Research into the Safety Issues Arising from Using ASIC Devices as a Potential Replacement Technology for Analogue Trip Amplifiers in Existing Reactor Safety Systems

Abstract

There are a large number of ageing analogue trip amplifiers used on the UK’s reactor safety systems. The licensees can replace these obsolete units with either modern analogue equivalents or with digital units. This paper describes, from a regulator’s perspective, the research carried out into the safety issues that arise from the use of digital application specific integrated circuits (ASICs) in a safety-critical reactor protection role. Issues covered include probabilistic risk assessment, formal methods and exhaustive testing. Early indicators are showing that ASIC devices can be made and demonstrated to be sufficiently reliable for safety-critical applications.