tag:blogger.com,1999:blog-8150340806781551727.post2009034428701231567..comments2024-03-29T07:43:40.648+00:00Comments on ToughSF: The Big List of Propulsion Failures IIIMatter Beamhttp://www.blogger.com/profile/16721504049578296529noreply@blogger.comBlogger15125tag:blogger.com,1999:blog-8150340806781551727.post-14127791595185225922019-04-22T22:48:41.063+01:002019-04-22T22:48:41.063+01:00The closed cycle gas core reactor must reduce its ...The closed cycle gas core reactor must reduce its temperature enough that the quartz tubes holding the uranium gas not melt. Reduced temperature means reduce exhaust velocity. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-84144601254836433032019-04-22T20:59:41.936+01:002019-04-22T20:59:41.936+01:00I ment uv rays. Sry for inconvenience I ment uv rays. Sry for inconvenience The Librarianhttps://www.blogger.com/profile/01646848861149556379noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-8071358522513792032019-04-22T20:25:47.070+01:002019-04-22T20:25:47.070+01:00If closed cycle and open cycle both heats the prop...If closed cycle and open cycle both heats the propellant primarily by Xrays why does open cycle performs better than closed one. <br /><br />The Librarianhttps://www.blogger.com/profile/01646848861149556379noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-65059758528590566182019-03-13T09:25:18.144+00:002019-03-13T09:25:18.144+00:00Can the target material be the fissile material it...Can the target material be the fissile material itself? The Librarianhttps://www.blogger.com/profile/01646848861149556379noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-24644514671707746252019-03-13T02:09:36.699+00:002019-03-13T02:09:36.699+00:00No no, let me be clear: Thorium has no place on a ...No no, let me be clear: Thorium has no place on a Nuclear Salt Water Rocket. You use Uranium instead. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-87646021147837775892019-03-12T16:36:25.399+00:002019-03-12T16:36:25.399+00:00My bad, I hadn't realized that Th232 could be ...My bad, I hadn't realized that Th232 could be fissioned directly with fast neutrons. I thought you had to have it absorb a neutron to turn into an unstable isotope.Ethhttps://www.blogger.com/profile/13196257853962186227noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-68114557272848637282019-03-12T12:40:29.924+00:002019-03-12T12:40:29.924+00:00The accelerator can shoot protons into a target ma...The accelerator can shoot protons into a target material and knock off neutrons from its atoms, creating a neutron source exactly where you want it. That way, we have no need for heavy neutron reflectors. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-23766020263528109972019-03-12T12:39:41.078+00:002019-03-12T12:39:41.078+00:00Eth: Unless there are strong economic reasons for ...Eth: Unless there are strong economic reasons for it, it is unlikely that a rocket engine like an NSWR will be creating its own fuel. The extra equipment is basically a second nuclear reactor. It is best to use uranium from fuel tanks directly. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-37407287178504754512019-03-10T10:11:44.694+00:002019-03-10T10:11:44.694+00:00I dont know what fission has to do with half -life...I dont know what fission has to do with half -life I think if you give enough neutron to thorium it should go critical .<br /><br />BTW can we use neutron reflectors to focus the neutrons on a fission fusion pellet and drive a antimatter catalysed fission-fusion without antimatter. The Librarianhttps://www.blogger.com/profile/01646848861149556379noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-5791587652157124032019-03-10T01:01:54.948+00:002019-03-10T01:01:54.948+00:00Wouldn't thorium be too long to react? Adding ...Wouldn't thorium be too long to react? Adding neutrons to stable thorium isotopes seem to only produce isotopes that have, a long half-life. The best seems to be Th232 + n -> Th233, which has a half-life of 22 min. That seems too long to work in a NSWR.<br />Or neutrons would have a different effect?Ethhttps://www.blogger.com/profile/13196257853962186227noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-14047047009352310822019-03-09T23:38:28.111+00:002019-03-09T23:38:28.111+00:00That's a neat idea. Thorium cannot be used as ...That's a neat idea. Thorium cannot be used as fuel directly, and you cannot turn it into Uranium 233 inside a NSWR, but the use of an accelerator to drive criticality in a stream of fissile salts in water can have a lot of built in safety.<br /><br />Most importantly, if you switch off the accelerator, there is no more risk of the fuel collecting in dangerous densities and causing an explosion. