SNS target module remote replacement experience

The Spallation Neutron Source provides the world's most intense pulsed neutron beams for scientific research and industrial development. The pulsed neutrons are generated by directing a high-energy proton beam onto a liquid mercury target. Radiation-induced material degradation necessitates periodic replacement of the mercury target modules. Since the commencement of SNS operations, three target modules have been replaced. Due to the high activation and mercury contamination of the modules, replacement of the target is performed entirely using remote handling methods. Replacement operations are completed in a hot cell environment utilizing a combination of through-the-wall manipulators, a bridge-mounted servo-manipulator, an in-cell overhead crane and a variety of specialized tooling. The details of these replacement operations will be discussed along with the tooling and procedures developed to facilitate remote handling. Lessons learned from the replacement operations will also be discussed.