JPH04235394A - Isolation valve of incore instrumentation system - Google Patents

Abstract

PURPOSE:To provide an incore instrumentation system isolation valve by which a detector cable, or, simultaneously, its guide tube and the cable can be cut off, without using gun powder at all. CONSTITUTION:An electrode part 30 is arranged in a valve box 20 of an incore instrumentation system isolation valve and, by utilizing shock wave at electrical discharge by the electrode part 30, a piston 22 is driven and thereby a detector cable 4a is cut off.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isolation valve that constitutes a containment vessel boundary of a mobile in-core instrumentation (hereinafter referred to as TIP) system inserted into a nuclear reactor from outside the containment vessel.

0002

2. Description of the Related Art As illustrated in FIG. 4, a TIP system includes a calibration tube 3 installed in a plurality of output range detectors 2 placed at predetermined positions in a pressure vessel 1, and connected to the lower end of the calibration tube 3. an isolation valve 8 connected sequentially to the detector guide tube 4 drawn out of the containment vessel 7 through the indexing device 5 and the penetration flange 6, a shielding container 9, and a detector drive device 10.
It is composed of.

[0003] The TIP detector (not shown) is attached to the tip of a detector cable 4a of several tens of meters long, and is housed in a shielding container 9 when not in use, and the cable is wound on a reel in a detector drive device 10. It has been taken.

On the other hand, when measuring the neutron flux inside a nuclear reactor, the TIP detector is sent into the detector guide tube 4 by the detector cable 4a unwound from the reel of the detector drive device 10. The TIP detector moves forward in the detector guide tube 4 by the length of the cable sent out. When the TIP detector leaves the shielding vessel 9, a ball valve (not shown) of the isolation valve 8 opens, and the TIP detector is introduced into the containment vessel 7 through the isolation valve 8 and finally into the core of the calibration tube 3. It stops at the top and begins an extraction operation to measure the neutron flux inside the reactor. A conventional isolation valve 8 that is used when some abnormality occurs in the reactor in this state and a containment vessel isolation signal is transmitted will be described with reference to FIG. 5. Since the detector guide tube 4 and the detector cable 4a pass through the isolation valve 8, the ball valve cannot be closed. In such a case, the cutting blade 23 of the isolation valve 8 is operated to cut the detector guide tube 4 and the detector cable 4a, and at the same time the cut end of the detector guide tube 4 is sealed. Isolate the penetration.

The isolation valve 8 through which the detector guide tube 4 penetrates is provided with a cylinder 21 in a valve box 20 which also serves as a holder for holding the detector guide tube 4, and is cut at the tip of a piston 22 housed in the cylinder 21. It has a blade 23, and has a structure in which a plug 25 containing gunpowder 24 is screwed into the upper end of a cylinder 21. To operate this isolation valve 8, the gunpowder 24 of the plug 25 is
The gunpowder is exploded by energizing a coil (not shown) provided therein, and the resulting pressure moves the piston 22 to drive the cutting blade 23 toward the detector guide tube 4. The detector cable 4a inserted therein is cut, and the valve seat 26 is closed by the plane of the cutting blade 23.

[0006]

However, the isolation valve 8 having such a structure has the following problems.

[0007] In order to handle explosives, it is necessary to notify or obtain approval from a person in charge of handling hazardous materials and related organizations. Further, if the gunpowder 24 is accidentally detonated during inspection and repair, there is a risk of danger to workers.

Furthermore, once a gunpowder plug is used, the gunpowder powder is burned onto the cylinder wall of the piston portion, making it impossible to reuse it, making it impossible to test its operation during periodic inspections, resulting in low reliability. The present invention has been made to solve the above-mentioned problems, and its purpose is to provide an isolation valve for an in-core instrumentation system that can simultaneously disconnect a detector cable or a guide tube and cable without using explosives. It is about providing. [Structure of the invention]

[0009]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, an electrode section is disposed within the valve box, and the piston is driven by using the shock wave generated by the electrode section when electric discharge occurs. An isolation valve for an in-core instrumentation system is provided, which is characterized in that it disconnects a detector cable.

0010

[Operation] In the isolation valve of the in-core instrumentation system configured in this way, when the capacitor equipment starts charging and the discharge switch is turned on after charging, a discharge phenomenon occurs in the electrode section, and a shock wave is generated at the upper part of the piston. act. Therefore, the piston descends, and the blade at the tip of the piston can cut the detector cable.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Note that the same parts as those of the conventional example already explained are given the same reference numerals.

