The aim of a scientific and technical report is to present scientific results obtained during the past 12 month period. It is not intended to be exhaustive, in contrast to the annual report, but rather stresses actions conducted in a programme that has terminated, or one that has reached a particularly important step in its development. The 2005 report covers the period from mid-2004 to mid-2005.
Research, Assessment, Transmission of Knowledge
The complete restructuring of the Institute, begun in 2003, enabled us to fully rethink such issues as the Institute’s scientific and technical excellence.
Ionising Radiation and Human Health
We and our environment are constantly exposed to sources of ionising radiation, whether natural or artificial. In addition to this chronic exposure, there are also cases of occasional exposure, most of which are the result of incidents or accidents that occur during nuclear activities or the result of doses received by patients during medical treatments.
Radioactivity and Environment
Radioecology, or the study of environmental radioactivity and its effects on human health and ecosystems, is one of IRSN’s longstanding areas of excellence. This part of the report will outline the wide range of projects recently carried out by the IRSN. This work is part of a strategy to better describe, explain and anticipate environmental radiology and how it will develop in space and time, and to understand the mechanims involved.
Safety of the Geological Disposal of Radioactive Waste
Certain types of waste generated by industrial activity contain radionuclides with periods spanning tens or thousands of years, if not more, that can in no way be compared with the duration of human lives. This is the case of waste from the reprocessing of the spent fuel discharged from electronuclear reactors. To protect the biosphere throughout the duration of their potential nuisance, which is about 10 to 20 times the period of the radionuclides contained in them, the international nuclear scientific and technical community has, for the past 50 years, been studying the possibility to dispose of this waste in a deep rocky layer that is geologically stable.
Safety of Facilities, Accident Scenarios
The safety assessment of a nuclear facility (or industrial facility) is inherently a questioning of the validity of the arguments put forward by the operator to justify the design and operating conditions for this facility. These questions regularly highlight “grey areas” which require further investigations. This leads to research being carried out either by the operators or directly by the IRSN (to assess the pertinence of the questions raised), or by both, inasmuch as safety issues tend to be a general concern shared by all.
Severe Accidents and Crisis Anticipation
The probability of a severe accident leading to reactor core meltdown is low because the occurrence of such an accident would require the combination of a number of failures, in particular safety system failures. However, this low probability is offset by the gravity of the consequences if a release of radioactive substances into the environment were to occur. That is why the IRSN placed a great deal of emphasis on the study of this type of accident.