Biota Dose Assessment Methods used at the Idaho National Engineering and Environmental Laboratory

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Biota Dose Assessment Methods used at the Idaho
National Engineering and Environmental Laboratory
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PRESENTERS
Randall C. Morris Environmental Science and
Research Foundation 101 S. Park Ave., Suite
2 P.O. Box 51838 Idaho Falls, ID
834-05-1838 [phone] morrisr_at_env.esrf.isu.e
du Robin VanHorn Lockheed Martin Idaho
Technologies P.O. Box 1625 Idaho Falls, ID
83415-3960 [phone] rh9_at_inel.gov
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Text slide The Idaho National Engineering and
Environmental Laboratory (INEEL)

• The INEEL is a Department of Energy facility
  established in 1949 for nuclear research and
  related activities. Today, research, training,
  and production activities related to defense and
  non-defense programs are conducted at the INEEL.
• The INEEL occupies 2,300 km2 on the northwestern
  portion of the eastern Snake River Plain in
  southeastern Idaho. The Lost River, Lemhi, and
  Bitterroot mountain ranges border the INEEL on
  the north and west.
• Elevation ranges from 1,460 m in the south to
  1,650 m in the northeast, with the exception of
  the East (2,003 m) and Middle (1,948 m) Buttes.
• Approximately 95 of the INEEL is controlled by
  DOE the remaining 5 includes public highways
  and the Naval Reactors Facility (Department of
  Defense).

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TEXT SLIDE The Ecology of the INEEL

• Cool desert ecosystem characterized by
  shrub-steppe vegetative communities.
• Relatively, flat, with several prominent volcanic
  buttes and numerous basalt flows that provide
  important habitat for small and large mammals,
  reptiles, and some raptors.
• Dominated by sagebrush provides habitat for
  numerous fauna such as sage grouse, pronghorn,
  and sage sparrows. Rabbitbrush, grasses and
  forbs, salt desert shrubs, and exotic/weed
  species make up other communities. Since 1957,
  the central portion of the INEEL (approximately
  1,385 km2 ) has been maintained as a grazing
  exclusion area.
• In 1972 , the DOE established the INEEL as a
  National Environmental Research Park. It is the
  second largest of seven such Parks and is one of
  two which contain sagebrush-steppe ecosystems.

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TEXT SLIDE CERCLA Activities at the INEEL

• In 1989, the INEEL was placed on the
  Comprehensive Environmental Response,
  Compensation and Liability Act (CERCLA) National
  Priorities List.
• In 1991, the Federal Facility Agreement and
  Consent Order (FFA/CO DOE-ID 1991) was signed
  to establish a procedural framework and schedule
  for CERCLA activities at the INEEL. The FFA/CO
  divides the INEEL into 10 waste area groups
  (WAGs).
• Within a WAG, the multiple sites of contamination
  are grouped by similar contamination problems or
  boundaries and are called operable units (OUs).
• Sites range from large facilities to small rubble
  piles and include pits, percolation ponds,
  landfills, septic systems, injection wells,
  trenches, and abandoned tanks.

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TEXT SLIDE WAG Descriptions

• Test Area North - (WAG 1)
• TAN, located at the northern end of the INEEL
  Site, consists of facilities for handling,
  storage, examination and research of spent
  nuclear fuel. TAN also houses a project to
  manufacture armor packages for Army tanks.
• Test Reactor Area - (WAG 2)
• TRA, the world's most sophisticated materials
  testing complex, houses extensive facilities for
  studying the effects of radiation on materials,
  fuels and equipment. The Advanced Test Reactor
  (ATR), located at TRA, produces a neutron flux
  that allows simulation of long-duration radiation
  effects on materials and fuels. ATR is also used
  for production of important isotopes used in
  medicine, research and industry.

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TEXT SLIDE WAG Descriptions (Continued)

• Idaho Nuclear Technology and Engineering Center -
  (WAG 3)
• INTEC, houses facilities that provide safe
  interim storage for government-owned defense and
  research spent nuclear fuels. Other facilities at
  INTEC include a waste solidification facility and
  related waste storage bins, a state-of-the-art
  remote analytical laboratory and a coal-fired
  steam generating plant.
• Central Facilities Area - (WAG 4)
• CFA is where services for the entire site are
  headquartered. These services include
  environmental laboratories, security, fire
  protection, medical facilities, communications
  systems, warehouses, a cafeteria, vehicle and
  equipment pools, bus system and laundry.

