Re: Nuclear Power Plants
In reply to #5437 Re: Nuclear Power Plants by Seth 'the Lesser
> First, 5% enrichment is good for commercial electric generating stations > and the efficiency of 36% is good. > > However, for any sort of space reactor propulsion, enrichment better go > up to near 60% or even higher depending on the fuel. For the most part > the extra U-238 is just wasted weight (ok, maybe a little conversion to > plutonium but not much (relatively speaking.)) I haven't figured out this figures by myself. (I'm only a CS student.) The table gets a lot more complicated when we're including enrichment rate and burndown rate. But you're right in that radioactives can be enriched to a much higher degree. But I don't know about the risks in enriching radioactives to a much higher degree. How safe is your reactor then ? Handling becomes more dangerous with a higher enrichment rate as you get to the critical mass more quickly. "Burning Through" your reactor is also easier. Besides, the power plants should be used for civilian and military vessels alike. This might not be very realistic. And then there's the question of cost efficiency. How expensive would be fuel enriched to 10%, 25%, 50%, or even 75% or 90% ? Lastly, highly enriched radioactives (90% or more enrichment) make bomb grade material. As Imperial law make clear that nuclear bombs are for nobody but the imperial military, I don't think that imperial authorities allow highly enriched nuclear material to be carried aroound like gasoline. Perhaps I can include a variety of new fuel types. Like Radioactives with 5%, 10%, 25%, 50% and 75% enrichment. Enriching radioactives is a very complicated task I've heard and gets more complicated the higher the enrichment, so the price would increase proportional to the square of the enrichment rate while efficiency would only increase linearly as less fuel is needed with higher enrichment rate. > Also, efficiency for the space reactors is a lot higher than 36% > if you figure just for propulsion. If you want to make some sort of > black box energy conversion for electrical energy production, I can > see something anywhere from 45 to 60 percent efficient within the next > few hundred years. We're already looking at 40 percent and > up in some high tech applications today. Well, my first attempt of the table at home had a conversion efficiency of 60% for fusion plants but assumed a much lower rate of fusing atoms. The efficiency was around 16% then. (In fact, I was simply increasing the efficiency of MT fusion plants by 1000.) > Also, this black box conversion from thermal energy to electrical energy > would be the same regardless of the power source, fission or fusion or > antimatter (for a given tech level.) > The "efficiency" better be defined before putting it in table form. I think > most people are used to efficiency meaning "energy out/energy available" > (to be simplistic.) The efficiency is in the table, because I figured in the scale efficiency from the rules. (I don't know if they're reasonable). Some of the low tech fusion plants have minimum size that are above the size for large scale plants. (The TL 9 early fusion plant has a minimum size of 20 Kl which is above the 11 Kl figure that triples fusion plant output.) On the other hand, not all plants can be build under the lowest scale efficiency (which cuts down output by 75%). My major concern is about the balance in the design system when this table is used. Nuclear powered starships can use their maneuver drive, weapons, etc. now for years and still have much less space devoted to fuel storage than before. I haven't done designs with it yet, but it would influence design in many ways. Commercial ships can have much more cargo space, military ships can have much more weapons with a higher energy usage and get much more expensive this way... One way out of this would be to drop the reactionless drives and keep only antigrav drives and have fusion rockets for deep space maneuvering. The thrust of anti grav would not drop by 50% after 10 planetary diameters but I would use something like 100 % for up to 10 diameters 50 % beyond 10 diameters 25 % beyond 20 diameters 11 % beyond 30 diameters 6 % beyond 40 diameters 4 % beyonf 50 diameters and so on down to 1 % or no thrust beyond 100 diameters This way, spaceships are forced to use fusion rockets when they are going to another planet but anti grav would be enough to reach geostationary orbit. The fuel for the fusion rockets must be then included on top of the fuel for the power plant(s). This could perhaps even thing out a bit. There was a table about fusion rockets on the list a year ago or so. The consumpition rate was around 1 KL per hour per 200 thrust if I remember correctly. The table was not complete but perhaps the one who posted it has worked on it since then ? The nice side effect would be the elemination of the reactionless thrusters and their physical impossiblities. (High Tech)Deep Space going craft would then have three drive systems. Antigrav for use inside a planets atmosphere. (I don't like the idea of using fusion rockets inside an atmosphere.) Fusion rockets outside the 10 diameter limit. And jump drive for interstellar distances. Klaus - -- / Klaus Moeller, Leiteweg 2, 2940 Wilhelmshaven, West - Germany \ < [email removed] [email removed] > \ security is an exercise in applied paranoia /