Patent Number: 041475887
Section: description

Referring now to the attached drawings, the proposed recharging device for a fast-neutron reactor, shown in FIGS. 1 and 2, comprises a recharging mechanism 1 installed in rotating plugs 2 which are rotatable around their axes in a nuclear reactor vessel 3 above a reactor core 4. The device further includes a mechanism for transferring fuel assemblies 5 and rods 6 of the control and safety system. Elsewhere in this text, when mention is made of the fuel assemblies 5 and rods 6 in conjunction, these will be referred to as "assemblies" for reasons of brevity. The assembly transfer mechanism comprises an elevator 7 with a charging socket 8 and a recharging socket 9, and an assembly handling mechanism 10. The proposed device also includes a storage drum 11 for new assemblies and a storage drum 12 for spent assemblies. The recharging mechanism 1 has a grip 13 which terminates in a stop 14. FIG. 3 is a sectional view taken on line III--III of FIG. 1 and shows compartments 15 in the storage drum 11, which are all identical and intended to receive assemblies. A rod 6 of the control and safety system is placed in a sleeve-type holder 16, so that its overall dimensions are equal to those of the fuel assembly 5. FIG. 4 is an elevation view of a rod 6 of the control and safety system, placed in the holder 16 which in its upper portion is provided with a collet 17 having a cone-shaped inner surface 18. The collet 17 interacts with an encircling groove 19 provided on the surface of the rod 6, near its profiled head 20. Between the bottom of the holder 16 and the end face of the rod 6, there is arranged a spring 21 with a pusher 22, intended to push the rod 6 from the holder 16 during a recharging operation. When placed in the holder 16, the rod 6 is referred to as an assembly 23. FIG. 5 is a view of the unit A of FIG. 1, taken at a moment when the new rod 6 is disengaged from the holder due to the interaction of the stop 14, protruding from the grip 13 of the mechanism 1, with the cone-shaped surface of the collet 17 of the holder 16. FIG. 6 is a view of the unit B of FIG. 1, taken at a moment when the spent rod 6 is engaged with the holder 16 due to the interaction of a grip body 24 of the mechanism 10 with the profiled head 20 of the rod 6. The proposed device for recharging a fast-neutron reactor operates as follows. Prior to the recharging, a new rod 6 (FIG. 4) of the control and safety system is placed in the sleeve-type holder 16; the collet 17 is received in the encircling groove 19, making up the assembly 23 which is inserted into any compartment 15 (FIG. 3) of the storage drum 11 (FIG. 2) for new assemblies, adjacent to the new fuel assemblies 5 placed in the similar compartments 15. The rotor of the storage drum 11 for new assemblies is set into rotation, and one of the compartments 15 (FIG. 3), holding the assembly 23, is matched with the axis of the mechanism 10 (FIGS. 1 and 2). The latter extracts the assembly 23, transfers it and places it in the charging socket 8 of the elevator 7. The latter transfers the assembly 23 received in the socket 8 to the periphery of the reactor core 4. By rotating the plugs 2, the mechanism 1 is matched with the axis of the socket 8 which holds the assembly 23. The cone-shaped surface of the stop 14 protruding from the grip 13 of the mechanism 1 slides over the cone-shaped surface 18 of the jaws of the collet 17, unclamps the latter and disengages it from the encircling groove 19 provided on the surface of the rod 6, near its profiled head 20. At the same time the pusher 22 pushes the rod 6 upwards under the action of the spring 21, until the collet 17 leaves the encircling groove 19. The grip 13 of the mechanism 1 grips the profiled head 20 on the outside and withdraws the new rod 6 from the holder 16. As this takes place, the holder 16 remains in the socket 8 of the elevator 7. After this, by rotating the plugs 2, the mechanism 1 with the new rod 6 clamped in the grip 13 is directed at the transfer socket (not shown) provided in the screen of the core 4, wherein there is temporarily placed the new rod 6. The rotating plugs 2 then point the mechanism 1 at the spent rod 6 in the core 4, which is to be replaced. The latter rod 6 is removed with the aid of the grip 13 and transferred to the holder 16 found at this time in the socket 8 of the elevator 7. From its temporary storage place in the socket in the screen of the core 4, the new rod 6 is placed, with the aid of the rotating plugs 2 and the mechanism 1, in the vacated socket of the core 4, wherefrom the spent rod 6 has been just removed. The elevator 7 then moves the socket 8 with the holder 16 holding the spent rod 6 down the inclined surface until it comes into contact with the mechanism 10. As the mechanism 10 reaches the holder 16 with the spent rod 6, its body 24 presses upon the head 20 of the rod 6, whereby the spring 21 is compressed and the rod 6 is forced into the holder 16 until the collet 17 engages with the encircling groove 19. As a result, another assembly 23 is produced and placed by the mechanism 10 in the compartment 15 of the spent assembly storage drum 12. At this point the recharging process is completed. The recharging of fuel assemblies is carried out in a similar manner, with the exception of the operation of removing the new assembly from the holder and placing the spent assembly in this holder. However, the duration of both processes (the recharging of fuel assemblies and rods of the control and safety system) is equal, because the removal of a rod of the control and safety system from the holder and placing it in the holder are carried out simultaneously with the removal of this rod from or placing it in the respective socket of the core or compartment of the storage drum.