
Small nuclear reactors: tiny NuScale reactor gets safety approval - natcombs
https://www.popularmechanics.com/science/a33896110/tiny-nuclear-reactor-government-approval/
======
jhallenworld
Here is the NRC website about this reactor:

[https://www.nrc.gov/reactors/new-
reactors/smr/nuscale.html](https://www.nrc.gov/reactors/new-
reactors/smr/nuscale.html)

Here is an interesting sub-report:

[https://www.nrc.gov/docs/ML2022/ML20224A525.pdf](https://www.nrc.gov/docs/ML2022/ML20224A525.pdf)

Information withheld for security reasons. One item concerns the "ultimate
heat sink". What happens when the ultimate heat sink is lost?

Well a design assumption is that it is not lost:

[https://www.nrc.gov/docs/ML2020/ML20205L410.pdf](https://www.nrc.gov/docs/ML2020/ML20205L410.pdf)

"A key assumption of the PRA is the availability of the UHS to provide an
adequate heat sink. To support passive heat removal with the DHRS or ECCS, the
reactor modules are housed and partially submerged in the UHS such that most
of the outer surface of the CNV directly contacts the UHS, which is a large
pool of water in the reactor building (RXB). "

DHRC is decay heat. CNV is reactor containment vessel. So drain the pool and
the reactor is in trouble.

~~~
i_am_proteus
Nuclear engineer here. I've read through a good portion of the regulatory
submission to the NRC and have a few takeaways that oppose some of the less-
well-informed takes in this thread:

\- The reactor differs substantially from existing PWRs by encasing the
primary in double containment, using natural circulation flow for both normal
operation and emergency cooling. There are no pumps needed (or installed) to
move coolant through the reactor.

\- During normal operation, the primary is entirely contained within the
primary containment, and circulates naturally, using the differential
temperature and gravity. The steam system can is used to remove heat.

\- During an emergency, valves open to admit the reactor coolant into the
backup containment. These valves are normally held shut by hydraulics with
positive control from electronics-- their failure mode is to open with no
other operator action in case of a loss of power. No additional operator
action is needed to initiate the emergency cooling flow, which is _also_ a
natural circulation loop to the backup containment shell, which then conducts
heat to the pool.

\- The backup containment shell is designed to withstand hydrogen explosions
such as those that occurred at Fukushima, and which was possibly prevented at
Three Mile Island by venting (whether there was a hydrogen explosion at TMI-2
is not fully understood).

\- There is no mechanism for positive reactivity addition via graphite
moderator rod such as in the Chernobyl design. The specific failure mode at
Chernobyl is not possible with this reactor.

\- The pool is specified as a stainless-steel-lined reinforced concrete and
designed to withstand earthquakes. The safety systems are such that no reactor
electricity supply is needed to remove heat-- the pool could be filled e.g.
from a fire truck, and the immediate decay heat from shutdown does not require
any additional heat removal or water addition. So the failure mode we saw at
Fukushima (inability to remove decay heat due to loss of electricity) and
hydrogen explosion breaching containment does not apply to this design.

~~~
sandworm101
So it _requires_ gravity. It may seem trivial, but how would this thing react
if suddenly not mounted vertically, say if it got knocked onto its side while
running? Would coolant still flow as planned?

~~~
crowbahr
Anything that knocks a fully functional multiple thousands of tonnes of
concrete, steel, water and fissile material onto it's side was already going
to fuck up your day.

As far as I'm aware we've never had a nuclear reactor go sideways, and it's
kinda ludicrous to even ask. It's one of the most massive structures, built on
bedrock because it's too heavy to be built on anything else, and even these
"small" reactors will be incredibly heavy.

~~~
sandworm101
They are vertical cylinders to be suspended vertically in a pool of water, not
massive squat objects sitting on bedrock. They are thin and relatively top-
heavy. It is not ludicrous to ask what could happen should they not remain as
vertical as designed.

