Modern Naval Submarine Discussion

[Bacle]

One of my colleagues has been looking at this class of system and for land use it seems to have a fair level of potential. The problem is that it has a major disadvantage in that it is one of those "ebil nooklir def mashines" that will kill us all. It's almost impossible to get any nuclear things built in the USA right now and unless there is a fundamental change in how people think, its going to be a long time before we see any appreciable in new technologies reaching commercial acceptance. This is a huge pity because nuclear is actually just about the "greenest" technologies there is. At least where carbon emissions are concerned. Personally I think the end of nuclear was just about the worst mistake that has been made from an environmental point of view. But, it illustrates the basic accuracy of Rickover's belief that one nuclear accident will kill an entire industry.

It's worth noting that SSBNs tend to use gravity-fed cooling systems on their reactor to cut down emitted noise (most of the noise from a nuclear power plant comes from the cooling system). So its quite possible that we'll see some of the technology being developed here vanishing into the maw of the military-industrial complex.

Yeah, I personally blame The Simpsons, more than any other bit of media, for scaring people away from nuclear power. I actually did a paper on that in my undergrad, just to get through a writing course.

And when I did nuclear power as a subject for a class in my MEM program, I actually directly asked how many people got their first impression on nuclear power from The Simpsons, and about 1/3 of the class (including the professor) raised their hands.

 

[bullethead]

Rickover's basic driver in this area was that he understood that if there was a major reactor accident on one of his nuclear submarines, the public reaction would probably kill the submarine fleet. Thus, he always went for the safe option. Having said that we did look at several alternate technologies in the early days. One was a liquid metal cooled reactor which, in theory, was a very good idea. We built a submarine (the 1950s Seawolf) that had a liquid-metal cooled reactor but she was very unsuccessful and was rebuilt with a PWR. The Russians built several submarines powered by liquid-metal cooled reactors and they all failed very badly. At the moment water-cooled reactors offer the best balance of capability, cost, weight and volume within the overriding parameter of being safe. There are other approaches as propulsion for naval vessels (details classified) but AFAIK none yet rival the PWR as a practical solution.

I don't have any problem with Rickover putting safety first. It was his weird refusal to let anyone do anything but PWR that was the problem, to the point he wouldn't let anyone make prototypes due to his position on the AEC. Like, I understand the reluctance to put a new kind of reactor in service, but that's why you build prototypes on land, refine the design, then put it in a service vessel.

AFAIK, no one did that for the liquid metal reactors, which is why they all turned out to be shit.

If we combined the technology of both Narwhal and Lipscombe we could have an incredibly stealthy coastal nuke sub capable of speeds up to 20+kts, but I don’t think the rationale for the US to build such a boat ever really existed.

Interestingly, that would probably be an ideal design if you wanted a boat for commerce warfare in the modern world, though, i.e., the classic WW1 and 2 submarine function.

From what I've read in Norman Polmar's book covering Cold War subs, the Lipscombe's D/C (IIRC) motor didn't work and overheated, while making the sub heavier. Supposedly nuke subs might be moving to A/C motors, but I can't remember if I read that from an official bit of naval news, or if I'm somehow conflating something with a thing that Michael DiMercurio did in his submarine novels.

 

[Deleted member]

I don't have any problem with Rickover putting safety first. It was his weird refusal to let anyone do anything but PWR that was the problem, to the point he wouldn't let anyone make prototypes due to his position on the AEC. Like, I understand the reluctance to put a new kind of reactor in service, but that's why you build prototypes on land, refine the design, then put it in a service vessel.

AFAIK, no one did that for the liquid metal reactors, which is why they all turned out to be shit.

From what I've read in Norman Polmar's book covering Cold War subs, the Lipscombe's D/C (IIRC) motor didn't work and overheated, while making the sub heavier. Supposedly nuke subs might be moving to A/C motors, but I can't remember if I read that from an official bit of naval news, or if I'm somehow conflating something with a thing that Michael DiMercurio did in his submarine novels.

I haven't a bloody idea why Lipscombe had DC motors when we laid our first AC motor'd capital ship in 1915.

 

[Francis Urquhart]

I don't have any problem with Rickover putting safety first. It was his weird refusal to let anyone do anything but PWR that was the problem, to the point he wouldn't let anyone make prototypes due to his position on the AEC. Like, I understand the reluctance to put a new kind of reactor in service, but that's why you build prototypes on land, refine the design, then put it in a service vessel.

