Realization of a Simple Mechanism to Simulate Core Subassembly Growth of FBR

Under sodium ultrasonic transducer is used for in-service inspection in a fast breeder reactor to detect the protrusion or growth of core subassemblies. Transducer with its carrier mechanism is to be tested with subassemblies arranged identically to a typical fast breeder reactor. An important test is to demonstrate the capability of transducer to detect the growth of subassembly in sodium at 200 °C. To simulate core subassembly growth in a sodium vessel, different methods/mechanisms are proposed and studied thoroughly to arrive at the simplest way to perform the said task. A trapezoidal screw-nut mechanism, as selected, forms the key feature of the proposed design. The mechanism is tested in the sodium loop under simulated normal and abnormal conditions to demonstrate the reliable operation. Through these tests, a good insight into this mechanism’s operation is obtained in particular and a fairly good understanding of screw-nut working in sodium is acquired in general.