Monotoring of radioactivity in deposition. Results for 1990

Abstract niet beschikbaarThis report presents the results of measurements of radionuclides deposited in the Netherlands (Bilthoven) in 1990. Measurements were carried out to determine the weekly activities of gamma-emitters, of H-3 (on a weekly basis) and of Pb-210 and Po-210 (on a monthly basis). The gross alpha, gross beta and gross gamma-activity were also determined on a weekly basis. The yearly average concentration of H-3 in rain was 1.8 +- 0.2 kBq/m3, lower than in 1989. The total deposition of H-3 was 1360 +- 120 Bq/m2, which is lower than in the period 1985 - 1989. The total deposition of Be-7 was 810 +- 36 Bq/m2, slightly higher than in 1989. The weekly deposition of Cs-134 was always below the detection limit of 0.05 Bq/m2. The total activity of Cs-137 in deposition was less than 5.5 Bq/m2. The total depositions of the natural radionuclides Pb-210 and Po-210 were 85 +- 4 Bq/m2 respectively 16 +- 2 Bq/m2. These values are below those found in 1989. In 1990 the gross alpha-activity in deposition was 68 +- 1 Bq/m2, which is slightly higher than in previous years. The gross beta-activity in deposition was 121 +- 4 Bq/m2, which is also higher than the value found in 1989. The gross gamma-activity was 109 +- 4 Bq/m2. This was lower than in the years 1985 - 1989.HIMH/T