Nuclear storage cask inspection robotics as a case study in system design challenges

Spent nuclear fuel, after cooling within a pool storage system, is generally stored in stainless steel dry storage casks. Some dry storage casks have been in regular use for decades, causing increasing interest in technologies to inspect these units. This work presents a case study on the design and prototyping challenges of a robotic inspection system known as PRINSE. PRINSE is designed for in-use dry nuclear waste storage casks, and its development was motivated by a recently completed multi-university NEUP study to develop, deploy, and test sensor systems enabling novel inspection capabilities. The field deployment situation presented particular design challenges not commonly seen in robotics for three reasons: geometric constraints to enter the in-situ cask environment, severe operational temperatures within the cask inspection area, and a high-radiation environment requiring stand-off human tele-operation and remote actuation of the robot from outside the cask. From a design standpoint, project hurdles included the teaming across multiple universities, the need to rapidly develop new prototype systems, and the novel design constraints which had to be managed carefully with the technology development process. This paper presents the specific mechanical engineering design challenges related to this complex system built to inspect dry storage casks. Additionally, it presents insights gained during the completion of the project, with specific focus on the challenges and methods used to achieve design coordination across sub-teams. Key experiences from this project are presented in a design-centric analysis of the management of technical constraints and how these constraints were distributed among the sub-teams.