The high temp. reactor would be good with a thermo-electric system. NASA likes that idea to get rid of Pu-238.
Sent from my Verizon Wireless 4G LTE SmartphoneJed Rothwell <jedrothw...@gmail.com> wrote: <mix...@bigpond.com> wrote: > > Even if 300C were the limit, would that really be a problem? IIRC Jed has > mentioned that 300-350C is the usual working temperature of fission > reactors, so > it appears to be a usable temperature range. > Yup. See: http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/reactor.html QUOTE: "A typical operating pressure for such reactors is about 70 atmospheres at which pressure the water boils at about 285 deg C. This operating temperature gives a Carnot efficiency of only 42% with a practical operating efficiency of around 32%, somewhat less than the PWR." They use such low temperatures because it reduces wear and tear on the reactor vessel, the boilers and the turbines. Essentially, they trade off efficiency for longer equipment life. They can do this because uranium fuel is so cheap per megajoule. Nowadays, 32% for a combustion reactor would be scandalous. Combined cycle plants are ~50% efficient. This would be a crazy temperature for any other type of power generator. It would be wasteful. The Carnot efficiency is low. It would be even worse operating a combustion reactor at this temperature, because combustion is so much hotter. A large temperature difference between the initial reaction and the pressurized water makes a system difficult to engineer. A low temperature would be fine for a cold fusion system because the fuel is free. Carnot efficiency does not matter. However, it would mean the reactor is bulky, and it would produce a lot of waste heat, so it needs a big radiator. It would not be good for an automobile engine. It might look a little like a 19th century steam tractor -- all engine! - Jed
