IRSN, Institut de radioprotection et de sûreté nucléaire

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Scientific news - 1st semester 2006




Two former IRSN doctorate students receive SFEN awards
On 13 June, two former IRSN doctorate students each received an award from the SFEN – the French Nuclear Energy Society – for their theses completed in 2005.

Patrick Roux was awarded the “Jean Bourgeois” prize for his work on “Modélisation de la solidification colonnaire et équiaxe de mélanges binaires” (Modelling columnar/equiax transition in the solidification of binary mixtures), in the field of research on the behaviour of corium at the bottom of the vessel and its solidification in the event of a serious reactor accident. Based on his model, a computer code has been developed and validated by several experimental test cases. In particular, this should serve to enhance the Astec and Icare/Cathare codes used by the IRSN to simulate an entire accident sequence. Since completing his thesis, Patrick Roux has been working at the CEA (French Atomic Energy Commission).
Frédéric Péralès received a special distinction for his thesis on the “Modélisation et simulation numérique de l’amorçage et de la propagation de fissures dans les gaines de combustible lors de transitoires accidentels de type RIA” (Digital simulation and modelling of initiation and propagation of fissuring in fuel cladding during RIA accidental transients), which sets out to understand and predict fissuring phenomena in Zircaloy cladding subjected to the effects of a high burning rate. Since finishing his thesis, Frédéric Péralès has been working at one of IRSN’s laboratories.
Radiological protection and environment

Chernobyl Gardens
At the beginning of the spring, as has happened every year since 2000, fresh seeds will be sown in open field plots located near to the reactor in Chernobyl, in an area that was seriously affected by radioactive fallout after the accident. Planting these crops is part of an experimental programme developed by the IRSN's Radioecology and Ecotoxicology Laboratory (LRE) in partnership with the Ukrainian Institute of Agricultural Radiology in Kiev and which is scheduled to continue until 2007.
Nuclear safety
First EPICUR tests
Since its commissioning in May last year, the new EPICUR installation has already been used to conduct eight experiments for the SOURCE TERM international research programme. This programme aims to reduce uncertainties in the evaluation of releases of radioactive products into the environment in the event of a core meltdown accident in a water reactor.
Radiation protection and human health and environment
Second progress report on the chronic contamination to low-level radionuclides (ENVIRHOM)
IRSN publishes the second progress report of the ENVIRHOM programme, with the first results obtained for uranium, for both 'Environmental' and 'Health' aspects. ENVIRHOM is aimed at bringing together human health and environmental specialists to observe the effects of very low-level chronic exposure to radionuclides.

Nuclear safety
Specific agreement signed with CNRS-LATP


On February 9, 2006, IRSN's Fires, Corium and Containment Department (SEMIC) signed a cooperation agreement with LATP, a CNRS-University of Provence joint laboratory, specialising in analysis, topology and probabilities.
The agreement concerns the study of numerical methods for solving fluid mechanics problems, including:

  • methods for solving Navier-Stokes equations for incompressible or low-Mach-number flows,
  • numerical methods for simulating fires,
  • numerical methods for simulating two-phase flow, either directly (using diffuse-interface models) or on a macroscopic scale, after calculating an average,
  • schemes for solving hyperbolic systems, in particular for simulating shallow flows (radionuclide transport in rivers and estuaries).
Framework agreement signed with ENS Cachan
On December 15, 2005, IRSN signed a framework agreement for scientific cooperation with the ENS higher education institute in Cachan. The agreement provides for cooperation with several ENS laboratories. Work with LMT (laboratory of mechanics and technology) will focus on the mechanics of solids and structures, experimental aspects of materials, numerical simulation and structural computing in the fields of mechanical engineering, materials, civil engineering and the environment. With CMLA (centre for mathematics and its applications), IRSN will study applied analysis (applied to physics, geometry and mechanics), applied probabilities (combinatorial optimisation, image analysis), wavelets, numerical analysis, scientific computing, modelling, control theory and some questions related to parallel computing. Lastly, work with the Institut d'Alembert will focus on physics, chemistry, biochemistry and, in particular, molecular photonics and its applications in the related fields of information technology and biotechnology.
Radiation protection and human health
Occupational exposure to ionizing radiation
IRSN has just published its annual report on occupational exposure to ionizing radiation. Collective doses have been falling since the late 1990s and this year is no exception, although slight variations can be seen from one sector of activity to another.
Radiation protection and environment 
Pollutants under surveillance
At the end of 2005, the Mediterranean Mussel Watch, the network set up for the surveillance of radioactive pollutants (and of Cs137 in particular) around the Mediterranean coast and the Black Sea, completed its first technical stage, in the form of an exercise in the intercomparison of measurements. Conceived in 2002 by the International Commission for the Scientific Exploration of the Mediterranean Sea (CIESM) and coordinated by the IRSN, surveillance carried out by this new network is based on analysis of the Mytilus galloprovincialis mussel as the unique bioindicator. Furthermore, in order to be able to correctly analyse and compare the results of the measurements provided by the various laboratories that form the network, it needs to know the comparable technical characteristics of all the laboratories involved.
Thanks to this, it has been possible to perform the intercomparison exercise, coordinated by the International Atomic Energy Agency (IAEA) laboratory in Monaco: the 15 laboratories that are members of the network (plus the 15 IAEA reference laboratories) performed gamma and alpha spectrometric measurements on the same reference sample. These initial measurements have been fed into the network’s database, which will be available on the Net and regularly updated with surveillance data. In 2006, the network will continue to expand, in geographic terms, across the Mediterranean, in particular by transplanting mussels to areas where the species is rare (Syria, Israel, Egypt and Tunisia).

Nuclear safety
Agreement signed between the IRSN and the LCPC


On 12 December 2005, the IRSN and the LCPC (Laboratoire central des ponts et chaussées - the French Public Works Research Laboratory) signed an agreement on scientific and technical cooperation. Within the framework of this agreement, it will be possible to develop various topics for potential joint research, concerning structural analysis, particularly of concrete: the behaviour of civil engineering materials, seismic risks, structural reinforcement processes and underground structures. A first, specific, agreement concerning coupling, cracking and creep of concrete in tension is also in the process of being signed. This latter action is being developed within the framework of the Nanthilde Reviron‘s IRSN/DSR/SAMS/BAGS thesis.