Nuclear Reactor - Using Gas Instead of Water

You might perhaps start at the MAGNOX gas-cooled reactor and the AGR advanced gas- cooled reactor?

Im not saying cool the reactor with gas, but use gas to transfer heat. like the water goes through the rods and into a tank that produces steam from pipes containing the Uranium heated water, take out that super heated water and put in a kind of gas.

Any idea of the desired temperatures?

"Im not saying cool the reactor with gas, but use gas to transfer heat."

When you transfer heat, you cool the heat source and you heat up the heat sink, so you are talking about using gas to cool the reactor core. This is perfectly feasible and, though less common than using water (which can also serve as the neutron moderator to maintain criticality) is practiced in quite a few reactors. Look up "pebble bed reactor" and "gas-cooled reactor."

For space applications there were even plans to build reactors in which the core itself was gaseous - typically uranium hexafluoride - and the core material itself would be the primary coolant. Needless to say, that cooling loop would have to be far away from anything living...

Actually, the steam generated by the nuclear fission is dry, meaning very little to no moisture in it, and can more easily be explained as a superheated gas that is easily and cheaply reclaimed and re-used. Use of any other gas would be more costly to contain or reclaim, and any leaks in the piping or equipment at things such as bearing housings, would be a constant demand for more of this 'gas'. So which would be more cost effective?

You should ask your dad, he was a "Nuke" in the Navy and knows the engineering of these plants inside and out.

Regards

Why....?

If there is high enough temperature to produce plasma, wouldn't it melt (or otherwise degrade) whatever material is containing the gas?

"Steam" is actually a gas. If I remember rightly from my Navy days, we used super-heated steam at 1200 psi (I believe the operating temperature was in the 900º F range, but I will let our steam gurus confirm this with their steam tables). The vessel I was on was conventional fuel- I believe the nuclear powered vessels were using similar parameters. The superheated steam was used to drive the turbines directly, both for powering the ship and for generating electricity. You do not need a plasma to do this. Water vapor happens to have fluid characteristics that make it very efficient for converting thermal energy into mechanical energy. Note that you need a vacuum where the steam exits the turbine so that it doesn't get stuck inside the turbine, condense on the turbine blades and destroy said blades.

I don't think you want to make plasma for driving a turbine, because I don't think you could build a turbine that could handle this...

cwarner,

Your numbers are right, but your concept is a little off. The steam side of a surface nuke plant is nearly identical to a conventional system, but the reactor cooling medium (primary coolant in navy lingo) is physically separated from the steam (secondary) loop. Since turbines, deaerators, feedwater heaters, condensers, etc. all leak, it would not be a good idea to put radioactive steam through them. The steam generator is a heat exchanger which effectively replaces the boiler of a conventional system. The hot pressurized reactor water is on one side, and clean secondary water/steam is on the other side.

I agree with you about plasma through a turbine. I think the only way to contain plasma is with magnetics. If you can control magnetics that well, why bother with something as primitive as a turbine?

It's being tried as we speak.

http://en.wikipedia.org/wiki/Very_high_temperature_reactor

The difficulty is not in the concept, but in finding materials that can withstand the extremely high temperatures required to achieve reasonable efficiencies with a gaseous heat transfer medium (same as "coolant"). Plasma temperatures are higher than anything used in any operational gas-cooled reactor, so containment is even a greater challenge.

Experiments with tokamaks, which utilize the magnetic properties of plasma to keep it away from the container walls of the reactor, have been ongoing for decades. So far, more knowledge but no power production.

The purpose of using water in the first place is to get the benefits of the properties of water flashing to steam. (See Mollier chart or steam tables)When water goes from a liquid to a gas, it increases in volume tremendously (Approximately 1600 times the volume). If you start with a gas, it will never expand proportionately to give you the work required. Given this fact, your generator will fail to be very much of a generator at all. That is not to mention a lot of other problems related to cooling which also come along with the use of water. My thought is that the system will have catastrophic meltdown on the first use.

There was a limited research on this topic in the 70ies and a resulting booklet (in German language): Der Gasphasen-Reaktor.

This concept was not followed as energy density will be low and cooling will be difficult.

RHABE

fyi.

Already done in the past. French technology, but not to be implemented in new ones.

http://en.wikipedia.org/wiki/Vandell%C3%B2s_Nuclear_Power_Plant

Water works so well and is readily and cheaply available. So why change?

Steam works so well in turning the turbines and be recycled. Why go to something different?

look at the pebble bed reactors that are currently being designed and built (but not in the US, FU very much Greenpiss!). they use Helium.

Another point is that water not only works well for a heat transfer medium (which is why it is used in the coolant loop of every kind of IC engine that has a coolant loop. and as the most aggressive quenchant available for heat treating steel.), but it is also the moderator for a PWR type reactor. without water, the chain reaction STOPS because the neutrons are moving too fast. you've got to slow them down enough to maintain the chain reaction.

Yes, most (all?) current reactors use thermal (slow) neutrons. But I have heard that there is a reactor design that uses fast (unmoderated) neutrons, and that it eliminates many of the problems with the current reactors. That is, it can burn as fuel the "waste" from current reactors, the waste from it has a much shorter half-life, and several other benefits. I need to learn more about this, 'cause it sounds so promising. Any guidance?

AGR and Magnox are BRITISH technology and work very well. In fact the last AGR reactor to be built came in on budget and time.

Since then the UK has built PWR reactors at enormous cost over run (mainly to be fair due to changes to the legal framework and the need for public enquiry). My understanding was that PWR is a development of submarine nuclear reactors which obviously need to be smaller and lighter than reactors on land for power generation.

Gas cooling of the pile has the advantage that you cant get a gas bubble (like at Three Mile Island). The gas is heated in the coil and then raises steam for power generation in secondary coolers. Although this has another efficiency problem it does mean that the water / steam used in the power generation cycle is not highly radioactive so its easier to work with the steam turbines.

Like others I am not sure where the plasma usage goes.