Patent Number: 049960202
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 illustrates one embodiment of the present invention which has been applied to a piping of a fast reactor. Hereinafter, the same portion of FIGS. 2, 5 and 6 as that of FIGS. 1 and 3 carries the same reference number. A tubular thin strip 16 made of a hydrogen-absorbing metal surrounds a piping 11 and a preheater 12 mounted in parallel to the outer surface of the piping 11. The thin strip 16 was 0.1 mm to several mm in thickness. However, the thickness of the thin strip 16 is not, of course, restricted to this value. The hydrogen-absorbing metal for the thin strip 16 is, e.g., Mg.sub.2 Ni and a Ti-Mn based alloy such as TiMn.sub.1.5. The outer cylindrical surface of the thin strip 16 has a heat reserving material or heat insulator 14 disposed thereon. Along the outer circumference of the heat reserving material 14 is disposed a thin steel strip 15 to confine the material 14. A sheet of a hydrogen-absorbing metal e.g. Ti-Mn based alloy may be used instead of the thin steel strip 15. Thus, there are three cases, that is, a first case in which along the inner periphery of the heat reserving material 14 is disposed the hydrogen-absorbing metal, a second case in which along the outer periphery of the heat reserving material 14 is disposed the hydrogen-absorbing metal, and a third case in which along both the outer and inner peripheries of the heat reserving material 14 are disposed the hydrogen-absorbing metals. FIG. 2 illustrates a cross-section of a heat reserving arrangement showing another embodiment of the invention. A heat reserving material 14 includes a hydrogen-absorbing metal 17 scattered therein at a rate of 0.1 to 0.3 g/cm.sup.2 in the form of fiber (alternatively, chip or powder) so that the heat reserving material 14 and the hydrogen-absorbing metal 17 are uniformly mixed with each other. The heat reserving material 14 is normally divided into blocks for easy handling. FIG. 5 illustrates the wall arrangement of a piping showing still another embodiment of the present invention. The wall arrangement of the piping 11 comprises a wall 18 and a layer made of a hydrogen-absorbing metal 19 e.g. Ti-Mn based alloy which layer is jointed by spot-welding or by use of fittings such as bands, bolts and nuts, or is sprayed or coated integrally to the outer surface of the wall 18. FIG. 6 illustrates a piping showing another embodiment of the invention. A piping has an arrangement in which the inner cylindrical wall 20 or outer cylindrical wall 21 for conbining the heat reserving material 14 has a layer made of the hydrogen-absorbing metal 19 e.g. Ti-Mn based alloy which layer is jointed or sprayed or coated integrally to the inner or outer cylindrical wall 20 or 21. While Ti-Mn alloy composition was used as the hydrogen-absorbing metal, the following alloy compositions may be alternatively employed: Mg-Ni, Mg.sub.2 Ni, Mg.sub.2 Ni.sub.0.9 Cr.sub.0.1, LaNi.sub.5, MmNi.sub.5, MmCo.sub.5, MmNi.sub.4.5 Mn.sub.0.5, MmNi.sub.4.5 Al.sub.0.5, MmNi.sub.4.5 Cr.sub.0.5, TiFe, TiCr, TiCr.sub.2, TiFe.sub.0.9 Nb.sub.0.1, Ti-Zr-Mn-Mo, Ti-Mn-Fe-V, Ti-Zr-Mn-Fe and CaNi.sub.5. The character "Mm" represents a miSch metal consisting of a mixture of La, Ce, Pr, Nd, Sm and the like. In accordance with the above embodiments of the invention, tritium which occurs in the reactor core and may escape through the wall of the piping of the reactor to an outside atmosphere can be captured near the surface of the piping, so that a contamination of the outside atmosphere i.e. radiation exposure can be reduced and a gas cleaner in a containment vessel containing the reactor vessel can be simplified.