A FORMAL METHOD

In order to allow the introduction of safety-related digital control in nuclear power reactors, the software used by the systems must be demonstrated to be highly reliable. One method of improving software reliability is testing. A study of the complete testing of software was performed based upon past research. The literature search found two complete testing methods, only one of which, complete path testing, was feasible for use. The literature contained a practical and nearly complete testing method known as Structured Path Testing, developed by Howden (Howd77). Structured Path Testing was adapted here as the basis for a new testing method known as Feasible Structured Path Testing (FSPT). The FSPT involves a five step formal method which examines the code's data flow structure and develops test cases based upon the analysis. The FSPT eliminates unfeasible paths from the test case which greatly speeds the testing process. The FSPT was applied to several simple programs. Many of the test programs are written in the 001 case tool language developed by Hamilton Technology (Hami92.). The ultimate example test bed program, known as the Reactor Protection System (RPS) was written by M. Ouyang (Ouya95)