Principles for guiding the ONKALO prediction-outcome studies

This document provides the necessary foundation for establishing the strategy for the Prediction-Outcome studies currently being conducted by the ONKALO Modelling Task Force (OMTF) during the construction of the ONKALO ramp. These studies relate to the geology, rock mechanics, hydrogeology and hydrogeochemistry. The purpose of the Prediction-Outcome campaign currently underway in the ONKALO ramp tunnel is to optimize Posiva's ability to predict rock conditions ahead of the excavation face. The aim of the work is: to enhance confidence in ability to predict rock conditions in general - and especially for the repository volumes; (later) testing and verification of repository design rules as it would not be possible to make too many additional boreholes in repository volume; and to support the ongoing construction work and make possible the application of the CEIC method. The document also presents current plans for at what stages of the ONKALO construction predictions and outcome assessments will be made as well as current plans for what properties and impacts will be predicted. These plans will evidently be subject to revision during the course of the work. (orig.)