It's not public opinion, is economics:

-Reactors are extremely capital-intense to produce and manpower-intense to operate. Security costs would also be high.

-Merchant ships have a build-scrap cycle of ca. 30 years. That's a lot of reactors to regularly decommission, a very expensive task.

-A reactor running on low-enriched uranium would not be useful for making a nuclear weapons, but a malicious actor could make a dirty bomb.

The US Navy used to have nuclear-powered cruisers, and phased then out because it wasn't really worth it. Nuclear propulsion only makes sense for a few tactical cases, like submarines (which can't use air-breathing motors underwater) and carriers (huge ships that routinely steam into the wind at very high speed for flight operations).

The issue with carriers is they want to carry as much jet fuel, supplies, and munitions as possible to minimize the amount of refining and resupplying they need to continue operating. Plus space for their crew, aircraft storage and repair etc. On top of this they need vast amounts of electrical power for internal operations and the ~6,000 personnel onboard.

It’s so bad the Navy is seriously looking into generating jet fuel onboard via Nuclear power. Even if it’s not cost effective it would be a huge logistics benefit.

USN phased out the CGNs mostly during the collapse of the military after the Soviets quit. CGNs are extremely useful, and as directed energy weapons become common, will have a place in the Navy.

The US Navy has no plans to use nuclear power in the Large Surface Combatant program. Those are the only cruisers they're likely to get over the next several decades. Regardless of potential advantages the budget just isn't sufficient for nuclear.

The LSC will never float anyways. We'll just continue to build Burkes. Columbia, Ford-Class CVNs and Virginia SSNs will eat all of the Navy's shipbuilding budget. 2020-2030 is going to be a hard time for the USN.

I'd add the FFG(X) frigate program in there too, but that'll probably just end up taking the place of a few Burkes.

I think we'll see FFG(X). Odds are the shipyards building the execrable LSC will win the contract, and the Congresscritters will want to keep those jobs going.

Depending on the chosen config, the FFG(X) might end up being a good vessel; we'll need lots of them.

There's some issues with pirates in many parts of the world though (source: Captain Phillips movie). It's just not practical to really secure container ships from every feasible sea and air attack surface, unless there was a big red button that just drops the reactor into the depths of the ocean.

And even without pirates, merchant vessels have incidents with disturbing frequency. A lot of these incidents never have a cause firmly attached to them, because the crew's all dead, the ship is somewhere in a 10,000 square kilometer stretch of ocean, and that ocean is 1km+ deep. Not that the wreck being known and (relatively) shallow is a panacea either, as the variety [0] of hypotheses concerning the cause of the Edmund Fitzgerald wreck should demonstrate.

I trust the US Navy to operate reactors at sea - they've done a damn good job of it over the years, with no losses since 1968. And even those losses (USS Thresher, SSN-593 [1] and USS Scorpion, SSN-589 [2]) haven't caused radiation leaks. Merchant shippers? Yeahhhhh.... No.

0: https://en.wikipedia.org/wiki/SS_Edmund_Fitzgerald#Hypothese...

1: https://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)

2: https://en.wikipedia.org/wiki/USS_Scorpion_(SSN-589)

Maybe you could get the US Navy to crew a few container mega-ships in the national interest of international commerce? Reducing climate change and political concern over the carbon involved is arguably a better use of the Navy's time than fleet exercises, and it wouldn't take that many people.

There are over 9,000 fully cellular container ships operational right now, and container ships are only 13% of global merchant shipping capacity. The roughly 70 ~20k TEU megaships all together are only 10% of total container ship capacity. A few megaships is insignificant in overall economic terms.

What is the other 87%? How is that possible if 90% of goods are transported by sea?

The majority of goods are on bulk carriers and tankers. Grain, coal, oil, etc.

The parent said “container ships are only 13% of global merchant shipping capacity”. I’m wondering how else goods are being transported...

Indeed, bulk carriers and tankers are ships that aren't container ships.

Sure, but as a whole they have had a few rough years.

https://features.propublica.org/navy-accidents/us-navy-crash...

Right, but even those accidents wouldn't have caused a radiation leak if the destroyers in question were nuclear powered.

How often are subs lost? I have no recollection of numerous losses, but I think they’re also only ran by nations. I wonder if they’re inherently more stable.

I'm pretty sure submarines are lost more often than surface warships are - the difference between small incident and loss of ship is just so much smaller. And to confirm that I can't think of any surface warships that have been lost by the US or Russian navies out of combat since 1950, but both have lost several submarines in that same time period.

