[2300] Fission reactor questions

[Anonymous]

I’m researching power plants for a home brew ship and vehicle design sequence. I’m looking at TL10 thru 12 (it’s for a variant 2300 setting) and am happy taking some liberties with the numbers but I’d like to have some semblance of believability.

Fission reactors are first up:

I started looking at naval reactors as it seemed they would present the closest facsimile for a starship based reactor, they’re built to be self contained and as I understand it, to a higher degree of engineering than commercial reactors as they’re operating in hostile environments underwater and in combat!

From FAS I found sizes of the reactor vessel for a number of older US naval ships. From the image I can see what’s probably inside the reactor vessel but I don’t know what else is needed to generate power (turbines, generators and stuff like that) and most importantly, it’s volume and mass.

Question 1, what’s an approximate volume and mass for the stuff not in the reactor vessel?

Wikipedia lists several others but the information isn’t up to date or complete as I assume that the current reactors are classified.

Question 2, What are the volumes and masses for the more recent US naval reactor vessels?

The reactors were rated by what I believe to be thermal output and then a SHP rating/number of shafts. I converted SHP to MW to make it a comparison easier (if indeed it’s even valid). I don’t know what their electrical output is, I assume that would be proportionate to their thermal out put but I’m not sure if it is or at what ratio.

Question 3, what’s the electrical output of the US naval reactors?

Question 4, is the electrical output likely a percentage of it’s thermal output and will it increase as more efficient (higher tech level) models are designed?

I then started looking for small reactors, the intention to get an idea of minimum volumes at different tech levels and found this and bwxt.com/nuclear-energy/utility-solutions/smr/bwxt-mpower . Wiki gave me the stats for the mPower reactor, hopefully they’re about right, a lot smaller than the naval reactors and with the Babcock and Wilcox it would appear to have a similar thermal output and lists it’s electrical output to a 1960s naval model, it's not an apple and apple comparison tho as I don't know the peripheral machines for both and what's actually in the naval vessel that the numbers refer to. Now in part that’s the advancement of technology, partly not being built “mil spec” and partly cos I don’t know what peripheral machinery I’m missing.

Question 5, how do these reactors compare to the kind the USN uses? Are they as reliable and efficient?

Question 6, what are the other aspects of a reactor I should be looking at?

(ETA: I have tried to edit the link to work but failed, not sure why but you'll need to CNP the url and add the http stuff to view the reactor)

 

[phavoc]

(1) It's not clear (mostly because it's classified). Janes or some other source of info would be your best bet, but they are a pricey bunch. From the FAS site (http://fas.org/man/dod-101/sys/ship/ssn-688.htm) you can see the engineering spaces take up about 1/3rd of the boat. This is probably a better illustration (http://americanhistory.si.edu/subs/const/anatomy/attacks/cutaway.html) that shows just how massive their engineering spaces are. Keep in mind that space craft have no need for reduction gears, drive shafts or all the myriad naval tech that is required to turn a shaft. And in the future everything is smaller and more effecient. But the image will help you with your idea, as it seems to take up roughly 8-10% of total ships displacement. Mass would be something else, but you need not worry about that for Traveller.

(2) That's classified too.

(3) The LISTED output for a Virginia-class SSN reactor is about 40MW. You can probably assume that's incorrect and it will be higher. 20% or more would be a safe bet.

(4) As far as I know, no. The enrichment process for a naval reactor is different than standard ones, as the cores are designed to last the lifetime (30+ years) of the unit, and then the whole thing is retired. And electrical output is based upon the conversion of steam to drive a turbine. Some US and Russian models have experimented with sodium to make super-heated steam. Traveller tech assumes a direct energy to electricity conversion process with fusion power, so the same thing should be possible with fission plants. It would be interesting to see if you could safely scale up RTG power plants to have nuclear "batteries" powering starships too. Something similar to that was used by Piper in his Space Vikings universe (they also had direct matter to energy conversion). The RTG's they used powered pretty much everything but the starships themselves.

(5) I have not heard of the NuScale ever being built. And it looks like a civilian version, thus it uses different tech like you point out. Naval reactors are built to never require refueling or service (sub ones at least, carrier ones are). And that reactor would also require steam generation gear to make electricity. Standard reactors all use pumps to drive coolant, this one does not, utilzing only gravity. I'm not sure that would pass safety snuff. Your second link doesn't work.

