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The Essence of REMP

Jim Key

Key Solutions, Inc.

2002 RETS/REMP Workshop

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Reasons for Environmental Monitoring

• Document Compliance with Regulations

• Verify Proper Functioning of Effluent Controls and Monitoring

• Identify Trends Related to Plant Releases

• Assess Impact of Releases on Environment and Public

• Allow Assessment of Impact of Accidental Releases

• Provide Information to Public

• Provide Documentation for Litigation Defense

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Regulatory Requirementsfor the REMP

The Radiological Environmental Monitoring Program is Required by 10 CFR 50,

Appendix I, Section IV.B.2 and IV.B.3.

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Critical Components of the REMP

• Pre-Operational Data (P.S. Where’s yours?)

• General Program Description

• Sample and Analysis Selection Criteria

• Land Use Census

• Personnel and Vendor Qualification

• Statistical Requirements

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Design Considerations

Sampling Media and Location Driven By:

• Likely Critical Exposure Pathways

• Critical Population Group

• Verified By Land Use Census

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Sampling Frequency

Driven By:

• Variation in Release Rate of Activity

• Radiological Half-life

• Dispersion and Deposition in Environment

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Dispersion and Deposition in Environment

• Reg Guide 1.109 and NUREG 0133 Use Very Simple Dispersion and Deposition Models

• Source of Greatest Model Uncertainty

• Important To Monitor Environment To Insure Doses Are Not Substantially Underestimated

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Types of Exposure Pathways

• Transitory Exposure Pathways

• Integrating Exposure Pathways

• Cumulative-Integrating Exposure Pathways

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Transitory Exposure Pathway

• Radionuclide concentration in environmental media is directly proportional to the rate of release of activity into the environment.

• Environmental concentrations will exist only as long as activity is released.

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Transitory Exposure PathwayExamples

• Direct Radiation

• Noble Gas Immersion

• Inhalation

• Potable Water (Fast Flowing Stream or Large Water Body)

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Transitory Exposure PathwayMonitoring Strategy

• Potential To Be Highly Variable With Time

• Requires Continuous or Integrating Monitoring– TLD– Continuous Air Sampling

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Integrating Exposure Pathway

• Radionuclide concentration in environmental media increases with continued release of activity into the environment.

• Environmental concentrations can continue to increase even after release to environment ceases.

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Integrating Exposure PathwayExamples

• Ground Plane

• Sediment and Soil (Including Shoreline)

• Potable Water (Slow Flowing Stream)

• Aquatic Food Ingestion

• Leafy Vegetation Ingestion

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Integrating Exposure PathwayMonitoring Strategy

• Concentration Less Variable With Time

• Batch Sampling

• Frequency Driven Primarily by Half Life

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Cumulative-Integrating Exposure Pathway

• Radionuclide concentration in environmental media is described by two integrating processes.

• Environmental concentration in media is driven by a primary integration pathway.

• Potential to be particularly sensitive environmental indicators.

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Cumulative-Integrating Exposure Pathway - Examples

• Aquatic Food Ingestion (Small Water Body)

• Shoreline Exposure (Small Water Body)

• Grass-Cow-Milk Ingestion

• Grass-Cow-Meat Ingestion

• Uptake From Soil by Crops

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Cumulative-Integrating Exposure Pathway – Monitoring Strategy

• Concentration Varies Slowly With Time

• Sampling Time May Be:– Determined by Growing Season– Semi-annual or Annual

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Sampling

• Ideal – Sample in Human Food Chain.

• May Not Always Be Practical of Possible– No Local Agriculture– Species Unavailable or Endangered– Acceptable To Use Alternate Environmental

Indicators.

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Useful Aquatic IndicatorsAquatic Plants Not Considered Part of Human

Food Chain in U.S.• Kelp

– Concentrates Iodine• Algae/Plankton

– Concentrate Co-58, Co-60, Zn-65, Cs-137• Shellfish

– Filter Feeders– Freshwater Bioaccumulation Higher Than Fish

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Leafy Vegetation

• Required to sample “broad leaf vegetation”

• NUREG 0472 – “similar to lettuce and cabbage”

• Also Turnips (leafy portion), Spinach, Celery

• What If Unavailable?

• Reg Guide 4.8 “Nonedible plants with similar characteristics may be substituted.”

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Leafy Vegetation - Substitute

• Broad Leaf Vegetation defined as: “A plant with leaf area typically greater than 1 square inch.”