From a planning perspective, if verticality is a requirement then that
verticality has to be protected as strongly as any other aspect. Any
attachment or mounting points that maintain verticality must therefore be
earthquake proof. If, as in the pictures, these reactors are held in place
from the top, horizontal shaking from even a small earthquake would put
massive strain on that joint. It isn't just the long/thin/heavy reactor but
all the water sloshing around too. A super-strong joint and maybe something
important bends/breaks under load? A flexible joint to allow the reactor to
sway? Sway how much? What happens at the travel limit of the joint? Can we
risk the reactor contracting its neighbours? These are not trivial engineering
questions.

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

~~~
sandworm101
I;m not saying it is impossible, just interesting. One option could be to
suspend these reactors on cables from above. That might let them swing around
all they want during even a huge quake. The water would act as the dampener.
Not much extra engineering required.

------
marshray
I think it's disingenuous to argue the economics of nuclear without
mentioning:

"DOE reported that it faced an estimated $494 billion in future environmental
cleanup costs — a liability that roughly tripled during the previous 20
years."

[https://www.gao.gov/assets/700/696956.pdf](https://www.gao.gov/assets/700/696956.pdf)

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

~~~
marshray
If only a method for permanent disposal of nuclear waste actually existed.

~~~
manigandham
We could dump it into the ocean and not worry about it. There's so much
cooling capacity and radiation shielding in the oceans alone that we'd never
run out of space, so all of the current disposal strategies are way above and
beyond what's needed. Containment is solved problem.

It's important to note that other energy types also produce waste. For
example, coal ash is incredibly toxic and hard to dispose of, and we create
much more of it every year.

~~~
gambiting
Another option which is completely safe and permanent* is drilling a borehole
few km down and dumping the waste there. It's not coming back no matter what.
The research done into it shows that "only" 800 boreholes would be required to
store literally all nuclear waste ever produced.

[https://en.wikipedia.org/wiki/Deep_borehole_disposal](https://en.wikipedia.org/wiki/Deep_borehole_disposal)

*to a point where it was actually brought up as a negative, because if we ever wanted to recycle that waste into something else, it's literally impossible this way.

~~~
moneytide1
There's one in Finland:

[https://en.m.wikipedia.org/wiki/Onkalo_spent_nuclear_fuel_re...](https://en.m.wikipedia.org/wiki/Onkalo_spent_nuclear_fuel_repository)

They have thought thousands of years ahead and set up many different types of
warning signs and symbols in case a future civilization discovers it.

~~~
jaggirs
No, they put zero warnings. Warnings only make it more likely that someone
decides to start digging.

~~~
ClumsyPilot
The idea that civilisation collapses and then recovers to the specific extent,
where it is advanced enough to have coal-mines or similar, but not to know
about radiation. Then it must find this particular repository and start
digging, and die. Thousands of years must pass but they must dig up this sight
withing a particular 100-year period of their development.

This is such a stupidly contrives scenario that you might as well plan for an
alien incasion or zombie apocalypse. Lime prerequisite for that theory is
civilisation collapsing, our investment in making sirebcovilisation does not
xollapse is zero. You deal with it by making sure civilisation does not
collapse.

~~~
rtx
Then they will know about radiation.

------
EricE
This is huge. Not only are micro reactors far more economical, it dramatically
reduces the need to maintain a massive nationwide grid and provides
flexibility to people in remote areas including greater autonomy. Efficiency
should be greater without massive transmission line losses. Might start fewer
fires in California too.

~~~
adrianmonk
I'm not an expert, but I'm not convinced about it reducing the need to
maintain a nationwide grid.

Nuclear reactors take ages to ramp up and down. It's basically going to be
generating the same amount of power 24x7, but demand is going to fluctuate.
The more other areas you're connected to, the more opportunity there is to
send that power to someone who can use it.

Obviously there's a law of diminishing returns at some point, so maybe the
grid doesn't need to be as large as possible.

There are alternatives like energy storage (batteries, etc.), but you'd have
to compare all the costs and benefits.

~~~
stickfigure
Nukes are slow from a cold start but they can throttle up and down with load.

