The Industry Standard Tool-set (IST) of Codes for CANDU Safety Analysis

Computer codes are used in the Canadian nuclear industry for design support and safety analysis of CANDU reactors and small reactors, and in the provision of analysis services to its internal and external customers. Many of these codes were brought into service during the growth years of the nuclear power industry in Canada (mid 1970's to late 1980's). Typically, validation was conducted during the development of the codes to ensure their adequacy, however the validation process followed was not formalized. Similarly, the software engineering processes employed during their development and subsequent maintenance were not necessarily consistent with modern standards. In the mid-1990's the Canadian nuclear industry undertook a number of projects to upgrade the quality of safety analysis software. Atomic Energy of Canada Limited (AECL) established a safety analysis code Validation Project and Ontario Power Generation Incorporated (OPGI) - formerly Ontario Hydro - established a Verification and Validation of Safety Analysis Software Project as part of its Integrated Improvement Program (IIP). Underlying forces driving these projects included concerns raised by the regulator regarding the quality of safety analysis software and the need to conform to newly-issued Canadian quality assurance standards, specifically CSA N286.7. These projects involve establishing either formal software validation or software verification and validation methods, together with design recovery of the software and its documentation. The objectives of the projects are to ensure: - that there is a low likelihood of errors being introduced into safety analysis that are due to deficiencies in the software, - a documentation base exists for the codes that would demonstrate to the regulator that acceptable quality exists and - that the codes are formally qualified for their intended applications. As these projects were being established it was recognized that developments to enhance capabilities, verification, validation, qualification and maintenance of these codes represents a large commitment of resources from organizations within the industry. Furthermore, there was the definite likelihood of redundant work being executed at the different organizations. Compounding these considerations was the fact that the timeliness and effectiveness of review by the regulator of licensing submissions based upon results obtained with these codes could be detrimentally affected by the number and diversity of codes. Therefore, in order to achieve benefits from more efficient resource utilization and reduced licensing risk, an initiative has been undertaken to establish a consolidated common set of computer codes for safety analysis, referred to as the Industry Standard Toolset (IST) initiative. (authors)