Objective The aim of the project is to adapt an existing radioactive aerosol calibration installation, ICARE, at the Saclay Nuclear Research Centre (CEA), in order to provide precise activity concentrations of 222Rn and its short life decay products that may be used to calibrate measuring instruments. An existing radioactive aerosol calibration installation was adapted to provide precise activity concentrations of radon-222 and its short lived decay products to be used to calibrate instruments employed in measuring natural radioactivity. A new radon gas injection line, which includes 3 standard solid sources of radon-222 and a container for reference measurement of radon volume activity, enables the entire desired range of radon-222 volume activity, from 4 Bq m{-3} to 4000 Bq m{-3}, to be provided in the test chamber.A pneumatic collison type nebulizer generates caesium chloride particles to carry a part of the radon decay products. The particles concentration of this aerosol can be adjusted by a system filtering a part of the particles in the airflow. Two radon decay product samplers are located before the inlet of the test chamber in order to simultaneously measure the deposited activity of radon free fraction and attached fraction decay products by alpha counter. The signals are analyzed by a new computing system, DECADE, which gives the volume activity, potential alpha energy concentration and relative uncertainty of these values for each decay product, the equilibrium factor and the percentage of attached radon decay products.A series of sequential and continuous measurements of radon by an ionization chamber, connected to the test chamber outlet, confirm a very good stability and reproducibility of the concentration.ICARE is currently being used for the certification of instruments employed in measurement of artificial radioactive particulate airborne contamination. ICARE is essentially a wind tunnel in which aerosols calibrated in size and labelled with 137Cs or 239Pu are injected upstream of the test section. To extend ICARE's field of application to the case of instruments employed in measurement of natural radioactivity, a new line of injection has been designed during 1989 including three standard sources of 222Rn and a reference device for the activity concentration measurements of this gas. These new processes and devices are covered in two patent applications. The supplementary test bench equipment used to produce and measure 222Rn decay products, and the instrument test chamber, are subject to a second CEC contract in 1990. The new system will be designed for: producing aerosols, size and number concentration calibrated, to carry a fraction of radon daughters; the AMAD of this fraction being representative of environmental conditions (0.2 to 0.3 um), and the attached fraction adjustable from a few percent to 100%; measuring the three daughters activity concentrations and potential alpha energies, using a computing system and a new software based on a mathematical deconvolution of the scintillation counting of alpha particles deposited on two sampling filters located downstream from the ageing volume; allowing the calibration tests of instruments either inside a chamber for the smallest ones or outside for the biggest ones, the velocity of the chamber air flow being adjustable up to 5 cm/s and the activity concentration of 222Rn from 4 to 4000 Bq/m{2}. Fields of science natural scienceschemical sciencesinorganic chemistrynoble gasesnatural sciencescomputer and information sciencessoftwareengineering and technologymechanical engineeringvehicle engineeringaerospace engineeringaircraft Programme(s) FP1-RADPROT 6C - Multiannual research and training programme (Euratom) in the field of radiation protection, 1985-1989 Topic(s) Data not available Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator Commissariat à l'Energie Atomique (CEA) EU contribution No data Address Centre d'Études de Fontenay-aux-Roses 60-68 avenue du Général Leclerc 92265 Fontenay-aux-Roses France See on map Total cost No data
