Written for use by regulatory bodies and the operating organizations of nuclear power plants, this Safety Guide addresses the commissioning, operation and preparation for decommissioning stages for a nuclear power plant. The role of the operating organization in the siting, design, manufacturing and construction of a nuclear power plant is outside the scope. In most States, the operating organization is the legal entity responsible for safety, financial and commercial obligations, as well as other obligations that are connected with the operation of a nuclear power plant. This Safety Guide is solely concerned with those responsibilities and obligations that are necessary to ensure the safe operation of the nuclear power plant(s) under the control of the operating organization.