| 摘要 |
PURPOSE:To reduce the possibility of generation of thermal stress by forming a vapor flow-in window in a heat transfer tube and by forming a vapor flow path to an upper water chamber in a cylinder by inserting a heat transfer accelerator thereinto so as to provide a thermal insulation layer between the heat transfer accelerator and the inner circumferential surface of a heat transfer tube communicating hole, as well as the inner circumferential surface of the upper end part of the heat transfer tube, respectively. CONSTITUTION:Water in a heat transfer tube 1 is adapted to flow through an annular flow path 48 having small sectional area and formed between the inner circumferential surface of the heat transfer tube 1 and the outer circumferential surface of an inner solid cylindrical rod 42, and this serves to increase the mass speed inside the heat transfer tube 1, whereby the heat transfer efficiency at the hat transfer surface is improved. Heat exchange is then made between water and liquid sodium, and vapor generated is then allowed to move upwardly through the annular flow path 48. When vapor reaches the upper end portion of the heat transfer tube 1, it is allowed to enter a vapor flow path 43 through a vapor flow-in window 41 formed around the lower end part of the cylinder 40 so as to flow into an upper water chamber 12 since a thermal insulation layer 45 is formed between the inner circumferential surface of the upper end part of the heat transfer tube 1 and the inner circumferential surface of a heat transfer tube communicating hole 31 of an upper tube plate 11 and the outer circumferential surface of a cylinder 40 at the upper end part of a heat accelerator 38 in such a manner as to choke the same. Vapor fed into the upper water chamber 12 is adapted to flow out in the direction shown by arrow head D. |
