Pelletised fuel for water reactor - has fission product duct through pellet centres connected to grooves at periphery

摘要

Fuel rod, esp. for a light water reactor, consists of a sealed tubular can containing a stack of fuel pellets and a helium atmosphere. Each fuel pellet has a central bore to permit gaseous fission products to escape to the accumulation spaces within the can. The cylindrical outer face of the pellet comprises a number of (vertical) grooves designed to offer min. hinderance to heat transfer between pellet and can. These grooves are pref. connected to the central bore by depressions or grooves on the upper and/or lower faces of the pellet. In additions, there may be radial bores connecting the vertical grooves on the outer face of the pellet to the central bore. Arrangement conveys fission products away from the gap around the perimeter of the pellet and thus prevents precipitation of these prods. there, which can lead to a deterioration in the heat transfer between pellet and wall and consequent damage to the can.