Patent Number: 046559973
Section: summary

BACKGROUND OF THE INVENTION This invention relates to nuclear reactors in which a nuclear fuel assembly is contained in a concrete containment. One example of nuclear reactor of this description is a liquid metal cooled fast reactor. Another is a gas-cooled nuclear reactor of either the fast or thermal variety. In the case of the former, a nuclear fuel assembly is disposed in a liquid metal containing primary vessel which is housed in a concrete containment vault, heat being transferred from the fuel to the liquid metal and from thence to steam generators via intermediate heat exchangers. In the case of the latter, a nuclear fuel assembly is supported within a prestressed concrete pressure vessel and gaseous coolant is circulated between fuel assembly and steam generators to transfer heat thereto. In both cases it is necessary to provide thermal insulation to protect the concrete. In the former example, the concrete of the roof of the vault as well as that of the vault sides and base needs to be protected. In the latter example, the concrete of the roof of the pressure vessel as well as that of the wall and floor, requires protection. This invention is concerned with such roof insulation and not with the insulation of walls or base of concrete vault or pressure vessel as the case may be. Such thermal insulation is generally suspended from the appropriate roof by hangers or tie rods, and various proposals have been made for compensating for the changes in dimensions of the insulation as temperature-dictated expansion and contraction, depending on the state of operation of the reactor, occur. One proposal has been to provide both upper and lower ends of the hangers or tie rods with spherical bearings or seatings, but these are liable to stick and then unacceptable straining of insulation and/or hangers or tie rods can occur which can result in insulation becoming detached from the roof. It is an object of the present invention to provide a construction for the securing of heat insulation to a concrete roof structure which is less liable to damage as aforesaid. FEATURES AND ASPECTS OF THE INVENTION According to the invention, the roof of a concrete containment or pressure vessel of a nuclear reactor has thermal insulation secured to it by hanging therefrom, through the medium of a plurality of hangers, wherein each hanger is secured to the said roof by a linkage connection at its upper end and which permits movement of the hanger in two dimensions, and the other end of each hanger being adapted to support the thermal insulation from beneath by means which permit lateral movement of the insulation in two dimensions. The said linkage connection may comprise an eye or hook on the said roof for engagement with an eye or hook constituting the said upper end of the respective hanger. Thus combinations involving double hook, or double eye, or eye and hook, or hook and eye, are all envisaged. Preferably according to the invention, in a nuclear reactor having a roof, depending hangers supported at the upper ends thereof from the roof by hook and eye type connections to allow two dimensional movement of the hangers, and thermal insulation located under the roof and defining apertures through which the hangers extend to support the insulation, there is provided the improvement comprising a support assembly at a lower end of each hanger, the assembly comprising a first element about the hanger and defining a first one dimensional ridge at the upper end of the first element, the first ridge engaging the underside of the insulation to support the insulation and being pivotal on the insulation, a second element about the hanger and below the first element, a second one dimensional ridge at the upper end of the second element to allow relative pivotal movement between the first element and the second element, means for aligning the first element and the second element such that the first ridge and the second ridge are aligned at substantially 90.degree. with respect to each other, and securing means for retaining the first element and the second element on the hanger.