a +3C world"

Personally I am rooting for fission and fusion because technological stasis is a recipe for disaster. Nukes will be flying way before the 3C treshold becomes a concern, people need constant improvement in their quality of life, if that doesn't happen they'll seek satisfaction into subjugating others.

Thermal generation is much more constrained than PV via waste heat.

LWRs also can't even match current world energy consumption for a variety of reasons.

On top of that, energy isn't quality of life. Happiness indeces and life expectancy are not better in Bahrain, Qatar and USA than Uruguay, Switzerland, and Spain.

A mix would always be nice because of diversification. I don’t think anyone wants full nuclear.

Building water, geo and hydro is (as of now) cheaper to build compared to nuclear [citation needed]. And it’s also “free” energy. Why not use it to reduce the usage of nuclear fuel?

> Safety isn’t the only reason I’m excited about the Natrium design. It also includes an energy storage system that will allow it to control how much electricity it produces at any given time. That’s unique among nuclear reactors, and it’s essential for integrating with power grids that use variable sources like solar and wind.

I'm surprised this is all he says on this matter. As far as I'm aware, this problem is largely unsolved, and one of the reasons dams can't go away: they're the only power generation technology that we can spin up and down in response to fluctuation in wind power and so on. That's because we don't have a good solution for storing energy on this scale, and thus must use the energy we generate. Have we finally come up with one? A water battery (pumping water into a reservoir behind a dam) is the only one I know of, which doesn't seem to scale well.

Any of the high-temperature reactor designs (sodium, molten salt, TRISO, etc.) can be combined with thermal energy storage.

Light water reactors only get up to 300°C, which is barely hot enough to spin a turbine. At >600°C, you can heat an intermediate fluid, lose some energy, and still spin a turbine.

So the idea is that there are chambers of molten salt (or similar) that can be heated when a spinning turbine is not needed, and it'll stay hot enough to spin one later? Any idea how long it stays hot? What happens when they're all already heated?

12-24 hours of molten salt storage should be enough to generate power all day, and sell it at times when electricity is most expensive. There's not much point storing for multiple days, when the reactor itself behaves like long-duration storage.

If your reactor is producing energy with no buyers, and your thermal storage is full, then you probably should've built it somewhere else, but in that case you can just power down the reactor.

> which doesn’t scale well

It also has the problem of only being applicable to geographies with abundant water and the topography suited to create giant reservoirs.

Right, I don't mean that individual water batteries don't scale well, but that the concept in general doesn't scale well as a solution to this problem. That's definitely one of the reasons.

Interestingly there has been a lot of discussion about hydrogen lately[0] because the Inflation Reduction Act provides a tax credit for production of clean hydrogen (e.g. hydrogen not from methane). Nuclear is one of the best possible methods to ways to generate this (high electricity, high heat) given that its operation does not generate carbon (just like renewables). The problem? Nuclear power generates $30/MWhr and will make between $60-$70MWhr producing hydrogen. Sounds like a win, but reactors are already at 90% capacity and supply ~20% of the US's energy and half of our zero emission energy.

Variability isn't that much of an advantage. Excess energy can often be sold off as well, reducing other areas' reliance on fossil fuels. France, Norway (almost all hydro), and Sweden (also a major nuclear player) and the main energy exporters in Europe (also lowest energy based carbon emitters)[1,2]. We see a similar thing with Quebec (major nuclear). But it is concerning given that nuclear is the main source of zero emission energy in the American South East[3]. Gates probably isn't concerning himself with the variability since there's no shortage of regions where selling a zero emission source isn't going to help reduce its neighbors energy emissions. The only areas where there is a shortage is where regions already rely heavily on either nuclear or hydro (or a combination).

There's no reason to not run at max load. You either sell the energy or your produce hydrogen. This is also a big reason that a carbon tax makes nuclear a viable option. Just for reference, here's an annual solar radiance map[4], wind (10m)[5], and hydro[6] as they might help explain the situation in the South East.

[0] https://heatmap.news/economy/the-nuclear-hydrogen-conundrum

[1] https://www.enappsys.com/interconnectorreview/

[2] https://app.electricitymaps.com/zone/FR

[3] 80% of TVA's zero carbon, 77% of SCS, 86% of Duke Carolinas, 81% of Duke Ease, 80% of PJM(looking at 12 months)

[4] https://www.nrel.gov/gis/assets/images/solar-annual-ghi-2018...

