NEA Mandates and Structures

Expert Group on Operational Safety (EGOS)

Chair(s): Satoru SUZUKI, Japan
Secretary:  Tomohiro HIGASHIHARA
Member(s):All NEA member countries
Full participant(s): European Commission
Under the NEA Statute
Observer(s)(International Organisation): International Atomic Energy Agency (IAEA)
By agreement
Date of creation:01 June 2013
End of mandate:31 December 2021

Mandate (Document reference):

Mandate (Document extract):

Extract from document NEA/RWM/IGSC(2019)2/PROV


The mandate of the EGOS is to identify, evaluate and help define international best practices in safe operation of deep geological repositories (DGRs).


The scope of issues covers the pre-closure phase of DGRs, but the connection between operational safety and long-term safety should also be addressed.


The overall operational safety objectives in deep geological repositories (DGRs) for radioactive waste are similar to those in operating other nuclear facilities. Those objectives notably include: preventing release of radioactive substances; protecting workers and environment from irradiation; dissipating thermal power from the waste; ventilating any radioactive gases; etc. Risks are managed in accordance with the principle of defence-in-depth (as defined in the INSAG-10 report by the International Nuclear Safety Advisory Group) and “as low as reasonably achievable” (ALARA). 

The excavation volumes, potentially much longer operational durations and limited possibilities for direct monitoring in geological repositories, as compared to other nuclear facilities, will impose specific design requirements of DGRs. The applicability and transferability of classical nuclear safety and mining safety regulations to DGRs must be examined. Conflicting regulatory requirements must be identified and addressed. For instance, ventilation requirements addressing mining safety may conflict with requirements addressing radiation protection. Confliction between operational safety and long-term safety should also be addressed.

The Joint Workshop of the Integration Group for the Safety Case (IGSC) and the Regulators Forum (RF) “Preparing for Construction and Operation of Geological Repositories – Challenges to the Regulator and the Implementer”, held in January 2012, confirmed the need to address operational safety issues in repository implementation. Particularly, safety case experts expressed their interest and needs to develop consensus on the best operational practices and operational guidelines of DGRs as well as to understand commonalities and differences in operation procedures among member countries. As more high level waste (HLW) disposal projects move towards implementation and some low and intermediate level waste (L&ILW) disposal projects come into operation, achieving and demonstrating operational safety of geological disposal facilities becomes essential. Following this situation, the Radioactive Waste Management Committee (RWMC) pointed out in March 2012 that this area of work is important in further developing DGRs. In the 2012 IGSC plenary meeting, the members confirmed their will to share their practical experiences and approved unanimously the creation of an Expert Group on Operational Safety (EGOS).