PRISME-FAIR Program
The PRISME (Fire Propagation for Elementary Multi-location Scenarios) and FAIR (Fire Risk Assessment through Innovative Research) programmes are international research programmes led by the IRSN and subsequently by the ASNR under the auspices of the OECD.
The experimental work is carried out on the ASNR’s GALAXIE experimental platform.
These programmes experimentally study, on the one hand, the spread of smoke released by a fire in a nuclear facility via openings between rooms and the ventilation system. On the other hand, they study the behaviour under oxygen-deprived conditions (confined and ventilated rooms) of real fire sources (electrical cabinets and cables).
The PRISME programme was divided into three successive phases:
- PRISME 1 (2006 to 2011)
- PRISME 2 (2011 to 2016)
- PRISME 3 (2017 to 2022)
Following PRISME, the FAIR programme began in 2023 for a duration of five years, continuing and expanding on the work undertaken.
In parallel with the experimental work, Analytical Working Groups (AWGs) were established. These working groups bring together experts from partner organisations and facilitate discussion on methods of modelling, simulation and interpretation of the data obtained.
For the ASNR, this work represents a major contribution to the validation of the fire simulation software within the S3AFER software platform.
FAIR
Project characteristics : Programs carried out under the auspices of the OECD, with the ASNR acting as the operating agent.
Project duration : June 2023 – 2028
Funding : €3.7 million
Partners :
- BEL V, TRACTEBEL-ENGIE (Belgium)
- VTT (Finland) until the end of 2025
- EDF, FRAMATOME, ASNR (France)
- GRS (Germany)
- NRA (Japan)
- KAERI, KHNP, KINS (South Korea)
- CSN (Spain)
- ONR (United Kingdom)
- ENSI (Switzerland)
- CERN (EU)
Publications :
- March, P., et al. FAIR: A New OECD/NEA Fire Risk Research Project Under Development as a Follow-Up to PRISME 3. Proceedings of SMiRT 26
- Nerisson, P. et al. OECD/NEA FAIR (Fire Risk Assessment Through Innovative Research) Project: Progress Two Years After Project Launch. Proceedings of SMiRT 27
Background :
The main objective of the FAIR project is to obtain additional or complementary data to that produced by the three PRISME programs, in order to improve fire risk assessment in nuclear facilities.
Its scientific scope was defined on the basis of the conclusions of a PIRT (Phenomena Identification and Ranking Table) exercise. This exercise, conducted with partners from the former PRISME projects, identified topics of common interest, both in terms of safety issues and knowledge requirements.
On this basis, the FAIR program is structured around three research areas :
- Fire propagation along cable trays
- The effects of hot and contaminated environments on fires in confined and mechanically ventilated compartments
- Complex multi-source and multi-compartment fire scenarios.
The FAIR project’s experimental campaigns are carried out at the ASNR’s GALAXIE experimental platform in Cadarache, providing an experimental setting representative of the conditions encountered in nuclear facilities.
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Fire propagation along long cable trays
The first focus area of the FAIR programme aims to better understand fire propagation along cable trays, whether vertical or horizontal, in confined and mechanically ventilated compartments.
An initial series of large-scale tests focused on fire propagation along vertical cable trays. These tests were carried out in 2025 at the DIVA facility, using a 6-metre-long vertical cable tray, in order to study both the spread of the fire and its consequences in confined, ventilated spaces.
A second series of tests, also on a large scale, focuses on fire propagation along long horizontal cable trays. This complements the campaign conducted as part of PRISME 3 CFP (Cable Fire Propagation), which was carried out in the DIVA facility’s test tunnel using 6-metre-long horizontal cable trays.
These tests have shown that the use of longer cable trays is more suitable for avoiding any edge effects and thus allows for more thorough validation of analytical models. Taking into account feedback regarding the DIVA safety criteria, new tests using 9-metre-long cable trays will be carried out in 2026 in the DIVA facility corridor.
Effects of cable ageing on fire behaviour
The FAIR project also examines the effects of ageing on electrical cables, and in particular on sheathing materials (insulation), on fire behaviour and fire spread. Two test strands are proposed :
- Part 1: natural ageing
This phase aims to analyse the fire behaviour of naturally aged cables in order to obtain representative results. The main challenge is to be able to collect suitable cables from nuclear facilities: cables that are neither contaminated nor activated, and for which the fire resistance standards were initially known and complied with.
