JP2015050859A - Electric penetration assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the airtight function and electric insulating function of an electric penetration assembly even under severe accident environment of a nuclear power plant.SOLUTION: An electric penetration assembly comprises: a metal ring which is air-tightly welded to a metal sleeve; a hollow metal body, having a diameter smaller than that of the metal sleeve, which is air-tightly welded to the metal ring; a metal first end plate on which a first internal thread is formed and which is air-tightly welded to one side of the metal body; a metal first joint body which is fastened together with a first metal packing to the first internal thread and which engages with a metal first nut; a metal second end plate on which a second internal thread is formed and which is air-tightly welded to the other side of the metal body; a metal second joint body which is fastened together with a second metal packing to the second internal thread and which engages with a metal second nut; and a mineral insulated cable penetrating through the first joint body and the second joint body.

Description

  The present invention relates to electrical penetration, and more particularly to electrical penetration attached to a nuclear reactor containment vessel.

  An electrical penetration is attached to a reactor containment vessel (CV: Container Vessel) in order to maintain hermeticity and electrical insulation (for example, Patent Documents 1 to 5). At a nuclear power plant, measurement signals from a water level gauge, a thermometer, a pressure gauge, a power unit, etc. installed inside the reactor containment vessel are transmitted to the outside through electric penetration. Electric power from the outside is also supplied to a power unit or the like installed inside the reactor containment vessel through electric penetration. The inside of the electric penetration is potted with an organic material such as epoxy resin or silicon resin. As the insulated wire, an organic insulated wire covered with ethylene propylene rubber, silicon rubber or the like is used.

Japanese Patent Laid-Open No. 50-1000048 Japanese Patent Laid-Open No. 60-200719 Japanese Patent Application Laid-Open No. 60-200720 JP-A-60-204210 JP-A 61-273115

  The reactor containment vessel monitors the internal state by taking out a measurement signal from an electric measurement product installed in the vessel through electric penetration. Electrical penetration is required to maintain hermeticity and electrical insulation even under high temperature conditions (˜300 ° C.) and high pressure conditions corresponding to severe accidents at nuclear power plants. It is difficult to maintain the airtightness and the electrical insulation function under high temperature and high pressure conditions in electrical penetrations using organic insulated wires covered with rubber etc. and potted with organic materials such as epoxy resin. .

  The present invention has been made to solve the above-described problems, and an object thereof is to maintain an airtight function and an electric insulation function of electric penetration even in a severe accident environment of a nuclear power plant.

  The electric penetration according to the present invention includes a metal ring that is hermetically welded to a metal sleeve, a hollow metal body that is smaller in diameter than the metal sleeve and is hermetically welded to the metal ring, and a first female screw. A metal first end plate that is formed and hermetically welded to one side of the metal body, and is fastened together with a first metal packing to a first female screw and engages with a metal first nut A metal first joint body, a second metal end plate formed with a second female screw and hermetically welded to the other side of the metal body, a second metal packing on the second female screw, A metal second joint body that is fastened together and engages with a metal second nut, and an inorganic insulated cable that penetrates the first joint body and the second joint body. The inorganic insulated cable is caulked to the first end plate using a first nut, and is caulked to the second end plate using a second nut.

  According to the present invention, since the metal penetration material and the inorganic insulation cable are used as the constituent material of the electric penetration and the welding structure and the metal seal are used, the airtight function and the electric insulation function can be maintained even in a high temperature and high pressure environment. .

It is sectional drawing which shows the whole nuclear reactor in connection with this application. It is sectional drawing which shows the whole structure of the electric penetration concerning this application. It is sectional drawing which shows the detailed structure of the joint for piping in connection with this application.

  Embodiments of electric penetration according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably.

  FIG. 1 is an overview diagram showing the overall configuration of the nuclear reactor 100. A steam generator 12, a pressurizer 13, a reactor vessel 14, a primary coolant pump 15, and the like are stored inside a reactor containment vessel (CV: Container Vessel) 11. The inside of the reactor containment vessel 11 is exposed to a high temperature (˜300 ° C.) and high pressure environment at the time of an accident. The pressure of the pressurizer 13 is measured using the measuring instrument 20a. The temperature of the reactor vessel 14 is measured using a measuring instrument 20b. The flow rate of the primary coolant is measured using the measuring instrument 20c. The reactor containment vessel 11 has through holes 11a at a plurality of locations. A sleeve 11b, which is a tubular tube made of carbon steel, is hermetically welded to the through hole 11a.

