RU2695778C1 - Method of dismantling the cover of a steam generator of a nuclear power plant - Google Patents

Abstract

FIELD: nuclear energy.

SUBSTANCE: invention relates to nuclear power engineering, in particular to repair of steam generators of ship nuclear power plants. Method of dismantling the cover of the steam generator of a nuclear power plant consists in performing a blind hole in the body of the welded seam between the cover of the steam generator and its housing. Tilting angle of blind hole cavity axis corresponds to chamfer angle of steam generator housing edge. Thin layer of uncut metal remains between the blind opening hole and the steam generator inner volume. Circular groove is cut out in weld joint seam. Thin layer of uncut metal is cut using a metal cutting device. Bore-hole in body of weld seam between steam generator cover and its body is made by drilling. Before performing the annular groove a series of similar non-through holes is drilled along the entire perimeter of the weld. Thin webs remain between drilled through holes arranged nearby.

EFFECT: invention increases efficiency of dismantling the cover of a steam generator of a nuclear power plant, preventing the need for multiple replacement of end mills in the process of cutting an annular groove due to their wear.

1 cl, 7 dwg

Description

The invention relates to nuclear energy, in particular to the repair of steam generators of marine nuclear power plants.

A known method of dismantling the cover of a steam generator of a nuclear power plant (Pat. 2619581 Russian Federation, IPC G21D 1/00. Method of dismantling the cover of a steam generator of a nuclear power plant [Text] / Bogdanov GA, Kulikov KN, Malygin I.Yu., Pantyukhin A.N., Applicant and Patent Holder, Onega Research and Development Design Bureau Joint-Stock Company - No. 2016108047; filed March 4, 2016; published May 17, 2017), in which an annular ring is cut around the cover of the steam generator of a nuclear power plant groove, while before cutting A non-through hole in the body of the weld between the cover of the steam generator and its body is made with a milling ring-shaped groove using a milling device with an installed end mill so that the angle of inclination of the axis of the cavity of the through hole corresponds to the angle of the chamfer of the edge of the case of the steam generator in contact with the weld, so that between the completely through hole and the internal volume of the steam generator there remains a thin layer of uncut metal; An annular groove is cut in the body of the weld between the steam generator cover and its body to the depth of the cavity through the hole, moving the milling device with the installed end mill, starting from the hole through, along the perimeter of the weld by oblique milling at an angle corresponding to the angle of inclination of the axis of the cavity through the hole ; then metal chips and contaminants are removed from the cavity of the annular groove; further, from three to four bursting devices are installed around the circumference of the annular groove in the cavity of the annular groove, designed to fix the cover of the steam generator relative to its body; then, using a metal-cutting device with an installed conical cutting roller, a thin layer of uncut metal is cut between the cavity of the annular groove and the full steam generator along the perimeter of the annular groove; then the cover of the steam generator is connected to the working body of the hoisting-and-transport device, the bursting devices are removed from the cavity of the annular groove and the cover of the steam generator is removed using the lifting-transport device.

This method is closest to the claimed technical solution, therefore, is selected as a prototype.

The disadvantage of the prototype is the low productivity of the process of dismantling the cover of the steam generator of a nuclear power plant, due to the need for multiple replacement of end mills in the process of cutting an annular groove due to their wear.

The essence of the claimed technical solution is that in the known method of dismantling the cover of the steam generator of a nuclear power plant, in which a through hole is made in the body of the weld between the cover of the steam generator and its body in such a way that the angle of inclination of the axis of the cavity of the through hole corresponds to the angle of the chamfer of the edge of the body of the steam generator in contact with the weld, so that between the cavity of the through hole and the internal volume of the steam generator remains a thin layer of uncut metal; moving the milling device with the end mill installed, cut the annular groove along the perimeter of the weld in the body of the weld between the cover of the steam generator and its body to the depth of the cavity of the through hole by oblique milling at an angle corresponding to the angle of inclination of the axis of the cavity of the through hole; then metal chips and contaminants are removed from the cavity of the annular groove; further, from three to four bursting devices are installed around the circumference of the annular groove in the cavity of the annular groove, designed to fix the cover of the steam generator relative to its body; then, using a metal-cutting device with a conical cutting roller mounted, a thin layer of uncut metal is cut between the cavity of the annular groove and the cavity of the steam generator along the perimeter of the annular groove; then the steam generator cover is attached to the working body of the hoisting device, the bursting devices are removed from the cavity of the annular groove and the steam generator cover is removed using the lifting and transportation device, and a through hole in the body of the weld between the steam generator cover and its body is drilled, after which by making an annular groove, a series of similar non-through holes are drilled around the entire perimeter of the weld in such a way that between the drilled holes through holes adjacent remain thin webs.

Thus, the claimed technical solution differs from the prototype in that a through hole in the body of the weld between the cover of the steam generator and its body is drilled, after which a series of similar through holes are drilled around the entire perimeter of the weld in such a way that between the drilled through holes openings located nearby, thin jumpers remain.

