Software Important To Safety In Nuclear Power Plants

This report provides guidance on current practices, documenting their strengths and weaknesses in dealing with the important issues of software engineering that nuclear power plant system designers, software producers and regulators are facing. It focuses on safety critical applications of general purpose processors controlled by custom developed software; however, it should also have application in safety related applications and in other types of computers.

Nuclear-electric power stations, Nuclear reactors, Nuclear power, Equipment safety, Occupational safety, Instruments, Control systems, Control equipment, Control technology, Computerized control, Computer applications, Computer software, Software engineering techniques, Nuclear safety, Performance

Nuclear-electric power stations, Nuclear safety, Computer software, Safety measures, Reliability

Provides guidance in the assurance of quality of specification, design, implementation, maintenance and use of computer software related to items and activities important to safety in nuclear power plants.

Provides guidance on the collection of evidence and preparation of documentation to be used in the demonstration of safety and reliability of the software for computer based systems important to safety in nuclear power plants for all phases of the system life cycle.

The nuclear industry and the U.S. Nuclear Regulatory Commission (USNRC) have been working for several years on the development of an adequate process to guide the replacement of aging analog monitoring and control instrumentation in nuclear power plants with modern digital instrumentation without introducing off-setting safety problems. This book identifies criteria for the USNRC's review and acceptance of digital applications in nuclear power plants. It focuses on eight areas: software quality assurance, common-mode software failure potential, systems aspects of digital instrumentation and control technology, human factors and human-machine interfaces, safety and reliability assessment methods, dedication of commercial off-the-shelf hardware and software, the case-by-case licensing process, and the adequacy of technical infrastructure.

This publication defines a framework that represents the state of the art in assessment methodologies for safety and instrumentation and control software used at nuclear power plants. It describes an approach for developing and communicating assessments based on claims, argument and evidence. The assessment of software dependability, which encompasses properties such as safety, reliability, availability, maintainability and security, is an essential and challenging aspect of the safety justification. Guiding principles for a dependability assessment are established to provide the basis for defining an assessment strategy and implementing the assessment process. Sources of evidence for the assessment are provided and lessons learned from past digital instrumentation and control system implementation in areas such as software development, operational usage, regulatory review and platform certification are also described.

Nuclear-electric power stations, Nuclear power, Equipment safety, Nuclear instruments, Instruments, Control systems, Computer software