The unique capabilities of the first-principles-based PRODIAG diagnostic system to identify unanticipated process component faults and to be ported across different processes/plants through modification of only input data files are demonstrated in two validation tests. The Braidwood Nuclear Power Plant full-scope operator training simulator is used to generate transient data for two plant systems used in the validation tests. The first test consists of a blind test performed with 39 simulated transients of 20 distinct types in the Braidwood chemical and volume control system. Of the 39 transients, 37 are correctly identified with varying precision within the first 40 s into the transient while the remaining two transients are not identified. The second validation test consists of a double-blind test performed with 14 simulated transients in the Braidwood component coolant water system. In addition to having no prior knowledge of the identity of the transients, in the double-blind test we also had no prior information regarding the identity of the component faults that the simulator was capable of modeling. All 14 transient events are correctly identified with varying precision within the first 30 s into the transient. The test results provide enough evidence to successfully confirm the unique capabilities of the plant-level PRODIAG diagnostic system.