Low-Level Waste Disposal Analysis
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LOW-LEVEL WASTE DISPOSAL ANALYSIS DANIEL ENSMINGER, CHARLES KOPLIK, STEVEN OSTON, AND JAMES NALBANDIAN
MAUREEN KAPLAN,
ABSTRACT The safety of low-level radioactive waste disposal sites is analyzed using the computer code LOTRAN. Radiation doses to off-site individuals and to future land reclaimers are computed for a generic disposal site located in a humid Eastern environment. The predicted doses are compared to illustrative performance criteria developed under this project. Results provide insight into those characteristics of low-level waste disposal systems most important to public safety and will allow analyses of tradeoffs among natural and engineered features. INTRODUCTION There is a growing need to develop safe and effective means for disposal of the ever increasing quantities of low-level radioactive wastes (LLW) being generated by industry, utilities, hospitals, and research institutions. This paper describes a method for analyzing one disposal option -- shallow land burial. The objective of our work is to develop effective, viable systems of relationships between data analysis methods and technical criteria neededto assure safe disposal of LLW, and to demonstrate the safety of the proposed approach. We first describe the systems analysis model (LOTRAN) developed to assess the performance of disposal sites. The model employs simple analytic descriptions which facilitate sensitivity analyses. The results of the model simulations must be compared to measures of site performance. A set of illustrative performance objectives are proposed against which site performance may be compared. A generic LLW disposal site is then described and analyzed. The characteristics of the site are typical of what might be expected for future sites in humid environments. The results are compared to the illustrative performance criteria. SAFETY ANALYSIS Description of LOTRAN The LOTRAN package of computer programs calculates doses to humans from radioactivity escaping from low-level waste (LLW) burial sites. It consists of three programs: * ORIGEN (developed by Oak Ridge National Laboratory), which treats the formation and decay of radionuclides [1]. * TRENCH, which computes the release rates of radionuclides from a LLW site (or direct exposure to radioactivity at the site) for several release pathways [2]. * BIODOSE, which calculates the concentrations of released radionuclides in surface waters and ecosystems and the resulting potential hazard (dose to man per unit rate of release) [3].
506 A data flow diagram of the LOTRAN system is given in Fig. 1. The important aspects of the TRENCH and BIODOSE codes will be discussed in the context of each release pathway modeled. LOTRAN is based on simple analytic descriptions and is thus rapid in execution, requiring only seconds per case. This facility of use enables LOTRAN to be applied to sensitivity studies to determine the relationships between input variables and output dose results. Thus, in addition to conventional safety analyses the user is able to "work backwards"
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