Joint NEA and IAEA International Symposium on PSA for Reactors of Singular Designs
Hosted by the Office for Nuclear Regulation (ONR)

The Symposium is free of charge for all participants and is scheduled to take place in person at the ONR’s offices near Liverpool in the United Kingdom. 


Key Dates

31 March 2022  Deadline for abstract submission   Registration form  
12 April Decision on abstract acceptance  
24 May Deadline for attendance registration  Registration form  
24 May Deadline for presentation submission    
7-9 June or 7-10 June if virtual event  Symposium
General Information

This is the announcement and call for presentations for an International Symposium on PSA for Reactors of Singular Designs organised under the auspices of the OECD Nuclear Energy Agency (NEA) Committee on the Safety of Nuclear Installations (CSNI) Working Group on Risk Assessment (WGRISK) in collaboration with the International Atomic Energy Agency (IAEA), Division of Nuclear Installation Safety (NSNI), Safety Assessment Section (SAS). The Symposium will be hosted by the Office for Nuclear Regulation (ONR) in Liverpool, United Kingdom from 7th to 9th June, 2022.

Working under the mandate of the CSNI, the main mission of the WGRISK is to advance the understanding and utilisation of probabilistic safety assessment (PSA) in ensuring the continued safety of nuclear installations in OECD member countries.

IAEA Safety Assessment Section develops and maintains a broad range of Safety Standards related to the design safety and the safety assessment, in particular related to probabilistic safety assessment. Currently the IAEA is developing several technical publications related to Small Modular Reactors (including the topic of PSA).

Background and format

The use of PSA in the assessment of risk and the improvement of safety for nuclear power plants follows clear international methodologies and has provided significant benefits in the past decades. However, there are significant challenges in conducting PSA for reactors of singular designs. This activity aims to provide a forum for sharing knowledge and experience related to the challenges of conduction PSA for such unique reactors.

The term “Reactors of Singular Designs” is broad and can include:

  • Research Reactors
  • Demonstration Reactors
  • Prototype Reactors
  • First of a Kind (FOAK) Reactors
  • Small Modular Reactors (SMRs)
  • Generation IV Reactors

The scope covers all aspects of PSA, from small-scale probabilistic investigations and risk informed applications up to full-scope PSA covering Level 1, 2 and 3, all plant operational modes, plant internal events as well as risk aggregation from internal and external hazards. Analysis conducted to support the development of the PSA is also within the scope (success criteria, reliability data, severe accident analysis, hazard analysis, etc.).

The expected result of the symposium is a common understanding of possible benefits and application areas, challenges, and possible solution paths in the field of PSA for reactors of singular designs.

The focus of the Symposium is on exchanging information concerning the use and application of PSA for reactors of singular designs covering also key differences and challenges for performing the analysis. The Symposium will provide a platform for discussions and exchange ideas between nuclear safety professionals and PSA specialists.

The Symposium will include plenary and technical sessions in addition to facilitated discussion sessions. Active participation of the Symposium attendees in the discussions as well as formulating conclusions and recommendations is highly appreciated. Information obtained as a result of the Symposium should provide a better understanding and improved interpretations of subjects, topics and issues related to risk assessment for reactors of singular designs.

The Symposium proceedings containing the summarised results, conclusions and recommendations for follow-up activities will be prepared on the basis of information presented and discussed during the Symposium.

Suggested symposium topics

Presentations addressing all issues and topics related to PSA developments for reactors of singular designs are requested.

The following topics are intended to be addressed by the Symposium:

  • Experience of conducting PSA for reactors of singular designs (including supporting analysis).
  • Differences and challenges of PSA for singular design reactors compared to classic PSA (including supporting analysis).
  • Operational experience from reactors of singular designs.
  • Lessons learned and recommendations for development of PSAs and use of risk-informed decision-making processes for reactors of singular designs.
Logistics and participation in the Symposium


The organisers kindly invite experts from all aspects of the industry to attend and contribute to the Symposium. This includes operating organisations, regulatory authorities, vendors, design organisations, technical support organisations (TSOs), research institutes, safety analysis practitioners and consultants involved in safety assessment of reactors of singular designs. Attendance is not limited to NEA members.

In-person or virtual symposium

The event will take place in Liverpool, virtual participation is not possible.


All participants have to register by 24th May 2022 filling the Registration Form. Please email the completed form to ANT@ONR.GOV.UK to register. Access to the symposium cannot be provided without prior registration and acceptance.

Registration form  


Participants intending to present shall submit an abstract providing a brief overview of their proposed presentation. All abstracts should be submitted by 31st March 2022 by completing the Registration Form. Please email the completed form to ANT@ONR.GOV.UK to submit the abstract. The Organising Committee will review the abstracts and notify the authors by 12th April 2022 on the accepted abstracts. Presentation slides should be sent to ANT@ONR.GOV.UK latest by 24th May 2022.  Presenters not able to attend in person will be requested to submit a recording of their presentation by 30th May 2022

Attendance fee

The Symposium is free of charge for all participants. Accommodation and travel will not be provided and must be organised by the participants.


All presentations and discussions will be in English, translation cannot be provided.

Symposium Proceedings

The Symposium Proceedings will be published by NEA and will include objectives and important comments provided during the Symposium, all Symposium presentations (as attachment), summaries, conclusions and recommendations raised during the facilitated discussions, concluding remarks as well as new areas of interest identified in the final closing session. A specific part of the report will be dedicated to the discussion of good practices and experiences.