i attached a picture to illustrate the nulcear fuel cycle.
p-man: fissible material refers to material that are susceptible to nuclear fission, eg. plutonium-239.
constant-thinker: arguing that nuclear power is beneficial or not is irrelevant to its secondary uses, such as CAT scan. You can't actually transport radiation from a nuclear reactor directly for CAT scans. Neither are the radioisotopes used in generating X-rays for CAT scans are obtained from nuclear reactors. Reprocessing the spent nuclear fuel (SNF) is a very expensive and thus ineconomic process to obtain radioisotopes for CAT scans. microwaves are generated using electronic devices, not through a nuclear source.
nuclear power refers to generation of electricity using atomic energy. typically, there are few types of nuclear reactors available in the market: LWR (light water reactor, normally american), HWR (heavy water reactor, normally canadian), MAGNOX (uses CO2 as the heat transport agent, british), and the french type (that employs liquid metal, normally Na or Li, as the heat transport agent)
Jdsurg is right to point out we should examine the entire fuel cycle to determine the "green-ness" that nuclear power offers. on one hand, uranium mining generates alot of CO2 (according to Jdsurg); on the hand, nuclear reactors can operate for many years without refueling. Comparing the CO2 generated by uranium mining per MW of electrical energy generated in nuclear plants, the nuclear plant still beats conventional fossil fuel power plants. In fact, the amount of CO2 generated by fossil fuel plants during the same operation span of the nuclear plant exceeds the amount of CO2 generated in mining sufficient uranium to run the nuclear plant for that particular operational span.
Moreover, modern nuclear reactors are much more efficient than fossil fuel power plants, espeically the french and british type of nuclear reactors. Gas and liquid metal exhibit higher heat transfer coefficient, and they can operate at much higher temperature (unlike the pressurised water reactors). This means more energetic neutrons from fission are allowed to heat up the the heat transport agent, instead of being absorbed (and thus wasted) by the control rods.
it all points out that nuclear plants are not only more green, but also more efficient. however, from an engineering point of view, the operational cost must be taken in account to evaluate the economic value of the nuclear plant, unless fossil fuel is fast becoming scarce, then nuclear plants are the next power generators we can turn to, to meet mankind's demand for energy. harnessing nuclear power is inevitable.
The rising oil price in view of much-talk-about petroleum shortage will make fossil fuel plants less and less economic to run as time goes by. increased operational cost is inevitable, and this is where nuclear plants prove their capability over fossil fuel plants.
SNF reprocessing is an area that still needs alot of research breakthrough in order to convince the cynics of their short-sightedness. The current procedure for handing SNF is to let it stand for few weeks, so that all the short-life radioactive nuclei will decay, leaving the less radioactive elements present in the SNF. (if electromagnetic radiation energy can be captured and stored as a standing wave, we could extract so much more energy from the fresh SNF)