DE2831646A1 - SHIELDING CONTAINER FOR THE TRANSPORT AND STORAGE OF BLASTED FUEL ELEMENTS - Google Patents

Description

TRANSNUKLEAR GmbH 6450 Hanau 11

Shielded container for the transport and storage of irradiated

Fuel assemblies.

The invention relates to shielded containers for the transport and / or the storage of irradiated fuel assemblies, as they occur in particular in nuclear power plants.

For the transport and storage of irradiated or spent For fuel elements from nuclear reactors, you need containers that safely hold back the radioactivity of the material. The construction this container is therefore subject to strict regulations, especially with regard to the indestructibility of the container in the event of accidents and protection . concerns the environment from radioactive rays.

The containers for the transport and storage of spent fuel you must be stable and robust and must, offer protection against radioactive rays. However, there is Select the material for the radioactive shielding so that the weight of the shielding covers most of the weight "of the transport container, is kept as small as possible for economic reasons. that the decay heat of the transported or stored fuel elements can be safely dissipated to the outside.

The shielding of the container must hold back all the biologically effective radiation, which is preferably done by means of a sheathing made of uranium, lead or steel, especially the Gamma radiation absorbed. This shield also has

'909885/0296

the advantage that it has good thermal conductivity and therefore the decay heat of the fuel assemblies can dissipate well from the interior to the container surface.

The fuel elements in the newer reactors are subject to higher burn-up and therefore take effect after they have been removed from the Reactor also used as a high-intensity neutron source. In the preparation of of jackets for transport containers can therefore Neutron radiation can no longer be neglected. A greater thickness of the known gamma shielding materials that also absorb neutron radiation would significantly reduce the size of the container and result in an increased weight, which is not desirable for economic reasons.

It has therefore already been proposed to use hydrogen-containing materials or water for shielding against neutron rays with dense materials for shielding against gamma rays to combine such containers. However, there are high manufacturing costs for the corresponding transport container and in addition, these are still very voluminous.

It was therefore the object of the present invention to provide a shielded container for the transport and / or storage of irradiated fuel assemblies, both gamma and neutron beams effectively retains, is relatively light and compact, dissipates the decay heat well and is cheap to produce.

This object was achieved according to the invention in that the shielding container works from the inside to the outside
a) from a cylindrical steel container with a centrally arranged square shaft for receiving a plurality of fuel assemblies

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b) a neutron shielding layer made of a hydrogen-containing one Material with this layer penetrating heat conducting webs and

c) consists of an outer steel jacket with attached cooling fins.

The figure shows schematically a cross-section through an exemplary Embodiment of the shielding container according to the invention.

The shielded container consists of a cylindrical steel container (l) for shielding the gamma radiation, which is centered with a square shaft (2) is provided for receiving a plurality of fuel assemblies. This container preferably has a wall thickness of 300 to 400 mm and consists in particular of cast. There are various arrangements in the square shaft (2) possible, with which the irradiated fuel assemblies can be accommodated. A double cross-shaped sieve has proven itself Insert basket (7) made of a neutron-absorbing material, such as boron steel, with nine square individual shafts (8) for Recording of the individual fuel elements. The middle position (9), which is problematic with regard to “heat dissipation and criticality security is, preferably remains empty and is advantageously locked by means of suitable components, such as rods or cover plates. Of course, other fuel element arrangements are also possible.

The steel container (1) is surrounded by a neutron shielding layer (3) made of a hydrogen-containing material, preferably polyethylene in the form of granules, embedded in a composite mass of casting resin or cement. Because of the poor thermal conductivity of such neutron shielding materials, thermally conductive webs (k)

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within this layer (3) required that the inner steel container (l) with the outer surface of the shielded container connect in a thermally conductive manner. These webs (4) can be welded or cast onto the inner container (l) be.

A relatively thin * - walled steel jacket (5) with preferably welded cooling fins (6), distributed over the entire circumference of this steel jacket (5)> for better dissipation of the heat of decay to the outside

The shielding container according to the invention advantageously has two connections - at the top and bottom - for filling and emptying water when loading and unloading with irradiated Fuel assemblies. ■

This structure of the shielding container has the advantage that it can be built very compact and with a relatively low weight.

Frankfurt / Main, July 17, 1978
Dr.Br.-Bi

909885/0296

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Claims (3)

78 152 ct TRANSNUCLEAR Ginbll
6450 Hanau 11 Shielded container for the transport and storage of irradiated Fuel assemblies. PATENT CLAIMS 1 / shielded container for transport and / or storage irradiated fuel assemblies, characterized in that it turns from the inside out a). from a cylindrical steel container (l) with a centrally arranged square shaft (2) for receiving a plurality of fuel assemblies b) from a neutron shielding layer (3) made of a hydrogen-containing material with this layer (3)
durchdingendeu heat conducting webs (k) and c) consists of an outer steel frame (5) with attached cooling fins ^x (6). 2. shielding container according to claim 1, characterized in that the square shaft (2) is provided with a double-cross-shaped insert basket (7) made of a neutron-absorbing material with nine square individual shafts (8). 3. shielding container according to claims 1 and 2, characterized
It is noted that the central individual shaft (9) is blocked for receiving a fuel assembly by means of suitable components. 909885/0296 originally inspected