Implementing a Model for a Computerised Nuclear Materials Accounting System.

The Computerised Nuclear Materials Accountancy System (CNMAS) project is a project to replace various nuclear materials accountancy and tracking systems used on the Sellafield Site with a single, up to date system. During the design phase of the project, the project team developed a business model. This was then implemented using an agile software development methodology (scrum) in a pilot, during which a system was developed to account for Uranium Oxide (UO3) being produced from Magnox Reprocessing Operations, its storage on site and its despatch off site. This paper documents the model as originally conceived, the way the model was implemented in the pilot area, and learning from experience in the pilot area. The model uses a system where the user enters records, which are filed. Once filed records cannot be changed, but they can be withdrawn or superseded by later versions. The records are used to calculate a view of the plants stock, and relevant accountancy reports. Correcting data proved difficult, and the authors are aware that this has been the case in other accounting systems. This is because of the bitemporal nature of the records, which all have both an event date (when the event being recorded happened) and a system date (when the event became known to the system). The paper will highlight the approach now being taken to corrections in the light of the pilot experience. The paper will also highlight the advantages of using an agile development methodology.