|
|
Post by newageofpower on May 16, 2017 2:48:55 GMT
Sodium would be at unrealistically high pressures to keep it liquid. Due to being above its critical temperature, sodium would also lose its thermal conductivity, which is the reason for its use. IIRC, Liquid Lithium would be an ideal coolant for non-liquid pellet (probably Civillian) designs; critical point ~3200k, even lighter and thermally superior to sodium. For minmaxed (military) ships, we'd use TaHfC kernels with liquified uranium (or plutonium, or whatever is optimal when we take melting points out of the consideration) metal cores and operate at 4200k core temp - a nice 200k away from meltdown! Then we can jack up the output to 3300-3500 and save radiator area. If we want a low pressure reactor (TaHfC has average structural properties) we'd probably use liquid Niobium or something as the coolant. Pretty heavy, but the 'giant cylinder of reactor coolant' design in CoADE is a little unrealistic! |
|
|
|
Post by anotherfirefox on Oct 3, 2018 13:04:17 GMT
I mean irl they use 97% enriched fuel on navy warship?
|
|
|
|
Post by tepidbread on Oct 4, 2018 18:15:40 GMT
I mean irl they use 97% enriched fuel on navy warship? Seriously? That seems insane! Perhaps my reactor designs are not all that far-fetched. |
|
|
|
Post by treptoplax on Oct 4, 2018 18:34:29 GMT
I mean irl they use 97% enriched fuel on navy warship? Seriously? That seems insane! Perhaps my reactor designs are not all that far-fetched. Yeah, Wikipedia references say >93%...! |
|
|
|
Post by AtomHeartDragon on Oct 5, 2018 6:34:48 GMT
Why not? It's expensive and would be concerning on units not already having multiple, ready to use nukes on board, not inherently insane.
|
|
|
|
Post by anotherfirefox on Oct 7, 2018 4:12:26 GMT
Because military don't give a shit on their budget. If you use HEU, you can shove more fissile fuel within the same mass, thus can rarely refuel.
|
|
|
|
Post by AtomHeartDragon on Oct 7, 2018 9:05:32 GMT
If you use HEU, you can shove more fissile fuel within the same mass And that's even more of a "yes, please" when building spaceships.
Submarine doesn't have a strained delta-v budget to worry about.
|
|
Echo
Full Member
Posts: 141
|
Post by Echo on Jun 28, 2020 9:13:02 GMT
|
|
|
|
Post by AtomHeartDragon on Jun 28, 2020 15:58:24 GMT
You can sleep next to most of my reactors.
|
|
Echo
Full Member
Posts: 141
|
Post by Echo on Jun 30, 2020 13:39:52 GMT
neutron flux much greater than real life thermoelectric fission reactors (rl: 3.5e19) Source for this? Is it this one? www.government.nl/documents/reports/2012/07/12/kcb-rpv-safety-assessmentIf it is, I'm afraid you mistook fluence for flux. In this case, flux is measured in neutrons per cm 2 per second, while fluence in neutrons per cm 2. Abbreviations used in the paper:
RPV: Reactor Pressure Vessel
EFPY: Effective Full Power Years
Quoting from page 29: The space between "n/cm" and the dot that ends the first sentence, plus "cm 2" in the second line seems to indicate that a " 2" is missing in the first line. The fast neutron (E > 1 MeV) flux can be calculated as fast neutron fluence over time, that is: 3.50E+19 n/cm 2 / 32 at = 3.50E+19 n/[cm 2 · (1 m / 100 cm) 2] / (32 a t · 31 556 925.445 s/at) = 3.50E+19 n/[cm 2 · 1 m 2 / 10 000 cm 2] / 1 009 821 614.24 s = 3.50E+19 · 10 000 n/m 2 / 1 009 821 614.24 s = = 3.50E+23 n/m2 / 1 009 821 614.24 s = 3.47E+14 n/(m2·s) Less than half fission neutrons are fast. However, since I don't have anything more concrete than "less than half", I'll have to be conservative and consider that the neutron flux is twice the fast neutron flux: 3.47E+14 n/(m2·s) · 2 = 6.93E+14 n/(m2·s)
This value is log10(1.00E+16/6.93E+14) = 1.159 orders of magnitude inferior to the minimum allowed by the game limits. A neutron flux so low seems to be in accordance with the links I posted two posts above.
Assuming that 3.50E+23 n/m2 is the maximum fast neutron fluence before the reactor reaches EOL, the years a reactor can operate at full power given a certain neutron flux is calculated as fast neutron fluence over fast neutron flux: Time [at] = 3.50E+23 n/m2 / [(Neutron flux / 2) · 31 556 925.445 s/at] = 3.50E+23 / 31 556 925.445 at·n/(m2·s) / (Neutron flux / 2) = 1.11E+16 · 2 at·n/(m2·s) / Neutron flux = 2.22E+16 at·n/(m2·s) / Neutron flux
Conversely, the neutron flux of a reactor that has to operate for a certain amount of years is twice the fast neutron flux, which in turn is calculated as fast neutron fluence over time (this formula can also be extrapolated from the one above): Neutron flux [n/(m2·s)] = Fast neutron flux · 2 = 3.50E+23 n/m2 / (Time · 31 556 925.445 s/at) · 2 = 3.50E+23 / 31 556 925.445 · 2 at·n/(m2·s) / Time = 2.22E+16 at·n/(m2·s) / Time
With a neutron flux of 1.00E+16 n/(m2·s), a nuclear reactor seems to be able to operate at full power for 2.22 years.
|
|
Echo
Full Member
Posts: 141
|
Post by Echo on Aug 18, 2020 9:03:15 GMT
SevenOfCarina (who I thank for) recently posted a bunch of links in the Discord server regarding this thread's topic. Namely: A non-exhaustive list things that came up in the conversation where: - sci-hub.st/10.1016/j.ceramint.2005.02.008 - boron carbide suffers of pressureless sintering at temperatures close to TEFRs operating temperatures, which means there is a chance for control rods made out of this material getting welded together.
- UN apparently has a C-14 problem which would make uranium carbides a better choice.
- U-233 fission chain might produce more toxic byproducts.
- US nuclear submarines' reactors currently use 93% enriched fuel.
- hafnium diboride is less effective than titanium carbide, but it might have fewer issues with swelling and hafnium stays useful for longer under irradiation.
Using the two links regarding TEFRs full-power operational lifetime, I updated the link above (that you can find in my signature too), since this method seems more accurate.
|
|