[https://en.wikipedia.org/wiki/Load_following_power_plant#Nuc...](https://en.wikipedia.org/wiki/Load_following_power_plant#Nuclear_power_plants)

 _Modern nuclear plants with light water reactors are designed to have
maneuvering capabilities in the 30-100% range with 5% /minute slope._

~~~
adrianmonk
Wow, that's pretty fast. So 12 minutes worst case. TIL.

Still, I wonder if the economics don't favor running near 100%. You've already
paid the high up-front cost of the equipment, and fuel costs are low, so I
assume you're better off selling excess power when possible.

~~~
jabl
Of course. Though with increasing deployment of intermittent sources like wind
and solar, occasionally the wholesale price can drop lower than the marginal
cost of the nuclear plant (or even negative, if said power sources receive
production subsidies regardless of the wholesale price), in which case it
makes sense to throttle down.

Future grids with more intermittent renewables will have increasingly volatile
prices, but not necessarily lower on average. So generators that can produce
during high price periods (e.g. if wind and solar aren't producing much) can
make a lot of money then, compensating for less income during low price
periods.

------
Animats
Four links down: _" The staff has determined that the plant design meets the
applicable requirements for the design certification stage of licensing. ...
The NRC staff’s issuance of this FSER does not constitute a commitment to
issue the design certification"_[1] The actual review document is not up yet;
search for "ML20023A318".

It's not that this is smaller. It's comparable to Shippingport or Vallecitos.
The argument is that it's safe enough against meltdowns not to need a full
containment vessel, which makes it cheaper. The idea is to have a group of
these sharing the same reactor pool. What they do if there's a leak into the
cooling pool. Does that take down all the reactors?

Anyway, the plan is to build the first one at the Idaho Reactor Test Station,
830 square miles with reactors spread miles apart. If something bad happens
there, it's not a major problem.

[1]
[https://www.nrc.gov/docs/ML2023/ML20231A804.pdf](https://www.nrc.gov/docs/ML2023/ML20231A804.pdf)

~~~
linuxlizard
> If something bad happens there, it's not a major problem.

Well, unless you're in Idaho like some of us. ;-)

~~~
Animats
The whole point of having 830 square miles of reactor test station is to keep
the problem on the property if something goes wrong. See the SL-1 disaster. It
happened there, but nobody outside the test station was affected.

------
eigenhombre
If you have 20 minutes, the video linked in the comments of the earlier HN
post is quite informative, giving a much better technical explanation than the
original article:
[https://www.youtube.com/watch?v=7gtog_gOaGQ](https://www.youtube.com/watch?v=7gtog_gOaGQ)

It is fascinating, for example, how a slight change in the packaging of the
fuel (as sand-sized pellets coated with carbon) affects the safety/stability
of the design, and how resonances in the cross section for neutron absorption
come into play (they broaden at higher temperatures, dampening rather than
enhancing the overall reaction speed, as temperatures rise).

------
jdeibele
One thing not addressed is physical security. As pointed out by @adrianmonk it
would take many of these tiny reactors to generate the same amount as a
typical older reactor.

Older reactors are designed like fortresses, supposedly able to take a direct
hit by a commercial jet and survive. They have armed guards, etc.

It would be interesting to see how they would try to protect these. Typical
electrical substations are protected by a chain-link fence and a padlock.

~~~
jabl
The idea is to put multiple reactors at the same site, not to spread out mini
reactors all over the landscape.

So the end result would be a powerplant that produces about as much power as a
"normal" nuclear power plant, just that it contains many small reactors
instead of a few big ones.

~~~
jessaustin
This undermines some of the claimed benefits. A bunch of little Fukushima
Daiichi reactors in the same location wouldn't have fared any better than the
actual Fukushima Daiichi reactor.

~~~
jabl
In this particular case, a power plant with these nuscale reactors would
probably have survived a Fukushima type accident. One effect of being small is
that the reactors are designed to be passively cooled after shutdown, using
convection instead of pumped flow. So there is no need for emergency diesel
generators to keep the coolant pumps running.

