Radioactive aerosols

CONTENTS o o o o o o o o o o o o o o o o o o o Preface xi 1 Radon 1 1.1 Physical properties 1 1.2 Radon in air - methods of measurement 3 1.3 Emanation of radon and thoron from the soil 5 1.4 Radon in air - variations in space and time 10 1.5 Radon indoors 12 1.6 Radon in mines 14 1.7 Thoron (220Rn) in air 14 1.8 Decay products of radon 15 1.9 Radon and thoron decay products as small ions 20 1.10 Mobility of decay products 23 1.11 Diffusivity of decay products 25 1.12 Attachment of decay products to nuclei 29 1.13 Deposition of decay products on surfaces 32 1.14 Potential alpha energy of unattached decay products 35 1.15 Radiation dose from inhalation of radon and decay products 39 1.16 Dose equivalent 45 1.17 Risk of cancer from inhalation of radon and decay products 46 1.18 Lead 210 and its daughter products 47 1.19 Residence time in atmosphere 48 1.20 Release of 210Po in accident to Windscale reactor 51 Appendix 1.1 52 Appendix 1.2 52 Appendix 1.3 53 References 53 2 Fission product aerosols 61 2.1 Process of fission 61 2.2 Major releases of fission products 64 2.3 Particle size and chemical fractionation 65 2.4 Emission from reactors 66 2.5 Windscale emissions, 1952-6 69 2.6 Windscale accident of October 1957 71 2.7 Accident to SL-1 reactor 77 2.8 Chemical explosion in USSR 77 2.9 Accident at Three Mile Island 80 2.10 Chernobyl accident 81 2.11 Deposition of fission products 90 2.12 Interception by foliage 95 2.13 Field loss of activity from foliage 98 viii Contents 2.14 Normalised specific activity 100 2.15 Transfer to milk 102 2.16 Transfer of fission products from soil to crops 106 References 108 3 Radioiodine 115 3.1 Formation in fission and release to atmosphere 115 3.2 Characterisation of radioiodine 117 3.3 Identification of penetrating forms of radioiodine 121 3.4 Environmental sampling of radioiodine 123 3.5 Particulate and gaseous stable iodine 125 3.6 Deposition of radioiodine to surfaces 127 3.7 Deposition of iodine in the field 129 3.8 Deposition near a reprocessing plant 133 3.9 Retention of 131I on herbage 134 3.10 Transfer of radioiodine to milk 136 3.11 131I in milk following single episodes of deposition 136 3.12 Dose to human thyroids from inhalation and from intake in milk 139 3.13 Relation between fallout of 131I and external gamma dose rate 141 References 148 4 Tritium 153 4.1 Definitions 153 4.2 Natural tritium 154 4.3 Tritium from weapons tests and reactors 154 4.4 Transport of HTO in the atmosphere 155 4.5 Deposition of HTO 159 4.6 Uptake of HTO by human body 163 4.7 Transport and deposition of HT 164 4.8 Field measurements of deposition of tritium gas 165 References 167 5 Plutonium 170 5.1 Formation of plutonium aerosols 170 5.2 Detection of airborne plutonium 176 5.3 Plutonium in the environment 178 5.4 The inhalation of plutonium 186 5.5 Entry of plutonium into diet 188 References 190 6 Mass transfer of radioactive vapours and aerosols 193 6.1 Application of radioactive measurement techniques 193 6.2 Notation 193 6.3 Conductances and resistances 195 6.4 Vapour transport to and from surfaces 196 6.5 Transport of small particles by Brownian diffusion 199 6.6 Deposition by impaction 200 6.7 Profiles of wind speed over extended surfaces 203 6.8 Profiles of vapour concentration over surfaces 206 6.9 Dependence of B~l on u* and z0 208 Contents ix 6.10 Deposition of particles to canopies in the wind tunnel 210 6.11 Field experiments on deposition of particles 215 6.12 Deposition of particles to forests 218 6.13 Resuspension of particles 219 6.14 Resuspension - wind-tunnel experiments 223 References 225 7 Studies with radioactive particles and human subjects 228 7.1 Introduction 228 7.2 Deposition of particles in the upper respiratory tract 230 7.3 Clearance of particles from the NP region 231 7.4 Deposition in the TB and P regions 232 7.5 Effect of smoking and of disease on mucociliary clearance 236 7.6 Clearance from the pulmonary region 236 7.7 Cigarette tar 237 7.8 Airborne lead from vehicle exhausts 238 7.9 Inhalation of lead aerosols 240 7.10 Radioactive labelling of exhaust lead 242 7.11 Deposition in the lungs of203 Pb-labelled exhaust particles 244 7.12 Clearance of 203Pb from the lung and transfer to blood 245 7.13 Contribution of petrol lead to blood lead 247 References 249 Index 253