IRPA Europe 2006 Paris poster

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A Chernobyl Lesson for Aerial Monitoring: Integration of Passive Measurements with Active Sampling in the Emergency Early Phase. D. Castelluccio1, S. Chiavarini2, E. Cisbani1, U. Delprato3, G. Fragasso4, R. Fratoni1, S. Frullani1, M. Gaddini5, F. Giuliani1, C. Marchiori6, A. Mostarda1, G. Paoloni6, E. Pianese5, L. Pierangeli1, A. Sbuelz7, G. Siciliano4, P. Veneroni1 1Technologies and Health Department, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161-Rome, Italy 2Centro Ricerche della Casaccia, ENEA, 00100-S. Maria di Galeria-Rome, Italy 3IES Solutions srl, Via del Babuino 99, 00187- Rome, Italy 4Galileo Avionica S.p.A., Via Albert Einstein 35, 50010-Campi di Bisenzio (FI), Italy 5Central Direction for Emergency and Technical Rescue, Ministry of Interior, Piazza Scilla 2, 00178-Rome, Italy 6Dipartimento di Meccanica e Aeronautica, Facoltà di Ingegneria, Università di Roma “La Sapienza”, Via Eudossiana 18, 00184 Rome, Italy 7Iniziative Industriali Italiane S.p.A., Viale Gorizia 6, 00198-Rome, Italy During the the Chernobyl accident in many European countries the radioactive contamination has been extensively measured using monitoring systems mounted in aircraft in order to map, in a relatively short time, large fractions of the affected areas. In Italy, a detection system consisting of a large (16”x4”x4”) NaI(Tl) module, mounted in an anti-vibrating frame under the fuselage of an Agusta-Bell 412 helicopter with the control and acquisition system installed on board hosted in the space made available with the removal of a row of seats, has been used. Several missions have been made, between the beginning of May and mid June, covering large portions of the Centre-Sud of Italy. While the presence of contamination was clearly seen since the first mission and the identification of the main radioisotope groups present, as well as the change in their composition with the time, was possible, A QUANTITATIVE ASSESSMENT ON THE CONTAMINATION PARAMETERS HAD NOT BEEN POSSIBLE UNTIL THE MISSION OF MAY 21ST. QUANTITATIVE MEASUREMENTS WERE ONLY POSSIBLE WHEN RADIOACTIVE CLOUD CONTRIBUTION BECAME NEGLIGIBLE. WHEN THE RADIOACTIVE PLUME IS CROSSING, A DIFFERENT TOOL FOR EMERGENCY SHOULD BE PROVIDED. AN AERIAL PLATFORM INSTRUMENTED FOR IN-PLUME MEASUREMENTS, AIMING TO CHARACTERIZE THE EXTENSION, COMPOSITION AND CONCENTRATION OF THE RADIOACTIVE MIXTURE IN THE PLUME, AS WELL AS TO MEASURE IN SITU METEOROLOGICAL PARAMETERS COULD BE OF INVALUABLE HELP IN THE EMERGENCY EARLY PHASE. The aircraft is equipped with a sampling unit. A representative sampling of aerosol is provided through a control system that regulates the air flow according to the aeroplane speed and compensates for temperature and pressure variations as well as for the filter progressive clogging. The flow regulation valve, actuated by a dedicated motor according to a control loop implemented by the supervising microprocessor performs this function. The flow of the aerosol along the sampling line, through a iris shutter valve, reaches the filter that is in working position. The aerosol is collected on the filter, while the carrier gas is driven behind the filter and through a flow regulation valve reaches the exhaust line, after a Venturi throat. The rotating filter holder has four filter locations, one for each of the possible independent aerosol collections during the same flight mission. Behind the filter that is aligned with the suction line, a Geiger counter and a small (1 cm3) BGO counter, allow real-time measurements of gross-beta activity, total gamma activity and low resolution gamma spectra. Beta counter scaler and gamma spectra are stored in predetermined time intervals. The occurrance of anomalous levels, predefined or chosen during the mission, generates an alarm flag popping out on the pilot screen. A large HPGe detector, featuring high resolution, has been located so that it faces the position reached by the filter previously used for sampling after the 90º rotation of the filter disk. In this way, at the end of one sampling period, it is possible to identify each gamma emitting radionuclide in the aerosol sample previously collected. The HPGe was specially designed to take into account the geometrical constraints imposed by the particular application. On the rear of the aircraft, a large volume NaI(Tl) counter is placed to collect gamma spectra from the total environment. From the information collected by this counter, after subtraction of the contribution from the air contamination, that can be inferred from the HPGe measurements, assessment on the ground contamination can be deduced even in the early phase when the plume, coming from a release from a far plant, cross over the interested country. A project to equip a UAV (Unmanned Air-Vehicle) with a similar sampling unit is under study in order to face near field emergency situation.

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