- Part 2: artificial ageing
This part aims to analyse the fire behaviour of artificially aged cables. This allows for a wide selection of cables and the choice of ageing sources. However, the main challenge lies in specifying representative accelerated ageing test protocols.
A selection of candidate cables has been made in accordance with the above specifications. The first ageing tests will take place in 2026. -
Combustion in hot and vitiated atmospheres
The second focus area concerns the study of fire behaviour in hot and vitiated environments, characterised by low oxygen concentrations and high temperatures.
The aim is to analyse the combined influence of oxygen depletion and increased gas temperature, or external heat flux, on fire development as well as ignition and extinction conditions.
To this end, the FAIR programme employs a dual experimental approach :
- large-scale experiments, designed to replicate realistic fire scenarios
- medium-scale experiments, with a more analytical focus, to support the understanding of large-scale test results and contribute to the development of a modelling methodology.
An initial series of tests carried out in 2024 includes large-scale experiments in a mechanically ventilated chamber at the DIVA facility. The aim is to replicate scenarios in which external heat fluxes to the fuels are significant and can offset the negative effect of oxygen contamination. Typical examples include fires in cable trays or electrical cabinets beneath the ceiling, submerged in the smoke layer.
A second series of medium-scale experiments was carried out in 2024–2025 in a controlled-atmosphere facility. Simple fire sources are considered (liquid pool). The intermediate experimental facility under consideration is the NYX test facility.
Ignition of unburned gases
Building on the lessons learned from the PRISME 2 project, the FAIR project aims to gain a better understanding of the smoke explosion phenomenon, and more specifically, the conditions that promote the formation of a premixed gas mixture and those that lead to deflagrations.
In fact, smoke explosion phenomena were observed during large-scale cable tray fire tests conducted as part of the PRISME 2 experiments.
Several deflagrations, characterized by overpressures exceeding 100 hPa and rapid flame propagation, occurred without any sudden change in ventilation.
Consequently, smoke explosions cannot be excluded from fire safety analyses of nuclear facilities. It is therefore planned to conduct medium-scale experiments, which are more conducive than large-scale experiments, to characterize the conditions under which deflagrations occur and develop. -
Propagation between discrete sources
The third research area focuses on propagation between several discrete sources within the same environment, leading to the movement of the fire source within the compartment or the occurrence of several simultaneous fires.
This campaign will include large-scale experiments conducted on the GALAXIE platform, focusing on both real-world configurations and academic scenarios (confined atmosphere using the DIVA facility or open atmosphere using the SATURNE facility).
The practical configurations will cover two fire propagation scenarios:
- vertical spread, mainly driven by convection due to smoke movement
- horizontal propagation, mainly driven by flame radiation.
The aim of this approach is to focus on the physical mechanisms involved and to propose academic cases for code validation.
The fire source will be well controlled, whether it is a spreading fire or a homogeneous solid with known thermal characteristics (critical heat fluxes and ignition temperatures).
The configuration will involve simple source arrangements, such as sources aligned horizontally or vertically. Testing is scheduled to begin in late 2026.
PRISME 3
Project characteristics : Programmes carried out under the auspices of the OECD, with the IRSN acting as the operating agent.
Duration : January 2017–December 2021
Funding : €7 million
Partners :
- BEL V, TRACTEBEL-ENGIE (Belgium)
- VTT (Finland)
- CRIEPI, NRA (Japan)
- EDF, ASNR (France)
- US-NRC (United States)
- GRS (Germany)
- KINS, KAERI (South Korea)
- HSE (United Kingdom)
Background : list of main publications (PDF)
The Prisme 3 programme comprises three research areas:
- S3 Campaign (Smoke Stratification and Spread): Stratification of smoke in a room and propagation of smoke through openings
- ECFS campaign (Electrical Cabinet Fire Spread) : Propagation of an electrical cabinet fire to neighbouring cabinets
- CFP Campaign (Cable Fire Propagation): Propagation of cable tray fires.
-
The first focus area of the FAIR programme aims to better understand fire propagation along cable trays, whether vertical or horizontal, in confined and mechanically ventilated compartments.
