All ETSON members are Technical Safety Organisations (TSO) as defined by the network. To fulfil the requirements according to this definition, a TSO

• is a public or a private non profit organisation,
• performs safety assessments with a global regulatory vision, on a regular basis and with a broad scope,
• delivers services supporting its national nuclear regulatory authorities in the field of nuclear safety, and/or waste management and/or radiation protection,
• develops and maintains a high level of competence in its field of safety assessment (knowledge, expertise, long standing experience, global overview, ethics, references),
• has a value charter and makes sure it is implemented at all levels in the organisation. The charter promotes values such as: honesty, impartiality, proactivity and initiative, consistency in the safety approach, respect for all stakeholders,
• is an independent organisation; this means that it is able to form and express its technical judgment independently from external interest,
• maintains an adequate training and knowledge management programme for its staff,
• maintains R&D programmes allowing the development of new knowledge and techniques in support of its missions, and an independence of judgement from licensees, and
• adheres to a code of ethics: if a TSO delivers services to a domestic or foreign licensee or vendor, it does so in full transparency with respect to the licensee's nuclear safety authority, and is able to demonstrate that conflicts of interest are avoided.

With respect to these requirements, each Member of ETSON has to obey rules imposed by national law and/or by the domestic regulatory authorities and may adopt complementary rules on a voluntary basis.

	BELGIUM Bel V www.belv.be​			CZECH REPUBLIC National Radiation Protection Institute (SÚRO) www.suro.cz
	FINLAND VTT Technical Research Centre of Finland www.vtt.fi			FRANCE Institut de Radioprotection et de Sûreté Nucléaire (IRSN) * www.irsn.fr
	GERMANY Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) www.grs.de			HUNGARY Centre for Energy Research (EK-CER) www.ek-cer.hu
	ITALY ENEA www.enea.it			LITHUANIA Lithuanian Energy Institute (LEI) www.lei.lt
	ROMANIA RATEN ICN www.nuclear.ro			SLOVAKIA VUJE www.vuje.sk
	SLOVENIA JSI www.ijs.si			SWITZERLAND Paul Scherrer Institut (PSI) www.psi.ch​

*(from 1 January 2025, IRSN will operate in a merger with the French supervisory authority ASN under the name “ASNR”)

ETSON associated members

	JAPAN Nuclear Regulation Authority (NRA) www.nsr.go.jp​			UNITED KINGDOM JACOBS www.jacobs.com
	UKRAINE State Scientific and Technical Center (SSTC) www.sstc.ua			RUSSIA Scientific and Engineering Center for Nuclear and Radiation Safety (SEC NRS) www.secnrs.ru Suspended from ETSON activities.