Quoting Leonard.Erickson%51 from a message in rec.arts.sf.science >RO> You don't generaly see it in a reactor. Too much lead steel >RO> and poly in the way. You might see it in a fuel holding pond. >You can see it in "swimming pool" type reactors. They are >unpressurised, and used a lot for research and education. Reed College >(a local college) has one.
That's why I said generally. Open pool reactors are not all that common. They also tend to be relatively low output with lots of water used as shielding. In a large percentage of power reactors being in a position to see the glow equates to death.
>They are nice and safe because the coolant is also the moderator. If >they somehow got hot enough to boil away the water (unlikely, as they >aren't designed for that sort of heat output), the reaction would stop >because there wouldn't be anything to slow down the fast neutrons >enough to interact with the fuel... >Much like the design Ma Nature used in the Congo a few million years >ago. :-) >.... John Galt, Call Your Office >.
It is the design used in most light water reactors pressurized or not. Negative alpha T factor and all that. The water also acts as a reflector and heat transfer medium. Works fine, lasts a long time, won't rust, won't bust, fails safe, drains to the bilge. Unless you go prompt critical that is.
Did not mean that you *will not* see the effect. Many people seem to think you see it all the time in every design. It may *happen* during most reactor operations being in position to see it is another matter.
Jonathan Cunningham <j...@bmtech.demon.co.uk> writes:
Jl> But to accelerate to greater than light speeds (in a Newtonian Jl> universe) would be tricky this way (understatement!).
Jl> The easiest way to do this, which is cheating only slightly, is to Jl> drop *very* close the gravitating mass, and fire some tiny amount of Jl> thrust. Heinlein uses this in one of his stories - "Space Family Jl> Stone" I think, to go from the Moon to Mars, they first drop deep Jl> into Earth's gravitational well, and boost for Mars from there. Jl> Saves fuel. This is not obvious, and even knowing it, it Jl> was not immediately obvious why it worked - if anyone asks (and no one Jl> else answers) I can explain it. But it would take too long for this Jl> post.
1) The basic idea idea isn't hard. e = (1/2)*m*v^2 de = m*v*dv [ + (1/2)*(v^2)*dm which we're treating as 0] So the change in energy you get from a change in velocity depends on the original velocity. If you are in an orbit about Earth, your energy WRT the Earth is the same at all points of the orbit. The change in velocity from a given expenditure of rocket fuel is also the same. So a blast at perigee (where you are closest, and moving fastest) will give you the most change in energy. And (the kinetic energy you have) - (the potential energy you must have to escape from Earth) = (the kinetic energy that you have to travel between planets).
2) I believe the book was "The Rolling Stones." This was long before the musical group.
3) This still ain't going to get you close to c easily. For a given place in a given gravity well, it's advantage tapers off as the difference in velocity increases. The relation, exact for derivatives, is only approximate for differences in velocity. And the approximation gets worse as (delta)v/v increases.
4) What was said in (1) [with an appropriate replacemant for "perigee"] is true for any other large mass.
Erik Max Francis (m...@alcyone.darkside.com) wrote: : aberg...@minerva.cis.yale.edu (Aaron Bergman) writes:
: > I believe that under Newtonian Gravity, you can create a system of 5 or so : > massive bodies that will escape to infinty in a finite amount of time. : > This is Bad(tm). :)
If I remember (I haven't looked at the problem, just had it described to me by one of my advisors) the system looks something like this:
o o | o --> | o o
where the "o" are the bodies. On the right and left, you have two bodies in orbits about each other. If the mass of the middle body is negligible, what happens is that it shuttles back and forth between the two pairs, gaining velocity. In Newtonian physics, there is no upper limit to velocity; relativity would actually introduce some complications.
je...@math.bu.edu (Jeff Suzuki) writes: > If the mass of the middle body is > negligible, what happens is that it shuttles back and forth between > the two pairs, gaining velocity. In Newtonian physics, there is no > upper limit to velocity; relativity would actually introduce some > complications.
Hmm. Where is the infinite velocity in finite time here? If it just moves faster and faster as it cycles through, there's nothing particularly wrong with that. After all, there's nothing that prevents you from continuously accelerating in a Newtonian universe by applying constant thrust; it's when your velocity is infinite at any specific time t that causes a problem. Limits of oo are not a problem.
Erik Max Francis, &tSftDotIotE // uuwest!alcyone!max, m...@alcyone.darkside.com San Jose, CA, USA // 37 20 07 N 121 53 38 W // GIGO, Omega, Psi // the 4th R! H.3`S,3,P,3$S,#$Q,C`Q,3,P,3$S,#$Q,3`Q,3,P,C$Q,#(Q.#`-"C`- // 1love // folasade _Omnia quia sunt, lumina sunt._ // mc2? oo? Nah. // http://www.spies.com/max/
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