[4.5] find other maps -- look at DNI -- for different months and energy sources here https://www.nrel.gov/gis/solar-resource-maps.html

[5] https://www.nrel.gov/gis/assets/images/wtk-10m-2017-01.jpg

[6] https://www.nrel.gov/gis/assets/images/map_hydrogen_kg_count...

The lifecycle cost of nuclear is still higher than solar PV even with storage and we have low-risk, low-tech solar-with-storage options such as molten-salt concentrated solar, which, while not as efficient as solar PV, is very simple technology.

Solar PV and wind are cheap enough that overbuilding is easy. One might wonder what we can do with surplus power during times of day when we have too much solar (middle of the day) or too much wind (middle of the night) -- we can do desalination with the surplus solar (matches the demand curve of water use across the day and across the year) and convert wind to nitrogen:

https://wcroc.cfans.umn.edu/research/renewable-energy/wind-f...

Its very tiring that there is always someone here telling us how inexpensive PV and wind are compared to other generation. Which is true per watt, until you try to assure that watt is actually available when its needed.

So its comparing the costs of two entirely different things, power which can be predicted and produced at a given level, and power which may or may not produce anything over a given time-frame. And so, i might say its a lie...

Particularly because the costs associated with making a watt of wind/PV reliable easily adds an order of magnitude in costs, making wind/PV a much worst cost proposition than just about anything else. And its particularly bad in places that don't have existing hydro and nukes because the only realistic way to back it up with today's technology/economy is fossil fuel sources. (aka grid scale batteries capable of multi day power storage simply don't exist, and you can't "overbuild" your way out of the problem.). So its not even carbon free.

Let's champion both.

Living in Austin, I plan to add solar to my house someday, and I would also love to see us build nuclear power plants.

I really cannot understand why people set these things at odds with each other. They are both better than fossil fuels or degrowth.

> I really cannot understand why people set these things at odds with each other. They are both better than fossil fuels or degrowth.

Mostly because in many places nuclear power is currently politically blocked from any further build-out, if not outright banned. One of the main rhetorical moves that various "green" (i.e. anti-nuclear) lobbies say to justify not building out nuclear power — which regulators seem to have absorbed and now believe — is "for everything we'd use nuclear for, we can just use PV."

This statement has a clear refutation: nuclear is base-load + grid-scale, while PV elastic-load + individual-site-scale; so if you need to e.g. double the electrical capacity of a large city in response to population growth, then PV isn't going to work—you want nuclear (or another base-load grid-scale power technology, like hydropower.)

But these arguments don't get heard; rather, the regulators say "but we have PV, what's the point in building nuclear rather than just supporting the build-out of more PV?" as a conversation-ending rhetorical statement.

In order to convince regulators to allow the build-out of nuclear, there has to be some equally-powerful rhetorical statement that can be used to "reopen the conversation." Which would, intuitively, come in the form of a clear and effective condemnation of PV as a base-load / grid-scale power technology. But if regulators don't understand terms like "base-load" or "grid-scale", then what you end up having to do to get them to stop packing up and shooing you out of the room, is to condemn PV full-stop.

They don't have especially complementary profiles for a generation mix, unfortunately. So at scale it seems like you have to pick one or the other.

I don't think it makes financial sense to build new nuclear, but solar and nuclear pair reasonably well if you have existing nuclear, at least in areas where air-con is used (demand peaks in summer afternoons).

The problem only arises when you don't charge coal and gas plants sufficient carbon/pollution fees, then they can underbid nuclear and drive it out of the market and stop it earning enough overnight.

to quote the nuclear industry:

https://www.theguardian.com/australia-news/2019/jun/04/nucle...

> Nuclear could provide cheap energy but would only be competitive with gas and coal if carbon pollution is priced, nuclear association says

>I really cannot understand why people set these things at odds with each other.

Because they compete for investment dollars from the government.

Why doesnt the government just fund the cheapest one?

Because the nuclear military industrial complex needs a civilian nuclear industry to operate cost effectively.

Because financialized/late-stage capitalism makes long-term investments like nuclear power generation financially infeasible, while funneling subsidies to "green energy" solar/wind industries is extremely profitable in the short-term.

In other words, the thing that actually works is significantly less likely to happen, and therefore requires far more support.

The comment you replied to explicitly addressed how to make cheap renewables more available.

