Joffan - 11/12/2006 12:01 PMAs I've mentioned elsewhere, the only way a never-powered-up space reactor can kill anyone is to fall on them. Radiation is way below harmful limiits (and those limits exist and are the basis of routine medical procedures). Even atmospheric burn-up of a used reactor in the atmosphere would almost certainly not cause any deaths, especially if it was shut down a few months beforehand. Using burnup as a routine method of reactor disposal might begin to cause problems.
khallow - 11/12/2006 1:11 PMQuoteJoffan - 11/12/2006 10:01 AMAs I've mentioned elsewhere, the only way a never-powered-up space reactor can kill anyone is to fall on them. Radiation is way below harmful limiits (and those limits exist and are the basis of routine medical procedures). Even atmospheric burn-up of a used reactor would almost certainly not cause any deaths, especially if it was shut down a few months beforehand. Using burnup in the atmosphere as a routine method of reactor disposal might begin to cause problems.Depends on whether they survive to landfall or not. Dropping one into a few thousand feet of ocean probably isn't a big deal. But having it burn up in atmosphere probably isn't a great idea. At the very least, it'll be detectable and hence, provide some ammunition for the anti-nuke side.
Joffan - 11/12/2006 10:01 AMAs I've mentioned elsewhere, the only way a never-powered-up space reactor can kill anyone is to fall on them. Radiation is way below harmful limiits (and those limits exist and are the basis of routine medical procedures). Even atmospheric burn-up of a used reactor would almost certainly not cause any deaths, especially if it was shut down a few months beforehand. Using burnup in the atmosphere as a routine method of reactor disposal might begin to cause problems.
Joffan - 11/12/2006 6:59 PMReal issues, absolutely, although since no-one had used the terms "envirowhackos" or "dirty hippies" on this thread, your post meiza is in fact a strawman itself.
vanilla - 9/12/2006 3:00 PMQuotekraisee - 9/12/2006 2:04 PMOkay, from the point of view of the DIRECT LV, the best value configuration is actually the basic 70mT launcher. What major physical parts of these example NEP & NTP systems could NOT be launched as modules in that mass category?None. The NEP vehicle breaks down into nice chunks. The mass breakdown here indicates that three DIRECT launches would put the whole thing up there. Throw in another one for the Mars lander and another one for the CEV taxi to L2 and you've got a five-launch Mars mission, where the launches can be spaced over about a year. (a few months to assemble it, 6-9 months to spiral unmanned to EML2, and then the crew launch).Quotekraisee - 9/12/2006 2:04 PMSecond - borrowing an idea I saw on another thread (sorry, I don't recall who posted it): DIRECT could probably be used to launch the dangerous fuel separately - in a modified CEV.The nuclear fuel isn't dangerous until the reactor has run at power. Before then you can hold it in your hand, unshielded.
kraisee - 9/12/2006 2:04 PMOkay, from the point of view of the DIRECT LV, the best value configuration is actually the basic 70mT launcher. What major physical parts of these example NEP & NTP systems could NOT be launched as modules in that mass category?
kraisee - 9/12/2006 2:04 PMSecond - borrowing an idea I saw on another thread (sorry, I don't recall who posted it): DIRECT could probably be used to launch the dangerous fuel separately - in a modified CEV.
publiusr - 19/12/2006 5:54 PMI must say, that looks do-able--a reasonable compromise? Ares V is better for NTRs and hydrogen--and carrying oxygen for high thrust 'afterburners' like what Stan wants...
vanilla - 19/12/2006 4:12 PMThe system-level performance of LOX-augmented NTRs is easily surpassed by chemical engines. By system-level, I mean accounting for development, boiloff, and astrodynamic issues that will arise with the use of NTRs.
khallow - 20/12/2006 2:40 PMI think I understand what you mean by development and boiloff issues. But what do you mean by "astrodynamic" issues? Low thrust for the weight of the engine? Looking around, NTR's seems to have the same problem that any low thrust engine does when move cargo or people out of LEO, namely, it passes through the Van Allen belts multiple times.
Scotty - 23/12/2006 1:04 PMDo a word search on "timberwind".Read everything you find, then we can talk about a real nuclear thermal propulsion system.The Moon is the practical limit for manned flights using only chemical propulsion.Mars can be done, but it will not be easy, and the time in transit between Earth and Mars will be long.How would you like being stuck on a Grayhound Bus for 6 to 9 months, both ways?NTP could cut that transit time to 6 weeks or less.Again read up on the subject first, then we can disscuss it.
publiusr - 22/12/2006 1:43 PMAres V is better for NTRs, and I wish Stan would come to the forum--because I am sure that NTRs do have strengths. Direct is perfect for NEP and would have made JIMO do-able.
Scotty - 23/12/2006 9:15 PMVanilla - That is interesting, the bit about the pellets melting.I worked on the LH2 feed systems on Timberwind, and I never heard of any such problem.