[en] This report describes the review results of the safety assessment and reliability analysis techniques of digital instrumentation and control (I and C) systems. The techniques are far from that of analog I and C systems because of the characteristics of digital systems. This report categorizes the current issues related to the safety assessment of digital I and C systems into three groups as follows: 1. The methodologies which could integrate the characteristics of hardware and that of software. 2. The methodologies which effectively represent safety improvement due to the fault-tolerant mechanisms embedded in digital I and C systems. 3. The methodologies which could effectively represent the phased-mission systems. (author)