15.23. The Simplified boiling-water reactor (SBWR) is a 600-MW(el) reactor which features natural circulation and passive features to enhance safety and simplify system design. An assembly view of the vessel and internals is shown in Fig. 15.3. Noteworthy is a chimney section above the core to promote the natural circulation of the coolant. As a result, the reactor pressure vessel (RPV) is 2.6 m higher than that required for the 1356-MW(el) ABWR (Table 13.4).

15.24. A summary of some design specifications is given in Table 15.2. The power density has been reduced by about 25 percent compared with present BWRs to increase safety margins. The relatively short (2.44 m) core consists of 732 fuel assemblies of the standard 8×8 lattice type. However, advanced fuel assembly designs can be accommodated. A 7.0- m-i. d. vessel is then needed to accommodate this geometry. A large water inventory for a reactor of this power rating provides an inherent damping of transient disturbances.