  Outputs of the measuring instruments 20 a to 20 c are connected to a primary system monitoring and measuring device 16 installed outside the reactor containment vessel 11 through an electric penetration 10. The electric penetration 10 maintains an airtight function and an electrical insulation function even in a high temperature environment or a high pressure environment. In addition to the measuring instruments 20a to 20c, many water level meters, thermometers, pressure gauges, power devices, and the like are installed inside the reactor containment vessel 11. Measurement signals from these measurement devices are also transmitted to the primary system monitoring measurement device 16 via the electric penetration 10. Also, control signals and motive power from the outside are transmitted through the electric penetration 10 to a power unit or the like installed inside the reactor containment vessel.

  FIG. 2 shows the structure of electrical penetration. The electric penetration 10 according to the present application exhibits a stable function even in an environment assuming a severe accident. The ring 4 is made of carbon steel. The body 2 and the end plates (3a, 3b) are made of 304 series stainless steel. The sleeve 11b and the ring 4 are hermetically welded. The body 2 has a smaller diameter than the sleeve 11b. The ring 4 and the body 2 are hermetically welded. The end plate 3a and the end plate 3b having a plurality of through holes are hermetically welded to the hollow body 2 respectively. Inorganic insulation (Mineral Insulation: MI) cables 1b pass through the through holes of the end plates (3a, 3b) attached to both ends of the body 2. The inorganic insulation cable is obtained by insulating a protective tube (metal sheath) and each conductor with an inorganic insulator such as magnesium oxide having high heat resistance. The function of the inorganic insulated cable is not impaired even in an environment that assumes severe accidents.

  The inorganic insulated cable 1 a is disposed inside the reactor containment vessel 11. The inorganic insulated cable 1 c is disposed outside the reactor containment vessel 11. The inorganic insulated cable 1a and the inorganic insulated cable 1b are airtightly connected by a metal connector 6a. The inorganic insulated cable 1b and the inorganic insulated cable 1c are hermetically connected by a metal connector 6b. The connector 6a and the connector 6b are composed of a male connector and a female connector, respectively. The pipe joint 5a is airtightly fixed to the end plate 3a. Similarly, the pipe joint 5b is airtightly fixed to the end plate 3b. The inorganic insulating cable 1b is caulked and fixed to the end plates (3a, 3b) by using pipe joints (5a, 5b).

  Since the connectors (6a, 6b) have a large diameter, the connectors (6a, 6b) are arranged so as to be displaced from each other so as not to interfere with each other. The trunk | drum 2 is hollow and the some inorganic insulated cable 1b is arrange | positioned. The body 2 is provided with a nitrogen supply pipe 8a and a pressure gauge 8b. The bending portion 1x is provided in the inorganic insulating cable 1b inside the body 2 to absorb the difference in thermal expansion between the body 2 and the inorganic insulating cable. Nitrogen gas is sealed inside the body 2. By monitoring the pressure of nitrogen gas, the soundness of each welded part and the sealing part of the inorganic insulated cable by the joint for piping is confirmed. By using the inorganic insulation cable, the electric penetration can maintain the electric insulation function even in a high temperature (up to 300 ° C.) environment and a high pressure environment.

  FIG. 3 shows the relationship between the end plates (3a, 3b) and the pipe joints (5a, 5b). A female parallel screw 3 x is formed in the through hole of the end plate 3. The end plate 3 and the inorganic insulated cable 1b are hermetically sealed using a joint 5 for piping such as Swagelok (registered trademark). The pipe joint 5 includes a nut 5w, a back ferrule 5y, a front ferrule 5x, a joint body 5m, and a metal packing 5z. By attaching the metal packing 5z to the joint body 5m and fastening the joint body 5m to the female parallel screw 3x, the metal packing 5z is compressed, and the airtightness between the joint body 5m and the end plate 3 is ensured. The joint body 5m is preferably spot welded to the end plate 3 to prevent loosening. When the inorganic insulated cable 1b is inserted into the joint body 5m and tightened with the nut 5w containing the back ferrule 5y and the front ferrule 5x, the front ferrule 5x bites into the protective copper pipe of the inorganic insulated cable. Seal the cable tightly. As described above, the inorganic insulating cable 1b is caulked and fixed to the end plate 3 using the pipe joint 5.

