RA2lover (2lazy2login)
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Post by RA2lover (2lazy2login) on Sept 29, 2016 4:32:44 GMT
That's the line bringing coolant from the radiators back to the reactor, which is outside the reactor itself. It's pegged to the melting point of the coolant, though - this might be a bug. I am fairly certain that this is a bug. It's notable because the thermocouple stress is computed based on this value, not the radiator temperature, and this makes a few thermocouple options unusable at high reactor temperatures as they cannot be made strong enough to not shatter with the bogus 2800K dT, even though there should only be 300K dT between the reactor and the radiator. Haven't seen that myself(though I didn't do much research on high temperature reactors). In particular, I don't have to change the thermocouple parameters as I slide through radiator output temperatures. The thermocouple's temperature delta stays the same when this is done(it would change assuming it's measured using the outer coolant's melting point). I'm not sure whether thermopile or tooltip behavior is incorrect, though I think the tooltip is wrong in this scenario. Increasing the thermopile length would allow more thermocouples to be shoved into it, which would increase its efficiency but put it under more thermal stress(and also affect delta-t as you have a longer path to the radiator). |
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Post by princesskibble on Sept 29, 2016 4:35:38 GMT
The game also ignores neutron embrittlement. Qswitched has done an amazing job with physical modelling in this game, but many constraining factors have been left out. What about neutron activation? |
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Post by quarkster on Sept 29, 2016 4:42:27 GMT
That's the line bringing coolant from the radiators back to the reactor, which is outside the reactor itself. It's pegged to the melting point of the coolant, though - this might be a bug. I don't know if it's a bug in the sense that it's not what qswitched intended, but it's certainly not accurate. The returning coolant should be slightly warmer than the radiator. |
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Post by boosters on Sept 29, 2016 13:40:57 GMT
I've been having some fun with nuclear reactors. [...] I built and installed your 208 MW design, and now I'm building lasers that start frying things at 250km, and railguns with an effective accuracy at 150km. It's a whole new world! Thanks for the tip. It really should have occurred to me before that reactor development sets an upper limit on ship capabilities. I will definitely be trying to max out reactor efficiency in the future. I built a 6kt warship with just two of the 208MW reactors and up-rated some lasers and railguns and now I'm shredded anything stock before they even open fire, usually. I'm just going to have to start fighting ships from the forums, clearly.  (while we wait for multiplayer, nudge nudge...) |
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Post by quarkster on Oct 1, 2016 16:50:58 GMT
Inner loop temperature on this is 3110 K, which is actually the limit set by the thermocouple and not by the fuel rods melting. I'm having a strange problem. This reactor design is putting out first stage coolant at well below the melting point of UO2, but it still says my fuel rods are melting. Is there a separate hidden reactor temperature? EDIT: Reactor design removed for reasons of state secrecy |
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tuna
New Member
Posts: 33 
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Post by tuna on Oct 1, 2016 17:13:00 GMT
Yes, I've noticed the same. You can bring this closer to the inner loop coolant temperature by making the inner turbopump more powerful. |
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Post by apophys on Oct 1, 2016 20:06:05 GMT
So, I've managed to get a power density of over 7 MW / m 3 on a reactor with output temp at 2500 K. As a side benefit, it's lighter and cheaper than any stock reactor, while outputting more raw power than any stock reactor. Stock reactors appear hilariously bad now. I call it the Thermos. Because it looks like one.  Diamond moderator is stuffed in there to reduce radiation leakage (this is why I use U-233 dioxide control instead of boron nitride; it's denser, leaving room for moar diamond). A moderator is also required for the design, as without any the range would not reach criticality and the fuel would not last long enough. 4kg is the bare minimum for diamond. And yeah, that's a lot of power from a single kg of fuel. Calcium is used for the outer turbopump because it's lighter and cheaper than amorphous carbon. Not that the difference is very large. Total cost is 51.9 kc (the screen isn't big enough to show that). Copy/paste design code (from my UserDesigns.txt file to yours): ThermoelectricFissionReactorModule 71.0 MW Thermoelectric Fission Reactor
ReactorCoreDimensions_m 0.1 0.11
NuclearReactor
Coolant Sodium
Moderator Diamond
ModeratorMass_kg 11
Fuel U-235 Dioxide
FuelMass_kg 1
FuelEnrichment_Percent 0.97
ControlRodComposition U-233 Dioxide
ControlRodMass_kg 1
NeutronReflector Diamond
ReflectorThickness_m 0.7
AverageNeutronFlux__m2_s 1.4e+020
InnerTurbopump
Composition Amorphous Carbon
PumpRadius_m 0.34
RotationalSpeed_RPM 1200
ThermocoupleInnerDimensions_m 0.79 2.4
Thermocouple
PTypeComposition Tungsten
NTypeComposition Tantalum
Length_m 0.001
ThermocoupleExitTemperature_K 2500
OuterCoolant Sodium
OuterTurbopump
Composition Calcium
PumpRadius_m 0.34
RotationalSpeed_RPM 1000 |
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Post by pokington on Oct 1, 2016 21:03:11 GMT
Gentlemen, for fun, I present the nuclear minifridge:  So tiny.  So adorable. It's true, it has no radiation shielding. Put it on a drone, or bring your own shielding (preferably 5 mm or so of lithium-6). My goal was to get as much power as possible out of the smallest and lightest possible reactor. This is kind of a bottom case, since you can increase power production by lowering the outlet temperature (at a corresponding cost of having larger radiators, and at this point already the radiators will probably weigh more than the reactor). I also tried using U-233 dioxide or Pu-238 dioxide but I couldn't get either to have an acceptable lifetime at this scale. (actually, since uploading the picture I realized you can save .1kg by replacing the polyethylene outer turbopump with a lithium one) |
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Post by pokington on Oct 1, 2016 21:17:08 GMT
