JPH03200095A - Device for holding fuel assembly with measuring line - Google Patents

Abstract

PURPOSE:To make work easy for exchanging a fuel assembly with measuring line by providing double seal parts between a guide pipe and an outside extended pipe and between the outside extended pipe and an inside extended pipe and providing a gas seal part between upper and lower seal parts. CONSTITUTION:Double seal parts 18 and 19 are provided between a guide pipe 4 and an outside extended pipe 5 and between the outside extended pipe 5 and an inside extended pipe 6. For these double seal parts 18 and 19, O rings 20 and 21 are vertically arranged and between the upside and downside O rings 20 and 21, gas seal parts 22 and 23 are provided while being composed of circular grooves. Seal gas such as nitrogen gas, etc., is supplied to these gas seal parts 22 and 23 with pressure higher than pressure in the vessel of a nuclear furnace and the gas seal parts 22 and 23 are provided for backup the double seal parts 18 and 19. At a lower position between the guide pipe 4 and the outside extended pipe 5, a sodium scraper is provided to prevent sodium from being vapor deposited onto the outer surface of the outside extended pipe 5 and to remove the stuck sodium.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a measurement wire fuel assembly holding method for holding a fuel assembly equipped with a measurement cable, and for guiding the measurement cable out of the reactor. It is related to the device.

(Prior Art) When designing the core of a fast breeder reactor, it is necessary to know the amount of fission product gas generated from the core fuel by neutron irradiation, the flow rate of coolant flowing in the core, and the temperature of each part of the fuel. In order to continuously measure the behavior of the core fuel, it is necessary to use a measurement wire fuel assembly equipped with various sensors (e.g. thermocouples, electromagnetic flowmeters, neutron detectors, etc.) A device is required to guide the body measurement cable out of the furnace.

Conventionally, as a device for guiding a measurement cable of a measurement wire fuel assembly out of the reactor, there is a measurement wire fuel assembly holding device disclosed in Japanese Patent Publication No. 59-25200. As shown in FIGS. 3 to 5, this measurement wire fuel assembly holding device has a guide tube 4 inserted into the reactor vessel 2 through the shielding plug 1, and can be moved up and down into the guide tube 4. It has an outer extension tube 5 provided at A latch mechanism 7 that holds the measurement wire fuel assembly 8 is provided so as to be openable and closable.

Inside the measurement wire fuel assembly 8, a plurality of fuel bottles are housed, and various sensors such as thermocouples, electromagnetic flow meters, and neutron detectors are provided.Measurement cables 9 are connected to these various sensors. passes through the inner extension tube 6 and is connected to a measuring device 10 installed outside the furnace. and,
A cutter 11 for cutting the measurement cable 9 is provided at the lower part of the outer extension tube 5.

Further, a drive section 12 is provided at the upper part of the guide tube 4 to drive the outer extension tube 5 up and down. A handle 13 is provided at the top of the drive unit 12, and the handle 13 rotates a lead screw 14 to move the outer extension tube 5 up and down. Note that the guide pipe 4 and the outer extension pipe 5 and the outer extension pipe 5 and the inner extension pipe 6 are connected to the bellows 1 in order to secure the pressure boundary inside the reactor vessel 2.
5.16 is connected.

The fuel assembly holding device with gauge #III configured as described above is configured so that when the handle 13 provided at the upper part of the drive unit 12 is operated to lower the outer extension pipe 5, the device is attached to the lower part of the outer extension pipe 5. At the same time, the cutter 11 cuts the measurement cable 9 of the measurement wire fuel assembly 8, and the guide 17 (see FIG. 5) provided at the lower part of the outer extension tube 5 descends, contacts the latch mechanism 7, and closes the latch mechanism. 7 is closed, cutting of the measurement cable 9 and separation of the measurement wire fuel assembly 8 can be performed in one operation.

By the way, the conventional measurement wire fuel assembly holding device cuts the measurement cable 9 of the measurement wire fuel assembly 8 with a cutter 11, separates the measurement wire fuel assembly 8 from the lower end of the inner extension tube 6, and then creates a new measurement wire fuel assembly. When attaching the fuel assembly 8 to the lower end of the inner extension pipe 6, the guide pipe 4 and the outer extension pipe 5 and the outer extension pipe 5 and the inner extension pipe 6 are connected by the bellows 15, 16 as described above, so the guide The entire device including tube 4 and drive 12 must be removed.

However, in order to remove the entire device, it is also necessary to remove the control rod drive device around the drive section, which requires a great deal of effort and time to replace the measurement wire fuel assembly 8.

(Problems to be Solved by the Invention) As described above, the conventional measurement wire fuel assembly holding device uses the guide pipe 4, the outer extension pipe 5, and the outer extension pipe to ensure the pressure boundary within the reactor pressure vessel 2. 5 and the inner extension pipe 6 were connected by bellows 15° and 16, it was necessary to remove the entire device when replacing the measuring wire fuel assembly 8, and it took a lot of effort to replace the measuring wire fuel assembly 8. The problem was that it took time.

