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Comment by javajosh | Hacker News Reader

Sub secrets are the most sensitive secrets we have

Source? I can't imagine what kind of secrets an opponent could want about a sub. I can see how operational data about the disposition of the fleet is useful, but the subs themselves? Subs have a ball of Pu powering a steam turbine that runs propulsion and onboard electronics. Some of them have strategic missiles for killing cities, some of them have torpedoes for killing ships and other subs.

Not asking for any secret data, obviously. Just wondering what kind of secret data is even useful to an adversary.

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I suspect a large portion of it is how to make those components sufficiently silent to be useful on a military submarine, where sonar is your enemy's primary way of finding you.

how to build a nuclear reactor is relatively well-known. but, how do you make a silent nuclear reactor? that's really only useful for a submarine. it wouldn't surprise me if existing commercial reactor designs would need to be completely redesigned for submarine use.

for an example of how much research goes into making subs silent, there is a very deep lake in Idaho the US Navy has used for acoustic testing since World War 2 [0]

the navy also has almost 70 years [1] of operational experience with nuclear reactors on subs. I imagine there's a enormous pile of "minor" things they've figured out as they chase down every last source of uncontrolled noise on the boat.

0: https://jalopnik.com/the-navys-most-vital-and-secretive-subm...

1: https://en.wikipedia.org/wiki/USS_Nautilus_(SSN-571)

And a silent nuclear submarine can run without needing to resurface for far longer than a conventional diesel sub. This is why AUKUS was such a big deal. With diesel subs, Australia could venture out into the South China Sea for 11 days. Once they have nuclear submarines they can remain there for 77. With diesel subs they couldn't reach the East China Sea, but with nuclear subs they can stay there for up to 73 days.

https://www.economist.com/img/b/640/724/90/sites/default/fil...

It would have been nice from Australia to realise that from the start and not start a procurement program for a diesel-electric sub, and pick the diesel-electric version of a nuclear sub to boot.

Diesel-electric sub have advantage if you want sub to do costs protection. They are more silent and can remain in position for a long time as they don't need to move to cool their reactor. It means they can stay in pockets of silence longer if they need to(sub exploit variation of pressure, salt density and temperature underwater to find place where their sound waves diffuse poorly).

Honestly Australia doesn't need nuclear sub. The only things they can do that diesel-electric sub couldn't is offensive missions in water further for the Australian costs. That might be useful if Australia decides to go fight in an hypothetical war against China but that would mostly serve the interest of the USA.

Diesel-electric was probably a better choice because Australia would have been able to service them. As is, they will be bound to the USA.

> need to move to cool their reactor

why do you think nuclear subs have to be moving to cool the reactor?

They can pump water but it's noisy and when they don't move all the warm water they generate stay above them and they become easy to spot from the surface. Meanwhile a diesel-electric sub can just stay on batteries and is then close to entierely silent.

Capabilities, technologies.

It's like asking why rocket engines are under ITAR. Rockets are just ICBMs without a warhead.

Knowing a technologies capabilities means you can focus on defeating the exact specs of the tech.

For example, F-22s purposely fly around with pods that deteriorate its stealth capabilities so nobody, not even allies, knows exactly how a F-22 looks like on radar/can study it closely.

So during wartime they’d jettison these?

yes

The number of nations with nuclear submarines is so small it’s clearly one of the strongest strategic advantages a nation state can have.

An example of how seriously the US takes this kind of thing look back to history. After Walker leaked secrets the US started getting even more protective of its submarine programs. The combination of power, propulsion, stealth, and attack capabilities make them the pinnacle of deployable mobile power. A carrier group can start a war, a single submarine can finish one with 24x12 100kt warheads.

The density of sensitive information relating to submarines is very very high.

Naval reactors tend to use HEU.

AIUI the mostly tightly held secrets are around the acoustics - acoustic signature, propeller design, that sort of thing. A sub relies on being hidden to carry out its mission, so anything that helps an opponent to find your subs has to be well guarded.