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TEXT SLIDE WAG Descriptions (Continued)
Power Burst Facility and Auxiliary Reactor Area -
(WAG 5) PBF, is located in an area originally
constructed for the Special Power Excursion
Reactor Tests (SPERT). Four SPERT reactors were
built beginning in the late 1950s. All of these
reactors were removed and the SPERT facilities
have undergone partial or complete DD. The PBF
reactor is still operational but is in a standby
mode. ARA, consists of four groupings of
buildings in which activities, including the
operation of test reactors occurred. All ARA
reactors were removed from the facility and have
undergone partial or complete DD. PBF/ARA sites
of concern include tanks and components of
wastewater disposal systems (e.g., evaporation
ponds, percolation ponds. Leach fields, pits, and
dry wells).
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TEXT SLIDE WAG Descriptions (Continued)

• Radioactive Waste Management Complex - (WAG 7)
• RWMC was established in 1952 as a controlled area
  for disposal of solid radioactive wastes
  generated in INEEL operations. Since 1954, the
  facility has also received defense wastes for
  storage and/or disposal from other sites.
  Currently, various strategies for waste storage,
  processing and disposal are studied at RWMC.

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TEXT SLIDE WAG Descriptions (Continued)
Naval Reactors Facility - (WAG 8) NRF is the
birthplace of the U.S. Nuclear Navy. Beginning in
the early 1950s, prototype reactors for both
submarines and surface ships were developed and
operated here. Until May 1995 when the last
prototype was shut down, NRF served as a training
school for officers and enlisted personnel
destined for service aboard nuclear-powered
ships. As it has for nearly 40 years, NRF
continues to receive and examine Naval spent
fuel.
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TEXT SLIDE WAG Descriptions (continued)

• Argonne National Laboratory-West - (WAG 9)
• ANL-W, part of Argonne National Laboratory
  operated by the University of Chicago, conducts
  research and development and operates facilities
  for DOE. Research is typically focused on areas
  of national concern including those relating to
  energy, nuclear safety, spent nuclear fuel
  treatment, nonproliferation, decommissioning and
  decontamination technologies, nuclear material
  dispositioning and similar work.

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TEXT SLIDE WAG Descriptions
WAG 10, includes miscellaneous surface sites and
liquid disposal areas throughout the INEEL that
are not included within other WAGs. WAG 10 also
includes regional Snake River Plain Aquifer
concerns related to INEEL that cannot be
addressed on a WAG-specific basis. This WAG will
also perform the INEEL-wide ecological risk
assessment.
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INEEL ISSUES

• Multiple stakeholders
• Approach and methodology developed was a result
  of negotiation between DOE-ID, EPA Region Ten,
  and State of Idaho.
• ERA guidance limited at that time
• Multiple CERCLA sites
• Multiple radionuclides ( 160)

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INEEL Guidance

• Guidance manual (1995) documented
• phased approach to ERA process
• functional grouping method
• method to address radionuclides and
  nonradionuclides
• pathways and routes of exposure identified
• parameter values
• ecologically based screening levels (EBSLs)

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Phased Approach

• Applies an iterative, tiered process in which
  preliminary assessments based on conservative
  assumptions support progressively more refined
  assessments, at each WAG.

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Phased Approach (continued)

• 1 Sites without potential exposure routes or
  pathways are eliminated,
• 2 contaminate concentrations at each site are
  compared to ecologically based screening values
  (EBSLs),
• 3 sites and/or contaminates remaining are
  assessed using more realistic modeling.

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Functional Grouping

• Functional groups should demonstrate
• Potential for contaminant exposure through shared
  dietary and physical pathways (trophic and
  habitat parameters)
• Potential for similar biological response to that
  exposure (taxon).

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Functional Groups

• As defined, all species are potential surrogates
  for the other members of the same functional
  group. For assessment, parameters were
  integrated from several species to address the
  risk to the group as a whole.

