DE1041177B - Fuel element for a nuclear reactor - Google Patents

Description

The invention relates to a fuel element for a nuclear reactor, in which the during the fission process released heat is dissipated by means of a gaseous heat carrier.

The energy generated in a nuclear reactor can currently only be obtained by converting heat in a thermal cycle can be converted into mechanical energy. Becomes an inactive one as a work tool Gas used, this can be fed directly to the reactor after compression, in which it is brought to a higher temperature. The working fluid heated in this way then relaxes in a turbine and is fed back to the compressor after recooling.

With the direct transfer of heat from the reactor to the working medium, the temperature difference between the reactor material and the working fluid of the cycle are kept small, which has a positive effect on the efficiency, since it is the maximum temperature of the cycle is held high.

The present invention aims to further increase the maximum temperature of the cycle and thus to enable its efficiency. In the case of a fuel element, the initially The type described is used for this purpose according to the invention the fissile material as a pile between two radial openings arranged one inside the other, made of heat-resistant material tubular bodies arranged, in turn, inside a third hollow body are arranged, and the gaseous heat carrier is the space between the wall of the third hollow body and the outer one of said tubular bodies and fed from this space through the radial openings in the outer tubular body, over the fissile material and drained the radial openings in the inner tubular body.

A more or less loose accumulation of small particles of the Fission material understood with gaps for the passage of the gaseous heat carrier.

In the drawing, exemplary embodiments of the subject matter of the invention are shown in a simplified representation illustrated. It shows

1 shows an axial vertical section through part of a fuel element and

2 shows an axial vertical section through another fuel element.

In the embodiment shown in FIG. 1, the fissile material 1 is coaxial as a pile between two tubes 2 and 3 arranged one inside the other, consisting of heat-resistant ceramic material, the radial openings 2 'or. 3 'have. The pipes 2

Applicant:

Esctier Wyss Aktiengesellschaft,
Zurich, Switzerland)

Representative: Dipl.-Ing. H. Albrecht, patent attorney,
Berlin-Frohnau, Edelhofdamm 26

Claimed priority:
Switzerland from May 31, 1957

Dr. phil. Walter Winkler, Winterthur (Switzerland),
and Dr.-Ing. Manfred Diederichs,

Eggenstein near Karlsruhe,
have been named as inventors

and 3 are arranged within a third tube 4 coaxially to this. The gaseous heat carrier is fed to the space between the wall of the third pipe 4 and the outer pipe 3, arrives from here through the radial openings 3 'in the pipe 3 to the Fissstoffhaufwerk 1 and then through the radial openings 2 'in the tube 2 into the interior of this tube 2 and is discharged from there again. That Tube 4 forms part of the casing of a moderator 5.

In this way, the heat transfer medium only in the interior of the fuel element and in the Interior subsequent line the 'high maximum temperature of the cycle on, while it is outside of the pipe 3 only has the much lower inlet temperature. The ones from the two Rotirs 2 and 3 parts of the fuel element or the moderator surrounding the existing fissile material container so only exposed to this lower temperature. This means that materials can also be used for these parts a less high heat resistance can be chosen, or it can if one for these parts Selects materials of high heat resistance, the maximum temperature of the cycle of the heat carrier can be increased significantly.

The tubes 2 and 3 are due to the low pressure difference between the incoming and outgoing Heat transfer medium practically not contaminated. These

809 658/346

Pipes only need to be resistant to the high gap temperatures. Beryllium oxide or zirconium oxide, for example, can be used as the threading material, which materials have practically no tensile strength, but are resistant _{to CO 2 up to 1500 ° C.}

To achieve the same high cracking temperatures over the entire length of the cracking material container, it is advisable to the cross-section of the openings 2 'or 3' per unit of the To increase the container length compared to the smaller heat accumulation at the points, for example by smaller mutual hole spacing, so that a correspondingly larger amount of heat transfer medium at these points passes through the layer of fissile material.

If the moderator 5 is not to be loaded by the pressure of the gaseous heat carrier flowing in the fuel element, it is advantageous to design the third tube 4 mentioned as a pressure-resistant tube that absorbs the pressure of the heat carrier. The tube 4 must be made of a material that has the required strength properties. In addition, however, the material must be as weakly neutron-absorbing as possible. Of the substances exhibiting both properties, however, z. B. Zirconium metal against CO gas only up to 500 ° C, aluminum metal against CO ₂ gas only up to 450 ° C. The advantage of the invention, namely that only the inlet temperature to the fuel element has to be below these low temperatures, while the maximum temperature of the cycle is not limited by this temperature, is therefore particularly useful here.

The parts shown in FIG. 2 are given the same reference numerals as the corresponding parts in FIG Fig. 1 denotes. The said third hollow body surrounding the fissile material container is shown in FIG. 2 as a bottle-shaped body 6 is formed which has a bottle neck 7 in which a tube 8 is arranged is. The gaseous heat carrier is through the space between the bottle neck 7 and the Pipe 8 is fed and, after passing through the layer of fissile material, through the interior of the pipe 8 discharged again. If the neck 7 and the pipe 8 are made long enough, they can be used as heat transfer media and discharge line for the fuel element.

In this way, the moderator parts and also other parts of the reactor from the pressure of the Heat carrier and are kept free from this itself. In the pipeline 7, 8 are high temperatures only present on the inside, while the outside is one of the inlet temperature of the heat transfer medium has a corresponding low temperature.

It is also of particular advantage that the inner one, which carries the heat carrier at a higher temperature Pipe 8 of the line only has the practically negligible pressure difference between the supplied and discharged heat transfer medium has to endure, while the full heat transfer medium pressure loaded tube (neck 7) has only the lower temperature, so less heat loaded is.

ίο The pipe 8 is expediently with a Insulation can be provided, which in the embodiment shown in FIG. 2 consists of a ceramic tube 9 consists.

Claims (6)

Patent claims: 1. Fuel element for a nuclear reactor, which is released during the fission process Heat is removed by means of a gaseous heat carrier, characterized in that the so fissile material as a pile (1) between two nested, radial openings (2 ', 3') having tubular bodies (2, 3) made of heat-resistant material which in turn is inside a third hollow a5 body (4 or 6) are arranged, and that the gaseous heat transfer medium the space between the wall of the third hollow body (4 or 6) and the outer (3) of said tubular body and from this space through the radial openings (3 ') in the outer tubular body (3), via the fissile material (1) and the radial openings (2 ') in the inner tubular body (2) is discharged. 2. Fuel element according to claim 1, characterized in that said third hollow body is formed by parts (4) of a moderator (5). 3. Fuel element according to claim 1, characterized in that said third hollow body is a pressure-resistant tube (4). 4. Fuel element according to claim 1, characterized in that said third hollow body is a bottle-shaped body (6) and that a tube (8) is arranged in its bottle neck (7) and the gaseous heat transfer medium through the space between the bottle neck (7) and fed to this tube (8) and discharged again through the interior of this tube (8). 5. Fuel element according to claim 4, characterized in that the arranged in the bottle neck (7) Tube (8) has an insulation (9). 6. Fuel element according to claim 1, characterized characterized in that said tubular bodies (2, 3) are made of ceramic material. 1 sheet of drawings