It wasn't really weird, it all comes back to the same basic cause - budgets. The problem that hit from the late 1950s on was that there were a huge number of projects going down, all of which were absolutely essential. There was a major crisis in naval aviation and it was really questionable whether the Navy actually could defend itself against air attack. Virtually an entire generation of naval fighters were failures and the missiles were horrible. Battle management issues were intractable. Then there was the need to replace war-built construction that was seriously outmoded. And we had the need to develop nuclear propulsion for both surface ships and submarines. We had the SSBN program that was draining funds at a terrifying rate. This was the time when major programs - such as the missile cruisers, fleet flagships etc were being cancelled because the funding wasn't there to pursue them.

Under those circumstances, the available R&D funding had to be allocated very carefully. Spread it too thin and nothing happens. Rickover's philosophy was the conventional response and the time-proven one. Concentrate the funding on the program(s) most likely to produce a successful result and rigidly refuse anything else. He wasn't unique; the same thing was happening all over the Navy. Regulus II was cancelled in favor of Polaris and it would be almost 15 years before the Navy got back into the cruise missile game. The F4H-2 Phantom was selected over the other naval fighter projects (most famously the F8U-3 but there were a clutch of others as well). If the Navy was going to get any nuclear-powered submarines at all, diversions of funding into other areas had to be ruthlessly suppressed. Which is what he did.

In the final analysis, if one asks why X wasn't done or why Project Y was abandoned, the answer almost invariable comes back to "Budget - lack thereof".

From what I've read in Norman Polmar's book covering Cold War subs, the Lipscombe's D/C (IIRC) motor didn't work and overheated, while making the sub heavier. Supposedly nuke subs might be moving to A/C motors, but I can't remember if I read that from an official bit of naval news, or if I'm somehow conflating something with a thing that Michael DiMercurio did in his submarine novels.

Lipscomb was very unreliable and was continually developing faults with her propulsion machinery. In contrast the other test-bed, Narwhal, was a brilliant success. By the way Lipscomb had DC motors because it cut the need for alternators out of the power train. Alternators were deemed to be an unacceptable generator of noise. Narwhal's power train was the basis for that in the Ohio class SSBNs and now the new Columbia class SSBNs. Lipscomb's power train was deemed a failure but a developed version of the technology is going into the Block VI Virginia class SSNs. I can't comment on whether the Block VIs will use AC or DC motors.

 

[Flintsteel]

To put the terrestrial power demand/weight balance. into context the Sentinel-100 RTGs used by the USAF weight 1,250 kg and generate 53 watts. Thus to be a substitute for a nuclear reactor used in a submarine, an RTG array would weigh 1,886 tons. I shudder to think at the space demands. Even to be useful for battery charging in a conventional submarine, we would be looking at a 200 - 300 ton installation. In each case that excludes the parasitic weight.

1250 kg for 53 watts? NASA gets 100+ watts out of the 45-kilo MMRTG! And that's designed for use in a vacuum - it could probably be made lighter if it's going to be in an atmosphere the whole time. And uses the DOE-approved GPHS modules, which are designed to be safe.

Lot of work going on in a variety of areas. Please leave it there. Military nuclear power systems are a classified area.

...since Sterling-cycle engines aren't that big a deal, I am going to take that to mean Polywell is in fact still under development, because I seriously want that think to actually work.

 

[Francis Urquhart]

1250 kg for 53 watts? NASA gets 100+ watts out of the 45-kilo MMRTG! And that's designed for use in a vacuum

You said it in your post. That's for space use, we are talking RTGs suitable for terrestrial use and that requires heavier construction, shielding etc. We're also talking about putting these things in submarines, a closed, very hostile environment in intimate association with people (if bubbleheads are people - opinions vary on that. Sea skimmers tend to argue otherwise).

it could probably be made lighter if it's going to be in an atmosphere the whole time. And uses the DOE-approved GPHS modules, which are designed to be safe.

