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New CRP: Advancing the State-of-Practice in Uncertainty and Sensitivity Methodologies for Severe Accident Analysis in Water Cooled Reactors (I31033)

New Coordinated Research Project

Under a new IAEA Coordinated Research Project, a PhD training programme on severe accidents simulation and modelling will be developed and implemented for students from countries embarking on nuclear power. (Photo: S.Krikorian/IAEA)

The IAEA supports Member States in the development of advanced water cooled reactor (WCR) technology by fostering information exchange and collaborative research and development, aimed at improving Member States’ capabilities in reactor design, assessment and analysis.

This new IAEA Coordinated Research Project (CRP) supports experts from Member States with capabilities in WCR severe accident analysis in their national programmes on severe accident code applications and improvements. These computer codes are applied to model the progression of accidents in nuclear power plants with WCRs. The CRP specifically aims to advance understanding and characterization of various types of uncertainty sources in the simulations and their effect on the variability of important calculated consequences, such as radiological releases, from different severe accident codes.  

Relevant benchmark scenarios will be developed to implement the uncertainty characterization, starting with a phenomena identification and ranking technique (PIRT process) and expert agreement on the input uncertainty distributions and the important calculated consequences. Uncertainties will be classified as random (aleatory), lack-of-knowledge based (epistemic) and logic-based core degradation and containment behaviour models (resulting in ’cliff-edge’ effects). The latter two are also termed “model form uncertainty’. The use of many different severe accident codes helps to determine the effects from these model form uncertainties, since the severe accident models in the different codes represent different approaches adopted by the code developers.

The major goal of this CRP is to raise the level of expertise and sophistication of severe accident code users and support a correct interpretation of code results, including their uncertainty.

CRP Overall Objectives

This CRP is aimed at promoting international collaboration among IAEA Member States through sharing expertise and participating in common benchmark calculations. The insights gained from the benchmark exercise will greatly improve the understanding and characterization of severe accident analysis uncertainty and thus allow a more defensible application of severe accident codes. The research will also identify code or model improvements to reduce these overall uncertainties.

In addition to the participants’ technical work during the first three years of the CRP, i.e. the collaborative PIRT, development of the benchmark scope and analysis of the benchmark, two unique long term activities are planned:

  1. A PhD training programme on severe accidents simulation and modelling will be developed and implemented for students from countries embarking on nuclear power, in which PhD candidates will be supported by organizations in experienced Member States.
  2. During the last years of the CRP and beyond, training workshops and fellowships will be organized for participants from nuclear newcomer countries in the state-of-practice in uncertainty and sensitivity methodologies for severe accident analyses in WCRs.

Specific Research Objectives

  • Review the advancement in methodologies used for uncertainty and sensitivity analysis for severe accident codes in participating Member States;
  • Make recommendations on good practices in uncertainty and sensitivity analysis and methods for severe accident codes;
  • Train early career engineers and scientists; establish opportunities for PhD dissertations; develop and conduct workshops and training and education courses on the topical areas of the CRP (see 1. and 2. above).

The project will be launched at its first Research Coordination Meeting in October 2019.

How to join the CRP

Interested institutions should submit their Proposal for a Research Contract or Agreement by 15 June 2019 directly to the IAEA’s Research Contracts Administration Section, using the proposal templates on the CRA web pages.

For further information related to this CRP, potential applicants can contact the Project Officers, Tatjana Jevremovic and Matthias Krause, Nuclear Power Technology Development Section, Division of Nuclear Power, IAEA Department of Nuclear Energy.


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