You might disagree, but acting like they never even mentioned it makes it seem more likely that you're just going on outdated info.

The storage in "PV with storage" is most commonly measured in single digit hours of capacity, and is primarily used in locations where the sun is predictable up during the day and has a predictable discharge/charging cycle of 24 hours. One of the biggest upside is that the economics of it is fairly simplistic with 365 cycles each year that produce predictable revenue.

There is a second form of storage that is also fairly common, which is storage that exist to balance the grid when different units goes up and down. Those generally have even less capacity and are not intended to operate under long periods.

For locations where the first form of PV with storage works, they should really replace everything (with imports handling any exceptional weather events). Storage of this form does however become significant more expensive the further away we get from this optimal weather pattern, and there is a multiple reasons why wind heavy nations can not survive on a few hours of storage. Latitude and seasons can also have a very large impact if a nation where to use this as their only strategy.

>Its very tiring that there is always someone here telling us how inexpensive PV and wind are compared to other generation. Which is true per watt, until you try to assure that watt is actually available when its needed.

It's 5x cheaper per watt. That goes up to 1.5-3x cheaper once you add "when needed".

OP already mentioned that it is cheaper with storage. You ignored them.

>Particularly because the costs associated with making a watt of wind/PV reliable easily adds an order of magnitude in costs

An order of magnitude is absurd.

I'm wondering what kinds of reliability we actually need.

Residential: it seems like we often accept less reliability? It's common for bad weather like thunderstorms to cause power outages, particularly in rural areas. Lots of places in California will get cut off during high winds.

If you need reliability, a battery backup protects you from more outages, including those that take out the grid. In some cases a generator makes sense (such as for a data center), but it's higher maintenance.

What solar storage technologies work in the winter? For instance, it has been rainy in California this year, and between Jan and March, we were at a production deficit of 1MWh for our house. So far, in May (so the last 5 days) we’re at a 275KWh deficit, and every day has seen a deficit so far.

I’d love to have a 1MWh battery, but current raw battery cost is $151/KWh, and actual residential systems are closer to $333 to $666 / KWh installed. At the raw battery cost (ignoring space requirements!), we’d have already burned through $41,000 of battery capacity this month, and the weather forecast suggests we’d need double of that to get through till wednesday. That’s $82K for raw batteries, or $275K at the midrange for residential installs (ignoring solar costs). Grid-scale storage is somewhere between those two numbers, and this is May. Winter this year was even more unworkable.

Small-scale solar installations are not supposed to get you off-grid and like you observe, a small-scale/battery storage isn't going to change that.

Instead, the idea is the grid-scale combination of solar, wind and hydro with various storage and adaptive consumption solutions. For example: when water levels are down, pump water up the dam during sunny/windy hours to store energy for the bad months.

Normal hydro is failing due to climate change (at least in the US west), so that’s not a great bet to make.

Nuclear is maybe 2-3x more than renewables at this point, but that’s actually a pretty good deal, given its safety record vs literally everything else.

Of course, it’s best to produce as much as possible with cheap wind, solar, and battery, but getting from 80% to 100% means over-provisioning to the point where nuclear would be cheaper.

That's part of the point: pumped storage (and other solutions) can be used even though the climate changes. Batteries won't have to be the main storage solution.

Another part: over-provisioning does not increase the costs much as there will be flexible demand for the additional electricity produced.

Yes, all the cheap surplus wind and solar power will be used for many things, also e.g. low-emission production of steel and hydrogen, running heat pumps and even boiling water for hot water reservoirs etc.

Also, this "nuclear breakthrough" concept is likewise complicated by storage:

> It also includes an energy storage system that will allow it to control how much electricity it produces at any given time.

Why do they have to complicate it? Otherwise, they wouldn't have a chance competing with the cheap price of renewables:

> it’s essential for integrating with power grids that use variable sources like solar and wind.

Basically, nuclear plants generate losses when it's sunny or windy, and profits from the dark and calm times won't make up for the losses. (The flexible power consumption will switch off rather than pay the higher nuclear power prices.)

For solar and wind you need TWh of storage capacity, in Europe many days without solar or wind (just bad weather) is relatively common.

Existing hydro is able to fill in for some of the storage needs, and pumping water up the dam will be one type of large-scale storage that can be built. See pumped-storage hydroelectricity: https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...