That's 180 degrees wrong. If we're putting these things on land or in water (or on aircraft flying in the atmosphere although I can't think offhand of anybody doing that) then they have to be built much more strongly and require a lot of protective measures that are not required for systems deployed in space. As an example, one reason why; the RTGs used by the Russians for remote lighthouses are mostly out of action because illegal scrappers have stolen the protective plating. Space is a very benign environment in comparison to terrestrial use. Space is also a weight-critical application and shaving few ounces here and there is critical.

.since Sterling-cycle engines aren't that big a deal, I am going to take that to mean Polywell is in fact still under development, because I seriously want that think to actually work.

Again, not so. Classified means just that, It's secret and cannot be discussed in open-source. Or, to use the correct formulation, "this matter can be neither confirmed nor denied and there is nothing to say beyond that." It doesn't matter if somebody says something somewhere about a classified matter. Such comments are usually based only on fantasy and are worthless. If people comment on classified subjects, they don't know anything about them; if they know something about them, they won't say anything.

For your information Sterling-cycle engines are diesels (which recycle oxygen-enriched exhaust gas) and, while there are secret aspects to their design and installation, most of the data is public domain. They are not nuclear reactors and it is quite wrong to relate or draw parallels between the two. Most modern future-systems nuclear design work whether on devices or reactors is highly classified and cannot be discussed.

 

[Flintsteel]

You said it in your post. That's for space use, we are talking RTGs suitable for terrestrial use and that requires heavier construction, shielding etc. We're also talking about putting these things in submarines, a closed, very hostile environment in intimate association with people (if bubbleheads are people - opinions vary on that. Sea skimmers tend to argue otherwise).

First, why would you need more shielding? The US has long used Pu-238, which is an alpha-emiter, so it's very easy to shield. Expensive though (the Soviets liked to use Sr-90 since it's a cheap waste product, but Sr-90 undergoes beta-decay). The GPHS is designed to survived failed rocket launches - I'm not sure how much more robust you can make it.

That's 180 degrees wrong. If we're putting these things on land or in water (or on aircraft flying in the atmosphere although I can't think offhand of anybody doing that) then they have to be built much more strongly and require a lot of protective measures that are not required for systems deployed in space. As an example, one reason why; the RTGs used by the Russians for remote lighthouses are mostly out of action because illegal scrappers have stolen the protective plating. Space is a very benign environment in comparison to terrestrial use. Space is also a weight-critical application and shaving few ounces here and there is critical.

Space may be fairly benign, but rocket launches sure aren't. The GPHS was designed to survive rocket failure and reentry. So the shielding systems are already built tough (the generator part I imagine not so much, but you'd want to redesign that anyway to take advantage of conduction cooling, rather that radiative one has to rely on in space).

For your information Sterling-cycle engines are diesels (which recycle oxygen-enriched exhaust gas) and, while there are secret aspects to their design and installation, most of the data is public domain. They are not nuclear reactors and it is quite wrong to relate or draw parallels between the two. Most modern future-systems nuclear design work whether on devices or reactors is highly classified and cannot be discussed.

...you know, if you're going to take such an authoritative stance, you should try to be correct.

The Sterling-cycle is a heat engine cycle. It can work with any heat source. NASA has considered using Sterling engines with radio-decay thermal sources (SRG - Stirling Radioisotope Generators) since Sterling engines get something like quadruple the thermal->electric efficiency of thermocouples as used in RTGs, with the downside of having moving parts. They have since moved on to using them with small nuclear reactors for the heat source rather than decay heat, for higher power output (the prior-mentioned Kilopower test reactor).

Now, I imaging that in specific to AIP systems for currently-purchasable submarines, 'Sterling engines' are referring to what you say. Since that sort of heat recovery is something the Sterling-cycle is very good at. But that's not what I was talking about.

 

[bullethead]

One thing that kind of surprises me about the current sub concepts/UUV designs is the lack of azipods for propulsion (see below for what that is). The closest thing I've seen to an implementation is the little engines on the Harpsichord AUV, but those seem to be fixed in place at an odd angle and provide no apparent maneuverability advantages.

 

[PsihoKekec]

As far as I heard these make a lot more noise than conventional propeller setting.

 

[Deleted member]

As far as I heard these make a lot more noise than conventional propeller setting.

Exactly this. Dampening motor oscillations inside of a pod flexibly attached to the hull is an order-of-magnitude harder challenge than using the mass of the entire submarine for this purpose.