Design influences on some neutronic properties of an advanced PWR

Using modified fast breeder computer programs the influences of reflectors, control systems and burnup was investigated for some different advanced pressurized water reactors. For the total void effect reflectors with a large amount of water are favorable. Control and burnup influences may lead to problems with respect to total void effect for both the rigid seed blanket design as well as the homogeneous version. Preliminary investigations of a heterogeneous zoned core show a much better total void behaviour. The conversion ratio of this not optimized design is somewhat lower at a value of approximately 0.90. (orig./RW)