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Illustration of HLW Repository Performance: Using Alternative Yardsticks to Assess Modeled Radionuclide Fluxes

Published online by Cambridge University Press:  01 February 2011

Kaname Miyahara
Affiliation:
Geological Isolation Research and Development Directorate, Japan Atomic Energy Agency (JAEA),4-33 Muramatsu, Tokai, Ibaraki, 319-1194 Japan
Tomoko Kato
Affiliation:
Geological Isolation Research and Development Directorate, Japan Atomic Energy Agency (JAEA),4-33 Muramatsu, Tokai, Ibaraki, 319-1194 Japan
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Abstract

Complementary indicators have been used in developing a safety case in order to avoid uncertainties in the biosphere modeling used to estimate conventional dose or risk. For example, radionuclide fluxes can be used to evaluate the effectiveness of barrier performance. However, it is difficult to define relevant yardsticks for comparison, because the fluxes of naturally occurring radionuclides due to geological processes vary considerably depending on time and location. This paper discusses the relevance of alternative yardsticks for assessing modeled radionuclide fluxes by selecting yardsticks calculated from fluxes of natural radionuclides at the groundwater discharge point from the geosphere to an aquifer; these are then compared with fluxes of repository-derived radionuclides at the same point. Such yardsticks avoid surface geological processes that may also contribute to natural fluxes, allowing comparison at a suitable, common evaluation point that avoids dependence on site-specific conditions. The effectiveness and robustness of barrier performance is demonstrated using the developed yardsticks and the sensitivity of the analysis to groundwater flux is illustrated.

Type
Research Article
Copyright
Copyright © Materials Research Society 2008

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