[Mitch]

I believe we actually DO have the technology to reuse the nuclear waste.

Pierre

Define reuse.

[constant thinker]

Wasn't it stated we have the technology, but it isn't economical. Meaning it is to expensive to be put to practical uses currently. Until we find a better cheaper way the waste will just sit there and decay.

[Mitch]

good, someone actually reads all the posts.

[billnotgatez]

This quote came up at the bottom of this tread randomly

"I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones." - Albert Einstein

I wonder what Albert would think of fission nuclear power plants. Surely his thoughts would have more intellectual weight than GWB and his cronies.

[Donaldson Tan]

I thought GWB (George W Bush) is some codename for a chemical nerve agent until i realise it's the big man himself. Haha.. GB is the codename for Sarin.

[P-man]

The point is that we have the technology to do it. It's just more expensive than just mining new uranium.

Pierre

[jdurg]

I thought GWB (George W Bush) is some codename for a chemical nerve agent until i realise it's the big man himself. Haha.. GB is the codename for Sarin.

Well, GWB does cause stupidity the more you are exposed to it, and numerous other adverse events such as heart attacks, high blood pressure, and uncontrolled retardation have been associated with expsoure to GWB.  

[Donaldson Tan]

This should be included in the MSDS sheet for the White House  

[flinguist]

Nuclear power is a good alternative to fossil fuels. The main problem right now is what to do with the spent fuel. This article has some interesting perspectives that are more realistic than what the general public has been fed by the media. http://www.nuc.berkeley.edu/thyd/ne161/ncabreza/sources.html

[constant thinker]

I see you haven't read all of the posts.

[P-man]

It's a good article anyways. I'll use it for my project on Nuclear Energy.

Pierre

[Mr. Pink]

Not all radiation is harmful. Radio waves are radiation. We use microwaves to cook our foods. As was previously stated it is because people are uneducated about the topic.

Well, that would be true, but I'm pretty sure they're referring to ionizing radiation (gamma rays, alpha particles, beta particles) and not radation on the red side of the spectrum.

[Mr. Pink]

Well, GWB does cause stupidity the more you are exposed to it, and numerous other adverse events such as heart attacks, high blood pressure, and uncontrolled retardation have been associated with expsoure to GWB.  

Not to mention a relaible amount of ignorance, and a severe tendancy to jackassism.

[Donaldson Tan]

Clean Nuclear Energy? A German Dr. Rudolf Schulten solved the problem in the 1950s. He invented the Pebble Bed Reactor (PBR). However, his research program was closed down by the German Government after Chernobyl due to political reasons.

it's called Pebble Bed because the fuel elements used are called pebbles. it uses an inert gas (helium) to act as the heat transfer agent. the helium gets heated up inside the reactor, which in turn runs a low pressure turbine to generate power. Helium has a low neutron cross-section, so it hardly gets radioactive despite exposure to the fuel elements. This allows the helium to directly power the generators instead of using heat exchangers (eg. sodium loop in fastbreeder reactors and heat exchangers in light-water reactors). This minimises the overall energy loss.

LWR has steam explosion point. This places an operational temperature limit on LWR. Helium, being a noble gas, has no explosion point. It can operate safely under high temperature. The high temperatures also let the turbine to extract mroe mechanical energy from the same amount of thermal energy. In another words, the pebble bed reactor uses less fuel per kilowatt-hour.

As the reactor gets hotter, the rate of neutron capture by U-238 increases, reducing the number of neutrons available to cause fission. This places a natural limit on the power produced by the reactor. In fact, the reactor is designed such that the cooling rate exceeds the heat generation rate. Even if the neutron moderators are removed, the idle temperature remains low. the case of a meltdown is thus very very unlikely.

Some designs of the pebble bed reactor allow it to be throttled by temperature, ie. by controlling the flow of helium, the energy generation can be increased or decreased, if the need arises. In another words, control rods are not necessary to moderate the reactor. Still then, it uses carbon rods as moderators (for maintenance sake).

PBRs are intentionally operated above the annealing temperature of graphite, so that Wigner energy is not accumulated. This solves a problem discovered in a famous accident, the Windscale fire. One of the reactors at the Windscale site in England (not a PBR) caught fire because of the release of energy stored as crystalline dislocations (Wigner energy) in the graphite. The dislocations are caused by neutron passage through the graphite. At Windscale, a program of regular annealing was put in place to release accumulated Wigner energy, but since the effect was not anticipated during the construction of the reactor, the process could not be reliably controlled and led to a fire.

 

[Donaldson Tan]

one more thing to add is the pebbled design of the fuel element allows radioactive waste to be self-contained. the fuel element (fissible material) is enclosed within a hollow pebble inside 15000 "seeds". Breaking the fuel element nto pebbles, and pebbles into seeds assures that the maximum release by a cascade of containment failures will be small. The pebble enclosement consist of layers of pyrolytic carbon and silicon carbide.

The layer of porous pyrolytic graphite right next to the fuel element absorbs the radioactive gases (mostly xenon) emitted when the heavy elements split. Most reaction products remain metals, and reoxidize. The gaseous fission products remain in the reactor to contribute their energy.

The low density layer of graphite is surrounded by a higher-density nonporous layer of pyrolytic graphite. This is another mechanical containment. The outer layer of each seed is surrounded by silicon carbide. The silicon carbide is nonporous, mechanically strong and fire-proof.

This allows the spent pebbles to be disposed as pebbles without additional chemical reprocessing. At the same time, the radioactivity level of the spent pebbles are minimised to meet criteria for safe disposal.