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Functional Grouping Example

• AV122
• Rock dove(Columba livia) Aves 1 Columbiformes
• Sage grouse(Centrocercus urophasianus) Aves 1 Ga
  lliformes
• AV222
• Western meadowlark(Sturnella neglecta) Aves 2 Pa
  sseriformes
• Brewer's sparrow(Spizella breweri) Aves 2 Passe
  riformes
• M122
• Pronghorn(Antilocapra americana) Mammalia 1 Arti
  odactyla
• Western harvest mouse
• (Reithrodontomys megalotis) Mammalia 1 Rodentia
  
• Black-tailed jackrabbit(Lepus californicus) Mamma
  lia 1 Lagomorpha
• M222
• Merriam shrew(Sorex merriami) Mammalia 2 Insecti
  vora
• Northern grasshopper mouse
• (Onychomys leucogaster) Mammalia 2 Rodentia

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Functional Grouping Methodology

• Trophic category - "Primary" feeding habits
  (based on gt50 of prey consumed).
• 1 Herbivore
• 2 Insectivore
• 3 Carnivore
• 4 Omnivore
• 5 Detritivore
• Feeding habitat - "Primary" feeding habitat
  (based on location of gt50 food or prey items).
• 1.0 AIR
• 2.0 TERRESTRIAL
• 2.1 Vegetation canopy
• 2.2 Surface/understory
• 2.3 Subsurface
• 2.4 Vertical habitat
• 3.0 TERRESTRIAL/AQUATIC INTERFACE
• 3.1 Vegetation canopy
• 3.2 Surface/understory
• 3.3 Subsurface
• 3.4 Vertical habitat
• 4.0 AQUATIC

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Chronic Radiation Dose for Ecological Receptors

• The International Atomic Energy Agency (IAEA)
  report on the Effects of Ionizing Radiation on
  Plants and Animals at Levels Implied by Current
  Radiation Protection Standards (IAEA 1992) was
  used as the basis for developing a dose.

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Chronic Radiation Dose (Continued)

• The IAEA (1992) technical report provides
  valuable information on the estimated doses to
  both plants and animals under current radiation
  protection standards for three different
  scenarios
• controlled releases of radionuclides to the
  atmosphere,
• controlled releases of radionuclides to a
  freshwater aquatic system, and
• uncontrolled releases of radionuclides from a
  shallow land nuclear waste repository.

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Chronic Radiation Dose (continued)

• The IAEA (1992) determined
• reproduction (including the processes from
  gametogenesis through to embryonic development)
  is likely to be the most limiting end point in
  terms of population maintenance
• that irradiation at chronic dose rates of 1
  mGy/day or less does not appear likely to cause
  observable changes in terrestrial animal
  populations
• that irradiation at chronic dose rates of
  10mGy/day or less does not appear likely to cause
  observable changes in terrestrial plant
  populations.

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Chronic Radiation Dose (continued)

• In 1995, the DOE Air, Water, and Radiation
  Division (EH-412) sponsored a workshop to
  evaluate the adequacy of the IAEA (1992) report
  as a basis for promulgating standards.
• The workshop concluded that currently available
  data adequately supported the dose limits for
  plants and animals recommended by the IAEA.
• Barnthouse, L.W. 1995. Effects of ionizing
  radiation on terrestrial plants and animals A
  workshop report. ORNL/TM-13141, Environmental
  Sciences Division Publication No. 4494. Oak
  RidgeNational Laboratory, Oak Ridge, TN. 20 p.

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BASIC ASSUMPTIONS

• An acceptable chronic dose rate of 0.1 rad/day
  for terrestrial animal populations and 1 rad/day
  for terrestrial plant species (IAEA 1992) was
  assumed.

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BASIC ASSUMPTIONS (Continued)

• It was assumed that radionuclides emitting alpha
  and beta particles would not present a external
  dose risk since the basic rule of thumb (Shleien
  1992) is that it requires an alpha particle of at
  least 7.5 MeV or a beta particle of at least 70
  keV to penetrate a protective layer of skin (.07
  mm thick). Therefore only the internal dose for
  these emitters was assessed. Gamma emitters can
  produce a dose rate to tissues from both external
  and internal exposure and were included in both
  assessments.

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BASIC ASSUMPTIONS (Continued)

• For terrestrial receptors (either plant or
  animal) the dose to reproductive organs from
  radionuclide contaminants is estimated by
  assuming it is equal to the internal radiation
  dose estimate, (calculated from the steady-state
  whole body concentration).
• A quality factor of 20 was used for alpha
  emitters.
• Population effects were evaluated. The
  assessment criteron was reduced by a factor of 10
  to account for potentially greater risk to
  individuals.

