The acronym PRISME comes from the French phrase propagation d’un incendie pour des scénarios multi-locaux élémentaires, which in English can be translated as "fire propagation in elementary, multi-room scenarios".

PRISME phases

First phase (2006-2011)

The first phase of the PRISME project consisted of a series of fire and smoke propagation tests in a dedicated facility at the French Institut de radioprotection et de sûreté nucléaire (IRSN) centre in Cadarache, France. The facility was used to investigate room-to-room heat and smoke propagation, the effect of network ventilation and the resulting thermal stresses to sensitive safety equipment of such room configurations. It was also planned to use data from the project to study multi-room fires and for validation of fire computer codes.

Several propagation modes were studied: through a door, along a ventilation duct that crosses the room containing the fire and that ventilates an adjacent room, along a ventilation duct when the flow is reversed within and through leakages between several rooms.

This phase planned to provide such critical information as the time that elapses before target equipment malfunctions and to qualify computer codes modelling heat and smoke propagation phenomena. The objective was to answer questions concerning smoke and heat propagation inside an installation, by means of experiments tailored for code validation purposes. In particular, this phase aimed to provide answers to the following questions:

• What is, for a given fire scenario, the failure time for equipment situated in the nearby rooms that communicate with the fire room by the ventilation network and/or by a door (which is open before the fire or opens during the fire)?
• Is it valid to assume that no propagation occurs beyond the second room from the fire room when the rooms communicate through doors, and beyond the first room when rooms communicate only by the ventilation network?
• What are the safety consequences of the damper or door failing to close, or of an intervention delay which is too long?
• What is the best way to operate the ventilation network in order to limit pressure-driven phenomena and releases to nearby rooms?
• Is it the admission damper closing following fire detection? Is it the extraction damper closing when the temperature threshold of filters has been reached or when the filters are plugged?

The results obtained were used as a basis for qualifying fire codes (either simplified zone model codes or computerised fluid dynamics codes used in the fire safety analysis of nuclear installations and plants). After qualification, these codes could be applied for simulating other fire propagation scenarios in various room configurations with a good degree of confidence. The information could be useful to designers in order to select the best fire protection strategy. For the operators, this data could be useful for establishing the suitable operation of the plant, such as the operation of the ventilation network (e.g. closing dampers to reduce the ventilation flow rate or to stop the ventilation) in case of a fire.

The first tests were carried out and reported on in 2006. At the same time, the conditions for the entire test series were discussed, including how to support the experimental projects with analyses and code assessments. Further tests were carried out and reported upon as scheduled in 2007. Two meetings of the project steering bodies were held in April and in October 2007. The conditions for the entire test series were addressed in the meetings, including ways to support the experimental projects with analyses and code assessments. As requested by the project members, the French IRSN also prepared and submitted the plans and conditions for the four tests to be carried out in 2008, which were circulated among participants and subsequently revised according to the input received. These tests also involved facility modifications to meet specific members' requirements. PRISME Integral tests were carried out as per the schedule (these involved fire scenarios with the possibility to integrate specific devices and conditions).

Second phase (2011-2016)

The second phase (PRISME-2) was a follow-up of the first which provided valuable results to participants on room-to-room heat and smoke propagation, the effects of ventilation and the resulting thermal stresses to sensitive safety equipment in specific room configurations. As with phase one, phase two consisted of a series of fire and smoke propagation tests at the IRSN dedicated facility in Cadarache. Again, data from the project was used to study multi-room fires and for validation of fire computer codes.

The PRISME-2 project results addressed some outstanding safety issues particularly with respect to the appreciable uncertainties that exist in risk assessments for nuclear power plants due to gaps in knowledge and modelling capabilities on fire growth and propagation, on fire extinction phenomena, on the prediction of damage to equipment and on the treatment of plant and operator response to a fire event. Phase two also provided useful information on outstanding questions with respect to fire probabilistic safety assessments, in particular regarding how heat and smoke propagate from one room to another and the impact of smoke on safety-critical systems.

The technical program of phase two consisted of the following:

• experiments related to smoke and hot gas propagation through a horizontal opening between two superimposed compartments
• fire spreading scenarios on real fire sources such as cable trays and electrical cabinets and fire propagation from one fire source to another
• fire extinction studies of the performance of various extinguishing systems
• an open test campaign to build-upon and further investigate some of the phenomena from the earlier campaigns.

Third phase (2017-2021)

Phase three (PRISME-3) is a follow up of the two previous phases. The technical program of phase three consisted of the following:

• answer questions concerning smoke, fire and heat propagation inside a plant by means of experiments tailored for code validation purposes for fire modelling computer codes
• undertake experiments related to smoke and hot gas propagation, through a horizontal opening between two superimposed compartments
• provide information on heat transfer to cables and on cable damage
• provide information on the effectiveness of fire extinguishing systems.

PRISME-2 members' area (password protected | reminder)