6.4. In the siting process for a radioactive waste disposal facility, four stages may be recognized (Fig. 2): (i) the conceptual and planning stage, (ii) the area survey stage, (iii) the site investigation stage and (iv) the stage of detailed site characterization leading to site confirmation for construction of the disposal facility (see Appendix I for information concerning the first three stages, which should be read in conjunction with this section). Site investigations progress from generalized studies at the early area survey stage to a programme of progressively more detailed characterization as specific objectives are addressed and uncertain features are targeted. Detailed site characterization is required for site confirmation for construction of the disposal facility and may continue through the phases of construction and operation.