A comparative analysis of the claimed invention with other technical solutions showed that the use of drilling is one of the main methods of making holes, however, only the use of drilling to make a through hole in the body of the weld between the cover of the steam generator and its body, and after that, before making an annular groove of drilling a series of similar non-through holes along the entire perimeter of the weld in such a way that between the drilled through holes located nearby, Thin webs will melt allows to increase productivity of the process of dismantling the cover of the steam generator of nuclear power plant, preventing the need for repeated replacement of the end mills during the cutting of the annular groove due to their wear.

The use of drilling to make a non-through hole, as well as a subsequent series of non-through holes, in the body of the weld between the cover of the steam generator and its body instead of milling with an end mill allows you to speed up the process of performing the specified through hole without losing the quality of the hole. Drilling a series of similar non-through holes around the entire perimeter of the weld will allow you to remove the bulk of the metal of the specified weld before making an annular groove with an end mill, and thus, when you subsequently make an annular groove used in this end mill, you only need to pierce a series of consecutive thin bridges between drilled non-through holes, which will significantly reduce wear of the end mill.

Thus, the claimed method allows to increase the productivity of the process of dismantling the cover of the steam generator of a nuclear power plant, preventing the need for multiple replacement of end mills in the process of cutting an annular groove due to their wear.

In FIG. 1 shows the case of a steam generator of a nuclear power plant with a lid welded to it and an installed device for drilling and milling with a drill.

In FIG. 2 shows a variant of a drilling pattern of through holes in the body of the weld between the cover of the steam generator and its body, top view.

In FIG. 3 shows a variant of a drilling pattern for non-through holes in the body of a weld between the cover of the steam generator and its body, section.

In FIG. 4 shows a diagram of an annular groove, view

from above.

In FIG. 5 shows a diagram of an annular groove,

incision.

In FIG. 6 shows an embodiment of a bursting device for fixing the cover of a steam generator relative to its body, mounted in a cavity of an annular groove.

In FIG. 7 shows the cutting of a thin layer of uncut metal between the cavity of the annular groove and the cavity of the steam generator using a metal cutting device with a conical cutting roller mounted.

The method is as follows: to dismantle the cover 1 of the steam generator of a nuclear power plant welded to the body 2, a device for drilling and milling 3 with an installed drill 4 is mounted on the body 2. A series of through holes are drilled through the device for drilling and milling 3 around the entire perimeter of the welded the seam in such a way that thin bridges remain between the drilled through holes located nearby, at an angle a corresponding to the angle of the bevel of the edge of the casing 2 of the steam generator, with touches the weld 5, so that between the cavity of each blind bore and the inner volume of the steam generator is a thin layer of metal unerupted. Next, using the device for drilling and milling 3, the end mill 12 cuts out the bridges remaining between the drilled holes in the body of the weld seam 5 to the depth of the cavity of the through holes at the same angle a, at which the through holes were cut by drilling. Then, to ensure the operation of the cutting roller 11 using the device for drilling and milling 3, inclined milling is performed by the end mill 13 of the formed annular groove. After that, the device for drilling and milling 3 is dismantled, and metal chips and dirt are removed from the cavity of the annular groove. After that, from the circumference of the annular groove, from three to four bursting devices are installed in the cavity, for example, including wedges 7 and a bursting roller 8, fixed by welds 9. After that, a metal cutting device 10 with a conical cutting roller 11 is mounted on the housing 2, with which a thin layer of uncut metal 6 is cut between the cavity of the annular groove and the cavity of the steam generator along the perimeter of the annular groove. Next, the cover 1 of the steam generator is connected to the working body of the lifting and transport device (not indicated), the bursting devices are removed from the cavity of the annular groove, and the cover 1 of the steam generator is removed using the lifting and transport device.

Thus, the claimed method allows to increase the productivity of the process of dismantling the cover of the steam generator of a nuclear power plant, preventing the need for multiple replacement of end mills in the process of cutting an annular groove due to their wear.

Claims (1)

A method of dismantling the cover of a steam generator of a nuclear power plant, in which a through hole is made in the body of the weld between the cover of the steam generator and its body in such a way that the angle of inclination of the axis of the cavity of the through hole corresponds to the angle of the chamfer of the edge of the body of the steam generator in contact with the weld so that between the cavity of the through hole holes and the internal volume of the steam generator remains a thin layer of uncut metal; moving the milling device with the end mill installed, cut the annular groove along the perimeter of the weld in the body of the weld between the cover of the steam generator and its body to the depth of the cavity of the through hole by oblique milling at an angle corresponding to the angle of inclination of the axis of the cavity of the through hole; then metal chips and contaminants are removed from the cavity of the annular groove; further, from three to four bursting devices are installed around the circumference of the annular groove in the cavity of the annular groove, designed to fix the cover of the steam generator relative to its body; then, using a metal-cutting device with a conical cutting roller mounted, a thin layer of uncut metal is cut between the cavity of the annular groove and the cavity of the steam generator along the perimeter of the annular groove; after which the steam generator cover is connected to the working body of the hoisting device, the bursting devices are removed from the cavity of the annular groove and the steam generator cover is removed using the lifting and transport device, characterized in that the through hole in the body of the weld between the steam generator cover and its body is drilled, after which, before performing an annular groove, a series of similar non-through holes are drilled around the entire perimeter of the weld in such a way that between drilling blind bore, adjacent remain thin webs.

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