Your general point is correct. But the USS Guardian surface ship was lost when it ran aground in 2013. It didn't quite sink but couldn't be repaired.

Other entries would be USS Benevolence [0] in 1950, USS Hobson (DMS 26) [1] in 1952, USNS Mission San Francisco (T-AO-123) [2] in 1957, USNS Mission San Miguel (T-AO-129) [3] in 1957, USS Stickleback (SS-415) [4] in 1958, USS Grouse (AMS-15) [5] in 1963, USS Bache (DD-470) [6] in 1968, USS Frank E Evans (DD 754) [7] in 1969, USNS Sgt. Jack J. Pendleton (T-AKV-5) [8] in 1973 and USS La Moure County (LST-1194) [9] in 2000.

But I think that's the rest of the noncombat, post-1950 losses. Lots of support ships, DDs and a single sub.

And thanks for the mention of the USS Guardian - I had no idea the USN still operated wooden-framed ships!

0: https://en.wikipedia.org/wiki/USS_Benevolence

1: https://en.wikipedia.org/wiki/USS_Hobson_(DD-464)

2: https://en.wikipedia.org/wiki/USNS_Mission_San_Francisco

3: https://en.wikipedia.org/wiki/USNS_Mission_San_Miguel

4: https://en.wikipedia.org/wiki/USS_Stickleback_(SS-415)

5: https://en.wikipedia.org/wiki/USS_Grouse_(AMS-15)

6: https://en.wikipedia.org/wiki/USS_Bache_(DD-470)

7: https://en.wikipedia.org/wiki/USS_Frank_E._Evans

8: https://en.wikipedia.org/wiki/USNS_Sgt._Jack_J._Pendleton_(T...

9: https://en.wikipedia.org/wiki/USS_La_Moure_County_(LST-1194)

K-431 - 1985 - https://en.wikipedia.org/wiki/Soviet_submarine_K-431

K-219 - 1986 - https://en.wikipedia.org/wiki/Soviet_submarine_K-219

Burevesnik - https://en.wikipedia.org/wiki/Nyonoksa_radiation_accident

I think the US Navy would be very interested to learn that it supposedly operated Soviet submarines.

I agree there's a problem with pirates in some parts of the world. Source: I used to work in this area.

I recall a shipping lane chart that showed large carriers making a wide swing around and away from somalia.

Ships can be obscenely ill-regulated at sea. Also the crew is, due to greedy owners, a skeleton thereof and paid like dirt (and not necessarily treated much better). Anyone pushing for nukes on large ships needs to work in the industry first before opining.

Pirates aren't stealing nuclear fuel from operating reactors. It will literally kill them before they get away with it.

They could potentially breach a reactor deliberately but again...why? It would kill them and not achieve anything.

The design for nuclear reactors in commercial shipping has been to use sealed modular units, who's security system would be that attempting to remove or breach would drop the whole unit to the bottom of the ocean where only nation-state level specialized resources could recover it expediently.

> Pirates aren't stealing nuclear fuel from operating reactors.

They don't need to steal the fuel, just find a buyer for the ship and the fuel that comes with it.

And what if they try doing it in shallow waters or on shore?

Um... I'm going to assume this isn't a troll or written while inebriated. What's the big deal for weapons of mass distruction. Okay well dirty bombs for one are easy to do once you have the nuclear material.

Maybe Somalian pirates are relatively chill on the non nation state armed groups out there crazy scale but ISIS and many other terror groups most definitely are not chill. When someone even figures out how to build a powerful conventional explosive you get things the Oklahoma City bombing.

So yeah that's kind of a big deal. The US did essentially invent the weapons and only one to use them in warfare. I think it's also the responsibility of the US make sure it doesn't happen again where they are used against humanity.

》I think it's also the responsibility of the US make sure it doesn't happen again where they are used against humanity.

Interesting. How would you suggest the United States goes about ensuring nuclear technology is never used against humanity again?

International law and arms control. Like they've been doing post WWII...

Isn't Al-Sheebab based in Somalia? They'd probably have a keen interest in nuclear material.

Al-Shabab, but yes.

US was even committed to building two LWR nuclear reactors in North Korea in the late-90's, and as per reports, even some work had started on the sites. If US can provide nuclear reactors to North Korea, I think there wouldn't be much fear of these reactors being repurposed for a weapons program.

The program you're referring to was about swapping out North Korea's breeder reactor program, designed to generate enriched weapons grade fissile material, for LWR reactors not usable for generating weapons grade fissiles.

They absolutely could be used to produce material for dirty bombs, but that's not a factor with North Korea, which has plenty of material to do that anyway.

