Abstract The geological, planning and environmental factors which have led to the definition of areas of search, and eventually to specific sites, which are potentially suitable for the disposal of low-level radioactive wastes in near-surface engineered structures are considered. Areas of search were determined for inland sites by first defining the areas of outcrop within the UK of the London Clay, Gault, Kimmeridge Clay, Oxford Clay, Lower Lias and Mercia Mudstone Group: the major argillaceous formations, chosen because of their low hydraulic conductivities, and then removing areas from such outcrops of clay using environmental and planning factors. The first of these factors was population density. Areas included within National Scenic Areas (Scotland), National Parks, Areas of Outstanding Natural Beauty and SSSIs were then removed. Transport of the waste from its sources of production is of major significance, and contours of equal accessibility were constructed. In assessing coastal environments, similar environmental and planning considerations were taken into account, but a variety of geological environments were considered. Within the areas of search thus defined, searches were made of all areas of available land of sufficient size for repository development. Each site found during this search was then examined for its suitability in terms of its geology, hydrogeology, planning and environmental factors, and separate shortlists drawn up for inland and coastal sites. In assessing these short-listed sites in more detail, three groups of factors were considered: safety (geological and hydrogeological), planning (population density, road and rail access, resource sterilisation, operational and constructional impact etc.) and technical (capacity of the site, ease of constructability). Small adaptations to the analysis, such as the type of coastal environment, were required for coastal sites to take into account different objectives underlying coastal repository development. Multi-attribute analysis was then carried out by ascribing scores and weightings to all the relevant factors, and the sensitivity of the total weighted scores to the values of the weightings determined. The four sites which were announced in February 1986 are those that performed well during the multi-attribute analysis and were available for acquisition by NIREX for potential future development.