This research is a part of the United States (U.S.) Department of Energy-sponsored Light Water Reactor Sustainability (LWRS) Program conducted by Idaho National Laboratory in close collaboration with representatives of the nuclear industry. The joint goal is to provide the technical foundations for licensing and managing the long-term, safe, and economical operation of current nuclear power plants (NPPs). Because NPPs maintain outdated or obsolete equipment, it is common practice to replace wornout equipment on an as-needed basis. This results in a series of like-for-like replacements of components on the control boards that address only the immediate need to replace equipment. Such upgrades rarely represent an encompassing or systematic vision for control room modernization and do not add the benefit of enhanced support for operators in the control room, missing the opportunity to reduce operation and maintenance costs through enhanced efficiency. The purpose of the research described in this report is to provide guidance on how to realize these opportunities by designing control room human-system interfaces (HSIs) with advanced capabilities in mind. Further, this work seeks to ensure that control room modernizations are undertaken with a sound understanding of the impacts to human operators and are designed based on state-of-the-art human factors principles. The goal of the research is to provide an industry-wide approach and road map for effective modernization that not only addresses obsolescence but provides guidance for enhancing the economic viability of the existing fleet. This can be done by improving efficiency and safety through effective design of the control room, incorporating human factors principles across the entire design. This report describes the conceptual design of the liquid radiological waste system and reports on several research activities that inform the design philosophy. Finally, this document presents recommended updates to the original design philosophy based on those findings.iv v We would also like to thank Micheal Hildebrandt, Robert McDonald, and Jens-Patrick Langstrand at the Institute of Energy Technology who were integral to the experimental design for the operator workshop by providing technical expertise and support with the micro-task data collection activities. Additionally, we would like to thank Jacob Lehmer, Maira Orozco, Tyson Hansen, and Brandon Rice of INL for their support in designing the prototypes, assistance in the study design, and help with implementation of prototypes. This report was made possible through funding by the United States Department of Energy Light Water Reactor Sustainability Program. Lastly, we would like to thank Alison Hahn of the Department of Energy and Ken Thomas, Craig Primer, and Bruce Hallbert of Idaho National Laboratory for championing this effort. vi vii CONTENTS ABSTRACT .