Limiting Device

Abstract

The limiting device relates to a device for limiting the effects of a severe accident on process equipment connected by a pipeline passing through the wall, which can be used in particular in the nuclear industry. The limiting device installed in the protective wall is configured in the form of an anchor with a horizontal groove and an insert with a horizontal tooth. The anchor is attached to the protective wall. The insert is attached to the pipeline outside the protective wall. The anchor and the insert are configured such that the horizontal tooth can be locked in the horizontal groove during torsion. The insert comprises a postulated rupture site. This limiting device can improve the safety of the operation of the high pressure pipeline.

Description

[Technical field]

[0001] The present invention relates to an apparatus for limiting the effects of severe accidents on process equipment connected by pipelines passing through a wall, and may be used in particular in the nuclear industry. [Background technology]

[0002] The main steam and feedwater pipelines run from the nuclear island, where the steam generators and main steam isolation valves (MSIVs) are located, through the space between two protective barriers, which contain equipment operated by Nuclear Power Plant (NPP) personnel.

[0003] The problem with placing pressurized main steam and feedwater pipelines between two walls is that in the event of an emergency, the loads on the pipelines can be very large and occur very quickly: the load-on time to 10,000 kN is about 0.2 seconds.

[0004] The pipeline itself is made of a flexible material with low thermal conductivity, because the space between the protective barriers, where people can enter and exit, needs to be insulated from the steam chamber.

[0005] This could cause the pipeline to swing violently towards or away from the nuclear island containing the steam room, which could result in the destruction of the MSIVs, which are necessary for the correct operation of the residual heat removal passive system (ARPS) in the event of an accident, and could cause steam to leak from the steam generators, boiling the coolant in the nuclear power plant's primary circuit and reactor.

[0006] Such threats make nuclear power plants less safe. Similar problems can occur when using conductors or other penetrations that penetrate the two barriers.

[0007] Therefore, in configurations where the main steam and feedwater pipelines penetrate the protective barrier, the following conditions must be met: In normal operating mode, temperature-induced pipeline displacements of up to 100 mm horizontally through the protective wall are permitted. Immobilize the pipeline at its penetrations so that in the assumed accident mode, rapid displacement accompanied by destruction of the MSIV in the turbine room is prevented. In a severe accident scenario where a pipeline rupture is unavoidable, it is necessary to ensure that the pipeline rupture occurs in the space outside the protective barrier.

[0008] A variety of technical solutions have been used to solve this problem.

[0009] In particular, solutions are known relating to fastening the pipeline to a protective wall in order to prevent the pipeline from jerking in the event of an accident.

[0010] For example, according to Russian Federation Utility Model No. 204147 (issued May 11, 2011), a burst limiting device for a pipeline connected to a pipe joint by a welded seam includes a sleeve mounted over the welded seam of the pipeline, the sleeve consisting of two symmetrical halves fixed by a threaded joint and provided with flanges at both longitudinal ends.

[0011] The sleeve has a variable diameter and flanges at both ends for engaging fitting elements welded to the pipeline and for engaging fitting elements welded to the outer surface of the fitting.

[0012] Such a pipeline burst limiting device can prevent the adverse effects of a burst at the weld between the pipeline and the pipe joint and can be applied in various economic sectors.

[0013] However, in normal operating mode, horizontal displacement due to temperature changes is not permitted, and in the event of a postulated accident, the pipeline would be restricted from being pulled outward through the protective wall, which could destroy equipment located on the nuclear island.

[0014] The closest to the present invention in terms of its problem and functional objectives is Russian Federation Utility Model No. 193982 (issued November 22, 2019).

[0015] In the present invention, the bursting limiting device for the welded seam of the pipeline comprises a cylindrical sleeve, which is mounted on the welded seam of the pipeline, which is in contact with the pipeline surface by means of mounting elements and has end flanges which interact with stoppers welded to the pipeline surface in the form of radial ribs, the sleeve consists of two semi-cylinders, each of which is provided with a flange along the longitudinal direction, the corresponding flanges of each of the semi-cylinders being fastened with a threaded connection, the mounting elements of the sleeve are made in the form of radial ribs welded to the inner surface of the semi-cylinders, the end flanges of the sleeve semi-cylinders are placed on the surface of the pipeline with a clearance relative to the surface of the pipeline and to the radial stoppers, respectively.

[0016] Such limiting devices can reduce the effects of a whiplash rupture on equipment in the vicinity of the rupture, but do not allow horizontal thermal displacement during normal operation and, in the event of a postulated accident, would limit the outward withdrawal of the pipeline through the protection barrier, potentially destroying equipment within the nuclear island. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Russian Federation Utility Model No. 204147 [Patent Document 2] Russian Federation Utility Model No. 193982 Summary of the Invention [Problem to be solved by the invention]

[0018] The object of the present invention is to create a limiting device that improves safety of use by eliminating damage to the equipment of the nuclear island in all operating modes, including in emergency situations of the nuclear power plant.

[0019] The technical result of the present invention is to improve the safety of nuclear power plants by eliminating damage to nuclear island equipment during all modes of operation, including nuclear power plant emergencies. [Means for solving the problem]

[0020] This technical result is achieved by means of a limiting device that is installed in the protective barrier.

[0021] The limiting device is in the form of an anchor having a horizontal groove and an insert having a horizontal tooth, the anchor being attached to a protective wall and the insert being attached to the pipeline outside the protective wall, the anchor and the insert being configured to be able to lock the horizontal tooth in the horizontal groove during torsion, and the insert being characterized in that it is provided with an anticipated rupture site. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is an overall view of a restriction device for a main steam pipeline and a feedwater pipeline. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The main steam and feedwater pipelines run from the steam room on the nuclear power plant's nuclear island through two protective barriers.

[0024] The restriction device is installed in each hole in each protective wall through which the pipeline passes, and comprises an anchor 1 having a horizontal groove 3 and attached to the protective wall, for example by a bolt, and an insert 2 having horizontal teeth 4 and attached to the pipeline, the horizontal teeth 4 fitting horizontally movably into the horizontal groove 3.

[0025] The operation of the limiting device is as follows.

[0026] In normal operating mode, the limiting device consisting of an anchor 1 attached to the protective wall and an insert 2 installed in the pipeline ensures the horizontal displacement due to the temperature of the pipeline.

[0027] In the assumed accident mode, the pipeline 6 has a bent portion outside the protective wall, and therefore is inevitably subjected to bending stress and deformation.

[0028] This causes the horizontal teeth 4 of the insert 2 attached to the pipeline to be pushed into the horizontal groove 3 of the anchor 1, fixing the pipeline to the protective wall and avoiding destruction of the equipment in the steam chamber.

[0029] In a severe accident mode, the load on the pipeline can reach 38.5 MN, so in order to protect the steam room equipment, the limiting device is further equipped with a postulated rupture site 5, which is located outside the protective wall and prevents the pipeline from being pulled out of the building.

[0030] The postulated rupture site 5 may be made in the form of a weakened portion of an insert into the pipeline, for example an annular groove, designed to break when a corresponding load is reached.

[0031] The restriction device can improve the safety of high pressure pipeline operation and is suitable for use in the energy industry.

Claims

[Claim 1] A limiting device installed on a protective wall, comprising: The anchor is configured in the form of an anchor having a horizontal groove and an insert having a horizontal tooth, The anchor is attached to the barrier and the insert is attached to the pipeline outside the barrier; The anchor and insert are configured to lock the horizontal teeth in the horizontal grooves during torsion; The insert has an anticipated rupture site A limiting device.

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