The present invention was made by focusing on these problems.
The purpose of this is to ensure the pressure boundary inside the reactor pressure vessel without connecting the guide tube and the outer extension tube and the outer extension tube and the inner extension tube with bellows, and to facilitate the replacement work of the measurement wire fuel assembly. The object of the present invention is to provide a measuring wire fuel assembly holding device that can perform measurements.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a first invention provides a guide tube inserted into a reactor vessel through a shielding plug, and an inner side of the guide tube. an outer extension tube provided on the outer extension tube; an inner extension tube provided on the inner side of the outer extension tube; and a drive provided on the upper part of the guide tube that drives either the outer extension tube or the inner extension tube up and down. a latch mechanism provided on the extension tube on the side of the outer extension tube and the inner extension tube that is not driven up and down by the driving section and holds the measurement wire fuel assembly; A measurement wire fuel assembly holding device comprising: a cutter that is provided on an extension tube on the side that is driven up and down by a drive unit and cuts the measurement cable of the measurement wire fuel assembly;
A double seal portion in which O-rings are arranged above and below is provided between the guide tube and the outer extension tube and between the outer extension tube and the inner extension tube, and an upper seal portion and a lower portion of the double seal portion are provided. It is characterized by providing a backup gas seal part between the seal part and the seal part.

The second invention also includes a guide tube inserted into the reactor vessel through a shielding plug, an outer extension tube provided inside the guide tube, and an inner extension provided inside the outer extension tube. a tube, a driving section provided at the upper part of the guide tube and driving one of the outer extension tube and the inner extension tube up and down; and one of the outer extension, tube, and inner extension tube that is not driven up and down by the drive section. a latch mechanism provided on a side extension tube to hold a fuel assembly having a measurement cable; and a latch mechanism provided on the extension tube on the side of the outer extension tube and the inner extension tube that is driven up and down by the driving section and equipped with the measurement cable. In the measurement wire fuel assembly holding device, the O-rings are arranged vertically between the guide tube and the outer extension tube and between the outer extension tube and the inner extension tube. A double seal portion is provided, a backup gas seal portion is provided between the upper seal portion and the lower seal portion of these double seal portions, and the outer extension tube is provided between the guide tube and the outer extension tube. It is characterized by the provision of a sodium souffle valve that removes sodium adhering to the tube.

(Function) In the first invention, the pressure boundary inside the reactor vessel is controlled by the double seal portion provided between the guide pipe and the outer extension pipe and between the outer extension pipe and the inner extension pipe. Therefore, only the outer extension tube and the inner extension tube can be pulled out from inside the reactor vessel, and the measurement wire fuel assembly can be easily replaced. Additionally, a backup gas seal is provided between the upper and lower seals of the double sill, so if the sealing function of the double seal is lost due to damage to the O-ring, etc. However, the pressure boundary inside the reactor pressure vessel can be secured.

In the second aspect of the present invention, since a sodium souffle valve is provided between the guide tube and the outer extension tube, the measurement wire fuel assembly can be easily replaced as in the first aspect, and the outer extension tube can be replaced easily. Sodium adhering to the extension tube can be removed with a sodium souffle valve.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2. Note that the same parts as shown in FIGS. 3 to 5 are given the same reference numerals, and explanations of those parts will be omitted.

In FIG. 1, double seals 18, 19 are provided between the guide tube 4 and the outer extension tube 5 and between the outer extension tube 5 and the inner extension tube 6.

As shown in Fig. 2, these double seal parts 18 and 19 are each composed of O rings 20 and 21 arranged above and below, and the O ring (upper seal part) arranged on the upper side
20 and O-ring (lower seal part) 21 placed on the lower side
A gas seal portion 22.23 consisting of an annular groove is provided between the two.

Seal gas such as nitrogen gas is supplied to these gas seal sections 22, 23 at a pressure higher than the pressure inside the reactor vessel, and is provided as a backup for the double seal sections 18, 19.

Further, a sodium souffle valve 24 is provided at a lower position between the guide tube 4 and the outer extension tube 5. This sodium souffle valve 24 is connected to the guide pipe 4 via a connecting pipe 25.
It has the function of preventing sodium from evaporating on the outer surface of the outer extension tube 5 and removing the sodium attached to the outer surface of the outer extension tube 5 when the outer extension tube 5 is raised and lowered. .

