Radiation in Your Environment
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Transcript of Radiation in Your Environment
Radiation in Your Environment
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
Environmental Monitoring
Primary Objective of a Nuclear Facility
Keep radioactive effluents at a minimumParticulate filters to remove
particles from air effluentsCharcoal filters to remove iodineHold-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 facilityTo look for high activities of
natural radioactivityVerify and validate radioactive
effluent monitoring program
Reasons for Environmental
MonitoringExternal regulators
Nuclear Regulatory CommissionEnvironmental Protection Agency
Internal motivationEnvironmental stewardshipInsurance (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 operationAssess natural radioactivity
Continual sampling during operationLook 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 regulationsDocumentation of unanticipated
environmental effectsProtection from legal liabilitiesResearch: verification of models
REMP: Design
Facility informationRadioactivity producedPhysical form
ParticulatesGassesChemical
Effluent controlsPathway information
REMP: What to Measure
Direct gamma radiationThermoluminescent dosimetersIonization meters (real time)
Air pathways (inhalation/ingestion)Air (particulates/iodine)CropsGrass-cow-milk pathway
REMP: How to Measure
Continuous measurements of effluentsStack monitors to measure airborne
effluentsRadiation monitors in liquid streams
Periodic grab samples from environmentFood products (milk, fish, vegetables,
etc.)Plants (pasture grass, broad leaf
vegetation)
REMP: MeasurementsDirect Radiation
Thermo- Luminescent Dosimeters (TLD) measure radiation from facility
REMP: MeasurementsDirect Radiation
REMP: Water Measurements
Water pathways (ingestion)WaterFishAquifersInvertebratesField/outfall mixing zones
REMP: Air Measurements
Noble gases: Not chemically reactiveReadily dispersed
Gases of interestXe-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 particulatesI-131, Cs-137, Sr-90,Co-60
Readily removed from effluentVery small releases
REMP: Air Measurements
Low volume air sampler measures particulate material and iodine
Natural Radioactivity
Cosmic ray producedH-3, C-14, Na-22, Be-7
4 million Curies of H-3 produced each year
TerrestrialUranium-238 and Thorium-232
seriesRadium and radon
Potassium-40, Rubidium-87
Typical Radioactivity in the EnvironmentAir particulates
Gross beta: 0.004 - 0.04 pCi/m3
Be-7: 0.02 - 0.2 pCi/m3
Air IodineNot detectable
SoilSr-90: 0.02 - 0.2 pCi/gCs-137: 0.1 - 1.0 pCi/gK-40: 5 - 20 pCi/gRa-226: 10 - 50 pCi/g
Typical Radioactivity in the EnvironmentPrecipitation
Gross beta: 1 - 4 pCi/LH-3: 75 - 200 pCi/LBe-7: 40 - 100 pCi/L
WaterGross beta: 0.5 - 5.0 pCi/LH-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 EnvironmentFish
Sr-90: 0.002 - 0.02 pCi/gCs-137: 0.01 - 0.02 pCi/g
Milk I-131: not detectableCs-137: 1 - 10 pCi/LK-40: 1000 - 2300 pCi/LSr-90: 0.5 - 5.0 pCi/L
Food productsK-40: 0.5 - 5.0 pCi/gSr-90: 0.002 - 0.02 pCi/g