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The PRISME-2 Project
Fire is a significant contributor to overall core damage
frequency for both new and old plant designs.
Some of the technical studies related to fire probabilistic
safety analysis (PSA) that remain open are
the following: the propagation of heat and smoke
through a horizontal opening between two superposed
compartments; fire spreading on real fire
sources such as cable trays and electrical cabinets;
and fire extinction studies of the performance of
various fire extinction systems.
The Fire Propagation in Elementary, Multi-room
Scenarios (PRISME-2) Project (from the French
Propagation d’un incendie pour des scénarios multi-locaux
élémentaires) is a follow-on project from the PRISME
project which ran from 2006 to 2011. A final report
of the PRISME Project was approved by the CSNI in
2012, and a concluding seminar was held in Aix-en-
Provence, France at the end of May 2012. This seminar
drew over 60 participants from 29 countries and
international organisations. The PRISME-2 Project
began in July 2011 and will run until June 2016. It
currently has nine participating countries. The
project’s objective is to answer questions concerning
smoke and heat propagation inside a plant by means
of experiments tailored for code validation purposes.
In particular, the project aims to provide answers
regarding the failure time for equipment situated in
nearby rooms and the effect of conditions such as
room-to-room communication and the configuration
of the ventilation network. The results obtained for
the experimentally studied scenarios will be used
as a basis for qualifying fire codes (either simplified
zone model codes or computational fluid dynamics
codes). After qualification, these codes could
be applied for simulating other fire propagation
scenarios in various room configurations with a
good degree of confidence.
The first experimental test campaign for
the PRISME-2 Project (vertical heat and smoke
propagation from one compartment to another) was
completed in 2012 at the IRSN experimental facilities
in Cadarache. The second test campaign (electrical
cabinet and cable fires) is now also well underway.
In 2012, meetings of the PRISME-2 management
board and programme review group took place
in May and November. Additionally, the project’s
analytical working group has been constituted and
has begun a series of benchmark exercises needed to
conduct cross-comparisons and validations of code
modelling approaches. At least three benchmark
exercises will be conducted as part of the PRISME-2
Project.
The ROSA-2 Project
A first Rig-of-safety Assessment (ROSA) Project was
carried out from 2005 to 2009 to address issues
in thermal-hydraulics analyses relevant to LWR
safety using the ROSA large-scale test facility of the
Japan Atomic Energy Agency (JAEA). In particular, it
focused on the validation of simulation models and
methods for complex phenomena that may occur
JAEA, Japan
The ROSA large-scale test facility (LSTF).
during transients/accidents. The project was supported
by safety organisations, research laboratories
and industry in 14 countries, and provided an integral
and separate-effect experimental database to
validate the code predictive capability and accuracy
of models. In particular, temperature stratification
and coolant mixing during emergency coolant injection,
unstable and disruptive phenomena such as
water hammer, natural circulation under high core
power conditions, natural circulation with superheated
steam, primary cooling through steam generator
secondary depressurisation, and upper-head
break and bottom break LOCA were addressed by
the 12 tests carried out. The project was successfully
completed and the final report was released on DVD.
A second phase of the project, called ROSA-2
and using the same large-scale test facility, started
in April 2009 with the support of 14 countries. The
ROSA-2 Project was scheduled to last for three years
(extended by six months due to the Fukushima
Daiichi accident) and to consist of six tests on:
• intermediate break LOCAs (for risk-informed,
break-size definition and verification of safety
analysis codes);
• steam generator tube rupture (SGTR) and SGTR
with steam line break (for improvement and new
proposals regarding accident management and
mitigation/emergency operation).
All six tests have been successfully performed,
including two counterpart tests with PKL. The recent
participation of China, which joined as an associate
member, enabled a seventh test based on an intermediate
cold leg break LOCA with full availability of
the emergency core cooling system.
As mentioned above, a joint PKL-2/ROSA-2 workshop
was organised on 15-19 October 2012 and
included a presentation and discussion of the two
counterpart tests and the related analytical work.
NEA Annual Report 2012
37