Software Qualification of a Real Time Kernel-based Programmable Logic Controller for Safety-Critical Applications: Tools and Techniques

摘要

To apply a real-time kernel based Programmable Logic Controller (PLC) to safety-critical applications including a nuclear power plant, a software qualification of the PLC is regarded as a very difficult and time-consuming task due to not only the complexity of the embedded software but also the criteria and requirements for a software qualification of safety-critical applications. The BTP HICB-14 of NUREG-0800, Regulatory Guide 1.168 and 1.152, and IEEE Std. 7-4.3.2 and 1012 should be referenced to qualify a software or software-based component for a nuclear safety-critical system or equipment in Korea. We plan to resolve this problem by applying matured techniques and their tools based on the principles of a software engineering to efficiently carry out the activities such as a software verification and validation, software safety analysis, and software configuration management for the PLC. The matured techniques such as a review and inspection, formal verification, traceability analysis, HAZard OPerability (HAZOP), and software inspection and testing are supported or automated by using various tools such as the Fagan's Inspection method, Statemate MAGNUM's ModelChecker/ModelCertifier, Nuclear Software Engineering Environment (NuSEE), HAZOP checklists, and Cantata++. This approach has been successfully applied to qualify system software of the PLC (called POSAFE-Q) and it will contribute to raising the Capability Maturity Model (CMM) level 3 estimated at the initial stage of the KNICS project to a CMM level 5. This approach can be easily extended to other safety-critical applications such as in the railways, military, medicine, etc.