To get an idea of the scale of hydro storage:

> European hydropower reservoirs provide a storage capacity of 220 TWh (85 TWh are located in Norway).

https://setis.ec.europa.eu/hydropower-and-pumped-hydropower-...

Europe is going through one of the worst drought we know of. There's literally no water to growth crops, let alone hydro, at least in Spain and Italy.

Pumped hydro does not need to consume water, it can pump the same water over and over. In some places, it can use saline water from the ocean.

The EU report says hydro power can help agriculture e.g. if big reservoirs are built and on dry years the water from them can be used in agriculture.

I'm italian, I live here, literally lakes in northern Italy have almost no water, it's now a drought almost two year long

> > is very simple technology

AKA it won't bring about the next industrial revolution. It will maybe secure a world where the Earth is 0.01 C cooler vis-a-vis fossil fuels.

Nuclear is exciting because humans can play God, that's where innovation lies, containing the power of the cosmos in a human friendly manner. With all due respect people who love renewables are un-imaginative and they resigned themselves to technological stasis in exchange for a reduction in CO2 emissions. That's a very underwhelming proposition, because in short, it means that there is nothing for us, but only benefits for maybe those who'd be alive in 200 years. That's unacceptable and un-American.

This initiative is to be encouraged and Mr. Gates has a history of being the person who had the privilege of signing off huge quality of life improvements for Americans . Which is mostly luck among those who had the right vision, in Windows case the GUI. But still it's something, I believe that other GUI pioneers would be financing the same projects had they been the ones ending up with a 200bn net worth.

>solar

I love the idea of being completely reliant on something where China controls 80% of the supply chain - https://www.iea.org/reports/solar-pv-global-supply-chains/ex...

Surely nothing could go wrong there, it's not like Russia pulled the same strategy and funded anti-nuclear activists in Germany to get them dependent on Russian natural gas.

>wind

I've talked to executives at energy companies who said they only built wind due to the massive subsidies. There's also major issues with what to do with the windmill husks once they are decommissioned and the fact they are a massive eye sore.

If the US was serious they'd spin out some of the US Navy's reactor tech and turn all that technology into a profit center. They could even do a "bases for reactors" program where nations get electricity in return for allowing the US to operate the reactors on their land

https://en.wikipedia.org/wiki/Destroyers-for-bases_deal

Buying solar panels from China is not the same kind of dependency as buying fossil fuels from Russia: the first is an investment, the latter is consumption. Also, solar panels can be built anywhere, while fossil fuels are a limited natural resource with no deposits in e.g. Germany.

> When it opens (potentially in 2030),

So this is an announcement of an announcement. Nuclear power plants have a very long history of being shut down right before they open, so now I'm more skeptical that this will ever work.

This happened a lot at Hanford in Washington. They built something like four power plants up there but when they were 90% complete Congress only approved one of them. It sounds really cool Congress approves its building but once it's about to open congress gets scared because of how people feel about nuclear power plants close to their house.

Regardless of how cool they say their technology is I will be more interested when it actually opens.

I think the real story here is that the project was successfully sold to the people of Wyoming, who now appear to be shouldering the responsibility of decarbonization.

I am in Wyoming. I think it makes sense to the people here. The state is going green and the mines are shutting down. A suitable replacement needs to be created first before all the mines are decommissioned. Some of the people will be employed by the nuclear plant and some will have to move or retire. The person I know at the mine is retiring soon. As this state provides a lot of power to the US power grid currently with coal [1] I think it makes sense to transition as much of it as possible to nuclear and renewables. The state is not limiting itself to one source, all options are on the table and more options are being added soon. We do not show up as a big number for wind and solar power because it is only augmenting some power for some of the small towns and not the US grid yet [2].

[1] - https://www.eia.gov/state/?sid=WY#tabs-3

[2] - https://www.transwestexpress.net/

Kind of surprising, given that coal mining is one of their largest industries. I’m actually kind of shocked.

...and Gates makes a profit. This makes me worry about how the plant is being sold. I mean what are the unknown unknowns?

Does a statement like this give you confidence?

"TerraPower says these risks have been considered and addressed as much as reasonably possible."

https://cowboystatedaily.com/2023/01/25/former-dea-nuclear-s...

"Tallen said he’s not ideologically opposed to nuclear power. He said he rubbed elbows with that crowd years ago, but it’s not where he stands today.