Diamond moderator is stuffed in there to reduce radiation leakage (this is why I use U-233 dioxide control instead of boron nitride; it's denser, leaving room for moar diamond). A moderator is also required for the design, as without any the range would not reach criticality and the fuel would not last long enough. 4kg is the bare minimum for diamond. Huh. That diamond trick is pretty cool. Very useful on all but the tiniest reactors. |
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Post by apophys on Oct 1, 2016 22:46:21 GMT
Huh. That diamond trick is pretty cool. Very useful on all but the tiniest reactors. I'd say it's especially useful for the smallest reactors, which do not have shielding around the core due to self-imposed size limitations. 10 kg of diamond moderator, with U-233 dioxide control, brings your minifridge down to ~179 W of radiation without increasing size. Still not safe, but definitely safer. |
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Post by aetreus on Oct 1, 2016 23:02:49 GMT
Inner loop temperature on this is 3110 K, which is actually the limit set by the thermocouple and not by the fuel rods melting. I'm having a strange problem. This reactor design is putting out first stage coolant at well below the melting point of UO2, but it still says my fuel rods are melting. Is there a separate hidden reactor temperature? EDIT: Reactor design removed for reasons of state secrecy I'm pretty certain that it's down to thermal transfer between the fuel rods and the coolant. The rods are generating heat via fission, and they'll grow hotter until the rate of heat transfer to the coolant equals that rate. The transfer rate is based on temperature difference between the coolant and the rods, the thermal properties of the coolant, and the coolant flow rate. Hence why having a better coolant and circulating it through the core faster allows for a higher reactor coolant temperature while keeping the fuel rods inside their temperature limits. The biggest unrealistic part of the reactor simulation is probably that it doesn't take into account mechanical issues related to high temperature. Running massive amounts of gas through materials operating at 2000 K+ temperatures would lead to creep deformation for even creep-resistant materials. There are proposals for high heat gas cooled reactors(and some of these have actually been built), but mostly these top out at the sort of 1600K range that conventional reactors operate at in game, not the 3000K range that reactors can be designed up to. |
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Post by pokington on Oct 1, 2016 23:21:33 GMT
I'm pretty certain that it's down to thermal transfer between the fuel rods and the coolant. The rods are generating heat via fission, and they'll grow hotter until the rate of heat transfer to the coolant equals that rate. The transfer rate is based on temperature difference between the coolant and the rods, the thermal properties of the coolant, and the coolant flow rate. Hence why having a better coolant and circulating it through the core faster allows for a higher reactor coolant temperature while keeping the fuel rods inside their temperature limits. The biggest unrealistic part of the reactor simulation is probably that it doesn't take into account mechanical issues related to high temperature. Running massive amounts of gas through materials operating at 2000 K+ temperatures would lead to creep deformation for even creep-resistant materials. There are proposals for high heat gas cooled reactors(and some of these have actually been built), but mostly these top out at the sort of 1600K range that conventional reactors operate at in game, not the 3000K range that reactors can be designed up to. Also, there is that we are all engineering reactors with literally zero safety margin. I suspect that even if some of these things could be built they would fail within minutes due to atomic-level imperfections. Given that we already have a minimum reactor life margin, perhaps a material safety margin could be a stopgap solution to help mitigate this to some degree without having to go back and model too much extra complexity. |
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Post by pokington on Oct 1, 2016 23:49:29 GMT
Huh. That diamond trick is pretty cool. Very useful on all but the tiniest reactors. I'd say it's especially useful for the smallest reactors, which do not have shielding around the core due to self-imposed size limitations. 10 kg of diamond moderator, with U-233 dioxide control, brings your minifridge down to ~179 W of radiation without increasing size. Still not safe, but definitely safer. For smaller human-rated reactors, I generally lower the outlet coolant temperature to 2400K. It lets you use boron carbide as shielding, which is a lot more effective than diamond. For larger reactors, it's probably not worth the trade in larger radiators. Also, radiation shields made from lithium-6 are kind of game-breakingly overpowered. 1mm of it is generally all you need unless you have a handful of nuclear minifridges. |
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Post by Crazy Tom on Oct 1, 2016 23:51:41 GMT
I'd say it's especially useful for the smallest reactors, which do not have shielding around the core due to self-imposed size limitations. 10 kg of diamond moderator, with U-233 dioxide control, brings your minifridge down to ~179 W of radiation without increasing size. Still not safe, but definitely safer. I just tried to wipe a bug off my monitor. apophys, I salute you, you magnificent asshole. |
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Post by Dhan on Oct 2, 2016 8:27:45 GMT
Gentlemen, for fun, I present the nuclear minifridge: So tiny. So adorable. It's true, it has no radiation shielding. Put it on a drone, or bring your own shielding (preferably 5 mm or so of lithium-6). My goal was to get as much power as possible out of the smallest and lightest possible reactor. This is kind of a bottom case, since you can increase power production by lowering the outlet temperature (at a corresponding cost of having larger radiators, and at this point already the radiators will probably weigh more than the reactor). I also tried using U-233 dioxide or Pu-238 dioxide but I couldn't get either to have an acceptable lifetime at this scale. (actually, since uploading the picture I realized you can save .1kg by replacing the polyethylene outer turbopump with a lithium one) Put this bad boy on my ship and now my game crashes when loading a mission. 10/10 would use again  |
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(while we wait for multiplayer, nudge nudge...)
