Design and Qualification Testing of Active Magnetic Bearings for High-Temperature Gas-Cooled Reactors

Active magnetic bearings have been utilized in all recent high-temperature helium-cooled reactor designs as the only mature dry bearing technology to provide high reliability and availability of operations for these highly demanding applications. High reliability and availability is accomplished through proper design of the magnetic bearings, auxiliary bearings, and control and monitoring systems, as well as the exploitation of provisions for remote observability and diagnostics. Designing magnetic bearings into HTR fluid machines such as primary helium circulators and fuel ball blowers eliminates bearing lubricant contamination and also eliminates the ancillary equipment associated with the sealing systems for bearing lubricant. Recently a helium circulator and a fuel ball blower supported with magnetic bearings were tested separately and fully qualified for HTR plant operation. The magnetic bearings and auxiliary bearing systems were fully tested in a helium environment inside the machines. The current paper addresses the unique attributes in the design of magnetic bearing systems and the qualification testing performed for the HTR-PM fuel ball blower.