Improvements in or relating to low parasitic capture fuel assembly structure

A fuel assembly is described for a nuclear reactor which comprises (1) an array of generally parallel elongated fuel elements, (2) a number of elongated hollow tubular members containing control elements strategically located among the array of fuel elements, (3) tubular members which are composed of a relatively low neutron capture metallic material, (4) a number of grid members longitudinally spaced along the tubular members and which are composed of a metallic material different from the material of the turular members. The grid members have aligned openings through which the fuel elements and the tubular members extend. Retaining members engage the tubular members at the openings, and tubular or retaining members cooperate with the other members to retain the tubular members in position in the grid members. (author)