Nuclear fission plasma reactor?

aquitaine

Is it possible to use fisssion to create plasmas, then use the plasma to generate electricity instead of suing steam to for elctricity? Just a thought.

Astronuc

It is possible to create a 'fission' plasma but that would be undesirable.

Perhaps one is referring to a plasma in which isotopes of hydrogen or other suitable element would under go fusion. The plasma can then be passed through a magnetic field and the charges (nuclei and electrons) separated and recombined in a process known a direct conversion. The current produced by the electrons in direct conversion is used to provide energy to a load.

theCandyman

Wouldn't the plasma lose most of its heat to the fission material?

Astronuc

I believe 'fission plasma' was a misnomer. Practical fission systems are usually based on solid fuel, where the enriched uranium is in a ceramic or metalic form, or liquid, e.g., molten salt reactor.

A gaseous fission reactor would require highly enriched fuel and would likely be driven by a driver core because of the inherent neutron reactor physics.

The energy loss from a plasma increases with atomic number, Z. Losses from brehmsstrahlung, ionization and recombination would be high to the point of rendering the system unsustainable.

aquitaine

I wasn't necessarily considering plasma for fusion, just plasma to generate electrical current. Obviously plasma needs some kind of heat source or it just fizzles out, and since we _still_ haven't gotten fusion down yet I was wondering if traditional fission could be used as sort of a plasma generator, so it wouldn't use fusion.

Yeah, although it always struck me as somewhat old fashioned. :p

Astronuc

Old fashioned works.

A plasma is 'very hot' which also means relatively low density. For a fission process, low density means highly enriched and/or large volume in order to maintain criticality. High temperatures (in conjunction with density) can also mean high pressures, and the combination of high pressure and large volume would mean a large containment system. Otherwise, one has a highly enriched fuel stream, which becomes the plasma and which is driven by a more conventional core.

The other key factor is the control or containment of radioactive fission products, which is a primary reason that conventional fission systems use 'solid' fuel. In fact, in LWRs, the utility is required by Federal regulation to ensure that the fuel does not melt under normal or antipated operational occurrences.

aquitaine

True but this is the 21st century, time to make stuff "cool". Another thought, assuming we actually could make this work, and have electricity being generated by plasma instead of stream through a turbine, how might the overall power output of the two systems be compared? Would the plasma system be more efficient than the steam system?

So it is theoretically possible, but we don't know how to make it safe?

Astronuc

Stuff doesn't need to be 'cool', just functional, economical and safe.

Putting a plasma through a turbine (turbomachinery) would be rather impractical. MHD generation would be the preferred conversion system.

Fission products must stay put in order to be effectively isolated from the environment.

aquitaine

Which isn't what I meant.

This is more like what I was referring to. Where can I find more info about?

aquitaine

Something just occured to me. If we were to use nuclear power in space, wouldn't this kind of a system be more useful than conventional solid core designs given the difficulty with dissipating large amounts of heat in space?