Seismic Optimisation Approach for CANDU Modules

Abstract

The CANDU 3 is the latest generation and the smallest version (450 MWe) of the high performance line of CANDU Pressurized Heavy Water Reactor (PHWR) systems developed in CANADA. To meet project objectives of reduced construction schedule and cost, particular attention towards construction has been made in the CANDU3 design. Modular construction techniques, developed by the shipbuilding and off-shore oil platform construction industries are utilized so that a construction schedule of just over three years can be achieved. A typical reactor building internal module consists of a structural steel frame containing one or more systems and floor levels that can weigh up to 500 tonnes. The CANDU 3 modules are easy to build and can be manufactured by various Canadian and international shops. Each module is completed and by inspected before installation at the site. The modules are installed by use of a very heavy lift (VHL) construction crane through the open reactor top. Once in place, the modules are fastened to the adjacent concrete internal structure and base slab (if necessary) at preselected points. The seismic design of the steel modules is based on an envelope encompassing ground accelerations up to 3g to permit siting at most potential sites without re-design. Conceptual analysis results of the steel modules indicated large seismic response. The objective of this study is to focus in an a typical CANDU 3 steel module (R40) and develop a process to optimize the design and reduce the seismic response of the module to an acceptable level. The process developed was then repeated for the design of Steel Modules RM10 and RM21 to obtain acceptable seismic designs.