10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Improvement of Monitoring of Radioactive Aerosols of Ground-Level Air near Chernobyl NPP
ALEXANDR KALYNOVSKYI, Victor Krasnov, Boris Ogorodnikov, Institute NSP NPP, Ukraine
Abstract Number: 340 Working Group: Control and Mitigation
Abstract In order to control a work safety in areas erection of new safe confinement "ARKA" construction and staff’s location near Chernobyl NPP (ChNPP) the radioactive aerosols (RA) of ground-level air were monitored. Sampling of aerosols was carried out by pumping air through filters FPP-15-1.5 which had area about 0.8 m2. Average filtration rate was 8 - 12 000 m3/day. The consist and activity of radionuclides in aerosols was determined by gamma spectrometer (CANBERRA). The concentration of 137Cs was varied within 1.1 · 10-4 - 2.3 · 10-1 Bq/m3, 154Eu - 2.8 · 10-7 - 1.4 · 10-3 Bq/m3, 241Am - 1.6 · 10-6 - 1.3 · 10-2 Bq/m3. The specific content of dust varied in range 3.2 · 10-3 - 1.6 · 10-1 mg/m3.
Researches of collecting aerosols using filter compositions from fibrous materials was carried out to improve informational data and reliability of monitoring. This researches included.
1. Laboratory studies of filter properties of composite materials are fulfilled at increased linear air flow rate (80 and 160 cm/s), where, first layer (prefilter) was coarse-fiber FPP-70-0.3, PET-100-0.02 and FPS-110-0.2, second - thin-fiber FPP-15-1.5. By analysis results of experiments data was revealed possibility of qualitative estimation of aerosol dispersion and were obtained mathematical models of filter resistance growth due to dust accumulation, which helped to determine that composition FPS-110-0.2 and FPP-15-1.2 is optimal.
2. Real sampling of aerosols by two-layer filters was performed on a regular air sampling system of near ChNPP. The natural 7Be, 210Pb and 212Pb were markers of submicron aerosols. Based on studies results carried out qualitative assessment of aerosol dispersion, which showed that radionuclides of Chernobyl’s genesis of 137Cs, 154Eu, 241Am were mainly on aerosols with AMAD more than 1 μm.
Analysis studies results showed that, firstly, aerosols distribution over the composite filter’s layers depends on type of fibrous material of first layer and weather conditions during sampling of air. Secondly, prefilter assumes main dust load during intensive construction, erection works and earthworks. As FPP-15-1.5 filter is clogged more slowly with dust and that increased a lifetime of sampling system.
Using the filters composition in observing passage of radioactive cloud from the accident Fukushima-1 NPP in Ukraine from March 24 to May 16, 2011 allowed us to say that 134Cs and 131I were in air on submicron particles.