Nuclear energy

From RationalWiki

Nuclear energy is electrical energy derived from reactions involving atomic nuclei. It takes several forms:

• Fission -- the use of neutron flux to smash atoms of isotopes of uranium, plutonium, or sometimes thorium. The reactor is essentially a tremendously powerful heating element for a complex steam-generation system. While not common in nature, a series of very old natural reactors found in a uranium mine in Oklo, Gabon proved to offer valuable insights into the age of the Earth as well as potential nuclear waste disposal methods.
• Fusion -- still not practical for power generation on Earth scales, nuclear fusion (the power source of the stars) takes hydrogen nuclei (in the stars, just protons, but on earth, usually ²H (deuterium) or ³H tritium) and compresses them into helium nuclei. Active research has gone on for decades to reach the "break-even" point, that is, the point at which the reactor generates enough power to maintain the reaction on its own. Nuclear fusion bombs are somewhat easier, and rather nastier.
• Radioisotope -- used in space probes and other long-lived, zero maintenance devices, radioisotope energy is derived from the heat given off during the decay of natural or artificial radioactive elements. The best-known form is the plutonium Radioisotope Thermal Generator, heavily used in deep-space probes.^[1]

Nuclear power (most especially fission) has been the subject of much controversy over the nearly 70 years that it has been worked on; while the process of using nuclear-fired electricity generators is fairly clean, the technology of fission reactors is sometimes prone to problems^[2], and waste disposal is a tremendous problem demanding answers that will allow the waste to stay stored for a time substantially longer than all of current recorded history.

Spent fuel can be reprocessed to extract fissionable material, but this raises security and proliferation concerns; much reprocessed uranium fuel is plutonium-239 created during the fission process, which is far more readily useful for building small nuclear weapons than uranium. Even with fuel reprocessing, however, the problem of disposal of support materials (contaminated gear and the like) remains.

In the United States, the construction of new nuclear plants ended with the opening of Seabrook-1 in New Hampshire in the mid-80s, after the Three Mile Island accident wiped out half the power generation capacity of a Pennsylvania plant in 1979 and risked contaminating a large part of the state. In the 2000s, public opinion seems (from unscientific observation) to be cautiously swinging back in favor of nuclear power, though no new plant licenses have been issued since Seabrook. (Further acceptance is probably contingent on coming up with a good solution to the disposal and reliability problems.) Other countries are sometimes less reticent about nuclear power; while much of Europe is a bit iffy about nuclear power, for example, France gets more than three quarters of its electricity from nuclear generation.

[edit] Footnotes

1. ↑ The use of plutonium RTGs in the Cassini spacecraft sent to probe Saturn was a significant news item, with considerable protest due to fear of the spacecraft either exploding on takeoff or crashing into the Earth on its flyby to Saturn and contaminating a large area with plutonium dust. The ESA scientists responsible for Cassini downplayed the risk due to the heavy construction of the RTGs, and the Cassini craft flew by Earth on its way to Saturn without incident.
2. ↑ Windscale, Three Mile Island, Chernobyl, and many rather less severe incidents that don't get a lot of play.