The Design And Process Development Of The Moulds For Outer Strip And Cell Of The Spacer Grid For Annular Assembly

The annular fuel assembly is aimed at the light water reactor.It is designed according to the design experience of feul assembly from America,French and Korea for improving the security and economy.The overall design has been conducted.The core of the annular assembly is compatible with PWR,so as the boundary dimension.The spacer grid spacer grid is the essential support part of fuel assembly,with which and the guide thimble,instrument tube,top nozzle,bottom nozzle,skeleton is constituted,and the spacer grid aim at clamping fuel rods;fixing position of fuel rods;keeping geometric arrangement and separating accuracy of fuel rods;Maintaining the lateral space between fuel rods and avoiding causing the force of transfiguration or distortion during the axial thermal expansion;Mixing the cooling liquid which bring away the heat of nuclear fission in order to making sure the optimum heat,nuclear,machinery,hydraulics performance in reactor;Ensuring the assembly is rigid and playing the guide role during loading and unloading process of the reactor.These are the function of the spacer grid.Due to the special role that the spacer grid plays,the safety and economics of nuclear power plant is closely related to the designing and manufacturing quality of the the spacer grid.In the 15×15 annular assembly,the distance between outer surfaces of two fuel rods is only 1mm,there is not enough space to assemble three curved spring of traditional the spacer grid is redesigned and the supporting components are moved from stripe cell center to cross area in order to guarantee the spacer grid can provide enough horizontal and vertical force and no damage when loading and unloading of the fuel assembly.In this paper,the drawing and specification of the outer strip and cell of the spacer grid for annular assembly are studied,the required manufacturing mould and tooling has been designed according to dimension of the outer strip and cell and coining test.The parameter has been determined by the process development of the outer strip and cell,it is concluded that coining mould and process parameter of outer strip and cell has been confirmed and a small batch of products wh ich meets specification have been produced.The outer strip and cell of the spacer grid has been designed and process test has been performed,the key process of the outer strip and cell of the spacer grid has been mastered,and the sample has been manufac tured.The results indicated ability of independent production for the outer strip and cell of the spacer grid have been possessed.