In accordance with the relevant IAEA safety standards, this publication complements IAEA Safety Standards Series No. SSG-1, Borehole Disposal Facilities for Radioactive Waste, by presenting a generic post-closure safety assessment for the IAEA borehole disposal concept of disused sealed radioactive sources in narrow boreholes. All the steps required to conduct such an assessment are covered by providing safety elements to ensure safety at borehole disposal sites. The publication identifies the key safety features, under varying disposal system conditions, in order to support the design and licensing processes of the borehole disposal concept, and facilitate its site specific implementation. The publication is primarily intended for those involved in developing or regulating the disposal of disused sealed radioactive sources to borehole facilities and will be of particular interest to States that have disused sealed radioactive sources but not suitable disposal options at present.