Interesting. I would have assumed a totally sealed Pu module, since it's a nice steady source of heat that lasts 80 years and as long the container doesn't rupture it's pretty safe. As opposed to HEU which AFAIK always requires moving parts to slow or stop the neutron cascade.

If you're talking about a Pu238 natural decay type device, like RTGs use, then at the level of power output you'd need to be able to supply propulsion the fact that you can't control the reaction rate would be a distinct negative, not a positive.

Naval reactors are basically a miniaturised version of a power station reactor. Some of the latest HEU ones are designed for the fuel to last for the life of the boat.

A few weeks ago when the US/Australian sub deal was announced it was notable(outside of the diplomatic snafu) because it was only the second country the US has ever shared its propulsion technology with[1]. The only other country at that point was the UK. Also see Q3 here: "Why is the technology so closely guarded?"[2]. Basically putting nuclear reactors on submarines and having those submarines remain silent is very hard to do.

[1] https://www.washingtonpost.com/politics/2021/09/15/us-will-s...

[2] https://defense360.csis.org/what-is-the-importance-of-the-au...

The Smarter Every Day channel on Youtube did a series onboard a sub, and a couple of specifics that I remember being censored from the videos were 1) Performance characteristics of the sub (ie, how fast it could dive, how deep) and 2) How it detected other submarines.

a link for the curious: https://www.youtube.com/playlist?list=PLjHf9jaFs8XWoGULb2HQR...

two security-related things that stuck with me were:

a) there is a door that leads to the reactor compartment, and that entire section of the ship is off-limits to him. he had a thorough background check before going, and someone from the Navy reviewed all his footage before he could publish it. but despite all that, he's not allowed to even be in the part of the ship where the reactor is. excellent defense-in-depth (pun not intended).

b) when discussing sonar, the XO was sitting right there along with the sonarman, to make sure nothing classified was recorded. there were a few times where the XO said "nope nope nope, can't talk about that". the most interesting one to me was, IIRC, a question about the active sonar system being relatively high frequency sound, and if they used any lower frequencies...they cut immediately after that.

My dad had a security clearance and spent most of his career working on navy projects ... Asking what he did at work during dinner would sometimes be interrupted by "I can't talk about that". It became normal for this phrase to cause a change of subject in our house.

My fluid mechanics prof told us a story about another prof who got in trouble for publishing the yield of the early A-bombs. He got off because he showed how the yield could be calculated from just the public films of the explosions.

https://youtu.be/_gaCAFcW6OY

Enjoy

or how Kodak found out about nukes before the public and had to keep that secret.

Subs are a big deal, when it comes to deterrence (M.A.D.). If a nation is wiped out by a first strike, the subs can pop up, six months later, and take out the attacker.

If a nation knows too much about the subs of the other nation, then it's quite possible that they may consider a first strike.

It's a horrible thought, but people can be really barking mad.

The Virginia-class sub is a fast attack sub; not a boomer, but the tech used between them is very similar.

I'm actually surprised that people don't know why subs are such a big deal, but I guess shouldn't be. The Cold War was really bad (my father was in the CIA). People, these days, may not know what it was like. I grew up in the Cold War. the current couple of generations have had the luxury of not growing up in that, but we may be bringing the band back together for a reunion tour.

This is like saying you can’t see what the value of the internet is. If you can’t imagine _any_ reason why technical info on subs would be highly sensitive, you are going to need to read some books, because there’s literally thousands of reasons, and no one here, or any blog or article, is going to fill that gap.

Blind Mans Bluff is as good a place to start as any I guess.

Missile subs are probably the most dangerous weapon in the world. Each can carry 200 independently targetable nuclear warheads with a 4,000 mile range.

A lot of people here are assuming COUNTRY1 is an adversary. I'm going to guess India. It's plausible to think that India would love to be able to build nuclear submarines with equivalent technology to the Virginia-class. It isn't crazy to think they might be willing to pay money for secrets. But it's also equally plausible that they would immediately tell the US to avoid diplomatic complications if it was discovered. It's also easier to justify selling to a friendly country instead of an enemy. He and his wife might have thought, "It's not like India is going to use the information to attack the US. What's the harm?"