The measurement wire fuel assembly holding device configured in this way is
Double seal parts 18 and 19 are provided between the guide tube 4 and the outer extension tube 5 and between the outer extension tube 5 and the inner extension tube 6, with O-rings 20 and 21 arranged above and below. The pressure boundary within the reactor pressure vessel can be secured by the double seal portions 18 and 19. Therefore, the pressure boundary inside the reactor pressure vessel can be secured without connecting the guide tube 4 and the outer extension tube 5 and the outer extension tube 5 and the inner extension tube 6 with bellows as in the past. Since only the extension tube 6 can be pulled out from inside the reactor pressure vessel, the measurement wire fuel assembly 8 can be easily replaced. In addition, the double seal part 18.1
Between the upper seal part 20 and the lower seal part 21 of 9,
Since the backup gas seal part 22.23 is provided, even if the sealing function of the double seal part 18.19 deteriorates due to deterioration or damage of the O-ring, the gas seal part 22.23 will protect the reactor pressure vessel. The pressure boundary within the reactor can be secured, and the safety and soundness of the reactor can be improved.

Furthermore, in this embodiment, since the sodium souffle bar 24 is provided between the guide tube 4 and the outer extension tube 5, the sodium adhering to the outer extension tube 5 is removed by the sodium souffle bar 24.
4 can be removed. Therefore, when pulling out the outer extension tube 5 and the inner extension tube 6 from inside the reactor vessel, the outer extension tube 5 does not stick to the guide tube 4 due to sodium, and the outer extension tube 5 and the inner extension tube 6 can be easily pulled out from inside the reactor vessel.

In the above embodiment, the cutter 11 for cutting the measurement cable 9 of the measurement wire fuel assembly 8 is provided on the outer extension tube 5, but the cutter 11 is provided on the inner extension tube 6 to hold the measurement wire fuel assembly 8. A latch mechanism 7 may be attached to the outer extension tube 5.

However, in that case, the inner extension tube 6 will be driven up and down.

[Effects of the Invention] As explained above, the first invention makes it possible to secure the pressure boundary in the reactor pressure vessel without connecting the guide tube and the outer extension tube and the outer extension tube and the inner extension tube with bellows. , the measurement wire fuel assembly can be easily replaced. Furthermore, even if the sealing function of the double seal section is degraded, the pressure boundary within the reactor pressure vessel can be secured by the gas seal section, and the safety and soundness of the nuclear reactor can be improved.

Further, the second invention allows the measurement wire fuel assembly to be easily replaced in the same manner as the first invention, and the sodium adhering to the outer extension tube can be removed by the sodium souffle bar. .

[Brief explanation of drawings]

Fig. 1 is a sectional view of a measurement wire fuel assembly holding device showing an embodiment of the present invention, Fig. 2 is a view showing the main parts thereof, and Figs.
FIG. 5 is a diagram showing a conventional measurement wire fuel assembly holding device. DESCRIPTION OF SYMBOLS 1... Shielding plug, 2... Reactor vessel, 3... Reactor core, 4... Guide tube, 5... Outer extension tube, 6...
Inner extension tube, 7...Latch mechanism, 8...Total 7IIl
Wire fuel assembly, 9...Measuring cable, 11...Cutter 12...Drive part, 18.19...Double seal part, 20...0 ring (upper seal part) 2 1...・0 ring (lower seal part) 22° 3...Gas seal part, 24...Sodium scraper.

Claims (2)

[Claims] (1) A guide tube inserted into the reactor vessel through a shielding plug, an outer extension tube provided inside this guide tube, and an inner extension tube provided inside this outer extension tube, a drive unit provided at the upper part of the guide tube and driving one of the outer extension tube and the inner extension tube up and down;
A latch mechanism that is provided on the side of the extension tube that is not driven up and down by the drive section among the outer extension tube and the inner extension tube and holds the measurement wire fuel assembly; In the fuel assembly holding device with a measurement wire, the cutter is provided on the extension pipe on the side that is driven up and down and cuts the measurement cable of the measurement wire fuel assembly, and the cutter is provided between the guide pipe and the outer extension pipe and on the outer side. A double seal part with O-rings arranged above and below is provided between the extension pipe and the inner extension pipe, and a backup gas seal part is provided between the upper seal part and the lower seal part of these double seal parts. A fuel assembly holding device with a measurement line. (2) a guide tube inserted into the reactor vessel through the shielding plug; an outer extension tube provided inside the guide tube; and an inner extension tube provided inside the outer extension tube; a drive unit provided at the upper part of the guide tube and driving one of the outer extension tube and the inner extension tube up and down;
A latch mechanism that is provided on the side of the extension tube that is not driven up and down by the drive section among the outer extension tube and the inner extension tube and holds the measurement wire fuel assembly; In the fuel assembly holding device with a measurement wire, the cutter is provided on the extension pipe on the side that is driven up and down and cuts the measurement cable of the measurement wire fuel assembly, and the cutter is provided between the guide pipe and the outer extension pipe and on the outer side. A double seal part with O-rings arranged above and below is provided between the extension pipe and the inner extension pipe, and a backup gas seal part is provided between the upper seal part and the lower seal part of these double seal parts. A measurement wire fuel assembly holding device characterized in that a sodium scraper is provided between the guide tube and the outer extension tube to remove sodium adhering to the outer extension tube.