METHOD OF DETACHING STACKS WITH LEAKY FUEL ELEMENTS IN LIQUID- METAL-COOLED REACTOR AND APPARATUS FOR EFFECTING SAME

摘要

1446763 Monitoring nuclear reactors N N ARISTARKHOV I A EFIMOV B I ZAITSEV I G PETERS B S TYMOSH V S FILONOV A L SHAROV A I SHILDIN G S BALASHOVA N I BETS S A SKVORTSOV V S YAKOVLEVA I I ZHUCHKOV V S GORJUNOV V A PETROV V P KEVROLEV V N RYBAKOV and N D TVERDOVSKY 2 Nov 1973 51046/73 Heading G6C A nuclear reactor BCD system, suitable for a liquid-metal cooled reactor, comprises a sampler tube 14 which can be positioned successively over fuel bundles 8, and a tube 22 by which an inert scrubbing gas can be passed into the interior of tube 14 to entrain gaseous fission products in the coolant 9 therein, the gases being drawn off and supplied to a detector 21. In the embodiment shown, the tube 14 is positioned through a bore in a plug 4 which is rotatably and eccentrically mounted in a second rotatable plug 3, when the system is to be put into use. The tube 14 is lowered, by a drive 12, until a lower seal 19 abuts a chosen bundle 8 whereby a body of coolant is trapped above bundle 8 and within tube 14. Inert gas supplied by doser 24 debouches from tube 22 below the surface of the trapped coolant so as to bubble up through the latter thereby entraining any coolant-borne fission products released into the trapped coolant from any burst cartridge in the bundle 8. The bundles are checked in succession by repeating the procedure after tube 14 has been repositioned by appropriate rotation of the plug 3 and/or 4. This embodiment is intended to be used in the instance that circulation of coolant in the reactor has ceased and steadystate conditions have been reached. In another embodiment (Fig. 4, not shown) intended for use in the instance that forced coolant circulation is continued during the tests, the lower part of the tube 14 embodies an upwardly convergent nozzle (30) through which coolant issuing from the bundle 8 under test sprays into the tube 14 to be mixed with the inert gas which is supplied to the space above the nozzle. A baffle (31) above the nozzle acts to enhance droplet formation in the coolant issuing from the nozzle.