~~~
jessaustin
Sure, it's safer for reactors to tolerate flooding, if indeed these reactors
actually do tolerate flooding. Definitely that would be a better design in
flood/tsunami-prone areas. No design (from history, _especially_ no reactor
design) is perfect. A set of smaller reactors that were _not_ co-located would
be more tolerant of site-specific vulnerabilities in their design.

~~~
MurMan
> ... if indeed these reactors actually do tolerate flooding

The reactor modules are partially immersed in a pond, the ultimate heat sink.
Cooling is passive, i.e., no cooling pumps, and does not require electrical
power.

------
nsxwolf
Article gave absolutely no indication of its dimensions. How "tiny" is it
exactly?

~~~
adrianmonk
Maybe tiny refers to the power output. The article says it makes 50 megawatts.

Compare that to a nuclear plant near me which has two reactors that each
generate 1280 megawatts.

So it would take about 25 of these to equal the power output of a traditional
nuclear reactor.

~~~
petre
Yes but it's inherently safer. Utility scale nuclear was scaled up from naval
reactors which are smaller, use highly enriched uranium as opposed to LEU and
are safer. Alvin Weinberg, the father of several LWR designs cautioned about
the safety of utility scale reactors (17:51):

[https://youtu.be/EviEN0ScOwg](https://youtu.be/EviEN0ScOwg)

The NuScale design also uses LEU and a plant is comprised of up to 12 of these
modules sitting in water pools. You can view it as a battery pack where
batteris are continously rotated as they are refuelled.

~~~
jabl
To nitpick, some naval reactors are designed to use LEU. E.g. French
submarines run on 7% enriched fuel. And reportedly Chinese subs also use LEU.

------
nickik
As a huge fan of nuclear power, I never felt like NuScale style 'SMR' were all
that great of an idea.

Yes, it gains you some of the economics of factory construction and that you
can start small and scale a location, but on the other side you lose that
again because you lose the economics of scale that traditional PWR gets.

I really believe we should be a nuclear society by now, and that regulations
both around reactors and fuel availability prevented this from happening. In
the 1960 lots and lots of innovative reactors were build, often with
relatively low budgets at that. The amount of untapped potential in nuclear
energy is incredible. We don't need fusion, fission is plenty energy dense, if
we can't figure out how to make fission practical, we want with fusion either.

Yet here we are in the year 2020 and we are still building new PWR reactors.
But the reality is, in the US it is essentially impossible to build anything
else. Regulations are designed so that the only reactor that can really get
approval is a PWR.

If you attempt to build anything new, you have to basically pay the government
to study your design and after a unknown amount of time and money, the
government might develop a new regulatory framework. By the time that happens
of course you have run out of money already, no buissness plan that depends on
the government figuring out how to regulate a new type of reactor would ever
really happen.

The good thing at least is that the DoE in the last 5 years seem to have
realized that their whole approach was a problem and they have done a lot of
good things to try to change. Outside of the US the energy sector is
government controlled or to small for a nuclear reactor startup to have a
large enough market to make a new reactor worth it.

Canada has established itself as basically the only viable place for new
reactor development, with Terrestrial Energy and Moltex Energy (moved from
Britain to Canada because regulation).

So, good luck to NuScale, I hope they can prove me wrong and deploy many of
these in an economical way.

~~~
rubber_duck
>Yes, it gains you some of the economics of factory construction and that you
can start small and scale a location, but on the other side you lose that
again because you lose the economics of scale that traditional PWR gets.

You mean they lose operational efficiency ? Economies of scale come from the
ability to mass produce.

You forgot to mention the largest differentiator - eliminates the possibility
of a global catastrophe.

~~~
acidburnNSA
Not in nuclear they haven't historically. Economies of scale drove light water
reactor designs from tens of megawatts to hundreds to over a thousand
universally from all vendors around the world historically. The big
institutional nuclear economics reports all agree that going big improves
nuclear economics. The hypothesis that SMRs will somehow overpower this is
popular but is very much unproven. This agrees with OECD reports like last
month's [1] and all the older ones listed in [2].

