The principle of "user pays" applies to the disposal of radioactive waste. In other words, those who produce radioactive waste are required to bear the costs of its disposal. It is the operators of nuclear power plants who are responsible for the disposal of waste produced from nuclear energy, while the federal government is responsible for waste from other sources (medicine, industry, research). Disposal costs that arise during the operating stage are covered by the operators on an ongoing basis. The disposal of radioactive waste after the nuclear power plants have been decommissioned is financed via the Decommissioning Fund and the Disposal Fund, both of which accumulate revenue through annual contributions from the operators.