(6) Not many that I can think of. Keep in mind for Traveller, at least MGT, a nuclear reactor would still require jump fuel. And with the changes in fuel usage, having a fission reactor onboard doesn't really provide much advantage. Hydrogen is cheap. If you want an alternative power source you might want to investigate fuel cells or even MHD for power generation. If your goal is long-term stealth, those would probably do just fine. If you aren't firing weapons or powering the engines your actual power consumption for a PC-run ship should be relatively negligible.

 

[Anonymous]

P,

Thanks for the replies.

I'm not sure what happened with the second link, I wrote the post off line a few days ago and the link was current then, I think the website has been updated as I went there to check info again and the info wasn't there, only on wiki.

One thing to note, using gravity not pumps isn't going to work in space! :mrgreen:

I've got to get to work now, will respond in more detail as time permits, probably this evening.

 

[Condottiere]

The fuel is way overpriced.

 

[Anonymous]

Essentially a marine reactor needs to be (a) salt-water resistant, (b) physically small as volume is the biggest limitation on a ship, (c) able to operate in adverse weather conditions, (d) have a higher maintenance interval.

Efficiency is not that important except when it relates to noise: the reactor does not have to generate electricity at a profit.

Output is not a concern: The reactor generates much less power than a power station and when existing nuclear ships were designed, the concept of "electric ship" did not exist.

When comparing the size of the support equipment, it's difficult, since submarine reactors have some extra stuff in there that isn't required for civilian use, such as acoustic "stealth" systems.

The other issues when comparing to present day is one of liability and maintenance.

Traveller seems to have magically safe fusion (you cannot overload your reactor and turn it into a nuclear fusion bomb, and the reactor does not become radioactive) but the same magic doesn't appear to apply to their fission plants.

Liability for military reactors isn't so much of a problem, but this does depend on nation. The US government will not stop its navy using nuclear powered ships due to an accident, but some Euro nations might - for example a lot of them will not use depleted uranium ammunition for toxicity reasons.

As for maintenance, "real" warships spend 1/3 of their time in a yard undergoing repair and refit. Traveller ships don't need this again due to their techno-magic. When a nuke ship comes in for refuelling, it's out of service for years.

 

[phavoc]

Traveller seems to have magically safe fusion (you cannot overload your reactor and turn it into a nuclear fusion bomb, and the reactor does not become radioactive) but the same magic doesn't appear to apply to their fission plants.

It wasn't in the old Starship Operators Manual, but it would be interesting to have a writeup on the fusion systems of Traveller, and little tid-bits like what it takes to start your fusion plant from cold, or even stand-by. Helpful knowledge for when you have to blast out of docking bay 94 in a big hurry. Too bad we can't fix the irradiation issue in our fusion tech. It would be very helpful!

Liability for military reactors isn't so much of a problem, but this does depend on nation. The US government will not stop its navy using nuclear powered ships due to an accident, but some Euro nations might - for example a lot of them will not use depleted uranium ammunition for toxicity reasons.

The cool/shitty thing about that is generally the results of said APFSDS dust is on somebody else's land - assuming you are lucky enough to fight 'over there' instead of at home. Makes for easy policies...

As for maintenance, "real" warships spend 1/3 of their time in a yard undergoing repair and refit. Traveller ships don't need this again due to their techno-magic. When a nuke ship comes in for refuelling, it's out of service for years.

If it's a full ROH, yeah, they are hangar queens for a couple of years. Part of the complexity involves cutting into the ship to access the reactor, and then putting it all back together again. But ships spend a lot of time in port for the crews too. It will be interesting to see how some of the newer ships, with their much smaller crew complements, handle being at sea over time and how that will affect their overall readiness. One thing about having lots of hands means you can keep a lot of little things fixed. Repair drones in Traveller might be the equivalent. But the techno-magic explanation works pretty well too.

 

[Anonymous]

The cool/shitty thing about that is generally the results of said APFSDS dust is on somebody else's land - assuming you are lucky enough to fight 'over there' instead of at home. Makes for easy policies...

Many people believe DU poisoning has affected service personnel. They would be exposed if, for example if the DU armor in their vehicle was hit, or in the wreckage of enemy vehicles hit by it. Its certainly true that the dust if inhaled will cause illness, but the amount of dust inhaled by soldiers is not known.

 

[phavoc]

Many people believe DU poisoning has affected service personnel. They would be exposed if, for example if the DU armor in their vehicle was hit, or in the wreckage of enemy vehicles hit by it. Its certainly true that the dust if inhaled will cause illness, but the amount of dust inhaled by soldiers is not known.

That is part of the shitty thing for US troops. The commanders sitting in the Pentagon who want a couple of extra F-35's or whatever pet project prefer to stonewall rather than fund the VA properly to diagnose and treat our soldiers.