[1] [http://www.oecd-nea.org/ndd/pubs/2020/7530-reducing-cost-
nuc...](http://www.oecd-nea.org/ndd/pubs/2020/7530-reducing-cost-nuclear-
construction.pdf)

[2] [https://whatisnuclear.com/economics.html#improving-modern-
nu...](https://whatisnuclear.com/economics.html#improving-modern-nuclear-
power-economics)

------
zymhan
Previous Discussion 2 days ago

[https://news.ycombinator.com/item?id=24345288](https://news.ycombinator.com/item?id=24345288)

~~~
dang
Yikes - that is a classic example of a post that accumulated lots of upvotes
but stayed underwater the whole time:
[http://hnrankings.info/24345288/](http://hnrankings.info/24345288/). This is
a known problem and it's on our list to fix.

Since that story didn't get much attention (relative to the interest in it),
we won't call the current thread a dupe.

------
jvanderbot
"The design is based on Multi-Application Small Light Water Reactor developed
at Oregon State University in the early 2000s. NuScale is a natural
circulation light water reactor with the reactor core and helical coil steam
generators located in a common reactor vessel in a cylindrical steel
containment. The reactor vessel containment module is submerged in water in
the reactor building safety related pool, which is also the ultimate heat sink
for the reactor. The pool portion of the reactor building is located below
grade. The reactor building is designed to uphold 12 SMRs. Each NuScale SMR
has a rated thermal output of 160 MWt and electrical output of 50 MWe,
yielding a total capacity of 600 MWe for 12 SMRs."

------
mlindner
Amazing how many people in this thread don't understand nuclear and are
spouting rampant fear mongering. Nuclear is fundamentally a safe technology,
and these new reactors are safer than anything before. Think about how many
deaths have actually been caused because of nuclear compared to coal power.
The difference is dramatic.

------
cm2187
I don’t understand what makes small reactors desirable. Don’t you loose
economies of scales, not only production, but also demand (ie if you have
small local sources of electricity you miss the diversification of the demand
you have in the central grid and you need to overprovision a lot more)?

~~~
credit_guy
> Don’t you loose economies of scales

On the contrary, you gain economies of scale. The way the economies of scale
work is if you build n identical widgets, it costs you less than n times the
cost of building one single widgets. In other words the unit cost of a widget
goes down as the number of produced widgets increases.

If you want to produce a bigger widget though, you generally have diseconomies
of scale. For example the Saturn V rocket was about 20 times bigger than the
Titan 2 rocket (from which it was derived) but cost about 60 times more.

So, if a Gigawatt-size nuclear power plant is too expensive to build, you
build 20 plants of 50 MW each. This is how you achieve economies of scale.

------
dangjc
How is nuclear compatible with variable renewable energy sources? It can’t
ramp up or down quickly, so it’s not good for filling the gaps in the day when
the sun is not shining. And solar is now so cheap during sunny days that the
excess power is curtailed or at a negative price.

~~~
enaaem
Nuclear can operate in load following mode for a long time now. It's already
done in Europe.

[https://www.oecd-nea.org/nea-news/2011/29-2/nea-
news-29-2-lo...](https://www.oecd-nea.org/nea-news/2011/29-2/nea-
news-29-2-load-following-e.pdf)

------
engineer_22
Is Bill Gates an investor in NuScale? Or am I thinking of another modular
reactor startup in the PNW?

~~~
ascales
Bill Gates is involved with TerraPower, the other PNW based nuclear startup

~~~
engineer_22
Thank you

------
RangerScience
Thinking about the cooling pool:

Could you just make an off-shore in-ocean "farm" of these?

~~~
pvaldes
> Could you just make an off-shore in-ocean "farm"

Not! Ocean is inherently unstable!.

The first serious storm would dislodge and damage the whole farm crashing one
module against the other before to vomit them in the shore. Some modules just
would dissapear.

And then you have a humongous environmental damage and a really expensive
rescue problem trying to clean the fragmented mess.

~~~
RangerScience
AFAIK, put em deep enough - which isn't that deep - and you're basically fine?
It's why subs (AFAIK) DGAF about storms.

Mutual impact issue sounds pretty resolvable with a big steel frame and the
like.

~~~
pvaldes
You will have still many deep currents that shouldn't be underestimated. Is
not so simple.

------
ed25519FUUU
> _The current design, which still has several steps until it can be
> constructed in the wild, is for 50 megawatts per module. NuScale seeks to
> apply for a 60-megawatt version next._

I'm very impressed by that output. It will make a difference with areas of
high solar and wind generation, which can't maintain a sustained high duty
cycle.

