At the beginning of 2001, IRSN launched a new research program called "ENVIRHOM", aimed at studying radionuclide bioaccumulation processes and the induced biological effects on living plant, animal, and human organisms under chronic exposure conditions.
Works conducted by the LRE (literature reviews, experiments and associated modelling), within SERLAB, are designed to acquire and complete knowledge required to assess the risk associated with the presence or emission – actual or forecast - of radionuclides in a continental environment under chronic or accident exposure conditions. These works are intended to generate or analyse currently lacking data regarding bioaccumulation and dose effect relationships in ecosystems and simultaneously improve knowledge concerning the transfer of radionuclides in a continental environment, notably knowledge necessary to assess repercussions and the health risk for humankind. The long-term objective is to offer and implement a general method intended to broaden the assessment of ecological risks to include radioactive substances, in association with the development of LMODE's modelling platform, SYMBIOSE.
Thus, LRE's research and development is organised around three closely linked main themes:
· Theme 1: The biogeochemical behaviour of radionuclides in the "reservoir" compartments of ecosystems – soils and sediments.
· Theme 2: Bioavailability of radionuclides and biological impact: terrestrial aquatic vegetable models.
· Theme 3: Bioavailabiltiy and biological impact: animal models and consideration of the trophic relationship.
Most projects involving these themes fall within the context of the research problems, issues and strategy of the ENVIRHOM programme. Furthermore, a significant number of said projects were performed in the framework of a joint research programme conducted with EDF (CT4) and ANDRA (collaboration agreement). The majority of works performed in collaboration with operators had clear operational objectives, and involved experiments mainly designed to establish and/or specify values for base parameters (transfer coefficients such as Kd, foliar transfer factor, etc.) used by impact models.
-> Reactivity of radionuclides and trace metals in an estuarine environment.
-> Physical-chemical behavior of cobalt-60 in effluent released to the sea by the La Hague nuclear fuel reprocessing plant.
-> Biological experiments: studies of transfer processes to living organisms.