A procedure for increasing the subcriticality of a stored or transported configuration of nuclear reactor fuel assemblies

Additional absorber rods are inserted into channels for intrareactor measuring sensors and into selected openings for coolant flow in the fuel assembly spacing rack; the inserted rods are secured against inadvertent pulling out of the fuel assembly in the storing or transporting unit. The rods are inserted either before or during the placing of the fuel assembly into the storing or transporting unit. The assets of the procedure include exploitation of existing technological holes in the fuel assembly and universal applicability. (J.B.)