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