PROCEDURE FOR TEMPORARY STORAGE OF RADIOACTIVE MATERIAL

Abstract: Method for the storage in a storage room (9) of radioactive materil and particularly for the temporary storage of radoactive nuclear fuel from nuclear reactors and of non-reprocessed radioactive material. A remote-controlled robot arrangement, comprising a transfer robot (4) and a lifting and carrying robot (5), is designed to fit into a lift (8) for moving the material from ground level to the storage room, to transfer the material into double-walled containers (1), and to carry stacks of containers. The material is transferred by the transfer robot (4) to and from the double-walled containers (1). The containers are provided with safety arrangement (2) with three safety locks to prevent the radioactive material from escaping during transfer. Heat removal from the double-walled containers (1) is effected by means which make the heat available for practical use and maintain the correct temperature in the containers.

Description: Procedure for temporary storage of radioactive material. The invention "NAGIVA Disposal Process" is a meth for the storage of radioactive material and particularly for the temporary storage of radioactive nuclear fuel from nuclear reactors and non-reprocessed radioactive material. The βpent fuel contains products which are highly radioactive and it is therefore necessary to keep it separated from living organisms. Spent non-reproce3sed fuel can be stored tempor¬ arily for a shorter or longer time pending a decision to -eprocess the material or to remove it to permanent j torage. The heat evolution of the fuel rods increases 'when they are lifted out of the reactor and in the prese state of the art they must be placed in a pool for cool¬ ing. After this initial cooling it has been proposed tha the spent £uel be converted into solid form for temporar container storage. It has also been proposed that the fuel be mixed with liquid glass to solidify it. The present invention provides a safe and practic • .ethod for the handling and storage of spent, non- .-eprocessed fuel from nuclear reactors. The invention is explained with reference to des¬ criptions and drawings. Figure 1 represents double-walle containers in a temporary storage room and Figure 2 represents a plan of the storage room. It will be easier to handle the spent fuel after it is taken out of the reactors if it is placed in an acid bath to separate the metal cans of the fuel rods from the fuel. The liquid material is then converted into pellets for direct transfer to a vehicle. The material may also be subjected to a separation process whereafter th e different waste products will be stored in separate containers. Another procedure is for the fuel, with the metal cans, to be loaded directly onto the vehicle for transport to the storage place. In an underground storage facility 9, blasted out of rock 7, a rail-mounted robot device approx. 5 metres x 5 metres in plan and 11 metres in height is arranged to run along a track 6. The robot arrangement consists of two sections, section 4 arranged to ' be raised and lowered and equipped with a container for the transfer of spent fuel to and from storage containers, and a section 5 with lifting and carrying arrangements. The robot is designed to fit into lift 8 for moving spent fuel from ground level down to the storage facility 6, and to carry and transfer fuel to double-walled containers 1. The double-walled containers are stacked one on to'p of the other on a structure 3 which is designed to suit the lifting and carrying robot 5. This robot can when required run under the structure 3, lift up one stack of containers, and shift it onto a structure common to both robots for transport from the storage room 9. The material of the containers and arrangements for heat removal and cooling comply with accepted en¬ gineering practice and are of types approved by the authorities. The containers are provided with safety valve arrangements 2 with three safety locks to prevent radioactive material from escaping during transfer to or from the robot 4. Transfer is effected either by remote control or manually. The method for heat removal may be chosen accord¬ ing to the practical use the heat is to be put to, such as water heating. The heat can be removed from the space between the inner and outer wall3 of the containers by the medium of e.g. air, liquid or gas. '.hen the thermal radiation from the material decreases and there is no longer any need for heat removal or cooling the material can be transferred into cheaner containers. The material OMPI is easily transferred from the double-walled container and moved to another storage place, e.g. after a decision to reprocess it. The containers, which are shown in Figure 1 as resting on a structure 3 adapted to a lifting and carrying robot, may alternati ely be cast into concrete. It will be apparent from the foregoing that my invention provides a safe, inexpensive, and practical means of handling and storing spent nuclear fuel. Human contact with the equipment will be negligible. OMPI

Claims: Patent Claims 1. Procedure for the temporary storage in storage room of radioactive material in containers, characteris¬ ed in that the material is transferred by a robot (4) into double-walled containers (1) and that a cooling agent is caused to circulate through the space between said double walls, to take up the heat given off by the material and thereby cool the containers amd material, the heated cooling agent being conducted away used as a source of energy. 2. Procedure according to Claim 1, charrac terised in that each container is connected independently to a thermostat-controlled heat discharge system. 3. Procedure according to Claim 1 or 2, character¬ ised in that the material, when it arrives at the storag« place, is transferred from the transport vehicle to the robot (4) for transfer by lift to storage room (9). Δ- . Procedure according to Claim 1, 2 or 3, char¬ acterised by the material being stored in units that can be cooled, monitored, and reused, which can be arranged in any desired manner in the storage room and with the type of heat removal suited to their condition at every time.

Inventors: CANEVALL JOHN, CANEVALL, JOHN
Applicants: CANEVALL JOHN, CANEVALL, JOHN
Application year: 1983
Main classification: G21F9
IPC codes: G21C19, G21F5, G21F9