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New CRP: Developing a Phenomena Identification and Ranking Table (PIRT) and a Validation Matrix, and Performing a Benchmark for In-Vessel Melt Retention (J46002)

New Coordinated Research Project

In-Vessel Melt Retention strategy:  Illustration of a severe accident in a nuclear power plant after melted reactor core material (i.e. corium) has relocated to the bottom of the reactor vessel. (Image: IAEA)

The IAEA is launching a four-year Coordinated Research Project (CRP) on In-Vessel Melt Retention (IVMR), a severe accident mitigation strategy for nuclear power plants. IVMR consists of cooling the melted reactor core material (i.e. corium) from outside the reactor vessel in order to avoid reactor vessel failure and retain the corium inside the reactor vessel.

In IAEA meetings that took place since the 2011 accident at the Fukushima Daiichi Nuclear Power Plant, IVMR was confirmed to be one of the highest research and development priority areas for the mitigation of severe accidents at nuclear power plants. This CRP will commence later in 2020.

Although there already are considerable methodological developments, as well as experimental and numerical simulation works, meetings on IVMR organized by the IAEA and other organizations have concluded that further work would be beneficial on various aspects including: the quality of numerical simulations, experimental data needed for validating individual models; and, the identification of most pertinent acceptance criteria to be considered in the safety demonstration of IVMR.

All of these aspects support the safety demonstration of IVMR, which aims at proving that this strategy effectively retains the corium inside the reactor vessel, hence ensuring the containment integrity and confinement of radioactive materials.

The IAEA held an international experts meeting, which was followed up by specific technical meetings, which provided an opportunity to exchange perspectives and strengthen research and development strategies on severe accidents at nuclear power plants. This CRP will provide a platform to continue facilitating interactions among experts from Member States and international organizations to advance the knowledge on and build more robust technical bases for the IVMR strategy.

CRP Overall Objective

The main objective of this CRP is to harmonize the international understanding of the scientific and technological bases underpinning crucial parts of the safety demonstration of IVMR. The output of the CRP will be disseminated in the form of an IAEA workshop, IAEA publications and conference papers.

Specific Research Objectives

  1. Develop a phenomena identification and ranking table (PIRT) and a validation matrix, and perform a benchmark for IVMR.
  2. Progress the identification of relevant high-quality experimental data requested for the validation of computer codes for modelling and simulation of IVMR, including for recently developed and more advanced models (e.g. corium properties and stratification in the lower plenum of the reactor vessel, heat transfer in the stratified pool; external reactor vessel cooling, mechanical resistance of ablated wall).
  3. Improve the quality of modelling and simulation, through both improvement of individual physical, thermomechanical and chemical models, and possibly improvement of the methodology developed for lower- to medium-power reactors (traditionally based on the assessment of the heat flux towards the vessel wall from the corium pool, which is then compared to the critical heat flux).
  4. Harmonize the international understanding of research and development conclusions underpinning the safety demonstration of IVMR.
  5. Train and educate young engineers and scientists, including from countries embarking on a nuclear power programme.

How to Join the CRP

Please submit your Proposal for Research Contract or Agreement by email, no later than 15 April 2020, to the IAEA’s Research Contracts Administration Section, using the appropriate template on the CRA web portal.

For further information related to this CRP, potential applicants should use the contact form under the CRP page.


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