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Surface Forces: Nuclear Power Secrets
   Next Article → PARAMILITARY: Why Mercenaries Survive and Thrive
December 31, 2007:  The U.S. decision to equip its next class of cruisers with nuclear power was driven largely by the rising cost of oil. Equipping a warship with a nuclear power plant increases cost by about $800 million. But with the expected growth of oil prices, the additional cost of a nuclear power plant is expected to pay for itself over the thirty year life of a warship.

 

Other than that, it's pretty much a wash. A nuclear power plant is much larger than an oil fueled one. While you eliminate the need for space to store oil, that just about takes care of the greater space requirements for the nuclear plant. OK, you don't have to spend all that time refueling at sea. But then there's the problems attendant with battle damage to a ship with a nuclear reactor on board. No one's had to face that one yet, but it's only a matter of time.

 

Another problem is getting qualified crew for the nuclear power plant. The nuclear subs have long had a problem with that, because the subs tend to be away from home, and out of touch with families, longer than the nuclear aircraft carriers. But even these carriers have to pay higher and higher bonuses to get, and retain, the sailors who can maintain and operate a nuclear plant. The latest generation of navy nuclear  plants are built to eliminate some of these personnel problems (being easier to operate and maintain), but you still need quality sailors to look after these expensive, and potentially dangerous, machines.

 

But with nuclear cruisers, there is another benefit. It will be possible to have a carrier task force that is entirely nuclear powered (one carrier, two cruisers and one nuclear attack sub). Such a force could move at high speed for long distances, giving the force enormous strategic mobility, covering over 1,200 kilometers a day, thus able to reach anywhere on the high seas within two weeks.

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hybrid       12/31/2007 11:43:32 AM
Not to mention giving nuclear powered cruisers enormous power generation capabilties. Do I hear DEW type weapon systems and railguns along with hypersonics being bandied about?
 
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Nanheyangrouchuan       12/31/2007 4:18:49 PM
For smaller vessels (and maybe some land vehicles), would it be possible to use NASA's nuclear decay generators (hardened even more for military apps) and use pelletized nuclear waste?  If so, we'd have a cradle to grave system for civi and military reactors because uranium/plutonium/thorium, etc are also experiencing sky rocketing prices due to demand from BRIC and renewed EU/US demand.
 
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hybrid       12/31/2007 5:55:23 PM
Size makes quite a bit of difference of whats viable. At drone sizes for UAVs/USV etc. then a radio isotope heater is more viable, same with a RTG. At say a cutter to corvette size vessel, energy density is probably more sought after rather than persistence needs. With the exception of corvettes historically most of these vessels operated closer to a nations sea waters. With the space you do end up having you gotta weigh the benefits vs the disadvantages (i.e reactors are heavy, and even RTGs and RHUs need lots of heavy shielding which in turn cuts into your vessel weight). To me at those sizes its debatable whether you gain major advantages.
 
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WarNerd       1/1/2008 5:34:16 AM

For smaller vessels (and maybe some land vehicles), would it be possible to use NASA's nuclear decay generators (hardened even more for military apps) and use pelletized nuclear waste?  If so, we'd have a cradle to grave system for civi and military reactors because uranium/plutonium/thorium, etc are also experiencing sky rocketing prices due to demand from BRIC and renewed EU/US demand.


Do NOT confuse nuclear decay generators with nuclear reactors.  They are VERY different.

 
The problem with nuclear decay generators is that there is no way to turn them off.  So you got heat (a LOT of heat) that you have to dispose of at all times.  If your coolant loop is damaged or becomes inoperatable for ANY reason the nuclear decay generators may well melt (though with ceramic fuel pellets it will probably be the generator rather than the fuel that melts, followed by the bottom of the hull).  Small units (beacons, pacemakers, etc.) used natural convection and heat pipes to achieve reliable cooling without pumps, but these are small and unarmored.
 
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lobofanina       1/1/2008 10:42:11 PM
Rail guns is the first thing I thought of too.   Yesterday watching Futureweapons they were discussing such guns that would protect 450 miles around a carrier group using projectiles traveling at mach 8.   At Sandia National Labs or White Sands ( can't remember which) it took a minute to charge enough capacitors to fire the weapon at mach 1.  You're either going to to need a hell of lot more capacitors or a whole lot higher base load of electricity to get up to mach 8, I guess that's where nuclear energy comes into the equation. 
 
