As foreseen in the IUR Statutes, the IUR does not only have a Membership policy on an individual basis but also on an "Organisation basis: Institutes and Companies". They are called "Sustaining Members". Sustaining Members are for profit and non-profit organizations, Institutions, or Associations concerned with the affairs and purpose of the Society and who wish to foster the Society's purposes. Information can be obtained from the General Secretary.
- NRPA - Norwegian Radiation Protection Authority
- SCK.CEN - The Belgian Nuclear Research Centre
- ANPA - Agenzia Nazionale per la Protezione dell' Ambiente
- IRSN-DEI/SECRE - Institute for Radioprotection and Nuclear Safety
- ANDRA - National Radioactive Waste Management Agency
- BNFL - British Nuclear Fuel Limited
- ENRESA - Empresa Nacional de Residuos Radiactivos
- NIREX
- NUMO - Japanese Waste Management Organisation
- POSIVA - Finnish Radioactive Waste Management Organisation
- SKB - Svensk Kärnbränslehantering AB
- UKAEA - UK Atomic Energy Authority
- EDF - Recherche et Developpement