Residual Radioactive Contamination from Decommissioning
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- - - NUREG/CR-55 12 PNL-7994 Vol. 1 Residual Radioactive Contamination From Decommissioning Technical Basis for Translating Contamination Levels to Annual Total Effective Dose Equivalent Final Report Prepared by W. E. Kennedy, Jr., D. L. Strenge Pacific Northwest Laboratory Operated by Battelle Memorial Institute Prepared for I U.S. Nuclear Regulatory Commission ---- I I. AVAILABILITY NOTICE Availability of Reference Matenals Cited in NRC Publicabons Most documents cited in NRC publications will be available from one of the following sources: 1. The NRC Public Document Room, 2120 L Street. NW., Lower Level. Washington, DC 20555 2. The Superintendent of Documents. U.S. Government Printing Office, P.O. Box 37082, Washington, DC 20013-7082 3. The National Technical Information Service, Springfield, VA 22161 Although the listing that follows represents the majority of documents cited in NRC publications. It Is not Intended to be exhaustive. 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J NUREG/CR-5512 PNL-7994 Vol. 1 Residual Radioactive Contamination From Decommissioning Technical Basis for Translating Contamination Levels to Annual Total Effective Dose Equivalent Final Report Manuscript Completed: September 1992 Date Published: October 1992 Prepared by W. E. Kennedy, Jr., D. L. Strenge R. A. Meek, Ph.D., NRC Project Manager Christine Daily, NRC -technical Specialist Pacific Northwest Laboratory Richland, WA 99352 Prepared for Division of Regulatory Applications Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission Washington, DC 20555 NRC FIN B2908 - Abstract This document is the first volume of a three-volume report to provide generic and site-specific estimates of radiation dose for exposures to residual radioactive contamination after the decommissioning of facilities licensed by the U.S. Nuclear Regulatory Commission (NRC). This first volume provides the details of the generic scenario and pathway modeling analysis. The level of detail included in this volume serves as the basis for user-friendly computer software to be developed under strict quality-assurance procedures. This volume is intended to be used as a reference to Vol- ume 2, a full description of the computer software. Included in Volume 1 are descriptions of the scenarios, models, mathematical formulations, assumptions, and justifications of parameter selections. Volume 1 was produced after consideration of public comments received on the January 1990 review draft. The generic modeling addresses residual radioactive contamination inside buildings and in soils. For buildings, two scenarios are presented to relate volume and surface contamination levels to estimates of the annual total effective dose equivalent (TEDE) or the TEDE (as defined in 10 CFR 20) received during a year of exposure with the conditions defined in the scenarios. Because of concerns regarding potential ground-water contamination from residual radioactive contamination in soil, a generic water-use model was developed to permit evaluation of the annual TEDE for drinking water from wells. The generic water-use model was also used in the evaluation of multiple pathways associated with contaminated soil. The generic treatment of potentially complex ground-water systems used here provides a conservative analysis that may only indi- cate that additional site data and more sophisticated modeling are warranted. The scenarios, models, mathematical formulations, and selected parameter values in this volume are intended to serve as the technical basis for the NRCs derivation of screening values supporting its development of policy applied to residual radioactive contamination from decommissioning. .H.i NUREG/CR-55 12 Contents Page Abstract ............ , ................................................................... iii Executive Summary . ............................................................................. xiii Foreword ........................................... Xv Acknowledgments................................................................................ xix 1 Introduction ............................................ 1.1 2 Methodology and Nomenclature .2.1 2.1 Dosimetry Definitions .2.1 2.2 Symbol Nomenclature .2.2 3 Scenario Descriptions for the Release of Buildings .. 3.1 3.1 Building Renovation Scenario .3.1 3.1.1 Time Frame for Building Renovation Scenario 3.2 3.1.2 Exposure Pathways for Building Renovation Scenario .3.3 3.1.3 External Dose .3.5 3.1.4 Inhalation Dose for Renovation .3.7 3.1.5 Ingestion Dose for Renovation .3.7 3.1.6 Annual TEDE Rate for the Building Renovation Scenario .3.8 3.2 Building Occupancy Scenario .3.9 3.2.1 Time Frame of Building Occupancy Scenario .3.9 3.2.2 Exposure Pathways ........... ..... 3.9 3.23ExtrnaDoe fr Buldig Ocupncy................................................................ 31 3.2.4 Inhalation Dose for Building Occupancy ..................... I .......................... 3.12 3.2.5 Ingestion Dose for Building Occupancy ................................................ 3.13 3.2.6 Annual TEDE Rate for Building Occupancy Scenario: ................................... 3.14 4 Drinking Water Scenario ....................................................................... 4.1 4.1 Water-Use Model ................................ 4.2 4.1.1 Characteristics of Water-Use Model Suitable for Screening .4.2 4.1.2 Three-Box Water-Use Model .4.3 4.1.3 Equations for Radionuclide Transfer in Soil Using the Water-Use Model .4.5 v NUREG/CR-5512 Contents 4.2 Calculation of Annual TEDE .............................. ................................ 4.11 5 Residential Scenario . .......................................................................... 5.1 5.1 Residential Scenario: Concepts and Assumptions ........ ............. ....................... 5.2 5.1.1 Time Frame for the Residential Scenario ............................................... 5.2 5.1.2 Exposure Pathways for the Residential Scenario ......................................... 5.2 5.2 Steps for Calculating Annual Dose from Agricultural Pathways ............. .. .................. 5.5 53 Concentrations and TIansfer Factors for Resuspension and Root Uptake From Soil ...... ......... 5.9 5.3.1 Soil-Plant-Human Pathway ..................... .......................... ....... 5.9 5.3.2 Animal Products Contaminated by Soil Sources ......................................... 5.14 5.4 Concentrations and Transfer Factors for Irrigation Water as the Contaminating Medium .... ....... 5.24 5.4.1 Food Crops Contaminated by Irrigation Water .......................................... 5.24 5.4.2 Animal Products Contaminated by Irrigation Water ...................................... 5.33 5.5 Calculation of Pathway Transfer Factors ......................... ............................ 5.51 5.6 Calculation of Total Dose From Pathways for the Residential Scenario .............. ... ........