¹³⁷Cs in Urine of Tourists Who Visited Kiev Late in April, 1986. —Estimation of the Intake of ¹³⁷Cs and ²³⁹Pu Due to the Nuclear Reactor Accident—

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Gamma-ray spectrometry analysis was made of urine samples from 43 tourists who had visited Kiev late in April, 1986. Seven of 43 samples contained significant amounts of ¹³⁷Cs ranging in concentration from 0.14 to 0.40 pCi/ml along with other fission products. The initial intake of ¹³⁷Cs was estimated to be 50 to 230 nCi, which would result in a rise of the level of ¹³⁷Cs retention up to two orders of magnitude.
Tourists'' baggage was also submitted to gamma-ray spectrometry analysis at NIRS^*. The results suggested the presence of ²³⁹Np in air in Kiev and the possibility of the inhalation of its daughter nuclides by tourists. The intake of ²³⁹Pu was estimated to be 220 to 1400 pCi from each estimated value of the ²³⁹Pu/ 239Np radioactivity ratio in the fuel, the 239Np/ ¹³⁷Cs ratio in air and the ¹³⁷Cs body burden.