“The distrust of nuclear power is one of the major ideological tenets of left-wing, anti-establishment politics,” Tallen said. “I had to say to them, I can’t agree with you on many of your basic assumptions. I’m just saying that this particular [Natrium] technology pursued the way it is right now – I don’t think it’s a good idea.” "

For some reason "reasonably possible. Sounds a lot like "economically reasonable".

Which should absolutely worry anybody who has the faintest ideas about how insidious Sodium is as a cooling material.

It’s a good thing we have solar, wind and batteries to do most of the work of decarbonization before 2050, because it seems like if these supposed breakthroughs in nuclear are going to deliver on their clean energy promises, we’re going to have to buy them lots of time to actually get working.

Today I posted this https://news.ycombinator.com/item?id=35840591 to HN. It is a YouTube video with some straightforward statistics that, in my opinion, imply a very rough road ahead for Solar and Wind.

The basic problem confronting us is the need for so many mined materials to build future solar, wind, and storage facilities. It's really quite daunting.

The road ahead was always going to be daunting. It's just far longer, harder and more expensive if with nuclear power.

It's great if you want to share costs with the nuclear military industrial complex or you might need to build a nuke in a hurry one day. Not so much if you just want to decarbonize as cheaply and quickly as possible.

The materials for a gwh/yr of solar are a strict subset of the materials for a gwh/yr of LWR with the exception of silver (which is about 4x).

Except the solar is improving rapidly and doesn't need to be buried for decades at EOL.

Capitalism fixes that if the product is something consumers demand.

Is the material too expensive then more production are brought online and alternatives are found, like cobalt being replaced in batteries.

The mineral reserves figures usually touted can be seen as the working inventory given the economic conditions today. USGS have a good explanation

> Reserves data are dynamic. They may be reduced as ore is mined and (or) the feasibility of extraction diminishes, or more commonly, they may continue to increase as additional deposits (known or recently discovered) are developed, or currently exploited deposits are more thoroughly explored and (or) new technology or economic variables improve their economic feasibility. Reserves may be considered a working inventory of mining companies’ supplies of an economically extractable mineral commodity. As such, the magnitude of that inventory is necessarily limited by many considerations, including cost of drilling, taxes, price of the mineral commodity being mined, and the demand for it. Reserves will be developed to the point of business needs and geologic limitations of economic ore grade and tonnage.

> For example, in 1970, identified and undiscovered world copper resources were estimated to contain 1.6 billion metric tons of copper, with reserves of about 280 million tons of copper. Since then, about 600 million tons of copper have been produced worldwide, but world copper reserves in 2021 were estimated to be 880 million tons of copper, more than triple those in 1970, despite the depletion by mining of much more than the 1970 estimated reserves.

https://pubs.usgs.gov/periodicals/mcs2022/mcs2022-appendixes...

Appendix C to 2022 Lithium Statistics and Information.

https://www.usgs.gov/centers/national-minerals-information-c...

If you get some time, try doing some napkin math on how many batteries you will need to actually do most of the work with wind and solar.

It is something you can work out a ballpark number for a given % of wind/solar and while not impossible it is really a big number. Way beyond what we will get out of actual chemical batteries by 2050, we need gigantic scale pump back hydro projects on top of that. Trillion dollar range. So Nuclear may be less daunting, expensive as it is.

The problem with that is that nobody who is seriously doing energy modelling would propose to do all storage with batteries. That's more a popular misunderstanding than an actual energy concept.

If you plan for a 100% renewable grid what you do is that you use different types of storage for what they're good at. Batteries can play a role in short-term storage, but for seasonal storage they're clearly not a good choice. Electrolyzers and H2 gas peaker plants (or maybe ammonia instead of H2) look like the most promising option.

I wish more people knew this, because all this "I calculated how many batteries you'd need for your renewables, we need nuclear!" clearly is neither an informed take nor helpful.

Let me try some napkin math with nuclear. France is usually taken as a positive example for nuclear. They have 56 reactors on a population of 67 million. For the whole world to get to that level we are talking about 6k-7k in reactors. There are a couple hundred in the world already so let's make it 6k. The costs depend on a lot of things, but 10 billion a pop is a nice round number and for the majority of the world a low estimate. So roughly 60 trillion in construction costs only. Then we need to run them and eventually decommission and store the waste, which even with much smaller scale nuclear programs today will cost hundreds of billions.

Not a realistic solution. We can do more, faster and cheaper with renewables. If you can't get to 100% with renewables, nuclear should anyway be the last option.

