International decommissioning strategies

Full text: The IAEA Safety Requirements for decommissioning states that the regulatory body shall establish requirements for the decommissioning of nuclear facilities, including conditions on the end points of decommissioning. One of the main important issues is that the operator shall be responsible for all aspects of safety of the facility during its lifetime and of the decommissioning activities until its completion. A mechanism for providing adequate financial resources shall be established to cover the costs of radioactive waste management and, in particular the cost of decommissioning. It shall be put in place before operation and shall be updated, as necessary. A safety assessment of the proposed decommissioning strategy shall be performed and its implementation shall not begin until approval has been received by the regulatory body. A decommissioning plan shall be prepared for each facility, to show that decommissioning can be accomplished safely. The decommissioning plan shall be reviewed regularly and shall be updated as required to reflect, in particular, changes in the facility or regulatory requirements, advances in technology and, finally, the needs of decommissioning operation. If it is intended to defer decommissioning, it shall be demonstrated in the final decommissioning plan that such an option is safe. Decontamination and dismantling techniques shall be chosen which minimizes waste and appropriate means shall be in place for safe managing any waste that might be generated during the decommissioning process. A quality assurance programme shall be established for the decommissioning process. Before a site may be released for unrestricted use, a survey shall be performed to demonstrate that the end point conditions, as established by regulatory body, have been met. If site cannot be released for unrestricted use, appropriate control shall be maintained to ensure protection of human health and environment. The IAEA Safety Guidance mainly addresses the radiological hazards resulting from the activities associated with the decommissioning of nuclear reactors, primarily with decommissioning after planned final shutdown. Many of the provisions are also applicable to decommissioning after an abnormal event that has resulted in serious facility damage or contamination. In this case, this Safety Guide may be used as a basis for developing special decommissioning provisions, although additional considerations will be necessary. Due to the short extension of the present paper, we will emphasize only on some critical tasks of decommissioning research reactors. The removal of nuclear fuel from the reactor installation at the end of its operational lifetime should preferably be performed as part of operations or as one of the initial activities in decommissioning. At the beginning of decommissioning, all readily removable radioactive sources (operational waste, sealed sources, liquids) should be removed for reuse, storage in approved location or disposal. The removal of sources will normally result in a significant reduction of the radiation hazards. The operating organization should have, or have access to, competent staff to cover areas such as: safety requirements of the licence, radiation protection, waste management, quality management etc. Personnel should be competent to perform their assigned work safely. The management and staff involved in the decommissioning project should be made aware of and trained, if necessary, in the methods of minimizing the waste generated in the tasks assigned. Appropriate levels of control and supervision should be provided to ensure safety. The organizational structure to be employed during decommissioning should be described in the decommissioning plan. In the description of the organizational structure, there should be a clear delineation of authorities and responsibilities amongst the various units. This is particularly necessary when the operating organization uses outside contractors. In this case all license conditions apply to them. The radiation protection programme should be clearly set out in the decommissioning plan. This programme should ensure that radiation protection is optimised and that doses are kept within appropriate limits. Although the principles and aims of radiation protection during operations and during decommissioning are fundamentally the same, the methods and procedures of implementation of the radiation protection may be different. On completion of decommissioning, it should be necessary to verify that end state conditions have been met and appropriate records should be retained. In accordance with the national legal framework, these will be held and maintained for purposes such as confirmation of completion of decommissioning activities in accordance with the approved plan, recording the disposal of wastes, materials and premises, and responding to possible liability claims The site should be controlled until approval is received from regulatory body. (author)