 

[Anonymous]

Gentlemen (Ladies?)

While I am frequently guilty of thread drift, may I respectfully request that we endeavor to keep this one on topic a little while longer?

Thank you kindly

H

 

[Condottiere]

For submarines, lifespans can be calculated in the structural integrity of the hull and viability of the propulsion system, otherwise, it's easier and cheaper to build a new one, though since they've kept most of theirs docked, the Russians are planning to refurbish their existing ones for another twenty years or so.

 

[phavoc]

Sorry... I did find that the Akula reactor is supposed to be rated for about 190MW. Far more than the stated rating for US subs. But none of these are going to be sufficiently powerful for a starship using MW for weaponry, let alone drives (which we don't really have a clue about). Assuming you hand-wave the issue, you could simply say it produces enough energy and be done with it.

(to continue thread drift, the Ruskies K222, the fastest sub ever built, was retired way early. It had a titanium hull, which is a pain to handle anyways, and experienced too much stress and cracking in just a few years. So how hard they run a sub also plays into the retirement question - actually the same goes for any ship or aircraft. They all have limited lifespans, in years or hours of use)

 

[-Daniel-]

Gentlemen (Ladies?)

While I am frequently guilty of thread drift, may I respectfully request that we endeavor to keep this one on topic a little while longer?

Thank you kindly

H

Request denied. Thread will now drift for three to five posts. :lol:

 

[FallingPhoenix]

Traveller seems to have magically safe fusion (you cannot overload your reactor and turn it into a nuclear fusion bomb, and the reactor does not become radioactive) but the same magic doesn't appear to apply to their fission plants.

Which is weird, because, as far as nuclear explosions, it shouldn't be possible for fission reactors to explode (unless they're using something dangerous like liquid sodium instead of water for power generation and cooling). Reactor fuel does not equal bomb fuel. You have to enrich your uranium way more to make it explode.

 

[Rikki Tikki Traveller]

It won't explode like a nuclear bomb, but it can still explode. More like a dirty bomb. Big explosion with lots of radiation. Kilotons of explosion though, not Megatons.

 

[phavoc]

Look at the disasters of chernobyl and fukushima on what can happen. Yes, no supercritical explosions but still a radioactive mess.

 

[Anonymous]

Which is weird, because, as far as nuclear explosions, it shouldn't be possible for fission reactors to explode ... Reactor fuel does not equal bomb fuel. You have to enrich your uranium way more to make it explode.

Say everyone has a reactor, and no-one can see what you're doing inside your spaceship, and the TL7 precision equipment needed to make the bombs is likely trivial at higher TLs, what do you reckon on the chances of a mad bomber existing?

I think Traveller "solves" the problem by putting up nuclear dampers everywhere but even then, there's a die roll to penertate them. Maybe that's for professionally made warheads, and dampers will stop home made nukes?

 

[Anonymous]

So much for killing the thread drift, thanks Daniel :roll:

I don't think Traveller solves anything with a bazillion nuclear dampers everywhere, especially not in the back waters like the Spinward Marches, it just ignores that everyone is wandering the galaxy with a dirty bomb capable of mass murder for the convenience of not having to think about how dumb it was to give everyone a dirty bomb capable of mass murder in the first place...

 

[phavoc]

Dampers only stop nuclear things from going super-critical, they don't stop dirty bombs or inhibit radiation.

My physics is mighty rusty, but if you have a field that prohibits fission reactions, might it also prohibit fusion reactions? Today our fusion bombs require a fission trigger, but who's to say they can't go directly to fusion in the future, thus those nuclear missiles would be fusion-tipped, not fission.

And there's always the Californium rounds for rail guns. whee!

 

[Anonymous]

My next bunch of questions will be about fusion but in all honesty as no one has made a working commercial or military fusion reactor I can just pluck those out of the ether and call it good...

 

[dragoner]

Traveller seems to have magically safe fusion (you cannot overload your reactor and turn it into a nuclear fusion bomb, and the reactor does not become radioactive) but the same magic doesn't appear to apply to their fission plants.

Which is weird, because, as far as nuclear explosions, it shouldn't be possible for fission reactors to explode (unless they're using something dangerous like liquid sodium instead of water for power generation and cooling). Reactor fuel does not equal bomb fuel. You have to enrich your uranium way more to make it explode.

At Fukushima, it was hydrogen gas that exploded. Fusion reactors don't have fissile material involved.

BTT - One engineering principle that would carry through is to make the reactors safer, also smaller as well.