Patent Number: 046613110
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A cavity 2 is excavated in the ground 1 and a nuclear power plant 3 is arranged therein. The nuclear power plant comprises a small high-temperature reactor 4 with a capacity of 100 MWe and a steam generator (not shown). The steam generator and the small reactor 4 are installed in a steel reactor pressure vessel 5. The reactor pressure vessel 5 has a cylindrical cross section and is narrowed in its upper part 5a which houses the steam generator. Two circulating blowers 7 for cooling gas are set on a vaulted cover 6 of the part 5a. The core of the small high-temperature reactor is formed of spherical operating elements (fuel and pure graphite elements), which pass through the core several times. A loading space 8 divided into several chambers is provided under the reactor pressure vessel. This loading space is followed laterally by a horizontal channel 9 which is connected with a vertical shaft (not shown). The addition and removal of the operating elements is effected by means of a loading installation comprising an upper and a lower part. The upper part further comprises an addition device 10 for fresh operating elements and a collector vessel 11 for used operating elements, both of which are housed in a shielded building 12 located on the surface of the ground adjacent to the cavity 2. The lower part further comprises a discharge device including a removal device 13, a depletion measuring device 14 and a sorting device 15. These devices are installed in the loading space 8, i.e., under the reactor pressure vessel 5. Secondly, the lower part of the loading installation comprises a conveyor device 16 which is also housed in the chambers of the loading space 8. The discharge device 13 comprises two operating element discharge tubes, each equipped with a decollator. Sphere fragments and scraps are sorted out in the sorting installation 15. The state of depletion of the operating elements is determined in the depletion measuring device 14. The depletion measuring device decidees whether the operating elements are removed from the circulation or returned to the reactor core. A vertical conduit 17 and 18 leads from both the addition device 10 and the collector vessel 11 along the outside of the reactor pressure vessel 5 to the lower part of the loading installation. The vertical conduit 17 connects the addition device 10 with an inward transfer block 19 which is part of the conveyor device 16. The inward transfer block 19 is also connected to a line 20 coming from the depletion measuring device 14. Operating elements that are still usable may also be fed into the conveyor device 16 through line 20. A conveyor block 21 transports all of the operating elements fed in through a conduit 22 and a decollator 23 to a vertical ascending conduit 24. The operating elements are thus conveyed upwards and introduced into a distributor device 25. The latter is located over the reactor core, outside the reactor pressure vessel 5, and in the area of transition to the narrowed part 5a. The distributor device 25 effects the insertion of the operating elements into the reactor core by means of the lines 26. In order to prevent mechanical damage to the fresh operating elements in the course of their conveyance through the vertical conduit 17, a column of operating elements is always present in the conduit. Operating elements determined not to be reusable in the depletion measuring device 14 pass through a line 27 into an outward transfer block 28, from whence they are transported through a conduit 29 to the vertical conduit 18. They are then conveyed upward to the collector vessel 11.