Why calculate when we have lots of empirical data? There are plenty of grids around the world are deriving 40% of their energy from wind and/or solar. Up to 65% is relatively easily accommodated according to grid engineering orthodoxy with current typical infrastructure/tech.

Intermittent energy. Doesn’t work well for manufacturing at all. Your argument, without nuclear, is an argument for natural gas and coal.

Industrials need steady power to function. Without nuclear, the world is going to just use natural gas. Coal for poorer countries. Solar and wind peppered in but not trusted for any base load and regionally limited.

Doesn't this mostly happen in counties like Denmark where it's relatively easy to buy / sell energy to the grids of neighboring countries?

This would work well in denser-populated parts of the US, like northeast, and would be harder in Midwest.

HVDC will handle moving energy on continental scales. China makes power in northwest inner parts and moves it thousands of kms to the coast for consumption.

Given that the world spends trillions annually on fossil fuels, spending trillions on batteries could still save money.

That's the thesis of the Tesla "master plan 3.0". It claims it will cost $10T to decarbonize the world, but that it would save $13T by doing so.

Tesla is obviously biased, but so is everybody else so might as well use a source where the biases are clear.

If you want to see some big numbers, look at fossil fuel capex. Those big numbers have been spent year after year for decades on getting us into this problem. Don't expect to get out of it for much less, even though individual renewables projects look cheap by comparison. It has to add up to the same power output.

We'll sooner build green hydrogen generators and peaker plants than those modular nuclear plants by the looks of it.

Analysis put covering the whole US with solar to cost about $5 trillion and the world about $65 trillion dollars. A lot, but it would pay for itself in about 5 years. The only blockade is all the people making all these trillions from the oil and all the power sources that make them all this money.

We’re never giving you 5 trillion.

$5T sounds like a lot but it's spread over the lifetime of the panels, 20 years. What do utilities spend on capex and opex over 20 years.

Who’s “we”, you and the mouse in your pocket? The solar industry is getting that money, one homeowner, building owner, or lot owner at a time. And then, over time, they earn a profit in the generated energy! Sorry you hate making money doing nothing!

People will loan it and be paid back, with interest.

So when will Terra Power actually begin construction? What really matters is that these small modular reactors actually get built.

Right - quite surprising how long it takes to get one of these up and running.

The article implies that sodium cooling is novel, but it's been used in (experimental) reactors since the 1950s.

https://en.wikipedia.org/wiki/Experimental_Breeder_Reactor_I...

Didn't the soviets use it on their fast attack submarines?

Lead not sodium

Yes. Lead-bismuth in the 7 boat Alfa class https://en.m.wikipedia.org/wiki/Alfa-class_submarine

Presumably you wouldn't want to use something that violently catches fire (sodium) in a vehicle designed to tolerate nearby explosions.

Presumably. The USA did build a sodium-cooled submarine at one point, the Seawolf. Having high thermal efficiency increases range, and liquid metals can be pumped electromagnetically and completely silently, with no moving parts.

It was converted to water coolant later due to technical challenges though.

https://en.wikipedia.org/wiki/USS_Seawolf_(SSN-575)

Also a vehicle that is immersed in a liquid that violently reacts with it.

He's still talking down renewables, which is unfortunate, but we got to the tipping point despite him so it's less annoying than it used to be.

> fact, in terms of lives lost, nuclear power is by far the safest way to produce energy.

I don't think this is true anymore even if you skip the "by far" and if you include the "by far" it's not been true for maybe as long as this plant has been in planning.

> I don't think this is true anymore even if you skip the "by far" and if you include the "by far" it's not been true for maybe as long as this plant has been in planning.

Source?

https://www.sciencedirect.com/science/article/abs/pii/S22113...

https://ourworldindata.org/safest-sources-of-energy

This is a pro-nuclear site. The original version of the article had nuclear coming out ahead but had no info on renewables:

https://web.archive.org/web/20200210102743/https://ourworldi...

They updated it with newer information, and now it is no longer winning.

That "new" information, is from 2014, from this paper:

https://www.sciencedirect.com/science/article/abs/pii/S09596...

