Single loop nuclear power plant for current generation with a helium cooled high temperature reactor

A single loop nuclear power plant with a helium cooled high temperature reactor for generation of electric current, designed for a capacity of 1-5 MWe. The plant, which in addition to the high temperature reactor includes a gas turbine assembly and a heat exchange apparatus, is housed in two pressure vessels located above each other and connected in a releasable manner. The lower pressure vessel contains the high temperature reactor and is charged with the primary gas. The other circulation components are located in the upper pressure vessel which is filled with a protective gas. The gas turbine, the radiators, the high temperature compressor, the intermediate radiators, and the low pressure compressor, are arranged above each other in this sequence and aligned with the high temperature reactor. the recuperator is laterally arranged. A generator may also be located in the upper pressure vessel or in a container set upon the upper pressure vessel.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a single loop nuclear power plant for electrical 
power generation, and more paprticularly to a plant with helium cooled 
high temperature reactor utilizing spherical fuel elements. The plant has 
a gas turbine aggregate made up of a gas turbine and a two-stage 
compressor, with a heat exchanger apparatus exhibiting radiators, 
intermediate radiators and a recuperator, together with gas carrying lines 
between components of the loop. 
2. Description of the Related Technology 
The installation described in DE Nos. 22 41 426 and 24 04 843 have a gas 
turbine aggregate located in a horizontal tunnel below the high 
temperature reactor installed in the center cavity of a prestressed 
pressure vessel. The heat exchange apparatuses are located in vertical 
shafts, arranged on a partial circle around the center cavity. The known 
single loop nuclear power plants are desired for higher capacities and 
require much space in spite of their compact layout. 
SUMMARY OF THE INVENTION 
An object of the invention is to develop a plant suitable for an output of 
1 to 5 MWe and requiring a small amount of space. 
The object may be attained by a single loop nuclear power plant for 
electric current generation with a helium cooled high temperature reactor 
charged with spherical fuel elements. A gas turbine aggregate or assembly 
of a gas turbine and a two-stage compressor with heat exchange apparatus 
is utilized. The heat exchange apparatus comprise radiators, intermediate 
radiators and a recuperator, together with gas carrying lines between the 
circulation components. The plant is housed in two releasably connected 
pressure vessels placed above each other. The pressure vessels are 
separated in a gas tight manner. The lower pressure vessel contains the 
high temperature reactor and is charged with the primary gas. The upper 
pressure vessel is filled with a protective gas and contains the 
circulation components. The gas turbine, radiators, low pressure 
compressor, intermediate radiators, high pressure compressor, and the 
generator are arranged above each other in sequence and aligned with the 
high temperature reactor. The recuperator may be located laterally from 
the other circulation components and connected to the gas turbine and the 
radiators by approximately horizontal gas lines. 
The installation is arranged for upward helium flow through the high 
temperature reactor. Thereafter the helium is conducted through a gas 
conduit directly to the inlet of the gas turbine. 
The two pressure vessels are preferably cylindrical and made of steel. The 
spherical fuel elements forming the reactor core remain in the high 
temperature reactor until their final burnup. If power production 
requirements are for a limited time period, use of a plant according to 
the invention is favorable. 
The installation may be laid out against external effects, such as for 
example earthquakes due to its compact configuration. 
The generator may be installed in the upper pressure vessel or in its own 
container set upon the upper pressure vessel. The gas turbine aggregate 
may be bearingly supported in either dry or magnetic bearings. 
Single loop nuclear power plant according to claims 2 or 3, characterized 
in that the generator may advantageously be a high speed generator without 
topping gear and equipped with magnetic bearings. The protective gas for 
the upper pressure vessel may be helium or nitrogen. Any decay heat may be 
removed by natural convection through the radiators. 
Advantageous further developments of the invention will become apparent 
from the description below of an embodiment with reference to the 
schematic drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The FIGURE shows a lower pressure vessel 1 and an upper pressure vessel 2, 
both made of steel and releasably connected to each other. They may be 
connected by a flange connection 3. 
A helium cooled high temperature reactor 4 is installed in the lower 
pressure vessel 1, the core 13 has spherical fuel elements with an upward 
helium flow. The pressure vessel 1 also contains helium which is under the 
same pressure as the cooling gas. A cold gas collector space 5 is located 
under the high temperature reactor 4, while over the reactor a hot gas 
collector space 6 is provided. 
All of the other circulation components are housed in the upper pressure 
vessel 2. The two pressure vessels 1 and 2 are separated from each other 
in a gas tight manner by an intermediate flange 21. The flange 21 is 
designed for full pressure. The circulator components comprise a gas 
turbine 7, a two-stage compressor exhibiting a low pressure compressor 8 
and a high pressure compressor 9. The heat exchange apparatuses including 
one or more radiators 10, one or more intermediate radiators 11 and a 
recuperator 12 are arranged in the upper pressure vessel. The gas turbine 
7, the low pressure compressor 8 and the high pressure compressor 9 are 
seated on a shaft 14 coupled to a generator 15. All of these components 
are supported in dry or magnetic bearings. 
The generator 15 is located within the pressure vessel 2 in the illustrated 
embodiment. The generator 15 may alternatively be placed in a separate 
container set on the pressure vessel 2. Preferably, a high speed generator 
without preceding topping gear is used. The pressure vessel 2 may be 
filled with a protective gas, such as helium or nitrogen. 
As shown by the figure, the gas turbine 7, the radiators 10, the low 
pressure compressor 8, the intermediate radiators 11 and the high pressure 
compressor 9 are arranged above each other, in an alignment with the high 
temperature reactor 4. The recuperator 12 occupies a lateral position, 
located in the gas between the gas turbine 7 and the radiators 10. It is 
connected to the outlet of the gas turbine 7 by an approximately 
horizontal gas line 16. It is connected to the radiators 10, preceding the 
low pressure compressor 8, by a similar gas line 17. 
The inlet of the gas turbine 7 is connected to the hot gas collector space 
6 by a gas conduit 18. A gas tight connector location is provided in the 
gas conduit 18 in the form of a slide connection 22. A vertical gas line 
20 is connected to the cold gas collector space 5, and to the outlet of 
the high pressure side of the recuperator 12. Alternatively, the cold gas 
carrying gas line 20 under the pressure vessel 1 may be eliminated. The 
cold gas is then conducted directly into the pressure vessel 1 wherein it 
flows to the cold gas collector space 5 (not shown). In this embodiment at 
the entry location of the gas line 20 into the pressure vessel 1 by a 
slide connection is provided. 
The circulation of the primary gas through the plant is described as 
follows. 
The heated helium coming from the reactor core 13 is transported through 
the hot gas collector space 6 and the gas conduit 18 to the gas turbine 7, 
expanding therein. Subsequently, it flows through the gas line 16 and on 
the jacket side, through the recuperator 12, while heating the high 
pressure cold helium flowing in the bundle tubes. The gas then passes 
through the gas line 17 to the radiators 10. In the radiators 10 the 
helium is further cooled and then enters the low pressure compressor 8. 
Following compression and repeated cooling in the intermediate radiators 
11 preceding the high pressure compressor 9, the helium is further 
compressed in the compressor 9 and is finally returned through the gas 
line 19 to the recuperator 12. Here it is distributed over the bundle 
tubes and heated by the low pressure gas. Subsequently, the helium is 
conducted through the gas line 20 to the cold gas collector space 5 and 
the circulation begins anew. 
Decay heat may be removed from an inactive plant by natural convection 
through the radiators 10. The shutdown and regulation of the installation 
ae effected by means of absorber rods, which may be displacably arranged 
in a reflector laterally surrounding the core 13 (not shown).