Patent Number: 047599014
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a prestressed concrete pressure vessel 1 with a center cavity 2. In the cavity 2 a high temperature reactor 3, surrounded by a thermal roof shield 4, a thermal side shield 5, and a thermal bottom shield 6, is installed, together with a pile 7 of spherical fuel elements. The pile 7 is traversed from top to bottom by a cooling gas. The wall of the cavity 2 and the thermal side shield 5 border an annular space 8, in which--distributed uniformly around the high temperature reactor 3--for example eight heat exchangers 9 are provided, with a blower 10 being associated with each of them. The heat exchangers 9, only one of which is shown, are connected by means of a hot gas conduit 11 with a hot gas collector space 12 located under the pile 7. Each of the heat exchangers 9 is connected by means of a feed water line 13 with a feed water pump 14, while the steam generated is removed through a live steam line 15, each from the heat exchangers 9. The associated blowers 10 are installed in a vertical passage 16 each in the roof of the prestressed concrete pressure vessel 1. In addition to the eight main loops comprising heat exchangers 9 and a blower 10, the nuclear reactor installation comprises two auxiliary loops for the removal of decay heat. Each of the latter contains an auxiliary heat exchanger 17 and an auxiliary blower 18. While the auxiliary heat exchangers 17 are located between the heat exchangers 9 in the annular space 8, the auxiliary blowers 18 are arranged in a vertical passage 19 each in the bottom of the prestressed concrete pressure vessel 1. The auxiliary blowers are equipped with butterfly valves (not shown). For the installation and removal of the auxiliary heat exchangers 17, vertical passages 20 are again provided above them, in the roof of the prestressed concrete pressure vessel 1. By means of a hot gas conduit 21, each auxiliary heat exchanger is connected with the hot gas collector space 12. Only one of the two auxiliary loops is shown. As seen in FIG. 1, each of the auxiliary heat exchangers 17 is connected with an intermediate cooling water loop 22, by means of the lines 23 and 24. Each of the intermediate water loops further contains a circulating pump 25 and an intermediate cooler 26; in the latter the water circulated in the loop 22 transfers its heat to a second loop, the service water cooling loop 27. Each service water cooling loop 27 contains a circulating pump 28 and a wet cooling tower 29. In the latter, the heat removed from the nuclear reactor 3 is released to the environment. FIG. 2 shows a nuclear reactor installation, which--with the exception of the apparatus for the removal of the decay heat--corresponds to the installation of FIG. 1. Identical reference symbols are used for identical structural parts. Here again, two auxiliary loops are provided for the removal of decay heat. In place of the auxiliary heat exchangers 17, each auxiliary loop contains a bundle 30 of parallel and independent heat pipes, the heat absorbing part 32 of which is arranged in a flow of cooling gas that may be interrupted by means of the butterfly valve of the auxiliary blower 18 involved. The heat emitting part 33 of the heat pipes 31 of each bundle is installed in a reservoir 34 filled with water and placed on top of the prestressed concrete pressure vessel 1. The part 35 transporting the heat, i.e., the connecting part between the parts 33 and 34, is located in each bundle 30 in one of the vertical passages 20. As a heat sink, an external cooling water system 36 is provided for each bundle 30 of heat pipes, in which by means of a circulating pump 37, cooling water is circulated and which is connected with the reservoir 34. For the recooling of the circulating water, the cooling water system 36 is equipped with a wet cooling tower 38. At least one evaporator line 39 is issuing from each reservoir 34; it is equipped with a safety valve 40. If there is a sufficiently large water supply in the reservoirs 34, the decay heat may be removed by evaporation for a certain period of time through the lines 39 in case of a failure of the active cooling water system. It is thus possible to remove the decay heat even without active components, such as the circulating pumps 37.