I expect these types of reactors to be in places to _augment_ solar and wind,
not replace it.

------
baron816
Have they announced an estimate of how much a reactor/cost of energy
production will be? That’s kind of the most important factor, isn’t it?

~~~
foxyv
$0.24 per kwh is a rough estimate I've seen for NuScale. Typically initial
costs for microreactors right now are around $0.25 to $0.30/kwh which is about
the cost of energy created by diesel generators. Natural gas is much lower.
However they hope that as we make a lot of them the cost will drop.

~~~
mikeyouse
Wow. That’s substantially more expensive than I was expecting. It’s been years
but we always assumed ~$0.08/KWh for on-site natural gas generated electricity
on US based projects.

~~~
therealdrag0
I wonder how much more would that be if the median carbon-tax proposal was
added?

~~~
mikeyouse
We did some calcs to that effect since we were operating in Australia, and
they had a $25/ton carbon tax at the time. If my memory serves, it would
increase natural gas costs by ~25%. So it'd likely still be right around
$0.10/KWh.

Actually I take that back - our calcs were all based on ~$4/mmBTU gas but I
just looked and gas prices have been below $3/mmBTU for years. So $0.08/KWh is
probably a worst case even if we had a reasonable carbon tax.

------
grandinj
I don't know why they are bothering to try and build this in the US. Between
the insane regulations, the anti-nuclear lobby, and the NIMBYs, they don't
stand a chance.

Surely they would have a much easier time selling things like that elsewhere?
Growing nations would probably love reliable power that could be plonked down
off a ship and added to incrementally.

------
pfdietz
The ratio of the weight of the reactor assembly for these reactors to their
power is about an order of magnitude worse than the similar ratio (using
weight of the reactor vessel + pressurizer + steam generators) of a
conventional PWR. How is this going to be competitive?

I understand they've given up on making that part themselves in a factory of
their own, btw.

------
m3kw9
Things are always different when deployed, I want to see how it performs
before real world before getting excited.

------
anonymousiam
From the article: "In the event of any runaway reactor event, NuScale says,
the reactor quenches itself in its pool, making it 'passively safe.'”

So what happens when an earthquake causes a rupture of the pool barrier and
all the water leaks out?

~~~
willis936
This is a solved problem. Tokyo is a good example.

[https://en.wikipedia.org/wiki/Earthquake-
resistant_structure...](https://en.wikipedia.org/wiki/Earthquake-
resistant_structures)

------
kyle_morris_
NRC Release: [https://www.nrc.gov/reading-rm/doc-
collections/news/2020/20-...](https://www.nrc.gov/reading-rm/doc-
collections/news/2020/20-043.pdf)

~~~
dang
Also
[https://apnews.com/910766c07afd96fbe2bd875e16087464](https://apnews.com/910766c07afd96fbe2bd875e16087464)

edit: and [https://arstechnica.com/science/2020/09/first-modular-
nuclea...](https://arstechnica.com/science/2020/09/first-modular-nuclear-
reactor-design-certified-in-the-us/), via
[https://news.ycombinator.com/item?id=24345288](https://news.ycombinator.com/item?id=24345288)

------
sriku
I was looking for a reference to the physical size of the reactor and couldn't
find it. The sites only say "smaller". Any links with size info and
requirements for containing infrastructure?

------
fareesh
If you build one of these things don't you also need to build an impervious
shell around them so they can't be attacked? I have read that the existing
reactors can withstand air crash impacts, etc.

------
sarcasmatwork
fyi, OSU college has a 1-megawatt research reactor.

