<P> Space disposal is attractive because it removes nuclear waste from the planet . It has significant disadvantages, such as the potential for catastrophic failure of a launch vehicle, which could spread radioactive material into the atmosphere and around the world . A high number of launches would be required because no individual rocket would be able to carry very much of the material relative to the total amount that needs to be disposed of . This makes the proposal impractical economically and it increases the risk of at least one or more launch failures . To further complicate matters, international agreements on the regulation of such a program would need to be established . Costs and inadequate reliability of modern rocket launch systems for space disposal has been one of the motives for interest in non-rocket space launch systems such as mass drivers, space elevators, and other proposals . </P> <P> Most countries are considerably ahead of the United States in developing plans for high - level radioactive waste disposal . Sweden and Finland are furthest along in committing to a particular disposal technology, while many others reprocess spent fuel or contract with France or Great Britain to do it, taking back the resulting plutonium and high - level waste . "An increasing backlog of plutonium from reprocessing is developing in many countries...It is doubtful that reprocessing makes economic sense in the present environment of cheap uranium ." </P> <P> In many European countries (e.g., Britain, Finland, the Netherlands, Sweden and Switzerland) the risk or dose limit for a member of the public exposed to radiation from a future high - level nuclear waste facility is considerably more stringent than that suggested by the International Commission on Radiation Protection or proposed in the United States . European limits are often more stringent than the standard suggested in 1990 by the International Commission on Radiation Protection by a factor of 20, and more stringent by a factor of ten than the standard proposed by the US Environmental Protection Agency (EPA) for Yucca Mountain nuclear waste repository for the first 10,000 years after closure . </P> <P> The U.S. EPA's proposed standard for greater than 10,000 years is 250 times more permissive than the European limit . The U.S. EPA proposed a legal limit of a maximum of 3.5 millisieverts (350 millirem) each annually to local individuals after 10,000 years, which would be up to several percent of the exposure currently received by some populations in the highest natural background regions on Earth, though the U.S. DOE predicted that received dose would be much below that limit . Over a timeframe of thousands of years, after the most active short half - life radioisotopes decayed, burying U.S. nuclear waste would increase the radioactivity in the top 2000 feet of rock and soil in the United States (10 million km) by ≈ 1 part in 10 million over the cumulative amount of natural radioisotopes in such a volume, but the vicinity of the site would have a far higher concentration of artificial radioisotopes underground than such an average . </P>

Where are the radioactive materials from the fission process kept