XI — 1. Introduction

In 1992, German utilities awarded FRAMATOME (former Siemens) a contract to develop a new BWR nuclear power plant using passive safety systems, and together with the utilities FRAMATOME started development work on a new BWR with a net capacity of 750 MW(e). During the conceptual phase, lasting from February 1992 until September 1993, priority was given to developing passive safety systems to replace or supplement active systems. At the end of the conceptual phase, it was decided that the new requirements for this advanced BWR, especially economic aspects, justified a concept with a reactor thermal output of 2778 MW and a net electrical output of 977 MW. Since 2000 the net electrical output was further increased to 1254 MW.

The four-year basic design phase for the resulting ‘SWR 1000’ plant started in mid-1995. In parallel, an experimental testing program was conducted at FRAMATOME’s own testing facilities and at other German and European research centers to provide verification of the mode of operation and effectiveness of the SWR 1000’s passive safety systems.

In the following sections, after a description of the general design principles and the safety systems, the passive safety components that use natural circulation are described in detail. In particular, descriptions are provided for the emergency condenser, the containment condenser and the pressure vessel cooling after a hypothetical severe accident.