1. NAME AND TITLE
PRESTO-II: Code System for Low-Level Waste Environmental Transport and Risk Assessment.
PRESTO-PREP: Data preprocessor for PRESTO-II accesses radionuclide data bases to prepare a radionuclide data set.
RADFMT: Converts RADRISK.BCD data file to unformatted records for use by
RADRISK.BCD: 1981 version of dose and risk factors for radionuclides written by CCC-422/RADRISK for use with the DARTAB Calculation in PRESTO-II.
Oak Ridge National Laboratory, Oak Ridge, Tennessee.
3. CODING LANGUAGE AND COMPUTER
Fortran 66; IBM 360/370. PRESTO-PREP runs on the PDP-10. Informal instructions are
provided for VAX/VMS Fortran 77 implementation.
4. NATURE OF PROBLEM SOLVED
The U.S. Environmental Protection Agency is responsible for developing a generally-applicable environmental standard for the disposal of low-level radioactive waste. PRESTO-EPA was developed in 1983 to assist in assessing potential human health impacts from such operations and is under continuing development. The PRESTO-II methodology, which differs from the EPA code in several respects, was developed for general release and application to a wider range of problems than its EPA predecessors.
PRESTO-II evaluates possible health effects from shallow-land and waste-disposal trenches. The
model is intended to serve as a non-site-specific screening model for assessing radionuclide transport,
ensuing exposure, and health impacts to a static local population for a 1000-year period following the
end of disposal operations. Human exposure scenarios considered include normal releases (including
leaching and operational spillage), human intrusion, and limited site farming or reclamation. Pathways
and processes of transit from the trench to an individual or population include ground-water transport,
overland flow, erosion, surface water dilution, suspension, atmospheric transport, deposition,
inhalation, external exposure, and ingestion of contaminated beef, milk, crops, and water. Both
population doses and individual doses, as well as doses to the intruder and farmer, may be calculated.
Cumulative health effects in terms of cancer deaths are calculated for the population over the 1000-year
period using a life-table approach developed by EPA [CCC-422/RADRISK]. The DARTAB model
is used in modified form to generate human health risk estimates from radionuclide concentrations and
5. METHOD OF SOLUTION
PRESTO-II tracks radionuclide transport through surface and subsurface pathways and human
exposures through external exposure, inhalation, and ingestion with a resolution of 1y. The
methodology is mechanistic, and physical transport processes are modeled separately and in detail.
PRESTO-II computes infiltration through the trench cap from experimentally determined permeability
and hourly precipitation values. Watershed infiltration is determined using a parametric evapotranspiration equation requiring input values for several site variables. A finite element approach is used to
compute trench water balance.
6. RESTRICTIONS OR LIMITATIONS
The PRESTO-II model is most appropriately used as a screening model, and site specific codes should be considered in cases where PRESTO-II numerical results fall close to reference values used for decision making. Some release and transport scenarios, such as those necessary to consider major meteorological changes, mining of the trench contents, in-situ combustion of trench wastes, and intrusion and radionuclide transport by burrowing animals or plant roots are not considered in the PRESTO-II model and code.
It should be noted that PRESTO-PREP runs only on the PDP-10.
7. TYPICAL RUNNING TIME
The sample case compiled, linked and executed on the IBM 3033 in less than 1.5 cpu minutes.
8. COMPUTER HARDWARE REQUIREMENTS
PRESTO-II is operable on the IBM 3033. PRESTO-PREP runs on the PDP-10.
9. COMPUTER SOFTWARE REQUIREMENTS
PRESTO-II compiled under OS/VS2 using the IBM VS compiler and language level 66 option.
a. Included in documentation:
D. E. Fields, C. J. Emerson, R. O. Chester, C. A. Little, G. Hiromoto, "PRESTO-II: A Low-Level Waste Environmental Transport and Risk Assessment Code," ORNL-5970 (April 1986).
M. A. Bell, C. J. Emerson, and D. E. Fields, "PRESTO-PREP: A Data Preprocessor for the PRESTO-II Code," ORNL-5981 (July 1984).
J. L. King and J. E. Horwedel, "Modifications to PRESTO-II for VAX/VMS Fortran 77,"
Informal Memo (August 1987).
b. Background information:
C. L. Begovich, K. F. Eckerman, E. C. Schlatter, S. Y. Ohr, R. O. Chester, "DARTAB, A Program to Combine Airborne Radionuclide Environmental Exposure Data with Dosimetric and Health Effects Data to Generate Tabulations of Predicted Health Impacts," ORNL-5692 (August 1981).
D. E. Dunning, Jr., R. W. Leggett, M. G. Yalcintas, "A Combined Methodology for Estimating
Dose Rates and Health Effects from Exposure to Radioactive Pollutants," ORNL/TM-7105 (December
11. CONTENTS OF CODE PACKAGE
Included are the documents in 10.a. and a DS/HD 5.25 (1.2MB) DOS diskette which contains the
source codes and data library plus output from the sample problem.
12. DATE OF ABSTRACT
June 1987; November 1987.
KEYWORDS: AIRBORNE; ENVIRONMENTAL DOSE; INTERNAL DOSE; LIQUID PATHWAY; NUCLIDE TRANSPORT; RADIOLOGICAL SAFETY; RISK ASSESSMENT; WASTE MANAGEMENT