Evaluation of Structural Integrity for the Magazine Housing of Fuelling Machine

Wolsong NPP 1 which is the reactor type of the PHWR uses the natural uranium and has 380 fuel channels. For 100% power operation, the refueling is accomplished in-service. The fuel changing operation is based on the combined use of two remotely controlled fuelling machines (F/M), one operating on each end of a fuel channel. New fuel bundles, from one F/M, are inserted into a fuel channel in the same direction as the coolant flow and the displaced irradiated fuel bundles are received into the second F/M at the other end of the fuel channel. The F/M Magazine acts as a temporary storage area for fuel bundles and the various plugs in the F/M during refueling. It generates thermal and mechanical loads in the F/M Magazine. Together with seismic loads during seismic activity, these loads are considered in the Magazine design. In this paper, the evaluation of the structural integrity of the F/M Magazine housing is performed for Design, Test and Service condition loads given in the analysis requirement for the extended life time from 30 years to 50 years. The Magazine is classified as Safety Class 1. A stress analysis of the Magazine is carried out based on the requirements of the ASME Boiler and Pressure Vessel Code, Section III, Subsection NB, 1998 Edition with 1999 Addenda. The Magazine housing is made up of a thick cylindrical shell and is connected to the End cover at one end through 30' Grayloc clamp. The other end of the Magazine is clamped to the ram housing with a 10' Grayloc clamp. The material of construction of the magazine housing is ASME SA-182, F6a, class 2. The stress analysis is done by using the finite element method