  In the electric penetration according to the present application, the inorganic insulating cable is hermetically sealed using a joint for piping. Since a tool for tightening the joint body 5m and the nut 5w only needs to secure a space for insertion and fastening between the pipe joints, a large number of pipe joints 5 can be attached to the end plates (3a, 3b). . On the other hand, since it is necessary to ensure a welding work space when welding the engaging part of the inorganic insulated cable 1b and the end plates (3a, 3b) all around, the pipe joint 5 that can be attached to the end plates The number is limited. In addition, when the inorganic insulated cable 1b is directly welded to the end plates (3a, 3b), the thickness of the protective tube and the end plate of the inorganic insulated cable are greatly different, so that a large difference occurs in the amount of heat input to both at the time of welding. As a result, a hole is opened in the protective tube, and a poor penetration occurs in the end plate.

  The electric penetration is made up of only metal materials and inorganic insulating materials, allowing airtightness and electrical insulation to be maintained even in high-temperature and high-pressure environments. By providing the bent portion 1x in the inorganic insulating cable inside the body 2 of the electric penetration, it becomes possible to absorb the thermal expansion difference from the body 2. Nitrogen gas is sealed in the internal space, and the soundness of each weld, the connection between the inorganic insulating cable 1 and the pipe joint 5 is confirmed by monitoring with a pressure gauge. By shifting the arrangement of the connector 6, interference is prevented and the number of inorganic insulation cable storage cores is increased. By using the joint 5 for piping for the connection method of the end plate 3 and the inorganic insulated cable 1, the number of storage cores is increased and welding failure is prevented.

  As described above, according to the present invention, welding, a joint for piping, and an inorganic insulating cable are used for the electric penetration installed in the penetration portion of the reactor containment vessel. By using only the metal material and the inorganic insulating material, it is possible to maintain the air tightness of the electrical penetration and the electrical insulation function even in a severe accident environment of a nuclear power plant.

  In the present invention, the embodiments can be appropriately modified and omitted within the scope of the invention.

1 Insulated cable, 1x bent part, 2 fuselage, 3 end plate, 3x female parallel screw, 4 ring, 5 pipe joint, 5m joint body, 5x front ferrule, 5y back ferrule, 5z metal packing, 5w nut, 6 connector , 8a Nitrogen supply pipe, 8b Pressure gauge, 10 Electric penetration, 11 Reactor containment vessel, 11a Through hole, 11b Sleeve, 12 Steam generator, 13 Pressurizer, 14 Reactor vessel, 15 Primary coolant pump, 20a-20b Measuring instrument, 100 nuclear reactor

Claims (4)

A metal ring hermetically welded to the metal sleeve;
A hollow metal body that is smaller in diameter than the metal sleeve and is hermetically welded to the metal ring;
A first metal end plate having a first female screw formed and hermetically welded to one side of the metal body;
A metal first joint body that is fastened to the first female screw with a first metal packing and engages with a metal first nut;
A second metal end plate formed with a second female screw and hermetically welded to the other side of the metal body;
A metal second joint body that is fastened to the second female screw together with a second metal packing and engages with a metal second nut;
An inorganic insulated cable penetrating the first joint body and the second joint body,
The electrical insulation wherein the inorganic insulated cable is caulked to the first end plate using the first nut and is caulked to the second end plate using the second nut.   The electric penetration according to claim 1, wherein the inorganic insulating cable has a bent portion inside the metal body.   The electric penetration according to claim 2, wherein the inorganic insulated cable comprises magnesium oxide.   The electric penetration according to claim 3, wherein a pressure gauge is attached to the metal body.