Re: But on further speculation...
Posted by Southern Man on Jun 06, 2002 at 08:53
(209.102.129.113)Re: But on further regurgitation... (Bobba)
“..The issue is whether or not we can design a self-contained zero maintenance reactor of a suitable small size and weight. Clearly we can as it’s already been done. It may not be of the pebble-bed variety but it exists. The Rapid-L was specifically (initially) designed for this very purpose….”
What does it weigh? Was my estimate in error by more than a couple of orders of magnitude?
“Neutron radiation does not necessarily a contaminated environment make – depending of course on your definition of contaminated. You originally asserted, as hyperbole i think, that it would produce radioactive steam.”
Not hyperbole – real concern. You plan to make steam from raw ground water in a well. That water contains more than just hydrogen and oxygen. It would contain large quantities of every element and molecule that dissolves in water. The steam that is used in commercial steam turbines must be very clean to prevent damaging the turbine blades. Your steam is going to be anything but clean. And many of the elements in the crud make radioactive isotopes when exposed to fast (or slow) neutrons.
“The original question regarded where the energy would come from to make the fuel. The best and possible only answer to that is nuclear. “
Well given the alternative of shipping solar panels to Mars, I would certainly have to grant your point.
“I believe we should plan on at least 10,000Kg of people/food/air/water/shielding to lift.
Does that include the weight of the craft as well? “
Yes.
“Presumable, there’d be a “mother ship” with the requisite food, water and shielding already in orbit.”
Granted. So we need to accelerate the mother ship with 5e10 joules which is also 5e10 watt-seconds. Going back a couple of messages you proposed a 50KW net conversion to fuel from what I believe is a very heavy reactor. So it takes 12 days to produce the net energy that will be used to accelerate the mother ship from Mars orbit to Earth. (Don’t you just hate it when you finally get out the calculator and find the numbers aren’t exactly what you expected ;) ) What is the energy release efficiency of hydrogen fuel? How much does that much fuel weigh? Should be a simple calculation from energy release of hydrogen-oxygen combustion and momentum transfer. Don’t have time this morning. Maybe tomorrow.