Direct determination of 90Sr and 147Pm in Chernobyl hot particles collected in Kiev using beta absorption method.

59 hot particles were collected in Kiev, Ukraine, in 1987. All but one were prepared from a moss carpet of 360 cm{sup 2} area. Radionuclide composition of the hot particles was investigated by gamma-spectrometry and beta absorption method. Pure beta emitters {sup 90}Sr and {sup 147}Pm were determined in 25 hot particles measuring the beta absorption curves of the hot particles with an end-window Geiger-Mueller counter and decomposing the curves in order to obtain the contributions of {sup 90}Sr and {sup 147}Pm to the total beta counting rate. All but one of the hot particles were found to be the debris of the fuel. The activity ratio {sup 90}Sr:{sup 144}Ce was 0.078 which is half of the theoretical result. Although {sup 147}Pm is considered to be a refractory nuclide, it seems that significant part of {sup 147}Pm went to the homogeneous fraction of the general fallout. The surface density of hot particles (of higher than about 50 Bq activity) was about 1,600 m{sup -2} and that of the activities of the nuclides {sup 90}Sr, {sup 106}Ru, {sup 134}Cs, {sup 137}Cs, {sup 144}Ce and {sup 147}Pm as components of hot particles was 12.2, 54.3, 5.9, 9.7, 234 and 18.3 kBq m{supmore » -2} (activity values counted for 26 April 1986), respectively, in downtown Kiev city in 1987.« less