Remotely operated equipment for post-irradiation examination of the spallation neutron source target vessel

The Spallation Neutron Source produces neutrons by accelerating protons into flowing mercury contained inside a stainless steel target vessel. During facility operation the target vessel is degraded by a combination of high-energy neutrons, the proton beam, and cavitation-induced erosion. The degradation is primarily concentrated at the nose of the target vessel, where the proton beam passes through. Currently, the Spallation Neutron Source has replaced three target vessels and is operating the fourth. Efforts are under way to increase the power capacity and operational lifetimes of the target vessels, which include post-irradiation examination of spent vessels. This examination involves remotely removing multiple disk specimens from the nose of the target vessel using a single piece of equipment, called the Nose Sampling Cutter, installed inside the Spallation Neutron Source's hot cell. The cutter produces disk specimens using a carbide-tipped hole saw. The nose of the target vessel consists of four layers of material, and the Nose Sampling Cutter is capable of cutting through the layers in a single stroke. This remote operation has been successfully completed twice. In addition to the Nose Sampling Cutter, a large reciprocation saw capable of removing a sizable section of the nose of the target vessel has been constructed and tested but not yet implemented. To support this large reciprocation saw, other equipment has also been designed. The details of the Nose Sampling Cutter, reciprocation saw, and associated equipment are discussed.