Patent Number: 041475887
Section: summary

The present invention relates to nuclear reactor recharging devices and, more particularly, to recharging devices for fast-neutron reactor with liquid metal coolant, wherein the replacement of spent fuel assemblies and rods of the control and safety system is carried out under conditions when the reactor is stopped, all the recharging operations are shielded, and the core circuit remains sealed. There is known a nuclear reactor recharging device comprising a separate mechanism for replacing fuel assemblies, and a separate mechanism for replacing rods of the control and safety system. The use of two separate mechanisms is due to substantial differences in the configuration and size of the fuel assemblies and rods of the control and safety system. In this specific case, the rods of the control and safety system are round, whereas the fuel assemblies are hexahedral and have a greater length and diameter. There is also a French device, known as Super Phoenix, for recharging fast reactors. In this device, fuel assemblies and rods of the control and safety system are handled by one mechanism. The rods are placed in cartridges so that both make up an assembly similar to a fuel assembly. The latter technical solution envisages the use of special end members for fuel assemblies, rods of the control and safety system, and cartridges. These end members are hollow cylinder-shaped heads with an internal groove to interact with the grip of the recharging mechanism. The device under review is not applicable to nuclear reactors, wherein the recharging mechanism has a grip to interact with profiled heads of fueld assemblies and rods of the control and safety system, which heads are gripped on the outside. However, there is a large group of nuclear reactors whose recharging mechanisms interact with profiled heads of core elements, which are gripped on the outside, because this type of gripping is the most effective. Besides, at present, use is made of a device for recharging a fast-neutron reactor, comprising a storage drum with compartments for new fuel assemblies and rods of the control and safety system, a mechanism for transferring fuel assemblies and rods from the storage drum to a recharging mechanism having a grip to interact with profiled heads of fuel assemblies and rods of the control and safety system to be gripped on the outside, and place new fuel assemblies and rods in the reactor's core and remove spent fuel assemblies and rods therefrom into a storage drum which receives spent fuel assemblies and rods removed by the recharging mechanism from the reactor's core and transferred by the transfer mechanism. In this recharging device, the compartments for rods of the control and safety system are different in shape from the compartments for fuel assemblies, which is due to differences in the dimensions of the rods and fuel assemblies. If rods of the control and safety system are placed by mistake in compartments for fuel assemblies, these rods are out of reach of the recharging mechanism and cannot be withdrawn from the compartments. In order to avoid accidents and damage of recharging mechanisms, the program control system of the recharging device must be designed to rule out placing of rods of the control and safety system in the compartments intended for fuel assemblies, and vice versa. For this purpose, program control systems for controlling recharging devices of known types envisage interlocking to prevent grips with fuel assemblies from approacing compartments in the storage drum intended for rods of the control and safety system, and vice versa. Besides, the presence of special compartments in the storage drum complicates the design and increases the size of the drum. Obviously, the foregoing design of the recharging device is too complicated; on the other hand, it is not reliable enough and does not rule out accidents in the course of recharging. It is the main object of the present invention to provide a recharging device for a fast-neutron reactor, intended for recharging fuel assemblies and rods of the control and safety system with profiled heads, and having a single mechanism for the transfer of fuel assemblies and rods of the control and safety system. It is another object of the present invention to raise the reliability of the recharging process and reduce the recharging time. The foregoing objects are attained by providing a recharging device for a fast-neutron reactor, comprising a storage drum with compartments for new fuel assemblies and rods of the control and safety system, a mechanism for transferring fuel assemblies and rods of the control and safety system from the storage drum to a recharging mechanism having a grip intended to interact with profiled heads of fuel assemblies and rods of the control and safety system to be gripped on the outside, as well as to place new rods and fuel assemblies in the reactor's core and remove spent ones therefrom and a storage drum for spent fuel assemblies and rods of the control and safety system, removed from the reactor's core and received by this second drum from the transfer mechanism, in which device the compartments of the storage drums for rods of the control and safety system are identical in accordance with the invention, with the compartments for fuel assemblies, the rods of the control and safety system being stored and transported from the storage drums to the recharging mechanism in sleeve-type holders, so that when placed in such holders, the dimensions of the rods of the control and safety system are equal to those of the fuel assemblies, the joining of each sleeve-type holder with a respective rod being effected with the aid of a collet provided on the open end of each holder, on the surface of each rod, near its head, there being provided an encircling groove to interact with the collet, the grip of the recharging mechanism being provided with a stop to interact with the internal surface of the collet to open the latter and release the rod of the control and safety system from the holder under the action of a spring arranged in the holder. The recharging device of this invention makes it possible to replace both fuel assemblies and rods of the control and safety system with the aid of the same mechanisms; the device is simple in design and rules out accidents due to placing rods of the control and safety system into compartments intended for fuel assemblies and vice versa.