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Internal Dose Calculations for Ingestion

• The equation of interest is

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TEXT SLIDE Internal Dose Calculations for
Ingestion

• where
• DR Internal radiation dose estimate (Gy/day)
• CS Concentration of contaminant in soil
  ingested (pCi/g)
• CF Concentration factor (unitless)
• ADE Average decay energy (MeV/dis)
• FA Fraction of decay energy absorbed
  (unitless). For ß or ? radiations the FA was set
  equal to 1 (100) and for ? the FA was set equal
  to .3 (30)
• ED Exposure duration
• SUF Site use factor
• f unit conversion factor
• Q Quality factor (a quality factor of 20 is
  added for ??radiation).

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Internal Dose Calculations for Water Ingestion

• A simple differential equation was used to
  determine tissue concentration from ingestion of
  water.
• where
• TC tissue concentration (pCi/g tissue)
• ?1 decay constant physical (1/day)
• ?2 decay constant biological (1/day)
• I intake (pCi/L)(L/g tissue-day)
• L other loss (e.g.,urination) (pCi/L)(L/g
  issue-day).

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Internal Dose Calculations for Water Ingestion
(continued)

• Conservatively assuming L 0 and solving for TC
  at equilibrium (i.e., dTC/dt0) gives

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Internal Dose Calculations for Water Ingestion
(continued)

• The daily ingestion rate of the radionuclide from
  water, I, is calculated as
• where
• CW concentration of the radionuclide in water
  pCi/L)
• WI water ingestion rate (L/d)
• BW body weight of receptor (kg)
• f unit conversion factor

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Internal Dose Calculations for Water Ingestion
(continued)

• So the tissue concentration (or steady state
  adsorbed dose) due to water ingestion is
• where the water ingestion (WI) for mammals and
  birds is found from allometric equations (EPA
  1993).

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External Dose Calculations

• where
• DR dose rate (rad/day)
• E the average gamma energy per disintegration
  (MeV)
• C the concentration (mCi/cm3)
• ? ? ?the density of the medium (g/cm3).

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TEXT SLIDE BASIC ASSUMPTIONS (Continued)

• The rule of thumb calculation for external dose
  is recommended to calculate the external dose to
  ecological receptors. This equation calculates
  the dose rate to tissue in an infinite medium
  uniformly contaminated by a gamma emitter
  (Shleien 1992).
• This was conservatively assumed to be the dose to
  burrowing functional groups. Nonburrowing
  functional groups were assumed to be at 50 of
  this exposure (a hemisphere).

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Conceptual Site Model
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Potential Food Web
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Exposure Pathways of Contamination Migration
Modeled

• Supported by human health sampling
• Surface and subsurface soil
• uptake by plants
• uptake by animals
• Water
• Not modeled (primarily waste disposal ponds and
  sewage lagoons)
• Groundwater
• not assessed
• Air pathways
• not assessed

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Exposure Routes Evaluated

• Ingestion
• plants, animals, water, soil
• Dermal
• not assessed, are evaluating for use during
  INEEL-wide ERA
• Inhalation
• not assessed, limited information is available to
  support this assessment.

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Parameters

• Concentration factors (CFs), Exposure duration
  (ED), and home range
• developed from existing literature, using site
  specific and native species as possible
• Ingestion rates were developed from allometric
  models

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Calculation of Ecologically Based Screening
Levels (EBSLs)

• The dose equations can be manipulated to yield
  equations for an Ecologically Based Screening
  Level (EBSL)

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TEXT FILE EBSL for Internal Exposure
For internal exposure to soil the equation
becomes
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TEXT FILE EBSL for Internal Exposure (continued)

• where
• EBSL Ecologically based screening level for
  radionuclides in soil (pCi/g)
• TRV Toxicity reference value Gray/day)
• CF Concentration factor (unitless)
• ADE Average decay energy (MeV/dis)
• FA Fraction of decay energy absorbed
  (unitless)
• Q Quality factor.

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TEXT FILE EBSL for External Exposure

• For external dose the equation becomes
• where
• EBSL Ecologically based screening level for
  radionuclides in soil (pCi/g)
• D the dose rate
• E the average gamma energy per disintegration
  (MeV).

