JPS6449890A - Heat transfer pipe - Google Patents

Abstract

PURPOSE:To detect earlier the breakage in an outer pipe or inner pipe by provid ing in the gap section between an inner pipe and outer pipe a porous metal section which comprises both a porous metal plate with a larger void ratio and another porous metal plate with a smaller void ratio. CONSTITUTION:A porous metal plates 111a and 111b are provided in the gap between the inner pipe 103 and outer pipe 104 of a heat transfer pipe 102 of double pipe type with the metal plates 111a and 111b alternating in the circum ferential direction. The porous metal plate 111a has a larger void ratio and the porous metal plate 111b has a smaller void ratio. When the inner pipe 103 is broken, the water and steam that leak out pass through the void section of the porous metal plates 111a and 111b and flow into the upper intermediate plenum 123 or lower intermediate plenum 124. The leaked water and steam reach a leak detection section through a leak detection nozzles 125 and 126 and the breakage of the inner pipe 103 can be detected in an early stage. If the outer pipe 104 is broken, the high pressure gas in the intermediate plenums 123 and 124 flows out through the porous metal plate 111a or 111b so that the gas pressure in the intermediate plenums 123 and 124 drops and the breakage of the outer pipe 104 can be detected.