Induced nuclear reactions: processes – systems – and elements – Fission reactor material treatment – Impurity removal
Patent
1998-05-14
2000-04-11
Jordan, Charles T.
Induced nuclear reactions: processes, systems, and elements
Fission reactor material treatment
Impurity removal
376310, 376260, 376248, G21C 1900, G21C 1942, G21C 1700
Patent
active
060495804
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
This invention relates to an installation for remote dismantling of irradiated structures.
In dismantling operations, and sometimes in maintenance operations on nuclear installations, it is desirable to make remote cuts underwater or above water, of large metallic structures, sometimes contaminated with high activity and with thicknesses of 200 mm or more, usually without the possibility of direct observation. Wherever possible, it is essential to carry out remote cutting operations in order to avoid irradiation that would otherwise be experienced by the operators. This means that it is necessary to design a tool that is firstly capable of working automatically, and also of recovering particles, chips, debris, aerosols, etc., that are always produced by cutting.
There are several known processes meeting these requirements, two of which are described in French patents 2 638 671 and 2 678 198; as in the invention, they use a high pressure abrasive liquid jet as a convenient and reliable means of cutting very thick parts, and means are provided for moving the cut part in front of the jet; the first of these patents also describes a way of recovering cutting debris and sand used as an abrasive, so that the debris can be poured into barrels where it will be stored for as long as necessary, the sand then being used as a material for coating contaminated debris and particles.
However, these processes have the disadvantages that their cutting capabilities are not sufficient, particularly due to limitations observed on movements of the ejection nozzle and that mean that the installations can only be used on structures of a given shape; and it is perhaps even more annoying to realize that it is sometimes difficult to satisfactorily distribute parts of the structure obtained after cutting in the barrels since some are excessively contaminated, and in this case the only solution (if it is authorized) is to send them to special storage installations at a much higher cost.
The article by Echert "Abrasive water jet cutting of thick concrete and water jet cleaning for nuclear facility decommissioning and decontamination", published in the proceedings of the 1987 international decommissioning symposium (Pittsburgh, USA, Oct. 4 to 8, 1987) describes an installation for dismantling of irradiated structures in which cutting and decontamination operations are carried out successively by independent devices that cannot be used to rationalize decontamination; all that is done is that a uniform and fairly large thickness is torn off the surface of the structure. The article by Drews and Fuchs "Development of measuring and control systems for underwater cutting of radioactive components", published in "Decommissioning of nuclear installations" (EUR 12690, Brussels, Oct. 24 to 27, 1989) describes a device for recognition of the shapes of an immersed part in an installation for dismantling of irradiated structures.
Therefore, the invention essentially refers to the ideas of making the abrasive liquid jet spraying tool more mobile and of adding means of contamination measurement and reduction for the structures to be cut, to the installation.
Another aspect of the invention is the possibility of guaranteeing correct operation by making sure that cutting is done properly; in this case, apart from remote cameras or observation means, it is possible to add a sensor or another structure detector to the installation in order to recognize its position and shape and to adjust the trajectory of the cutting tool, even if initial information supplied by a drawing or other means is available.
It must still be possible to collect cutting residue instead of leaving it scattered around the installation.
To summarize, the invention relates to an installation for dismantling irradiated structures comprising a structure support, a module carrying a cutting head forming part of a pressurized water spraying device and abrasive particles, characterized in that the module can move in front of the structure and is rotatable, and that it carri
REFERENCES:
patent: 4800063 (1989-01-01), Mierswa et al.
patent: 5427159 (1995-06-01), Burgess et al.
Database Inspec Institute of Electrical Engineers, Stevenage, GB, Inspec No. AN 524554, Merle; Bader: "High Pressure Wet-Blast Cleaning in Combination With Recycling Technology", XP002011815, voir abrege & Proceedings Kontec 95. "Conditionning of Radioactive Operational and Decommissioning Waste", Mar. 16-17, 1995, Hamburg, Germany, pp. 386-396.
Database Inspec Institute of Electrical Engineers, Stevenage, GB, Inspec No. AN3832154, Drews; Fuchs: "Developement of Measuring and Control Systems for Underwater Cutting of Radioactive Components", XP002011816, voir abrege, & Decommissioning of Nuclear Installations, Oct. 24-27, 1989, Brussels, pp. 201-207.
Database Inspec Institute of Electrical Engineers, Stevenage, GB, Inspec No. AN 3166646, Echert: "Abrasive Water Jet Cutting of Thick Concrete and Water Jet Cleaning for Nuclear Facility Decommissioning and Decontamination", XP002011817, voir abrege & Proceedings of the 1987 International Decommissioning Symposium, Oct. 4-8, 1987, Pittsburg, USA.
Database, Inspec Institute of Electrical Engineers, Stevenage, GB, Inspec No. AN4597124, Harada Et Al: "Reactor Dismanteling by Abrasive Water Jet", XP002011818, voir abrege & JSME International Journal, vol. 36, No. 3, Aout 1993, Japan, pp. 499-504.
Bodin Fran.cedilla.ois
Lebiez Georges
Martin Ludovic
Vivier Franck
Compagnie Generale des Matieres Nucleaires
Jordan Charles T.
Keith Jack
LandOfFree
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