An initial series of large-scale tests focused on fire propagation along vertical cable trays. These tests were carried out in 2025 at the DIVA facility, using a 6-metre-long vertical cable tray, in order to study both the spread of the fire and its consequences in confined, ventilated spaces.
A second series of tests, also on a large scale, focuses on fire propagation along long horizontal cable trays. This complements the campaign conducted as part of PRISME 3 CFP (Cable Fire Propagation), which was carried out in the DIVA facility’s test tunnel using 6-metre-long horizontal cable trays.
These tests have shown that the use of longer cable trays is more suitable for avoiding any edge effects and thus allows for more thorough validation of analytical models. Taking into account feedback regarding the DIVA safety criteria, new tests using 9-metre-long cable trays will be carried out in 2026 in the DIVA facility corridor.
Effects of cable ageing on fire behaviour
The FAIR project also examines the effects of ageing on electrical cables, and in particular on sheathing materials (insulation), on fire behaviour and fire spread. Two test strands are proposed :
- Part 1: natural ageing
This phase aims to analyse the fire behaviour of naturally aged cables in order to obtain representative results. The main challenge is to be able to collect suitable cables from nuclear facilities: cables that are neither contaminated nor activated, and for which the fire resistance standards were initially known and complied with.
- Part 2: artificial ageing
This part aims to analyse the fire behaviour of artificially aged cables. This allows for a wide selection of cables and the choice of ageing sources. However, the main challenge lies in specifying representative accelerated ageing test protocols.
A selection of candidate cables has been made in accordance with the above specifications. The first ageing tests will take place in 2026. -
Combustion in hot and vitiated atmospheres
The second focus area concerns the study of fire behaviour in hot and vitiated environments, characterised by low oxygen concentrations and high temperatures.
The aim is to analyse the combined influence of oxygen depletion and increased gas temperature, or external heat flux, on fire development as well as ignition and extinction conditions.
To this end, the FAIR programme employs a dual experimental approach :
- large-scale experiments, designed to replicate realistic fire scenarios
- medium-scale experiments, with a more analytical focus, to support the understanding of large-scale test results and contribute to the development of a modelling methodology.
An initial series of tests carried out in 2024 includes large-scale experiments in a mechanically ventilated chamber at the DIVA facility. The aim is to replicate scenarios in which external heat fluxes to the fuels are significant and can offset the negative effect of oxygen contamination. Typical examples include fires in cable trays or electrical cabinets beneath the ceiling, submerged in the smoke layer.
A second series of medium-scale experiments was carried out in 2024–2025 in a controlled-atmosphere facility. Simple fire sources are considered (liquid pool). The intermediate experimental facility under consideration is the NYX test facility.
Ignition of unburned gases
Building on the lessons learned from the PRISME 2 project, the FAIR project aims to gain a better understanding of the smoke explosion phenomenon, and more specifically, the conditions that promote the formation of a premixed gas mixture and those that lead to deflagrations.
In fact, smoke explosion phenomena were observed during large-scale cable tray fire tests conducted as part of the PRISME 2 experiments.
Several deflagrations, characterized by overpressures exceeding 100 hPa and rapid flame propagation, occurred without any sudden change in ventilation.
Consequently, smoke explosions cannot be excluded from fire safety analyses of nuclear facilities. It is therefore planned to conduct medium-scale experiments, which are more conducive than large-scale experiments, to characterize the conditions under which deflagrations occur and develop. -
Propagation between discrete sources
The third research area focuses on propagation between several discrete sources within the same environment, leading to the movement of the fire source within the compartment or the occurrence of several simultaneous fires.
This campaign will include large-scale experiments conducted on the GALAXIE platform, focusing on both real-world configurations and academic scenarios (confined atmosphere using the DIVA facility or open atmosphere using the SATURNE facility).
The practical configurations will cover two fire propagation scenarios:
- vertical spread, mainly driven by convection due to smoke movement
- horizontal propagation, mainly driven by flame radiation.
The aim of this approach is to focus on the physical mechanisms involved and to propose academic cases for code validation.
The fire source will be well controlled, whether it is a spreading fire or a homogeneous solid with known thermal characteristics (critical heat fluxes and ignition temperatures).
The configuration will involve simple source arrangements, such as sources aligned horizontally or vertically. Testing is scheduled to begin in late 2026.