Radiation in Your Environment
Radiation is an integral part of our environment, originating from natural sources like cosmic and terrestrial radiation as well as human activities involving medical, nuclear power, and consumer products. This comprehensive overview explores natural radioactivity, including primordial radionuclides and cosmogenic radioactivity, and highlights the importance of environmental monitoring programs, particularly in nuclear facilities. Learn how different radiation types are measured and regulated, ensuring protection for public health and the environment.
Radiation in Your Environment
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Presentation Transcript
Radiation Around You • Nature • Cosmic (direct and cosmic-produced radioactivity • Terrestrial (including radon) • Medical • Consumer Products • Transportation • Nuclear Power • Nuclear Weapons Fallout
Naturally Occurring Radioactive Material • Primordial radionuclides- left over from when the earth was created. • Cosmogenic radioactivity - Radionuclides produced when cosmic radiation interacts with the upper atmosphere
Cosmic Radiation • The primary source of cosmic radiation is outside this solar system: sun and stars • The atmosphere and the earth’s magnetic field act as a shield against radiation, reducing the radiation that reaches the earth’s surface. • Higher doses at higher altitudes.
Terrestrial Radiation • Primordial radionuclides in rock and soil • Primarily long lived nuclides • K-40 (also in food) • Body contains about 0.1 µCi which produces 0.2 mSv(20 mrem) per year • U-238 series • Source of radon in buildings • Th-232 series
Primary Objective of a Nuclear Facility • Keep radioactive effluents at a minimum • Particulate filters to remove particles from air effluents • Charcoal filters to remove iodine • Hold-up tanks or charcoal traps to allow radioactive noble gasses to decay • Filter liquid effluents
Environmental Monitoring • Purpose: • To detect any radioactivity released by a nuclear facility • To look for high activities of natural radioactivity • Verify and validate radioactive effluent monitoring program
Reasons for Environmental Monitoring • External regulators • Nuclear Regulatory Commission • Environmental Protection Agency • Internal motivation • Environmental stewardship • Insurance (American Nuclear Insurers) • Concern for ourselves, families, and neighbors
Nuclear Facilities • Program for nuclear facilities: • Radioactive Environmental Monitoring Program (REMP) • Sampling for a period of three years prior to operation • Assess natural radioactivity • Continual sampling during operation • Look for radionuclides from the plant
Nuclear Facilities REMP • Measure: • Radioactivity • Air • Water • Food • Radiation dose • At site boundary • Public exposures
REMP: Objectives • Protection of environment and people from releases • Documentation of existing and continuing radiological conditions • Compliance with regulations • Documentation of unanticipated environmental effects • Protection from legal liabilities • Research: verification of models
REMP: Design • Facility information • Radioactivity produced • Physical form • Particulates • Gasses • Chemical • Effluent controls • Pathway information
REMP: What to Measure • Direct gamma radiation • Thermoluminescent dosimeters • Ionization meters (real time) • Air pathways (inhalation/ingestion) • Air (particulates/iodine) • Crops • Grass-cow-milk pathway
REMP: How to Measure • Continuous measurements of effluents • Stack monitors to measure airborne effluents • Radiation monitors in liquid streams • Periodic grab samples from environment • Food products (milk, fish, vegetables, etc.) • Plants (pasture grass, broad leaf vegetation)
REMP: MeasurementsDirect Radiation Thermo- Luminescent Dosimeters (TLD) measure radiation from facility
REMP: Water Measurements • Water pathways (ingestion) • Water • Fish • Aquifers • Invertebrates • Field/outfall mixing zones
REMP: Air Measurements • Noble gases: • Not chemically reactive • Readily dispersed • Gases of interest • Xe-133, Xe-135 • Short half-lives (5.2 day, 9.1 hr) • Kr-85 • Long half-life (10.8 yr)
REMP: Air Measurements • Tritium (H-3) • Liquid effluents • Cannot remove from water • Iodine and particulates • I-131, Cs-137, Sr-90,Co-60 • Readily removed from effluent • Very small releases
REMP: Air Measurements Low volume air sampler measures particulate material and iodine
Natural Radioactivity • Cosmic ray produced • H-3, C-14, Na-22, Be-7 • 4 million Curies of H-3 produced each year • Terrestrial • Uranium-238 and Thorium-232 series • Radium and radon • Potassium-40, Rubidium-87
Typical Radioactivity in the Environment • Air particulates • Gross beta: 0.004 - 0.04 pCi/m3 • Be-7: 0.02 - 0.2 pCi/m3 • Air Iodine • Not detectable • Soil • Sr-90: 0.02 - 0.2 pCi/g • Cs-137: 0.1 - 1.0 pCi/g • K-40: 5 - 20 pCi/g • Ra-226: 10 - 50 pCi/g
Typical Radioactivity in the Environment • Precipitation • Gross beta: 1 - 4 pCi/L • H-3: 75 - 200 pCi/L • Be-7: 40 - 100 pCi/L • Water • Gross beta: 0.5 - 5.0 pCi/L • H-3: 75 - 200 pCi/:L • I-131: 0.25 - 1.0 pCi/L (hospital releases) • Sediment • Cs-137: 0.1 - 1.0 pCi/g
Typical Radioactivity in the Environment • Fish • Sr-90: 0.002 - 0.02 pCi/g • Cs-137: 0.01 - 0.02 pCi/g • Milk • I-131: not detectable • Cs-137: 1 - 10 pCi/L • K-40: 1000 - 2300 pCi/L • Sr-90: 0.5 - 5.0 pCi/L • Food products • K-40: 0.5 - 5.0 pCi/g • Sr-90: 0.002 - 0.02 pCi/g