It would make some sense ( from his point of view). India have nuclear powered ballistic missile subs, but no attack ones, and if i recall correctly they're working with Naval Group on an indigenous nuclear attack sub design.

I would think France, who just got worked over by Australia and the US in the AUKUS deal.

India is a stretch. Having routinely dealt with Indian companies, there would be endless negotiations and squabbling over money. Endless.

France ?.. You can't be serious.

The first contact was in april 2020. It's either Russia or China.

Also this was supposedly restricted info. There is a whole hierarchy of secrets, like SBU, secret, top secret, super duper tippy top secret with access codes that are classified in their own right, etc. I don't know where "restricted" fits into this, or whether it just referred to an unspecified level.

Restricted is at the very bottom. Well, SBU is below that, but SBU is not classified.

Restricted Data and Formerly Restricted Data are classification markings that concern nuclear information. These are the only two classifications that are established by federal law, being defined by the Atomic Energy Act of 1954. Nuclear information is not automatically declassified after 25 years. Documents with nuclear information covered under the Atomic Energy Act will be marked with a classification level (confidential, secret or top secret) and a restricted data or formerly restricted data marking. Nuclear information as specified in the act may inadvertently appear in unclassified documents and must be reclassified when discovered. Even documents created by private individuals have been seized for containing nuclear information and classified. Only the Department of Energy may declassify nuclear information. https://en.wikipedia.org/wiki/Classified_information_in_the_...

Restricted

During and before World War II, the U.S. had a category of classified information called Restricted, which was below confidential. The U.S. no longer has a Restricted classification, but many other nations and NATO do. The U.S. treats Restricted information it receives from other governments as Confidential. The U.S. does use the term restricted data in a completely different way to refer to nuclear secrets, as described above.

I was watching a youtube video that how different densities of water caused by differing temperatures make sound waves to bend in water and under some circumstance it can render pockets of water invisible to sound waves there could be lot of know how on to induce that or how to find those pockets in deep sea etc.

I'm no expert, but I think the most likely is stealth technology. This could be profiles of components designed to reduce turbulence and thus reduce vibration, or structures that minimize reflection from sonar etc.

Since military tech is a cat and mouse game, having access to stealth tech could put you ahead of your competitors in the arms race, until they design another level of protection that makes current tech obsolete.

Not an expert but Smarter Everyday has a playlist on a Nuclear Submarine. He explains the complicated math involved in various operations of the Submarine. As few others have pointed out, it also involves keeping the sub silent.

https://www.youtube.com/watch?v=XFJnWp1tAdU

Pretty much all data is useful in aggregate. Even how much power a sub can make can tell you something about it's speed or range

Material composition of whatever sonar absorbing paint they use to emulate it, the shape of the propeller to figure out it's sound signature, specs of the sonar system so opposing subs can evade it better, there's definitely good intel to be had.

Not an expert, but that's what comes to mind.

Purely an uneducated guess, but I would expect that any information pertaining to noise suppression or operational tactics would be useful for someone trying to track them.

Just the design of the screws alone is a highly guarded secret as are many other bits and pieces that could be used to create an acoustic footprint.

A sub that isn’t secret/stealth is basically just a peculiar boat.

Ahhh the classic "source" counter... Why so literal?

He is right. First hand knowledge.

The dinner menu. Much more complicated to keep a hundred people happy under their sea for 3 month with no access to fresh food, than keeping a nuclear reactor running.

> Not asking for any secret data, obviously. Just wondering what kind of secret data is even useful to an adversary.

I don't know either. And if Russians wanted it, they wouldn't have had an interest in a wayward scientist — that would be just too American style.

Rather, I'd say they would've gone after a person who could've given it to them on a golden platter, rather than having to read through somebody amateurish spy scoop compilation. That would be more Russian.

They had few spooks, but they spared no expense, and went to any lengths in getting somebody high rank like Ames, or Hansen.

Now... https://www.theguardian.com/us-news/2021/jan/29/trump-russia...

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