The United States (U.S.) nuclear industry, like similar process control industries, has moved toward upgrading its control rooms. The upgraded control rooms typically feature digital control system (DCS) displays embedded in the panels. These displays gather information from the system and represent that information on a single display surface. In this manner, the DCS combines many previously separate analog indicators and controls into a single digital display, whereby the operators can toggle between multiple windows to monitor and control different aspects of the plant. The design of the DCS depends on the function of the system it monitors, but revolves around presenting the information most germane to an operator at any point in time. DCSs require a carefully designed human system interface. This report centers on redesigning existing DCS displays for an example chemical volume control system (CVCS) at a U.S. nuclear power plant.The crucial nature of the CVCS, which controls coolant levels and boration in the primary system, requires a thorough human factors evaluation of its supporting DCS. The initial digital controls being developed for the DCSs tend to directly mimic the former analog controls. There are, however, unique operator interactions with a digital vs. analog interface, and the differences have not always been carefully factored in the translation of an analog interface to a replacement DCS.To ensure safety, efficiency, and usability of the emerging DCSs, a human factors usability evaluation was conducted on a CVCS DCS currently being used and refined at an existing U.S. nuclear power plant. Subject matter experts from process control engineering, software development, and human factors evaluated the DCS displays to document potential usability issues and propose design recommendations. The evaluation yielded 167 potential usability issues with the DCS. These issues should not be considered operator performance problems but rather opportunities identified by experts to improve upon the design of the DCS. A set of nine design recommendations was developed to address these potential issues. The design principles addressed the following areas: (1) color, (2) pop-up window structure, (3) navigation, (4) alarms, (5) process control diagram, (6) gestalt grouping, (7) typography, (8) terminology, and (9) data entry. Visuals illustrating the improved DCS displays accompany the design recommendations. These nine design principles serve as the starting point to a planned general DCS style guide that can be used across the U.S. nuclear industry to aid in the future design of effective DCS interfaces.ii iii ACKNOWLEDGMENTSThis research was made possible through the generous availability of digital control system screens and tutorials by staff at a participating nuclear power plant. We would like to acknowledge their support of this effort and their willingness to share the results of our human factors review with a broader nuclear audience. We also thank members of the Light Water Reactor Sustainability Pr...

A category of reactors called university research and teaching reactors, includes relatively high-power pool-type and low-power solid-core reactors. Many high-power university reactors are largely used for irradiations and isotope production. Their almost constant operation tends to impede student access. A university reactor can be particularly relevant to the university’s mission of preparing well-rounded students who have theoretical knowledge, reinforced by focused laboratory reactor experience. The solid-core Idaho State University Aerojet General Nucleonics (AGN) model 201 reactor operates at such a low power (5 W maximum) that it is not useful for isotope production activities. However, the AGN-201 reactor is well suited for teaching and research activities. The solid-core AGN-201 reactor requires no active cooling system, uses a simple shielding arrangement, and the very low operating power results in trivial burnup providing an operating lifetime exceeding many decades. It is thus worthwhile to examine the Idaho State University AGN-201 nuclear reactor more closely because it offers a wide range of research and teaching capabilities while being widely available to students.

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