Control and instrumentation (C&I) systems for nuclear power plants should support the operational personnel in observing the state of equipment. These systems should provide the operator with proficient, timely, and comprehensive information about equipment condition during stationary and transient operating conditions, as well as well-grounded assistance in alarming or ambiguous situations, relying on the properly processed measured data. In modern practice, these objectives are mainly attained with the help of highly computerized data acquisition and control systems (DACS). An example of such a relatively up-to-date system is a digital complex called the Nuclear Power Plant Control Complex with Advanced Man-Machine Interface 90 (NUCAMM-90), developed by Hitachi in the mid-1990s and adopted for nuclear power units with ABWR-type reactors. In particular, this complex is implemented at Japanese Kashiwazaki-Kariwa Unit 7 with the rated output of 1,356 MW. ^[170] The complex includes a main control panel that comprises an intensively arranged set of principal operation and observation devices and a wide display panel that provides the main bulk of information on the entire power unit, so as to make the man-machine interface obvious, comfortable, and practical (Fig. 4-69). The display panel contains 226 fixed mimic displays, 231 hard switches, and 170 annunciators arranged so as to make the current status of the power unit comprehensible at a glance. The number of operation devices on the operator console of the main control panel is minimized and concentrated so that they can be...