Nuclear Energy Agency (NEA) – Enhancing understanding of spent fuel assemblies during loss of coolant accidents

Nuclear Energy Agency (NEA) – Enhancing understanding of spent fuel assemblies during loss of coolant accidents

Following the Fukushima Daiichi Nuclear Power Plant accident, the international nuclear community began an in-depth assessment of the safety of spent fuel assemblies, which store spent fuel from nuclear reactors. A number of measures have been launched since the accident in an attempt to mitigate the risk of a potential accident at SFP.

The NEA Working Group on Accident Analysis and Management (WGAMA) is responsible for activities related to potential accidental situations at nuclear power plants, and helping to understand and reduce the risks and consequences of an SFP accident is a focus area for the group. .

Nearly 30 experts from WGAMA met at the French Institute for Radiation Protection and Nuclear Safety (IRSN) in Cadarache, France to discuss how to advance understanding of SFP phenomena during a loss of cooling accident.

The working group, representing 10 different countries at the meeting, also considered the proposal for “POLCA” (Pool During Loss of Cooling Accident), a possible future joint project that would pursue experimental analysis of the behavior of SFPs in the event of a loss of cooling accident.

Members of the Incident Analysis and Management Working Group visit the ASPIC and MIDI facilities at the IRSN in Cadarache, France

The POLCA joint project aims to:

  • Enhance knowledge about SFP incidents;
  • Support better understanding of large-scale complexes to provide thermal hydraulic data;
  • Support the development and validation of a thermohydraulics model for SFPs under cooling incident loss;
  • Evaluate some mitigation strategies related to collection management.

The POLCA project will focus on experimenting with large-scale utilities (MIDI and ASPIC) with custom hardware for the thermal-hydraulic behavior of SFPs during loss of cooling incidents. It also aims to contribute to enriching an experimental database, useful for improving thermo-hydraulic numerical tools in swimming pool conditions.

Many designs of heat removal systems in nuclear power plants consider large baths with submerged heat exchangers. These collectors have recently been considered in some passive reactor decay heat removal systems. Therefore, knowledge of normal circulation flow within a MIDI facility is important for validating any scientific computational tool used to model such passive systems.

Image source: IRSN's extensive MIDI facilityImage source: IRSN’s large-scale MIDI facility.

The POLCA joint project proposal will be submitted to the Committee for Safety of Nuclear Installations (CSNI) for approval.

During the meeting at IRSN, experts also shared the status of SFP regulation, incident analysis, and needs of R&D activities for SFPs in their countries.

You can read more about NEA’s work in nuclear power plant accident management on the WGAMA webpage.

    (Tags for translation) Joint project 

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