| 摘要 |
A nuclear reactor includes a unit 10, the internal unit, comprising a reactor core 11 and flow-guiding parts 38, 39, 40, 41, together with one or more heat exchangers 12 and one or more circulation pumps 13 in a circulation circuit 14 for the water 16 with, during normal operation, a low neutron absorber content. The internal unit is arranged in a basin situated in a tank, with water 15 with a higher neutron absorber content than that in the water in the circulation circuit, and the heat exchangers and the circulation pumps are arranged outside the tank. The water in the basin and the water in the circulation circuit is arranged so as, during normal operation, form interfaces in density locks 17a, 17b arranged on different levels in the internal unit, and the water in the tank to penetrate the internal unit via the density locks when the reactor is shut down. Arranged in the circulation circuit before the reactor core in the direction of movement of the water is a chamber 18 comprising two parts which are displaceable relative to one another in the vertical direction on thermal movements of parts in the internal unit, and one or more jet pumps 19. If relatively cold water with a low neutron absorber content should remain standing in the circulation circuit outside the internal unit, the design of the chamber allows a destructive criticality accident, when one or more of the circulation pumps are started, to be prevented as a result of the water with a high neutron absorber content then being sucked into the chamber and mixed with the water with the low neutron absorber content in the circulation circuit. <IMAGE> |
