A friend of mine who was trained as a physicist used to joke about a
future in which each of us would carry handheld fusion reactors that plug
in anywhere to provide copious amounts clean energy for our homes,
automobiles, offices and factories.
The reality of fusion power, however, is one of huge scale and vast
obstacles according to Daniel
Jassby, a former research physicist at the Princeton Plasma Physics
Lab. (All of what follows assumes that the remaining obstacles to producing net energy from fusion will be overcome. Addressing that issue would require a seperate and lengthy essay.)
Perhaps the most unexpected revelation Jassby offers runs entirely
contrary to the clean image that fusion energy has in the public mind. It
turns out that the most feasible designs for fusion reactors will generate
large amounts of radioactivity and radioactive waste.
As Jassby explains, inside the Sun, which is powered by fusion, normal
hydrogen atoms, each consisting of nuclei containing one proton, are fused
together and produce helium plus energy. Here on planet Earth, fusion
reactors "burn neutron-rich isotopes [that] have byproducts that are
anything but harmless: Energetic neutron streams comprise 80 percent of
the fusion energy output of deuterium-tritium reactions and 35 percent of
deuterium-deuterium reactions." (Deuterium is a hydrogen atom consisting
of one proton and one electron in its nucleus. Tritium is a radioactive
form of hydrogen having one proton and two neutrons.)
Jassby details the consequences:
[T]hese neutron streams lead directly to four regrettable problems with
nuclear energy [both fission and fusion]: radiation damage to
structures; radioactive waste; the need for biological shielding; and
the potential for the production of weapons-grade plutonium 239—thus
adding to the threat of nuclear weapons proliferation, not lessening it,
as fusion proponents would have it.