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ASL       1/2/2008 12:17:09 AM

For smaller vessels (and maybe some land vehicles), would it be possible to use NASA's nuclear decay generators (hardened even more for military apps) and use pelletized nuclear waste?  If so, we'd have a cradle to grave system for civi and military reactors because uranium/plutonium/thorium, etc are also experiencing sky rocketing prices due to demand from BRIC and renewed EU/US demand.
The price of uranium for fuel is almost negligeable compared to the cost of the reactor plant itself.  The price of uranium could double (and then some) and this would still be true.
 
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Bob Roberts       1/2/2008 10:49:17 AM
I still say the final cost of nuclear cruisers will preclude any large series production, at least at the levels to equip each carrier strike group with two, that is if any are actually built.  Congress can mandate all they want but I doubt they'll ever supply the funding for these, again at least at the levels the navy would need.
 
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Solomon2       1/2/2008 5:02:25 PM
The U.S. did build several nuclear-powered cruisers back in the sixties and seventies.  The advantage was precisely to create a task force that could keep up and maneuver with a nuclear carrier, thus utilizing the carrier to maximum advantage. Given multiple orders of a standard nuclear power unit - say, just one of the two reactors that power a nuclear carrier - development costs will be nil and marginal production costs low. 

I think it's a winner, the only question in my mind being how well these ships can deal with battle damage.  They will necessarily be more exposed to attack than a carrier. 
 
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dwightlooi       1/2/2008 7:37:14 PM

For smaller vessels (and maybe some land vehicles), would it be possible to use NASA's nuclear decay generators (hardened even more for military apps) and use pelletized nuclear waste?  If so, we'd have a cradle to grave system for civi and military reactors because uranium/plutonium/thorium, etc are also experiencing sky rocketing prices due to demand from BRIC and renewed EU/US demand.
(1) The power generation capacity of a nuclear plant is typically worse than that of a gas turbine generator plant. That is a nuclear plant of a given size or weight makes less power than a gas turbine generator set of a similar size or weight.
(2) The typical nuclear plant runs off a pressurized water reactor. These have a fission core to make heat (lots of heat) which in turn heats up a primary "coolant" loop of pure distilled water. The water does not boil because it is kept high pressurized. This primary loop is run through a heat exchanger to heat and boil a secondary loop of water and the high pressure steam is used to run steam turbines not dissimilar to those running on steam from a oil or coal fired boiler of yore. The turbine then turns gearbox which is connected to an electric generator or a propeller shaft or both. The reason this reactor plant setup is used is because it offers good power density and is relatively safe and proven.
(3) There are higher power density reactors (ie. liquid metal -- typically sodium -- cooled reactors), but they are more dangerous and in the case of the sodium reactors, once the coolant solidifies the reactor cannot be restarted. In other words they cannot typically be refueled.
(4) There are also safer reactors. But ALL of them offer inferior power density compared to the PWR. The radioactive decay heaters are VERY low output. Its good for making simple power devices to provide solar panel grade electric power to satellites for extended durations with minimal complexity, but a ship running on these will lucky to make 2 knots! The helium gas cooled reactors which runs gas turbines directly off the helium loop is much better, but again the power density is worse than with the PWR even though they are safer -- practical meltdown proof and even a leakage of the helium isn't very radioactive because the gas doesn't carry radioactivity like heavier compounds. However, the helium reactor is more fuel efficient and is probably better from a battle damage catastrophy standpoint.

 
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blacksmith       1/3/2008 9:51:47 PM
A radioactive decay reactor produces watts, not kilowatts.  It would be hard pressed to drag itself over the ground much less operate at some tactically useful speed.  They might support sensors, but just how many of these things do you want to leave laying around in hostile territory?
 
Nuclear is not automatically the solution for high energy weapons.  All the pain and cost to fill the hull with a nuclear plant and the weapons get used rarely and sporadically over the life of the ship.  Don't be surprised to see hybrid ships; nuclear propulsion/gas turbine-generators for weapons.
 
The Navy had nine nuclear cruisers and decided not to continue to build them.  The reason may have involved more than the cost of oil, which was essentially free when the ships were built.  It's not just that they cost more to build and then they're free.  With the exception of fuel, everything about a nuclear propulsion plant is more expensive.  They require specialized training, special port facilities, all the parts are certified to a much higher (and more expensive) standard.  And you can't just cut them up and send their steel to a smelter.
 
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