Patent Number: 042591554
Section: abstract

Fuel assemblies forming cores of gas-cooled reactors, operate at temperatures too high to permit the use of resilient contact elements for holding the fuel rods centered in the openings of the spacer grids of the fuel assemblies, solid and rigid contact elements not relying on resilience, being required. In such cases intercontacting surfaces of the fuel rod metal claddings and the spacer grid contact elements, are capable of sticking together, preventing relative sliding by these surfaces to accommodate thermally induced movements, resulting in the claddings being highly stressed. To prevent this, one or both of the intercontacting surfaces are roughened or otherwise processed to have peaks and valleys or depressions so that abrasion products are carried off between the peaks, permitting the intercontacting surfaces to remain relatively slidable with the result that the previously referred to stressing of the claddings is substantially reduced as compared to that resulting when there is surface sticking together.