Comparison of design concepts of extension shaft assemblies for integral reactor

The function of ESA is to connect the CEDM driving screw with Control Element Assembly(CEA) and transmit the CEDM driving force to CEA. In this report design characteristics of three types of Extension Shaft Assembly(ESA) applicable to SMART such as lug type, wing type, and linked arm type are compared. Since ESA is a component classified as Safety class 2 it should be designed according to KEPIC MNC. Lug type is structurally simple but needs another tie rod to connect the ESA with CEDM screw. The tie rod makes design of fuel handling system difficult, and has the possibility that the ESA locking arm interferes with control rod when it is locked in lower control rod grouping plate. Wing type makes up for the weak points in Lug type, but the structure is a little complicated and the tolerance control is difficult because it should be machined precisely. Linked arm type with self aligning function has high reliability in view of joint stability but it has low structural reliability due to lots of parts and complicated structure. Stress analysis are carried out for three types and the results show that all have enough design margin