> Our study shows how these energy systems collectively involved 686 accidents resulting in 182,794 human fatalities and $265.1 billion in property damages. Across the entire sample, the mean amount of property damage was $388.8 million and 267.2 fatalities per accident, though when reflected as a median the numbers substantially improve to $820,000 in damages per accident and zero fatalities. Wind energy is the most frequent to incur an accident within our sample (48.8 percent of accidents), hydroelectric accidents tend to be the most fatal (97.2 percent of all deaths), and nuclear energy accidents tend to be the most expensive (accounting for 90.8 percent of damages). The article uses this data to present a set of unique risk profiles: nuclear, hydro, and wind energy are categorized as having a “high” risk of accidents; hydrogen, biofuels, and biomass “moderate” a accident risk; solar and geothermal a “low” risk.

Think about how much renewables have been deployed since 2014.

https://ourworldindata.org/grapher/modern-renewable-prod?tim...

“ I’ll start with improved safety. Keep in mind that America’s current fleet of nuclear plants has been operating safely for decades—in fact, in terms of lives lost, nuclear power is by far the safest way to produce energy.”

Exactly, everyone has panic attacks when you mention any accident at a nuclear plant. When the majority of these plants are extremely safe.

> I can’t overstate how welcoming the people of Kemmerer are being.

That may be true, but I can't help but think billionaires are horrible judges of this. Most folks are very polite to the people who cut huge checks. They also do not react normally around famous people.

Folks may be great in great communities, but I really don't think famous billionaires are reliable observers of these qualities. I would be far more likely to trust a poor nobody to suss out what a town is really like.

Nothing brings out an honest accounting of character better than having nothing to gain from an interaction.

Excited to see the progress on this, as I have local connections.

One of my nearby neighbors is the engineering manager of this facility. He's an ex nuclear sub XO who before that was running launch operations for Blue Origin. He knows what he's doing in building things.

And another neighbor - although I only met him few times via our mutual kids being in same class - is the brain guy with two PhDs in nuclear engineering. I think he knows what they are designing. Plus we both drive same model car with custom license plates, his is nuclear-themed. Points!

That's awesome. What's the reception in the town of the new plant?

Misunderstanding. I am not in Wyoming. We're all in Seattle area, near Bill Gates... well, near enough.

It’s much more expensive than solar or wind + storage, so why exactly?

More expensive than "solar or wind +" which amount of storage? The amount of storage which would put wind/solar on par with nuclear in terms of reliable baseload is huge.

Exactly. Electricity is fungible and so is capital. Spend the capital on the technology that arrives soonest with the least capital.

Cost comparisons for nuclear are also dubious. The French are discovering their decommissioning costs are a multiple of what they predicted. Who, using what cash-generating capability, is going to pay for that?

And where to reprocess or stash the waste?

What we are seeing with uranium fission plants being touted as new tech is an attempt to forget the PWR uranium fission problems. TBF it is not for the sodium-cooled uranium reactor people to solve all the problems. But those problems still need solving.

No it isn’t. Electricity has to be delivered the instant it is consumed. You can pile up capital.

Storage in the form of batteries, pumped storage, hydrogen, or ammonia works. It is needed more for renewables than for nuclear, but nuclear is hard to throttle to a fine granularity like fossil fuel plants.

Anyway, I should have said power generating capacity is mostly fungible. You can mostly replace any capacity with a different kind, within some limits, the same way money isn't perfectly fungible if you need currency conversion, have FDI limits, repatriation limits, etc.

So a reasonable engineer would then conclude the practical route to a green grid is nuclear baseload + natural gas peaking + solar and windmills.

Storage is nowhere near practical today. A house can barely run off batteries. How about mines, factories, aluminum smelters.

In future it would be great if this changed.

That statement is being challenged.

https://www.ctvc.co/firming-costs-renewables/

More reliable, less of an eyesore.

I think windmills are rather beautiful. Subjective, obviously.

Have you ever been around a sizable wind farm at night when you have to look at bright red flashing lights for miles in every direction?

Can't say I have. Is it any worse than looking out at a big city at night?

Probably not as serene as the star-filled countryside they replaced.

Well, no, but better than a coal fired power station?

The anti-nuclear sentiment on this board is perplexing....

Way to go! I'm excited for the future of Nuclear fission, it's clearly going to be an important part of the sustainable future.

Sodium metal reacts explosively with water. Sure, it's fine when working as designed, but this piece aims to be reassuring people about disaster scenarios. And it's easy to imagine a disaster where part of the plant gets physically damaged and the sodium's exposed to the outside world, possibly including rain or flooding.

