NATIONAL DECOMMISSIONING DATA BASE AND EVALUATION TOOLS

摘要

Since 1980, the Agency is responsible by law for the safe management of all radioactive waste produced in Belgium, including decommissioning wastes. Since 1991, its responsibility has been extended to the field of decommissioning. More specific Agency's assignments in the field of decommissioning and related to this paper are: 1. collection and evaluation of data (physical and radiological inventories) from nuclear plants, 2. approval of decommissioning programs, including decommissioning cost evaluations and mechanisms of funding. In order to face to multiple and repeated evaluation processes, the Agency, already in the early 90's, started with the implementation of its own integrated data processing system, recording the physical and radiological inventories of nuclear plants, and allowing the evaluation of the quantities of decommissioning materials and wastes as well as of the decommissioning costs of the plants. The cost evaluations cover all decommissioning activities from final shutdown of the facility until final release from nuclear control, as well as conventional demolition and site restoration if required. Beside the information related to the inventories, the database involves so called auxiliary tables integrating unit prices of the various decontamination and dismantling techniques, unit rates for radioactive waste processing, interim storage and final disposal. In 2000, the Agency decided to upgrade its data processing system in order to: 1. meet the latest developments on IT technology, moving toward a relational data bases managing system, 2. enhance the data base quality (integrity, intrinsic validity, extrinsic validity, completeness and accuracy), 3. develop simultaneously the flexibility of the evaluation tools. This paper presents and describes the latest version of the Agency's decommissioning database and its evaluation tools: a fully linked data structure and its interfacing facilities, implemented on SQL Server 7.0. At a high level, the modular structure of the database as well as the main functionality of each module are described, the main modules being: 1. the "Inventory" modules, recording for the given sites the infrastructure elements, the equipments, the stored wastes, and their physical and radiological characteristics, 2. the "Decommissioning techniques" module, integrating measurement, decontamination, dismantling and special recycling techniques, possibly performed by different selected decommissioning companies, as well as their costs elements (consumables, manpower, etc.), 3. the "Wastes" module, integrating standard and special wastes categories, their packaging, transportation and processing possibilities, as well as their costs, 4. the "Nominal evaluation" module, linking an inventory, a selection of techniques and a selection of waste costs, associated to the "best estimate" reference calculation scenario, 5. the "Scenario" module, allowing to define and store alternative scenarios, pessimistic ones, optimistic ones, deferred dismantling, etc. At a lower level, some modules are more thoroughly described, in order to show how data quality has been structurally insured. A following section describes the interface main functionalities: consultation and selections, data inputting possibilities (for instance, when incoming data are stored in Excel files), data checking procedures, implemented calculations, reporting options. A last section discusses the foreseen further developments (e.g. the connection possibilities to other waste or nuclear site management databases).