[https://www.oregon.gov/energy/facilities-
safety/facilities/P...](https://www.oregon.gov/energy/facilities-
safety/facilities/Pages/OSU.aspx)

[https://www.corvallisadvocate.com/2012/got-nuke-state-of-
the...](https://www.corvallisadvocate.com/2012/got-nuke-state-of-the-osu-
reactor/)

~~~
adrianmonk
The University of Texas at Austin has a 1-megawatt nuclear reactor:

[https://nuclear.engr.utexas.edu/netl/triga-
reactor](https://nuclear.engr.utexas.edu/netl/triga-reactor)

BUT... it also has two 74-megawatt gas turbines that supply the campus with
electricity and steam:

[https://utilities.utexas.edu/chp/about-carl-j-eckhardt-
combi...](https://utilities.utexas.edu/chp/about-carl-j-eckhardt-combined-
heating-and-power-complex)

------
known
Aren't BIG nuclear plants with universal distribution system BETTER from
security/safety/management perspective?

------
NiceWayToDoIT
Why is most important left out? So, power output 50MW ...

How long does one "charge" last?

What is the price of unit and per kWh?

What is the maintenance procedure?

How long is the life?

What after expiry?

------
PeterStuer
Fwiw, any nuclear reactor design in history was sold as 100% safe. In reality,
shit happen. Contractors use subspec material, things on the building site get
overlooked and inspectors miss things or get told to look away,

But hey, I'm sure, this time, it will be different. 100%.

~~~
janmalec
Nothing is 100% safe, who said Nuclear power is? Nuclear power always has been
and still is one of the safest ways to generate electrical power and this is
what counts. Solar power for example causes a lot of fatalities due to
accidents that happen during installation and has it's own environmental
problems, yet nobody talks about it.

------
Mrdarknezz
Great, we really need a way to produce massive amounts of green energy.

------
EGreg
What’s keeping the nuclear fusion so long? It’s much safer.

Can we use Thorium for now?

------
SMAAART
So, what's the size of one of these tings?

small? how small is small?

Tiny? how tiny is tiny?

~~~
baking
Each containment, vessel which produces 50MW of electric power, can fit on a
truck. Each site might contain up to 12 separate reactors. That was basically
the design constraint so the can be manufactured off site and shipped as one
unit.

A regional power company might seek permitting at 10-20 locations. If some
locations didn't get a permit or if other locations proved to be uneconomical
to produce power at the time of construction, they could just build at the
sites they chose. Basically takes the two phase pre-construction permitting
and post-construction operating permit which has been killing nuclear power
and streamlines it. Because the designs are standard and modular they will be
pre-approved to operate.

------
guscost
Best news I’ve heard in years.

------
codecamper
why do we bother with this junk when we have a very large fusion reaction that
is located several million miles away from us & delivers it's energy to us in
the form of photons every single day.

~~~
p1mrx
> every single day

As a California resident, I would like the option to run A/C after sunset.

------
jv22222
Finally, 1.21 gigawatts for my DeLorean.

------
hikerclimb
Boom!

------
dang
@natcombs would you mind emailing hn@ycombinator.com? I'd like to suggest
something so we can send you repost invites in the future.

------
mimixco
"Officially safe" is a hilarious term which tries to predict the possibility
of an MCA or "Maximum Credible Accident." Of course, Three Mile Island,
Chernobyl, and Fukushima were also "officially safe" when they were built.

~~~
core-questions
What a bad faith post.

> Three Mile Island

Was handled reasonably well, resulted in safety improvements to procedures and
designs for future reactors.

From [https://www.nrc.gov/reading-rm/doc-collections/fact-
sheets/3...](https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-
isle.html#summary)

> The approximately 2 million people around TMI-2 during the accident are
> estimated to have received an average radiation dose of only about 1
> millirem above the usual background dose. To put this into context, exposure
> from a chest X-ray is about 6 millirem and the area's natural radioactive
> background dose is about 100-125 millirem per year for the area. The
> accident's maximum dose to a person at the site boundary would have been
> less than 100 millirem above background.

Not exactly the end of the world.

> Chernobyl

Accident caused by Communists who did not care about what happened to
Ukrainians, as usual for them, and experimented with something that any
nuclear physicist could have told them was a terrible idea. This is like
blaming vehicles and calling them unsafe after reaching over from the
passenger seat and yanking the wheel to drive a truck into a crowd. The moral
of the story here is to keep Communists away from anything important, which
applies to farms, industrial sectors, food distribution, and really most
things more complicated than a pitchfork or a torch.

> Fukushima

Was reasonably safe for its long life, but they cheaped out on the necessary
wall and drainage functionality; should probably have been decomm'd and
replaced before this happened.

The problem in the nuclear industry is that anti-nuclear people like you form
public opinion that causes it to be difficult for it to move forward. New
plants based on newer designs are orders of magnitude safer - e.g. the CANDU
Canadian reactor which is more fail-safe than most, and the push towards 4th
generation reactors.

Get out of the way and let the planet have a clean base load energy source, or
be sitting here bitching about carbon footprints 50 years from now when it
should be a solved problem already.

