CHANGES IN DOSE PERFORMANCE MEASURES AS MODELING PROGRESSED FOR THE PREVIOUSLY PROPOSED US REPOSITORY IN VOLCANIC TUFF

摘要

This paper examines changes in dose results as characterization and design of the US tuff disposal system progressed from 1993 to 2008 using two performance measures of dose from Monte Carlo type simulations: the expected dose as a function of time (as required by the US Environmental Protection Agency Standard) and the complementary cumulative distribution function (CCDF) of expected peak doses. Both measures are useful. The mean dose history visually emphasizes the long times prior to release and the long time to reach the peak dose. The expected dose history is greatly enhanced by also displaying the various percentiles (e.g., 5', 50th, and 95th percentiles) of the range of behavior (as requested by the US Nuclear Regulatory Commission). The CCDF of peak doses readily shows the range of behavior directly (but with a loss of when those peaks occur). The CCDF also provides a convenient summary measure for discerning differences in the behavior of conceptual models and design options.