Safety-related instrumentation and control systems and a problem of the hidden faults

This paper is dedicated to a problem of the hidden faults associated with development of the computer systems in form of their transformation into safety-related instrumentation and control systems. The hidden faults do not allow ensuring functional safety by construction of fault tolerant digital component without consideration of their checkability. Increase of checkability by imitation of accident is exposed to an unacceptable risk of transition into an emergency mode. The approaches to solving the problem during operational time using the methods for improvement of checkability in a normal mode and with analysis of both normal and emergency modes are offered.