Assurance of safety of public, occupational workers and protection of the environment are important needs to be met in the pursuance of activities for economic and social progress. These activities include the establishment and utilization of  nuclear facilities and use of radioactive sources and they have to be carried out in accordance with relevant provisions in the Atomic Energy act. Increasing use of computer based system necessitated to deploy in Nuclear reactors also. Since inception of Nuclear power development in the country, maintaining high safety standards has been of prime importance. Although today computer systems are more matured, but when it comes to use in Safety Critical Systems (SCS) it forces lots of challenges. These are systems important to safety, provided to assure under anticipated operational occurrences and accident conditions, the safe shutdown of the Nuclear reactor, the heat removal from the core and containment of any radioactivity. These systems are called SCS. These systems need to have high reliability and availability. The cost and consequences of critical system failure are potentially much greater than for non-critical systems. So SCS need an augment normal analysis and testing with additional processes that are designed to produce evidence that the systems are trustworthy. This paper discusses the aspects of Verification & Validation procedure to qualify the computer system for SCS. This paper elaborates program inspections, static & dynamic analysis and V&V techniques

Key words: Safety critical system, Verification, Validation, Walkthrough, Inspection, Static and dynamic analysis, Formal verification, Clean room, V&Vtechniques