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EBSL Screening

• For CERCLA purposes EBSLs allowed screening of
  radionuclides as COPCs at all WAGs except two.
• WAG 2 (Cs-134, Cs-137, Am-241, Pu 238/239, and
  Sr-90) at two sites
• WAG 3 (Am-241, Co-60, Cs-137, Eu-152, Eu-154, and
  Sr-90) at three sites

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Current Activities

• Comparing site specific CFs to those used in
  models
• Developing INEEL-wide approach
• Air deposition modeling
• long term monitoring

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Current Activities (ESRF)

• Revising dose calculations methods
• Surveys for sensitive species
• Proposed Big Lost River Sinks sampling
• Soil bioavailability studies

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Current Activities (ESRF)

• Environmental monitoring
• Evans, R.B., R.W. Brooks, D. Roush, and D.
  Martin. 1998. Idaho National Engineering and
  Environmental Laboratory site environmental
  report for calendar year 1997. ESRF-030,
  DOE/ID-12082(97). Environmental Science and
  Research Foundation, Inc. Idaho Falls, ID. 181
  p.
• Ecology and radioecology research
• Weigmann, D.L. and R.D. Blew. 1999.
  Environmental Science and Research Foundation,
  Inc. annual technical report to DOE-ID Calendar
  year 1998. ESRF-033. Environmental Science and
  Research Foundation, Inc. Idaho Falls, ID. 100
  p.
• http//esrf.org

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References

• DOE-ID, (Department of Energy, Idaho Operations
  Office), 1991, Federal Facility Agreement and
  Consent Order for the Idaho National Engineering
  Laboratory, State of Idaho Department of Health
  and Welfare, U.S. EPA, U.S. DOE, December 4.
• Environmental Protection Agency (EPA), 1993,
  Wildlife Exposure Factors Handbook,
  EPA/600/R-93/187a,b.
• IAEA (International Atomic Energy Agency), 1992,
  Effects of Ionizing Radiation on Plants and
  Animals at Levels Implied by Current Radiation
  Standards, Technical Report Series No. 332.

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References (continued)

• Shleien, B., 1992, The Health Physics and
  Radiological Health Handbook, Scinta Publishers,
  Silver Springs, MD.
• VanHorn, R. L., N. L. Hampton, and R. C. Morris,
  1995, Guidance Manual for Conducting Screening
  Level Ecological Risk Assessments at the INEL,
  Idaho National Engineering Laboratory, Idaho
  Falls, ID, INEL-95/0190, April, 1995.
• VanHorn, R.L., Hampton, N. L., and Morris, R.C.
  (1998) Methodology for Conducting Screening-level
  Ecological Risk Assessments for Hazardous Waste
  Sites. Part I. Overview. Int. J. of Environment
  and Pollution, Vol. 9, No. 1, 1998.

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References (continued)

• Hampton, N.L., Morris, R.C., and R.L. VanHorn
  (1998) Methodology for Conducting Screening-level
  Ecological Risk Assessments for Hazardous Waste
  Sites. Part II. Grouping ecological components.
  Int. J. of Environment and Pollution, Vol. 9, No.
  1, 1998.
• Kester, J. E., VanHorn, R.L., and Hampton, N.L.
  (1998) Methodology for Conducting Screening-level
  Ecological Risk Assessments for Hazardous Waste
  Sites. Part III. Exposure and effects assessment.
  Int. J. of Environment and Pollution, Vol. 9,
  No. 1, 1998.
• Morris, R.C. and VanHorn, R.L., 1999, Screening
  Risks to Terrestrial Vertebrates from
  Radionuclide Contamination in Soil and Water.
  Waste Management 99 Conference, Tuscon, Arizona.

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Additional References

• Cember, H. 1983, Introduction to Health Physics,
  (2nd Ed.) Pergamon Press. New York, NY.
• EPA, 1989, Risk Assessment Guidance for
  Superfund, Vol. 1, Chapter 10, EPA/540/1-89/001.
• Kocher, 1981, Radioactive Decay Data Tables, NTIS
  DOE-TIC-11026.
• National Council on Radiation Protection and
  Measurements (NCRP), 1984, Radiological
  Assessment Predicting the Transport,
  Bioaccumulation, and Uptake by Man of
  Radionuclides Released to the Environment, NCRP
  Report No. 76.

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Additional References

• Turner, J.E., 1986, Atoms, Radiation, and
  Radiation Protection, Pergamon Press, New York,
  N.Y.
• Schulz, V. and F. W. Whicker, 1982, Radioecology
  Nuclear Energy and the Environment. CRC Press,
  Inc., Boca Raton,FL.
• Till, J.E. and Meyer, H.R., 1983, Radiological
  Assessment A Textbook on Environmental Dose
  Analysis. NUREG/CR-3332.