2008:30 A model for fission gas release from mixed oxide nuclear fuel

Nuclear fuel containing mixed oxide (MOX) pellets have been used since the 1960's. MOX fuel pellets are made from a mixture of uranium and plutonium oxide. MOX allows the large quantities of fissile isotopes produced and remaining in spent nuclear fuel from light water reactors to be recycled. Producing MOX fuel can be seen as a method to more efficiently use the natural uranium since most isotopes in natural uranium are the Pu-producing U-238. In fact, programs for using MOX were developed in the 1970's to meet the feared or anticipated scarce supply of uranium at moderate prices. Although uranium prices have remained moderate, MOX is used in nuclear power reactors in for example Belgium, Germany, France and Switzerland, while other countries like Japan have programs for introducing MOX as part of their nuclear fuel cycle.

SKI has recently identified a need to gain knowledge about the in-reactor performance of mixed oxide nuclear fuel. Since issues regarding the properties, manufacturing and transportation of MOX fuel occasionally attract the attention of media it may be of public interest to gain knowledge of its utilisation as well. Small quantities of fuel rods have been irradiated in Swedish reactors, and there exist plans for using limited quantities of MOX fuel in Swedish power plants in the near future.