Comprehensive total system performance assessment (PA) is a key component of the safety case. Within this PA there are a number of tasks that reuse specific models and datasets, together with associated knowledge base for the disposal system considered. These are tasks where recent developments in the Knowledge Management System by Japan Atomic Energy Agency (JAEA KMS) can lead to optimisation of procedures. This paper will outline the reformulation of PA as a Knowledge Management (KM) task, discuss application of KM technologies to PA tasks, and illustrate how these can be handled electronically in a “Performance assessment All-In-one Report System (PAIRS)” utilising hyperlinks and embedded tools to minimise duplication of material, ease Quality Assurance (QA) and facilitate the regular updating required in the Japanese programme.

The exponential growth in the knowledge base for radioactive waste management is a cause for concern in many national programmes. In Japan, this problem is exacerbated by a volunteering approach to siting of a deep geological repository, which requires particular flexibility in the tailoring of site characterisation plans, repository concepts and associated performance assessments. Recognition of this situation led, in 2005, to initiation by Japan Atomic Energy Agency (JAEA) of an ambitious project to develop an advanced Knowledge Management System (KMS) aimed to facilitate its role as the supplier of background R&D support to both regulators and implementers of geological disposal. This overview outlines the boundary conditions and milestones for the Japanese radioactive waste management programmes, the roles of key organisations and the particular responsibilities of JAEA that led to definition of the goals of the KMS.

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The safety case, as defined in Japan, is an integrated set of arguments to show that a repository is sufficiently safe during both operational and post-closure phases. It explicitly includes the findings of a safety assessment and a demonstration of confidence in these findings. It is developed in a stepwise manner, with provisional cases used to support decisions at major project milestones. Social acceptance is acknowledged to be critical and hence a safety case includes not only technical components, but also the arguments required to explain fundamental issues to all key stakeholders. In the JAEA KMS project, the safety case has been found useful as a framework that allows all supporting R&D to be seen in the context of its applicability. Various tools have been examined to develop associated argumentation models and they have been seen to provide an overview that is valuable to both the users and producers of knowledge. The paper will review progress to date in this work, with illustrative examples of argumentation networks and an outline of future developments and challenges.

The characterisation of potential repository sites will produce huge volumes of information, which must be correlated, quality assured, integrated, analysed, documented and archived in a rigorous and efficient manner. While some of this work involves rather routine data handling that may be easily automated, much of it requires input of tacit knowledge which involves the experience of expert staff. To provide support for the Japanese implementer and also the regulator, a JAEA team is attempting to capture both Japanese and international geosynthesis experience within a Knowledge Management System (KMS) framework, which is termed ISIS. This is a hybrid system that combines “smart” software with human experts, although an aim is to capture tacit knowledge within expert systems to the maximum extent practicable. Initial tests, based mainly on field work carried out by JAEA at the sites of the Mizunami and Horonobe underground research laboratories, have utilised expert systems as modules in a “blackboard system” approach to planning or implementing the processing of field data. Examples are presented of sub-systems where this approach has already been demonstrated and perspectives for more extensive application to integrated geosynthesis management are discussed.