~~~
m0zg
> Communists who did not care about what happened to Ukrainians

They didn't really care what happened to _anybody_, not just Ukrainians.
Ukrainians (as well as about 30% of Russians) just happened to live in that
particular location. The plume made it all the way to the Nordics and Germany,
and I, as a kid, had to take iodine tablets in Russia, even though officially
everything was "under control" for a few days. Then the narrative shifted to
showing the heroism of the "liquidators", never fully acknowledging how
dangerous any of this really was.

~~~
core-questions
Good point, I agree entirely. It's clear that nuclear power needs to be under
the control of responsible governments, built in safe locations (i.e. not on
fault lines, not in tsunami zones), and needs solid maintenance budgets.

All of these things are solvable problems, but if we don't solve them before
all the current nuclear plant techs age out, we won't be able to apprentice
people and keep the culture of solid maintenance alive. At that point, they
really do become an albatross.

------
hinkley
Can someone refresh my memory?

Is generating electricity directly from the products of fission proven
[mathematically] to be less efficient than

decay->steam->mechanical->electrical

or is just that the applied science of steam power is so far ahead of
everything else?

My peace of mind would be much greater if the energy transfer went through
solid state systems instead of a working fluid that is pretty good at carrying
the bad products of a [malfunctioning] reactor.

~~~
cogman10
The problem is heat. fission produces a ton of it and it has to go somewhere.
Yes, you can absorb radiation thrown off by fission, but you still have the
problem that heat will melt everything.

So you throw water (or salt) on the reactor, heat it up, and do work with the
steam that is ultimately produced.

It has less to do with steam being the ideal route and more to do the the
practicality of dealing with heat.

AFAIK, most reactors are closed loops anyways, so there's not much of an issue
with water carrying away radioactive materials.

~~~
hinkley
Most people are worried about the reactor transitioning to an open loop
against the wishes of the maintainers.

But that’s good info, thanks. Molten salt still has to heat transfer to steam
because we don’t have any thermovoltaics in the 50% efficient range.

I think I now understand that most of the heat comes from absorbing neutrons,
which don’t like to generate electricity (vs betavoltaics and gammavoltaics).
And any device inside the pressure vessel would be altered by those neutrons,
need to be accounted for as another source of decaying particles, and need to
be replaced.

And/Or, you’d want a completely different reaction and then need a neutron
generator capable of running continuously.

That about right?

------
normanmatrix
I was thinking Nuclear would be the stable baseline for renewable. But this is
not a sustainable option. We need to enforce hydrogen.

Do not submit to the fallacy of nuclear waste disposal. First Elon needs to
fix space travel and make transport into the sun feasible. And we will have
iter by then.

~~~
nuccy
Hydrogen is not a good (at the moment at least) source of energy or fuel for
cars or industry (chemically speaking, obviously much better together with
Deuterium and Tritium for fission, though we are still from such a
technology). Steam reforming, which is currently the most common way of
hydrogen production, uses natural gas and water and produces plenty of CO2
[1]. Nice summary as for cars fuel application here [2].

[1]
[https://en.m.wikipedia.org/wiki/Hydrogen_production](https://en.m.wikipedia.org/wiki/Hydrogen_production)

[2]
[https://m.youtube.com/watch?v=f7MzFfuNOtY](https://m.youtube.com/watch?v=f7MzFfuNOtY)

~~~
pfdietz
Hydrogen is an answer to the question "how do renewables serve 100% of the
grid?". It enables renewables to cover that last 10% or so, and rare prolonged
dark/calm periods, without excessive amounts of overcapacity or batteries.

