Yablokov Chernobyl book

Yablokov & Nesterenko: Contamination through Time and Space 21of radioactivity ten times higher than the surroundingareas. The concentration density ofCs-137 can have several different values evenwithin the limits of the nutrient area of a singletree (Krasnov et al., 1997). In Poland, Ru-106was the predominant hot spot nuclide in 1986,although a few hot spots were due to Ba-140 orLa-140 (Rich, 1986).Figure 1.16. shows distinct large-scale spottyradioactive distribution of Sb, Cs, and Ag inareas of continental Greece.1.4.2. Problem of “Hot Particles”A fundamental complexity in estimating thelevels of Chernobyl radioactive contaminationis the problem of so-called “hot particles” or“Chernobyl dust.” When the reactor exploded,it expelled not only gases and aerosols (the productsof splitting of U (Cs-137, Sr-90, Pu, etc.),but also particles of U fuel melted togetherwith other radionuclides—firm hot particles.Near the Chernobyl NPP, heavy large particlesof U and Pu dropped out. Areas of Hungary,Germany, Finland, Poland, Bulgaria, andother European countries saw hot particles withan average size of about 15 μm. Their activitymostly was determined to be (UNSCEAR,2000) Zr-95 (half-life 35.1 days), La-140 (1.68days), and Ce-144 (284 days). Some hot particlesincluded beta-emitting radionuclides suchas Ru-103 and Ru-106 (39.3 and 368 days,respectively) and Ba-140 (12.7 days). Particleswith volatile elements that included I-131, Te-132, Cs-137, and Sb-126 (12.4 days) spreadover thousands of kilometers. “Liquid hot particles”were formed when radionuclides becameconcentrated in raindrops:“Hot particles” were found in new apartmenthouses in Kiev that were to be populated in theautumn of 1986. In April and May they stood withoutroofs or windows, so they absorbed a lot of aradioactive dust, which we found in concrete platesof walls and ceilings, in the carpenter’s room, underplastic covers on a floor, etc. For the most partthese houses are occupied by staff of the Chernobylatomic power station. While planning occupancythe special dosimeter commands I developed (Ithen was the deputy chief engineer of ChernobylNPP on radiation safety and was responsible forthe personnel in areas found to be contaminated)carried out a radiation check on the apartments. Asa result of these measurements I sent a report to theGovernmental Commission advising of the inadmissibilityof inhabiting these “dirty” apartments.The sanitation service of the Kiev municipality ...answered with a dishonest letter in which it agreedthat there was radioactivity in these apartments,but explained it away as dirt that was brought inby tenants.” (Karpan, 2007 by permission)Radioactivity of individual hot particlesreached 10 kBq. When absorbed into the body(with water, food, or inhaled air), such particlesgenerate high doses of radiation even ifan individual is in areas of low contamination.Fine particles (smaller than 1 μm) easilypenetrate the lungs, whereas larger ones(20–40 μm) are concentrated primarily in theupper respiratory system (Khruch et al., 1988;Ivanov et al., 1990; IAEA, 1994). Studies concerningthe peculiarities of the formation anddisintegration of hot particles, their properties,and their impact on the health of humans andother living organisms are meager and totallyinadequate.1.5. Changes in the RadionuclideDose SpectrumTo understand the impact of Chernobyl contaminationon public health and the environmentit is necessary to consider the essentialchanges in the radionuclide spectrum duringof the first days, weeks, months, and decadesafter the Chernobyl catastrophe. The maximumlevel of activity from Chernobyl’s falloutin the first days and weeks, which was duemostly to short-lived radionuclides, exceededbackground levels by more than 10,000-fold(Krishev and Ryazantsev, 2000; and many others).Today radioactive contamination is only a