Search - Issue 31 - MONITORING OF RADIOACTIVE AEROSOL RELEASES FROM

MONITORING OF RADIOACTIVE AEROSOL RELEASES FROM
DOI: https://doi.org/10.31717/1813-3584.18.31.8
Cover not present MONITORING OF RADIOACTIVE AEROSOL RELEASES FROM
Category: Issue 31
Publication: 31
Summary

The results of monitoring of radioactive aerosol emissions from the “Ukryttya” object in 2017 are addressed. The maximum value of unorganized release rate was observed in December and made 0,94 MBq/day. After the Arch was installed in its design position, a change occurred in scattering mechanism of particles being released into the environment. In the year of 2017, average daily specific density of radioactive particles precipitation on the light roofing totalled 1.6 kBq/(m2∙day), which was higher than in the previous years. Increase in release intensity of radioactive particle on the “Ukryttya” object’s light roofing is provided by implementation of building and assembly works under NSC Arch. The concentration of sum of long-lived beta-emitting aerosols entering the atmosphere through the Bypass system was, as a rule, within the range of 0.5 – 1 Bq/m3 (maximum concentration 2.7 Bq/m3). Stable trend is observed in reducing the sum of long-lived beta-emitting aerosols in unorganized releases through «Bypass» system. Aerosols sampling and their in-size classification was carried out with using 5-cascade impactor. This facility makes aerosol particle sorting for five aerodynamic diameter ranges. As the fifth cascade, finely dispersed filter is used. It allows more fully retaining submicron size aerosols. Their carriers were the particles with 5 – 10 μm active median aerodynamic diameter. Mean value over 2017 year made 8,9 mkm. During Arch installation in design position and erection of NSC enclosure contour in the years of 2016 - 2017, the share of large-sized particles in aerosol summary activities was essentially increasing as compared to the year of 2015. Airflow movement within “Bypass” system bears unstable character. In 2017 year, airflow direction inside the “Ukryttya” object was prevailing.

Keywords: New Safe Confinement, “Ukryttya” object, aerosols, volume activity, activity median aerodynamic diameter.

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