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention. As shown in the figure, a discharge plug 30 is provided on the upper part of a valve box 20, and a negative electrode 31 and a positive electrode 32 are installed inside the discharge plug. is provided. These electrodes 31 and 32 are short-circuited with a thin conductive wire 33. Further, a cylinder 21 is formed in the valve box 20, and a piston 22 accommodated therein has a cutting blade 23 at the tip thereof.
A plug 30 containing electrodes 31 and 32 is screwed into the upper end of the holder. Further, the detector cable 4a passes through an inlet flange 34 and an outlet flange 35 of the joint of the detector guide tube 4, which are provided oppositely on both sides of the valve box 20. Also,
Since flanges 34 and 35 are provided at both the inlet and outlet, a gasket 37 (or an O-ring) can be inserted. Therefore, the internal pressure of the containment vessel 7 can be applied in a direction in which the cutting blade 23 is pressed against the valve seat 38 with good sealing performance. Furthermore, the piston 22 is equipped with an O-ring 39. Furthermore, power storage equipment 36 necessary for discharging is installed separately. The charging and discharging circuits are as shown in Figure 2.
DC power supply 41, resistor 42, capacitor 43, discharge electrode 3
1, 32, wire 33, switch S1 44, and switch S2 45. The operation of the isolation valve of the in-core instrumentation system of the present invention configured as described above will be explained.

The detector cable 4a fed out by the detector drive device 10 leaves the shielding container 9, passes through the isolation valve 8, passes through the indexing device 5, and is inserted into the calibration tube 3, as shown in FIG. At this time, when the containment vessel isolation signal is transmitted, the detector drive device 10 automatically pulls out the detector cable 4a, but if a failure occurs in the detector drive device 10 at this time, the detector cable 4a is pulled out. It will no longer be possible to withdraw and therefore the ball valve (not shown) of the isolation valve 8 will not be able to close. In such a case, the capacitor 43 is charged by closing the switch S1 44 in the capacitor equipment 32 and turning on the power supply 41, and then the discharge phenomenon starts by turning on the discharge start switch S2 45, and the negative electrode in the discharge plug is turned on. The thin conductive wire short-circuited between 31 and the positive electrode 32 instantly melts, generating a shock wave. The shock wave at this time is transmitted through the air to move the piston 22 downward, and the cutting blade 23 further cuts the detector cable 4a.

FIG. 3 is a longitudinal sectional view of another embodiment of the invention. If the detector guide tube 4 is passed through the valve box 20 and the cable 4a is passed through the detector guide tube 4, the guide tube 4 and the cable 4a can be cut at the same time.
It is obvious that this embodiment has the same function as the above embodiment in which only the cable 4a is cut.

Furthermore, by filling the space between the piston 22 and the discharge plug 30 with a liquid 40 such as water or glycerin, it is possible to improve the transmission efficiency of shock waves during discharge and to increase the cutting force. In this case, since the piston is provided with an O-ring 39, the liquid 40 is effectively sealed.

[0016]

As described above, according to the isolation valve for the in-core instrumentation system of the present invention, it is possible to provide an isolation valve that does not use explosives and has the same functions as conventional ones. Additionally, since it does not use explosives compared to conventional methods, it not only eliminates the need for notification or approval from hazardous materials handling personnel and related organizations, but also improves reliability by allowing operation confirmation tests to be performed during annual inspections. Furthermore, by short-circuiting the electrodes for discharge with a thin wire, the energy efficiency during discharge can be increased, and the impact force can be reliably transmitted to the piston.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an isolation valve of an in-core instrumentation system according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of capacitor equipment applied to the isolation valve of the present invention.

FIG. 3 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 4 is a schematic diagram of a mobile in-core instrumentation system to which the present invention is applied.

FIG. 5 is a longitudinal sectional view showing a conventional example of an isolation valve for an in-core instrumentation system.

[Explanation of symbols]

4...Detector guide tube
4a...Detector cable

Claims (1)

[Claims] 1. A guide pipe passes through the valve box, a cable passes through the guide pipe, a cylinder and a piston are provided in the valve box, and an acute-angled blade is provided at the tip of the piston. An isolation valve for an in-core instrumentation system, further comprising a cutting device that simultaneously cuts the guide tube and cable by driving the piston by an impact force during discharge.