Editing Isotope separation (section)

==Alternatives==
The only alternative to isotope separation is to manufacture the required isotope in its pure form. This may be done by irradiation of a suitable target, but care is needed in target selection and other factors to ensure that only the required isotope of the element of interest is produced. Isotopes of other elements are not so great a problem as they can be removed by chemical means.

This is particularly relevant in the preparation of high-grade [[plutonium-239]] for use in weapons. It is not practical to separate Pu-239 from Pu-240 or Pu-241. [[Fissile]] Pu-239 is produced following neutron capture by uranium-238, but further neutron capture will produce [[Pu-240]] which is less fissile and worse, is a fairly strong neutron emitter, and [[Pu-241]] which decays to [[Am-241]], a strong alpha emitter that poses self-heating and radiotoxicity problems. Therefore, the uranium targets used to produce military plutonium must be irradiated for only a short time, to minimise the production of these unwanted isotopes. Conversely, blending plutonium with Pu-240 renders it less suitable for nuclear weapons.

If the desired goal is not an atom bomb but running a nuclear power plant, the alternative to enrichment of uranium for use in a [[light-water reactor]] is the use of a [[neutron moderator]] with a lower neutron absorption cross section than [[protium (isotope)|protium]]. Options include [[heavy water]] as used in [[CANDU]] type reactors or [[graphite moderated reactor|graphite]] as used in [[magnox]] or [[RBMK]] reactors. Obtaining heavy water however also requires isotope separation, in this case of hydrogen isotopes, which is easier due to the bigger variation in atomic weight. Both magnox and RBMK reactors had undesirable properties when run with [[natural uranium]], which ultimately led to the replacement of this fuel with low enriched uranium, negating the advantage of foregoing enrichment. [[Pressurized heavy-water reactor]]s such as the CANDU are still in active use and [[nuclear power in India|India]] which has limited domestic uranium resources and been under a partial nuclear embargo ever since [[Operation Smiling Buddha|it became an atom bomb state]] in particular relies on heavy water moderated reactors for its nuclear power. A big downside of heavy water reactors is the enormous upfront cost of the heavy water.