| 摘要 |
The core of this nuclear reactor having preferably spherical operating elements is surrounded by a reflector formed from a roof, cylindrical side wall and floor. Absorber rods which can be moved into the core are used to shut down and control the nuclear reactor. For safety reasons, the absorber rods (1) are assigned to two different shutdown systems which operate independently of one another. The first is provided for complete shutdown or long-term shutdown, while the second is used for partial shutdown or emergency shutdown. The absorber rods (1 B) of the second shutdown system are located in the space between the absorber rods (1 A) of the first shutdown system. Consequently, by contrast with known nuclear reactors, the number of absorber rods (1 A) for the long-term shutdown can be reduced in conjunction with the same shutdown effect, or the shutdown effect can be intensified in conjunction with the same number. The density with which the absorber rods (1 A) of the first shutdown system occupy the core cross-sectional area is higher at the edge of the core than at the centre of the core. Consequently, when a nuclear reactor is completely shut down a radially flattened importance distribution is obtained for neutrons. In this nuclear reactor, it is possible to dispense with feeding in absorber means with the aid of an emergency shutdown system without loss of safety. <IMAGE>
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