So why sodium? What does sodium accomplish that can't be done equally well with a cheap non-explosive metal like aluminum or iron?

https://en.wikipedia.org/wiki/Sodium-cooled_fast_reactor

How hard would it be to use all the heat to generate usable energy, rather than discarding a bunch of it via coolant? I don't know much about nuclear reactors and I'm sure I'm not the first to think of it, and I'd guess it's quite a bit of heat - but then it's quite a bit of usable energy.

That's exactly what it's doing.

The problem is not getting rid of excess heat, it's that the heat causes wear and maintenance issues due to pressure, needed pumping, etc.

>It also includes an energy storage system that will allow it to control how much electricity it produces at any given time.

Does anyone know more details about this? I'm thinking it's a monster flywheel. Which would be very cool.

The Natrium data sheet[1] says that it is "Molten salt energy storage", so based on the diagram[2] it appears that salt (not sodium) is being pumped to to the reactor and stored in large tanks, similar to thermal mass solar installations. I assume the sodium is internal to the reactor only, but can't say for sure.

[1]:https://www.terrapower.com/wp-content/uploads/2023/03/TP_202... [2]:https://www.terrapower.com/our-work/natriumpower/

Presumably just insulated storage of hot stuff to act as a buffer between the heat production and use for electricity generation. Very similar to what CSP plants do.

The molten sodium is a storage of energy in the form of heat. Keep it well contained and insulated, and you draw off only the heat that is needed to convert to kinetic energy, which then generates electric current through induction.

Like a monster flywheel, there are all kinds of things that might go wrong, but they're all far less scary than Chernobyl style meltdowns.

I am curious what HN thinks of RFK Jr's position on nuclear power. He was a guest on the latest all-in podcast and went into his positions in-depth.

Something to the affect that nuclear is more expensive than other traditional and renewable sources. No traditional insurance company will insure nuclear plants. No traditional bank will finance nuclear builds. Nuclear power is still too risky to be considered as a viable power source.

He adds, instead continue focus on wind and solar and improve transmission (using DC) to make it a viable power system for the US. Is he uninformed? Direct current (DC) is the worst kind of power type for long distance transmission. (Unless something has changed).

My understanding is that solar and wind generated power has shown not to be consistent enough and too localized to currently meet US power demands.

Powering the US without emitting CO2 generally requires either (1) lots of new transmission lines to share wind/solar between regions, or (2) lots of nuclear so we don't have to.

> Direct current (DC) is the worst kind of power type for long distance transmission.

AC was traditionally used for long range transmission because a transformer can easily increase or decrease the voltage. Transmitting DC is actually more efficient, but it requires modern semiconductor technology to generate the voltages necessary.

> My understanding is that solar and wind generated power has shown not to be consistent enough and too localized

That's why we would need transmission to make it non-local.

This title sounds like the opening to a Tom Scott video.

Unlike water, the sodium doesn’t need to be pumped, because as it gets hot, it rises, and as it rises, it cools off

Mr Gates, can you hire another copy editor please?

What's the problem?

Water also rises as it gets hot, and cools off

"cools down" is grammatically more correct.

Do you know what hot water does? Like liquid sodium, it rises. The point here isn't that liquid sodium has some magical lifting property water doesn't have, it's the enthalpy, latent heat: water can't hold as much heat energy without pressure to contain the phase change into steam. If you remove hot things from the primary heat source they cool. The sodium is just more tractable.

Einstein and (Leo) Szilard had patents in liquid metal pumped refrigerator designs using electro magnetics instead of mechanical pumps, Richard Rhodes talks about them, and applications to cooling nuclear systems.

Well, the same phylosophy is used in the Windows operating system with great results. /s

Cool now hook it up to Bitcoin miners

It'll be interesting to see who'll agree to insure this nuke.

Continuosly talking about providing workers and patriotically pumping US's independence on power, while only slightly touching the actual plant design and safety with questionable points.

Bill Gates keeps getting fishier every day.

I'd hazard that, given its content and writing, can16358p and technical reactor geeks are not the primary audience this was intended for.

We're definitely not the intended audience, though I believe what I'd said still applies the same way.

I'd say he realizes that a bit part of change is calibrating a message to a wide audience, to recruit them to your cause.

looking at how cutthroat he acted as CEO of Microsoft, should we have expected anything different?

I have zero respect for Bull Gates' opinion, ideas, and beliefs.

Wanna grab some pie later?

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