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-9378230378404003602019-03-09T20:06:34.727+00:002019-03-09T20:06:34.727+00:00Acclerator driven fission should make NSWR a possi...Acclerator driven fission should make NSWR a possibility. Thorium with whatever remass will be injected in the reaction chamber the acclerator system will provide nutrons for the thorium to fission. <br /><br />Thorium is safe (no neutron absorbing tubes needed) and you will use a very small amount of it at the same time. The Librarianhttps://www.blogger.com/profile/01646848861149556379noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-58643362465532974732018-05-05T05:04:18.006+01:002018-05-05T05:04:18.006+01:00I notice it looks like the Orion spacecraft is lau...I notice it looks like the Orion spacecraft is launching from roughly northern Ontario or Quebec. The Gulf of St Lawrence is visible behind the spacecraft to the south.<br />The politics of launching from outside the US might cause some difficulty, but there might be an actual good reason to launch from so far from the equatorJim Baerghttps://www.blogger.com/profile/03182949391365921637noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-37739448806924826472018-01-30T22:17:56.966+00:002018-01-30T22:17:56.966+00:00Welcome to the blog, Zuthal Soraniz!
Agreed, some ...Welcome to the blog, Zuthal Soraniz!<br />Agreed, some of the issues raised with the Orion pulse drive are not very significant, but that is only the case with certain designs and for a single launch.<br /><br />A larger Orion would create bigger EMP pulses, but the issue is that very satellite in orbit today would have to hardened against these blasts, which is a cost of billions. Many technologies which cannot be protected, such as thin-film solar panels and sensitive radio instruments, won't survive.<br /><br />As for contamination: one launch would be okay... but several launches will release tons of uranium into the atmosphere per year in the worst form possible. People will object!Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-74695990056652993682018-01-30T19:35:49.558+00:002018-01-30T19:35:49.558+00:00"The pulse units also produce fallout. In an ..."The pulse units also produce fallout. In an atmosphere, this would drift on air currents and affect places far from the launch site. In the upper atmosphere, it would produce EMP that would knock out electronics. In space, it is mostly harmless, but a spacecraft performing a retro-burn will have to fly through a cloud of radioactive debris. The outer surfaces would become contaminated and might prevent spacewalks."<br /><br />I doubt any of those would be serious issues with Orion drive spaceships. Orion propulsion units are very small - a 4000 t wet mass Orion design from the late 50s uses propulsion units with a yield of 140 tons TNT, and 300 of those would be fired to get into LEO - presumably one every few seconds, to match the few minutes to LEO insertion that conventional chemical rockets have.<br /><br />This on its own already solves the EMP issue - high-atmosphere EMP only occurs with relatively high-yield bombs, as far as I know, and I don't think the yields of subsequent bombs would add regarding the generation of EMP, especially as when in the upper atmosphere, the spacecraft will already be moving at several kilometers per second.<br /><br />The fallout problem is for one abated by the low amount of nuclear material due to the low total yield (at an assumed 10% fission efficiency) would require the fissioning of about 22.3 kg of Pu-239 - only a little less than four times the amount of Pu-239 in the Fat Man atomic bomb used on Nagasaki. Most of these detonations will be airbursts, i.e. ones in which no significant amounts of ground materials are sucked up into the fireball. Thus, the only fallout is in the form of the condensed fission products, which, as a very fine dust, will take quite a while and disperse widely before raining out.<br /><br />As for nuclear contamination of the spacecraft, I do not think that will be a problem at all. The fission products will leave, a large part of them directed rearwards with the propellant jet, at the exhaust velocity of the Orion drive, which is measured in tens of kilometers per second. There is thus not a serious concern of fission products condensing onto the spacecraft.<br /><br />One possible Orion drive concern you didn't directly mention is that, if the pulse units prove to be insufficiently absorbent to neutrons, the pusher plate may suffer from neutron embrittlement and activation, after all about 20% of the weapon's yield is released in the form of neutron radiation - though of course this could be counteracted by a sufficient choice of materials.Zuthalhttps://www.blogger.com/profile/10296446250895508593noreply@blogger.com