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'Radiation & Risk", 1993, issue 3 [17]. The results presented here allow independent estimation of 131 l deposition densities for Byelorus too and this enabled us to define more exactly the isopleths for both the Bryansk and Smolensk regions of Russia. Therefore, the pre • .;"'«J .!•' . l
'Radiation & Risk*, 1993, issue 3 Another major problem is the reconstruction of time history of the 131 l contamination in the CIS countries. The preliminary studies using the model of atmospheric turbulent diffusion of radioactive material developed in ICC of SPA "Typhoon" (presented in the first part of the issue) show a significantly different nature of contamination of I in the territories of Byelorus and Russia between isotope transport in aerosol and gas form. Obtaining more definitive data about the 131 l contamination dynamics over the territories of CIS is the goal of our future study. By comparing to 137 Cs we have reconstructed the activities of major short-lived radionuclides for all the settlements of Russia (except the Leningrad region which was beyond the analyzed coordinate corridor) in which 137 Cs levels were measured. The activities of some radionuclides reconstructed from different data differ significantly, and in such a case we give preference to the regression coefficient with a greater correlation coefficient. Figs. 32-34 illustrate activities reconstructed by this method and confidence limits for Novozybkov and Zlynka, Bryansk region and Zhizdra, Kaluga region. In estimation of confidence limits for activities reconstructed by 137 Cs account was taken of the spread of 137 Cs activir ties in the settlement. The above mentioned figures compare measured deposition densities of some radi Scientific Articles onuclides in these towns and reconstructed values. The confidence intervals for reconstructed deposition densities were estimated by the spread of measured activities of radionuclides used in the estimates. As can be seen from the figure the results of the reconstruction are quite satisfactory. The method for reconstructing the deposition density of short-lived radionuclides 132 Te, 133 l, 136 141 143 M Cs, Ce, Ce, M6 will be presented in our next work. Thus the statistical analysis of gammaspectrometry data of soil samples revealed relationships between activities of radionuclides deposited on the territory of Russia after the Chernobyl accident. The relieved relationships allow reconstruction of radionuclide depositions in Russia which later can be used as a basis for reconstructing absorbed external doses for people the contaminated areas of Russia. The authors are thankful to specialists of SPA Typhoon" V.S.Kosykh, A.V.Golubenkov, R.V. Borodin, A.N.Silanfev, M.Yu.Orlov, V.P. Snykov, L.P.Bochkov whose developments and collaboration has made a significant contribution to this work. We are also indebted to A.M. Ziborov for useful discussion of some aspects of the problem and providing references and literature data on radionuclide activities accumulated at the Chernobyl plant by the accident time. Fig. 32. Comparison of measured and reconstructed deposition densities of various radionuclides in Novosybkov, Bryansk region. Measured deposition densities are shown with the spread of values left to each radionuclide; boxes which are hatched more densely indicate both reconstructed values and that spread. An asterisk (*) next to the name of radionuclide means that deposition density was estimated for parent and daughter radionuclides. Deposition densities are reconstructed primarily by 137 Cs (last box in the group). Additionally ,w Ba deposition density is estimated by "°Ru. 68 "Radiation & Risk", 1993, issue 3 Ci/km' * 103 Bu 106 Rul * Scientific Articles 125 Sbj Fig. 33. Comparison of measured and reconstructed deposition densities of various radionuclides in Zlynka, Bryansk region. Symbols are the same as in Fig. 32. Additionally 10S Ru deposition density was estimated by measured 103 Ru deposition density. Ci/kin 2 Fig. 34. Comparison of measured and reconstructed deposition densities of various radionuclides in Zhisdra, Kaluga region. Symbols are the same as in Fig. 32. Additionally ,40 Ba deposition density was estimated by measured 103 Ru deposition density. The results of the work should be used with allowance for estimated confidence intervals which are not small in all the cases. The authors would appreciate if specialists suggest additions or corrections to the results, since the task of 69 i U reconstructing radiation parameters at an early stage of the Chernobyl accident is of major importance. Our work has made a small contribution to the solution of these problems. It will take a lot of joint efforts to reconstruct absorbed
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