FUEL ROD SPACER

• Main Author: MOROOKA SHINICHI
• Format: Patent
• Language: English
• Published: 15.05.1989
• Subjects: NUCLEAR ENGINEERING; NUCLEAR PHYSICS; NUCLEAR REACTORS; PHYSICS

PURPOSE:To improve heatproof performance and to improve the critical output by forming projections which divert the flow directions of the cooling liquid films moving axially along the inside walls of cylindrical cells toward the outside surfaces of fuel rods on the inside walls of the respective cylindrical cells in the circumferential direction thereof. CONSTITUTION:The respective cylindrical cells 8a are formed with fixing stoppers 10 at two points by recessing the upper edges of the bodies toward the inside. The projections 17 are formed circumferentially on the inside walls of the cylindrical cells 8a. The positions where the projections 17 are formed are preferably the upper half regions on the secondary side of the cylindrical cells with respect to the flow of the coolant flowing in the cylindrical cells. The liquid films of the two-phase flows flowing axially along the inside walls of the cylindrical cells 8a are turned in the flow direction toward the outside surfaces of the fuel rods 4 by collision against the projections 17. The coolant is, therefore, capable of effectively lowering the outside surface temp. of the fuel rods 4 by sufficient contact with the fuel rods 4. The critical output of the fuel assembly is thus improved, since the coolant is capable of effectively lowering the outside surface temp. of the fuel rods 4 and of preventing boiling transition.