Investigation of the Environmental Fate of Tritium in the Atmosphere

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INVESTIGATION OF THE ENVIRONMENTAL FATE OF TRITIUM IN THE ATMOSPHERE Investigation of the Environmental Fate of Tritium in the Atmosphere © Minister of Public Works and Government Services Canada 2009 Catalogue number CC172-51/2009E-PDF ISBN 978-1-100-13928-9 Published by the Canadian Nuclear Safety Commission (CNSC) Catalogue number: INFO-0792 Report prepared for the CNSC by ECOMETRIX Incorporated in association with RWDI Air Inc. (RSP-0247), March 2009. Extracts from this document may be reproduced for individual use without permission provided the source is fully acknowledged. However, reproduction in whole or in part for purposes of resale or redistribution requires prior written permission from the Canadian Nuclear Safety Commission. Également publié en français sous le titre de : Le devenir environnemental du tritium dans l’atmosphère Document availability This document can be viewed on the CNSC Web site at nuclearsafety.gc.ca. To order a printed copy of the document in English or French, please contact: Canadian Nuclear Safety Commission 280 Slater Street P.O. Box 1046, Station B Ottawa, Ontario K1P 5S9 CANADA Tel.: 613-995-5894 or 1-800-668-5284 (in Canada only) Facsimile: 613-995-5086 E-mail: info@cnsc-ccsn.gc.ca Web site: nuclearsafety.gc.ca Cover images The cover images depict the tritium cycle in the atmosphere. Tritium is released from the stack and disperses in the air. It is then deposited on vegetation and soil by rainfall (washout) or through vapour exchange. The tritium may then be re-emitted from the plants and soil to the atmosphere. b
TABLE OF CONTENTS INVESTIGATION OF THE ENVIRONMENTAL FATE OF TRITIUM IN THE ATMOSPHERE EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.0 SOURCES AND CHEMICAL FORMS OF TRITIUM . . . . . . . . . . . . . . . . . . . . 4 2.1 Chemical Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Natural Abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.3 Natural Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.4 Anthropogenic Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.4.1 Thermonuclear Detonation during Nuclear Weapons Testing . . . . . . . . . . . . 7 2.4.2 Nuclear Reactors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.4.2.1 Pressurized Water Reactors (PWRs) . . . . . . . . . . . . . . . . . . . . . . . 13 2.4.2.2 Boiling Water Reactors (BWRs) . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.4.2.3 Heavy Water Reactors (HWRs) . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.4.2.4 Gas-Cooled Reactors (GCRs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.4.2.5 Airborne Tritium Releases from Reactors . . . . . . . . . . . . . . . . . . . 19 2.4.2.6 Liquid Tritium Releases from Reactors . . . . . . . . . . . . . . . . . . . . . 19 2.4.2.7 Controlled Thermonuclear (or Fusion) Reactors . . . . . . . . . . . . . . 19 2.4.2.8 Influence of Cooling Water Systems on Tritium Release . . . . . . . . 20 2.4.3 Fuel Reprocessing Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4.4 Tritium Production Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4.5 Consumer Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.0 PHYSICAL AND CHEMICAL BEHAVIOUR OF TRITIUM IN THE ATMOSPHERE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.1 Physical Behaviour Of Tritium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.1.1 Radioactive Decay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.1.2 Other Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.1.3 Mobility in the Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 3.2 Chemical Transformations of Tritium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2.1 Tritium Transformation from HT to HTO . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3.2.2 Soil Oxidation of Tritiated CH4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3.3 Tritium Behaviour in Atmospheric Plumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.3.1 Relevant Forms of Tritium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.3.2 Characteristics of Tritium Releases at Nuclear Facilities . . . . . . . . . . . . . . . 34 3.3.3 Dispersion of Tritium Plumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.3.3.1 Normal Dispersion Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.3.3.2 Effects of Topography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.3.3.3 Plume Rise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.3.3.4 Stack and Building Wakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.3.3.5 Shoreline Fumigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3.3.4 Dry and Wet Deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3.3.5 Next Generation Dispersion Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 3.4 Impact of Climate Change on Tritium Dispersion . . . . . . . . . . . . . . . . . . . . . . . . . . 42 i
Page 1: Investigation of the Environmental
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INVESTIGATION OF THE ENVIRONMENTAL
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Investigation of the Environmental Fate of Tritium in the Atmosphere

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