Abstract
Safety assessment for radioacitive waste disposal will be needed to extend over a long period of time in case of Long-lived nuclide.So that the results of safety assessment will includes some uncertainty. It is important to deal with those uncertainty, to calculate with thorough conservative assamptions, and to with realistic assamptions. It is thought that a geochemical opinion, various componet tests, and the use for the natural analogue data etc. are useful though the uncertainty is left ensuring the realistic assumption.
