Prospects for using microelements in VVER reactors

The paper deals with prospects for using micropins in VVER reactors in order to provide a radical improvement in station safety. The most efficient arrangement is direct micropin cooling by the water moderator in assemblies involving transverse flow around a micropin layer: That design provides neutron-physics and thermohydraulic characteristics similar to those of VVER reactors containing rod elements. The micropins do not require any change in the reactor design, and pin assemblies containing them may be built to be identical with those in traditional VVER reactors as regards dimensions, connecting units, and thermohydraulic and neutron-physics characteristics. The conditions occuring in major accidents show that such reactors containing micropins can provide radiation safety in any major accident, and it is particularly promising to use them to extend the working lives of first-generation power stations not fitted with pressurized vessels or sealed shells.