Cutting – Processes – Plural cutting steps
Patent
1997-03-05
1999-09-28
Rada, Rinaldi I.
Cutting
Processes
Plural cutting steps
83 49, 83130, 834372, 83449, 83916, 83930, B26D 300, B26D 706
Patent
active
059570180
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to the cutting up by shearing of elements used in the construction of a nuclear installation. It more particularly relates to the cutting up of melting pots.
The dismantling of nuclear installations is a particular problem worrying the authorities responsible for safety and nuclear protection, as well as nuclear plant operators. For several decades, numerous dismantling means have been developed and experience has shown that it is necessary to improve existing dismantling equipment or create new equipment for this purpose. Numerous countries have started up research and development programs in this connection.
As nuclear installations are of different sizes and types, it is necessary to have a considerable variety of means in order to carry out the dismantling operations. They are generally carried out by cutting up using one of the numerous existing processes, i.e. thermal, electrothermal, pyrotechnic, mechanical, etc.
The choice of a particular cutting up process is a function of numerous criteria, namely the efficiency of cutting up, its cost, use constraints, the pollution level emitted and the material to be cut up.
It is known to carry out mechanical cutting up by using a circular saw, reciprocating saw, disk, abrasive cable and wheel and boring cutting tools. The weight and overall dimensions of these tools make them difficult to remotely handle.
Certain constituents of nuclear installations are particularly difficult to cut up. This may be due to the nature of the material forming them, their thickness and their state. This is particularly the case with melting pots made from alloys of nickel, chromium and iron, such as Inconel 601.sup.(R), which have a thickness of about 10 mm. In addition, spent melting pots have a residual glass deposit on their inner wall, which increases cutting difficulties. As a result it is at present virtually impossible to cut up these pots. Reciprocating saw tests have revealed that roughly two months are needed to cut up such a pot.
BRIEF SUMMARY OF THE INVENTION
The present invention makes it possible to obviate this difficulty by developing a novel cutting up process in connection with dismantling procedures, namely cutting up by shearing. This process and its application to an appropriate apparatus for receiving nuclear installation elements have permitted a remarkable improvement in the cutting up efficiency. It is also pointed out that a priori such an improvement was completely unexpected. Thus, shearing tests performed on spent Inconel 601 melting pots have demonstrated that only 24 hours were required for cutting up a pot instead of two months using the reciprocating saw, which is the presently used method.
The present invention therefore relates to a process for cutting up an element used in the construction of a nuclear installation with a view to its dismantling, characterized in that it comprises the following steps: the shearing tool, which is in the working position, manipulating the tool in order to carry out a first shearing operation on the element, shearing tool and return of the tool to the working position, number of shearing operations necessary.
The invention also relates to an apparatus for performing the above process, which is characterized in that it comprises a support for receiving the element, the support being equipped with a shearing tool controllable by control means, the apparatus also incorporating means for holding the element in front of the cutting edge of the shearing tool, means for pushing the element towards the cutting edge of the tool and means for releasing the element from the shearing tool.
Advantageously, the shearing tool is a blade traversing the support, the part of the support which faces the cutting edge serving as a counterblade.
The part of the support facing the cutting edge of the blade can be provided with a detachable wearing member, which permits a rapid replacement of the part of the support damaged by the cutting operation.
The wearing part can be p
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Compagnie Generale des Matieres Nucleaires
Pryor Sean
Rada Rinaldi I.
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