The ACR-700 has been designed with safety, cost and schedule as major drivers. Early in the concept stage it was demonstrated that short construction schedules can be achieved by paralleling activities, using such techniques as extensive modularization, combined with open top construction of the reactor building, as well as using the latest construction techniques available such as climbing formwork, prefabricated rebar, automatic welding, etc. This paper looks at the continued evolution of detailed construction sequences as a planning tool tied to the Primavera schedule. It also looks at examples where cost and schedule become important factors in making engineering decisions associated with the construction method and sequence. Experience on the modularization benefits achieved from the recently completed Qinshan CANDU project is presented. Finally it draws conclusions on the confidence in achieving construction schedules for both the first and nth units of a series.
Atomic Energy of Canada Ltd. (AECL) has very successful experience in implementing new construction methods at the Qinshan (Phase III) twin unit CANDU 6 plant in China. This paper examines the construction method that must be implemented during the conceptual design phase of a project if short construction schedules are to be met. A project schedule of 48 months has been developed for the nth unit of NG (Next Generation) CANDU with a 42 month construction period from 1st Concrete to In-Service. An overall construction strategy has been developed involving paralleling project activities that are normally conducted in series. Many parts of the plant will be fabricated as modules and be installed using heavy lift cranes. The Reactor Building (RB), being on the critical path, has been the focus of considerable assessment, looking at alternative ways of applying the construction strategy to this building. A construction method has been chosen which will result in excess of 80% of internal work being completed as modules or as very streamlined traditional construction. This method is being further evaluated as the detailed layout proceeds. Other areas of the plant have been integrated into the schedule and new construction methods are being applied to these so that further modularization and even greater paralleling of activities will be achieved. It is concluded that the optimized construction method is a requirement, which must be implemented through all phases of design to make a 42 month construction schedule a reality. If the construction methods are appropriately chosen, the schedule reductions achieved will make nuclear more competitive.
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