[en] Radioactive Waste Management (RWM) is responsible for implementing geological disposal of the UK's higher-activity radioactive wastes. These wastes include large quantities of fissile nuclides and, therefore, demonstration of the criticality safety of the wastes under disposal conditions forms an important component of RWM's disposal system safety case. RWM has developed a methodology for establishing criticality controls on waste packages that contain intermediate level waste (ILW) and application of this methodology will support the criticality safety demonstration for the geological disposal facility (GDF). The methodology is based on the UK regulatory requirement to demonstrate that post-closure criticality is not a significant concern, which means showing that such a criticality event is unlikely to occur and, if it did occur, it would be of low consequence to the performance of the GDF. The GDF siting process in the UK is ongoing and the criticality safety assessment approach is currently based on consideration of illustrative GDF concepts. Necessarily, a cautious approach is taken to assessing post-closure criticality scenarios in order not to preclude any potential GDF concepts. This paper discusses how, even at the generic stage of GDF development, by working with waste packagers to understand ILW packaging concepts and characteristics, it is possible to develop waste package criticality controls that ensure that GDF post-closure criticality safety requirements can be met taking a cautious approach without imposing unnecessary radiological risks and costs in the waste packaging process. Interaction with waste packagers takes place through RWM's waste package Disposability Assessment process that includes discussion, development and review of the criticality safety strategy for specific waste forms through different stages of packaging concept development. The paper discusses how, through this process, criticality safety controls can be identified for potentially challenging wastes by focusing on how credit can be taken for specific properties of the wasteform and container in building criticality safety arguments. Recent examples of the application of the methodology are presented, where the long-term behaviour of particular components of the waste package (e.g., container, waste, encapsulating or immobilisation matrix) is taken into account when deriving post-closure criticality controls. The paper emphasises the importance of waste package records in this process as an evidence base for the criticality safety case that will need to be developed when a GDF site is available. (authors)