Thanks this a really great reply.

Why is it a great reply? It does not explain the fact that US would handover two nuclear reactors to North Korea sounds such a bold step, diplomatically speaking. Would US do that today with North Korea or even other countries.

OkC isn’t a great example anymore. Many security systems are in place to keep that from happening again. Takes a lot more these days. Fools with nukes have a way of harming themselves. Even Putin did so recently with his nuclear rocket blowing up.

I think you'd be wrong. I think it'd be easy for a single motivated and patient individual with the funds to pull off another OKC.

There simply are no effective mechanisms to prevent this, we're just lucky that domestic terrorism isn't very profitable.

The reactor would spend the vast majority of it's time running at much lower than peak capacity, which is a huge waste. An on-shore reactor can be put next to a rich CO2 / CH4 source such as a cement factory, and run at full capacity continuously feeding fuelstock to a whole fleet of vessels. It's tremendously more efficient.

> The reactor would spend the vast majority of it's time running at much lower than peak capacity, which is a huge waste.

Not so sure about that. I think current trans-oceanic cargo ships generally run at fairly high fraction of peak power (otherwise they could have saved money buy buying a smaller engine in the first place). Also port operations tend to be pretty fast and efficient these days.

Of course, for ships running shorter distances and spending a larger fraction of their time in port loading and unloading, synfuels, hydrogen or for really short routes even batteries are probably going to be a better option.

How is a reactor at partial power less efficient? I suspect you're not talking about thermodynamic efficiency, and it's not energy that (you think) would be wasted.

> How is a reactor at partial power less efficient? I suspect you're not talking about thermodynamic efficiency, and it's not energy that (you think) would be wasted.

Efficient in an economic sense. Nuclear plants are generally capital intensive, whereas fuel is very cheap. So you want to run them at close to max power as much as possible to recoup capital costs. But contrary to the previous poster, I think trans-oceanic ships generally do that.

There were a couple of commercial cargo ships built with nuclear propulsion, I think in the 1950s, but perhaps they weren't economically viable.

One problem they faced was that most ports would not allow them in, severely restricting the routes they could run.

(and with the exception of two Soviet outliers in 1959 and 1988 all nuclear civilian vessels are from the 1960ies or 70ies)

And the russians still have that nuclear icebreaker. The line between military combat ship, merchant marine, coast guard and fully civilian vessels is not bright, nor need it be. There is probably a case for running government-protected reactors on commercial ships, just as government-protected reactors power cities.

Three next-generation nuclear icebreakers are currently under construction in Russia. They are the largest and most powerful icebreakers ever built.

https://wikipedia.org/wiki/Project_22220_icebreaker

You can also book an arctic cruise aboard a nuclear-powered icebreaker!

https://www.polarcruises.com/arctic/ships/icebreaker/50-year...

What's the need for these icebreakers? I can understand that a nuclear icebreaker is a good thing for breaking ice - but I don't understand how it's economical. Is there really so much value in bringing cargo through pack ice?

People need food. Isolated northern communities dont get everything by air.

That seems like a very bad idea unless they each get a gunship(s) to prevent pirates and freedom to fire on anyone who doesn't hail back as they approach the ship.

Yeah, putting bomb-grade fuel into reactors that need to be run by a big crew of experts is a great idea! Pesky public opinion, what do they know?

Pure FUD. No commercial design uses highly-enriched uranium directly. The difference in effort between reactor-grade and bomb-grade fissile material is billions of dollars in time, effort, infrastructure and materials.

Please use language honestly rather than reinforcing ignorance and hysteria.

What is it about nuclear-related threads on HN that so many people assume bad faith and then begin name-calling?

Because many people have incredibly strong oppinions that are nothing but often repeated FUD and anybody that has informed himself gets pissed off.

I don't think anybody sane is suggesting running civilian ships on HEU.

Check out current ship and sub reactors, the overwhelming majority run on HEU.

I have never seen anyone talking about ship reactors on HN mention not using HEU.

> Check out current ship and sub reactors, the overwhelming majority run on HEU.

The overwhelming majority are military, who are not as constrained by non-proliferation concerns as civilian users. So this doesn't really prove anything.

As for whether it's technically possible to have naval reactors using LEU, yes it is, for instance French submarines run on 7% enriched fuel.

> I have never seen anyone talking about ship reactors on HN mention not using HEU.

When talking about a hypothetical large-scale use of civilian nuclear powered ships, I think it's a given.

> bomb-grade fuel

> Pesky public opinion, what do they know?

Not very much, apparently.