Dose Calculation Methodology and Data for Solid Waste Performance Assessment and Composite Analysis at the Savannah River Site

Abstract

This report provides a detailed description of the methodology developed to perform dose calculations for E-Area Low Level Waste Facility Performance Assessments and Savannah River Site Composite Analyses. Chapters 2-8 give a complete set of equations to be used to calculate dose for individual exposure pathways. The first set of dose scenarios assume that a member of the public establishes residence near the waste site and uses contaminated groundwater or contaminated surface water for personal consumption and to irrigate a garden and pasture where produce and farm animals are raised. Products from the garden and farm animals are used for personal consumption. This scenario applies to both E-Area Performance Assessments and Savannah River Site Composite Analyses. General dose exposure pathways for the resident farmer scenario are: 1. Ingestion pathways described in Chapter 2, 2. Inhalation pathways described in Chapter 3, 3. External exposure pathways described in Chapter 4, and 4. Recreational pathways described in Chapter 5 (Composite Analysis only). Doses from all of the above pathways are directly related to the contaminant concentration in the water. Additional dose scenarios considered for E-Area Performance Assessment assume that an inadvertent intruder encroaches on the waste disposal site after loss of institutional control. General dose exposure pathways considered for the inadvertent intruder are:

User Guide for GoldSim Model to Calculate PA/CA Doses and Limits

“…As described in Section 3.0, the appropriate data sets and modified dose equations are automatically used when calculations based on previous analyses are selected. The first worksheet in each section contains data extracted from the current SRNL_Rad_Data_Package (Smith et al 2015) which differs from the data used in any of the previous analyses. Because the radionuclide species are an integral part of the GoldSim model, the species data is not changed for the different calculations and in some cases it may not be possible to exactly reproduce previous results.…”

“…A complete description of the GoldSim Doses and Limits Model and all of the calculations performed is beyond the scope of this document. The dose calculations follow the equations described in SRNL-STI-2015-00056 (Smith et al, 2015). A brief overview of the model is provided in this section to help the user understand the model and as a guide for future development work.…”

“…Contents of the All_Pathways container are shown in Figure 4-7. The Uptake container holds functions that calculate the basic all-pathways dose equations described by Smith et al (2015). Figure 4-8 shows the contents of the Uptake container along with an expanded view of the vegetable uptake function Vege_Uptake which is typical of most GoldSim functions.…”

“…A GoldSim model has been developed to implement the dose calculations and parameters described in SRNL-STI-2015-00056, Rev. 0 "Dose Calculation Methodology and Data for Solid Waste Performance Assessment (PA) and Composite Analysis (CA) at the Savannah River Site" (Smith et al 2015). The model calculates doses and disposal limits for a resident farmer (i.e., the groundwater only all-pathways receptor) and an inadvertent intruder for Performance Assessment (PA), resident and recreational doses for Composite Analysis (CA), and PA disposal limits based on EPA water protection standards.…”

“…Therefore, the model requires modification only when the underlying dose calculations are changed. Any of the 1252 radionuclides in the SRNL_Rad_Data_Package (Smith et al, 2015) can be included in the dose calculations.…”