Studying Control Room Operations on a Shoestring Budget - Reflections on the Rancor Microworld
Authors: Ulrich Thomas , Boring Ronald , Lew Roger 
Published: June 2022

As the U.S. continues to develop and mature advanced reactor designs, the nuclear industry is becoming increasingly aware of the need for good human factors are to ensure safe, reliable, effective, and economical concept of operations. Advanced reactor designs aim to reduce staffing, and significant operational costs, by adopting high levels of automation. The highly automated control system designs must be informed with human factors and human reliability data. The proposed concepts of operations are unlike the current, largely manual, concept of operations found in operating nuclear power plants. Human performance data collection has proven difficult to obtain for existing nuclear power plants. Human factors researchers working on advanced reactor designs will encounter these same fundamental challenges and more. The novel concept of operations and accompanying human-system interfaces are novel and require human performance data for validation and licensing. Methods to evaluate novel concepts of operations for diverse advanced reactor designs must be identified to aid vendors in their system design activities. The Rancor microworld is a simulation platform that is currently used to support advanced reactor vendors in developing their control room concepts. The rationale and historical use of the Rancor microworld demonstrates a unique and complimentary approach to traditional full-scope simulator data collection methods that rely on expert licensed operators. The Rancor microworld is a reduced-order model of a small modular reactor conceived and developed to support human performance research on nuclear operations topics. The microworld represents the core elements of a nuclear power plant sans the complexity associated with full-scope simulators that are typically used to support human factors and human reliability research. The impetus for the microworld as an alternative method to acquire human performance data stems from the challenges in performing full-scope simulator studies. Full-scope simulators are expensive to build and maintain. Furthermore, they require extensive expertise to develop scenarios to support specific hypothesis testing. Operations data is historically difficult to obtain since even large research organizations that can afford a full-scope simulator facility encounter sample size issues. Licensed operators are expensive and fully time committed to their employing nuclear power plant. As such, it is very difficult to perform research on nuclear control room operations with sufficient sample sizes to approach statistical significance and draw generalizable conclusions applicable to different designs. Therefore, an alternative population using a simplified simulator offers an approach to evaluate human factors issues. Through numerous studies, the Rancor microworld has demonstrated an effective means to leverage inexpensive and ubiquitous student participants to expand the data collection capability and build a corpus of human performance data to inform advanced reactor control system designs and human reliability modeling. This paper provides an overview of the Rancor microworld studies and describes the benefits and disadvantages of using novice participants in simplified simulator environments in contrast with licensed operators in full-scope simulator environments.