NPP Control System has been recognized as extreme complex and precision as well as large scale product

thus it is one of the most major design activities that fully

accurately and operationally functional analysis. In this paper

it was discovered that several disadvantages of present functional analysis methods included FAST

the subtract and operate procedure and functional procedure method; owing to the identity of control system

the concept of function based on technological system constraints was introduced; the innovative functional analysis methods enveloped here was the combination of functional tree and structure

as well as its decomposition steps; and RCS Inventory function has been employed to demonstrate the feasibility of this method.