Due to the high complexity of the actual Productive Systems, the design of suitable control systems according to the applicable industrial standards, and the possible negative impacts on human beings, on the environment and on equipment, the development of control solutions are both-secure and stable-is very demanded. One way to develop safer and more reliable systems is the use of Safety Instrumented Systems (SIS) according to the standards IEC 61508 and IEC 61511. However, even when the control programs are developed according to the applicable standards SIS control programs are prone to specification and design errors, as on the developing of any kind of software. One way to improve the reliability of these control programs, method which is also required by the safety standards IEC 61508 and IEC 61511 is the application of the SIS safety programs development cycle, together with the use of formal verification techniques on the control software models as well the use a unified approach for modeling the SIS prevention and mitigation systems, and thus having a better understanding of their interactions.