[en] The paper will present an overview of the Ontario Hydro organization and processes for providing design support to the operating nuclear power plants. Examples of design support for Pickering GS will be highlighted. The process is described from identification of projects through the design, procurement, construction, commissioning and in-service phases. The practices for managing engineering deliverables are discussed in the context of how these integrate into the overall change control process. The interaction of Engineering with Operations, Construction, Supply and the regulatory bodies is discussed both for major retro-fit programs and for ongoing design support to the nuclear power plants. Recent experiences during the 1990 Pickering Station Outage and during the Unit 3 fuel channel replacement program are highlighted and an integrated 5 year plan for upgrading the safety related systems for the Pickering Nuclear Power Plant is presented. (author)