• Based on above definition, the leafy portion of the following would also meet the criteria:– Corn, Sugar Beet, Peas, Beans, Soybeans, Potato,

Cucumber, Tomato, Zucchini, Polkweed, Tobacco.– Fast Growing Broad Leaf Ornamentals

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Other Vegetation

• Slow Growing Plants Will Integrate Activity Over Long Period of Time– Moss & Lichens– Spanish Moss – Good Integrating Filter for

Airborne Particulate.– Not a part of human food chain, but potentially

sensitive indicators.

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Other Indicators

Species Considered Important If:• Commercially or Recreationally Valuable, or

• Affects The Well Being of Some Important Species, or

• Biological Indicator of Health of Ecosystem

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Large Animals

Examine– Lean Muscle (Consumable Portion)– Thyroid (Iodine)– Bone (Strontium)– Liver (Cobalt, Manganese)

Sources– Game Animals– Road Kill

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Small Animals

• Small Game Animals– Limited Use – Not Significant Part of Food

Chain– Rabbits and Field Mice could be considered

potential indicator species.

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Why Sample “Other” Indicators?

“Radioactive Kelp Washes Up On Beach”– San Onofre

• Radioiodines of plant origin?

– Koeburg• Newspapers claimed from plant.

• Later proved to be of medical origin.

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Relationship of the REMP to the ODCM - I

• Effluent Dose Limits of 10 CFR 50, Appendix I are so low as to be immeasurable in the environment.

• The Offsite Dose Calculation Manual contains the methodology and parameters used in the calculation of offsite doses due to radioactive liquid and gaseous effluents.

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Relationship of the REMP to the ODCM - II

• Appendix I allows accounting for real phenomenon or factors actually affecting the estimate of radiation exposure including physical processes tending to attenuate the quantity of radioactive material to which an individual would be exposed.

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Relationship of the REMP to the ODCM - III

The Dose Models of Reg Guide 1.109 and NUREG 0133 Consider:

• Site-Specific Exposure Pathways

• Site-Specific Parameters

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Relationship of the REMP to the ODCM - IV

• The Land Use Census data should indicate the presence or absence or pathways and provide information on site specific dose model parameters.

• Calculation of non-existing pathways results in significant over estimation of dose to a member of the public and is discouraged.

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Relationship of the REMP to the ODCM - V

• ODCM methodology contains numerous parameters which should be site specific.

• Use of Reg. Guide default values results in overestimation of dose to member of the public.

• NRC and ANI strongly encourage use of site specific parameters.

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Site Specific ODCM Parameters Which Have Greatest Effect On Dose - I

Age of Receptor

• Four age groups are considered:• Infant: 0 to 1 year old

• Child: 1 to 11 years old

• Teen: 11 to 17 years old

• Adult: 17 years and older

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Site Specific ODCM Parameters Which Have Greatest Effect On Dose - II

Agricultural Productivity - kg/m2

• Vegetation Pathway• Fresh Leafy Vegetables

• Stored Vegetable

• Cow/Goat Milk and Cow Meat• Pasture Grass

• Stored Feed

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Site Specific ODCM Parameters Which Have Greatest Effect On Dose - III

Usage Fractions

• Vegetation Pathway• Annual intake of leafy vegetation grown locally

• Annual intake of stored vegetation grown locally

• Cow/Goat Milk and Cow Meat• Fraction of year cow is on pasture

• Fraction of cow feed that is pasture grass when cow is on pasture

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Correlation of Effluent Concentrations with Concentrations in the Environment

• Environmental concentrations are typically below detection limits.

• ODCM models can be used to predict concentration in various environmental media.

• ODCM models tend to overestimate environmental concentration.

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Correlation of Effluent Concentrations with Concentrations in the Environment

• ODCM models can estimate an upper bound on environmental concentrations when REMP results are below detection limits.

• ODCM predicted concentrations well above detection limits with REMP being below detection limits may indicate:

• Excessively conservative ODCM methodology OR

• An ineffective REMP program

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Predicted Ground Plane Concentrations

i

iQQDConc

Where:

Conc = Predicted Concentration in Ci/m2

D/Q = Atmospheric Deposition in 1/m2

Qi = Activity Released in Ci

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Predicted Cow Milk Concentrations

Where:

QF = Cow Feed Consumption (kg/da)

Fm = Feed to Milk Transfer Term (Ci/l per Ci/da)

r = Fraction of activity retained on feed

fs fp = Grazing Fractions

Yp Ys = Agricultural Productivity

th tf = Pathway Transport Times

ii

t

s

tsp

p

spmF Qe

Y

eff1

Y

ffrFQQDConc fi

hi