JP2597781B2 - How to install nuclear instrumentation in the reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for installing nuclear instrumentation equipment in a nuclear reactor of a boiling water reactor (hereinafter referred to as "BWR"), and more particularly to a BWR atom having an electrically driven control rod drive mechanism. The present invention relates to a method for installing nuclear instrumentation in a reactor.

[0002]

2. Description of the Related Art A conventional method of installing nuclear instrumentation in a nuclear reactor in a BWR will be described with reference to FIGS. FIG. 6 shows a reactor core instrumentation monitor housing closing flange (hereinafter referred to as IC) to a reactor core instrumentation monitor housing at the bottom of a reactor pressure vessel in which a conventional hydraulically driven control rod drive mechanism is implanted.
FIG. 7 is an external view showing an attached state of an M closing flange).
Is a vertical cross-sectional view showing a detailed mounting state of the ICM closing flange in FIG. 6, and FIG. 8 is a view showing an installation process of conventional nuclear instrumentation equipment in a nuclear reactor.

A control rod drive mechanism housing 1 and an in-core nuclear instrumentation monitor housing 2 are implanted at the bottom of a reactor pressure vessel (not shown). Prior to the primary pressure test of the reactor pressure vessel, the control rod drive mechanism housing closing flange (hereinafter referred to as CRD closing flange) 19 and the ICM are provided at the lower ends of the control rod drive mechanism housing 1 and the in-core nuclear instrumentation monitor housing 2, respectively. Attach the closing flange 15. The bottom of the reactor pressure vessel is sealed with the CRD closing flange 19 and the ICM closing flange 15, and water is injected into the reactor pressure vessel to perform a primary hydraulic test. Next, a trial run of water injection into the reactor pressure vessel is performed. After the water injection test operation, the water in the reactor pressure vessel was discharged, and the CRD closing flange 19 of the control rod drive mechanism housing 1 was removed.
Next, the hydraulically driven control rod drive mechanism 16 is installed. With the hydraulic drive type control rod drive mechanism 16 installed, water is injected into the reactor pressure vessel, and an in-reactor fluid vibration test in the reactor pressure vessel is performed. After performing the in-reactor fluid vibration test, the water in the reactor pressure vessel is discharged. After this drainage, the ICM closing flange 15 is removed from the core nuclear instrumentation monitor housing 2, and a flange (not shown) for mounting the core nuclear instrumentation monitor is attached in place of the ICM closing flange 15. A nuclear instrumentation monitor (not shown) is installed through the flange.

[0004]

In the improved BWR, an electrically driven control rod drive mechanism is provided in place of the hydraulically driven control rod drive mechanism 16. FIG. 9 shows the outer shape of this electrically driven control rod drive mechanism.

A motor 5 for driving the control rod includes a motor bracket 6, a shaft seal housing 7, and a control rod driving mechanism flange 8.
Is attached to the lower end of the control rod drive mechanism housing 1 to form an electrically driven control rod drive mechanism 24.

Since the electrically driven control rod drive mechanism 24 is longer than the conventional hydraulically driven control rod drive mechanism 16, after the electrically driven control rod drive mechanism 24 is installed, the in-core nuclear instrumentation monitor is required. It becomes difficult to approach the flange 19 of the housing 2.

For this reason, the core nuclear instrumentation monitor housing 2
As shown in FIG. 7, the removal of the ICM closing flange 15 from the flange 19 and the mounting of the in-core instrumentation monitor mounting flange are performed by removing and mounting a plurality of mounting bolts 17 as shown in FIG.
The mounting of the ring 18 must be performed remotely. Therefore, in order to control the torque of the mounting bolt 17 and check the attachment of the O-ring 18, not only a large-scale special tool needs to be developed, but also problems remain in terms of work reliability.

The present invention has been made in view of the above points. Even when a motor-driven control rod drive mechanism is attached to the lower part of a reactor pressure vessel so that the reactor cannot access the nuclear instrumentation monitor housing in the reactor, the present invention is not limited thereto. It is an object of the present invention to provide a method for installing nuclear instrumentation equipment in a nuclear reactor, which can reliably install an internal instrumentation monitor in the nuclear instrumentation monitor housing.

[0009]

In order to achieve the above object, in the present invention, a step of attaching a flange for mounting an in-core instrumentation monitor to an in-core instrumentation monitor housing formed at a lower portion of a reactor pressure vessel. Attaching a plug that seals an inner wall surface of the in-core nuclear instrumentation monitor housing through the in-core nuclear instrumentation monitor mounting flange, and water-sealing the bottom of the reactor pressure vessel; and Performing a primary hydraulic pressure test by injecting water into the reactor pressure vessel with the bottom sealed, and discharging the water from the reactor pressure vessel after the primary hydraulic pressure test to perform the primary pressure test. Installing the electrically driven control rod drive mechanism therein, removing the plug with the electrically driven control mechanism drive mechanism installed, and removing the plug from the core instrumentation monitor after removal of the plug. Provides a mounting method of the nuclear reactor core instrumentation, characterized in that comprising a step of penetrating the flange with mounting the furnace nuclear instrumentation monitor.

[0010]

With this configuration, the in-core nuclear instrumentation monitor mounting flange is attached to the lower end of the in-core nuclear instrumentation monitor housing formed at the lower part of the reactor pressure vessel. A plug for sealing the inner wall surface of the in-core nuclear instrumentation monitor housing is fitted through the flange for mounting the in-core nuclear instrumentation monitor, and the bottom of the reactor pressure vessel is water-sealed. With the bottom of the reactor pressure vessel sealed with water, water is injected into the reactor pressure vessel to perform a primary pressure test of the reactor pressure vessel. After this primary water pressure test, the water in the reactor pressure vessel is drained, and an electrically driven control rod drive mechanism is installed in the reactor pressure vessel. With the electric drive type control rod drive mechanism installed, the plug is removed. After removing the plug, the in-core nuclear instrumentation monitor is installed through the flange for mounting the in-core nuclear instrumentation monitor.

In this way, even when the electrically driven control rod drive mechanism is installed below the reactor pressure vessel and the reactor core instrumentation monitor housing cannot be accessed, the reactor core instrumentation monitor can be kept high inside the reactor core instrumentation monitor housing. A method of installing nuclear instrumentation in a nuclear reactor that can be installed with high reliability can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an external view showing an attached state of a plug according to a method of installing nuclear instrumentation in a nuclear reactor according to the present invention. FIG. 2 is an enlarged longitudinal sectional view showing an attached state of the plug shown in FIG. Is a structural diagram showing a plug handling wrench,
FIG. 4 is a structural view showing the plug removal wrench, and FIG. 5 is an installation process diagram showing an installation process of the nuclear instrumentation equipment in the nuclear reactor according to the present invention.

As shown in FIG. 1, a CRD closing flange 19 is attached to the lower end of the control rod drive mechanism housing 1. At the lower end of the in-core nuclear instrumentation monitor housing 2, an in-core nuclear instrumentation monitor mounting flange 3 is attached, and further a plug 4 is attached, and the bottom of the reactor pressure vessel is water-sealed. After the primary water pressure test is completed with the bottom of the reactor pressure vessel sealed with water, the water in the reactor pressure vessel is drained, and the CRD closing flange 19 is removed from the control rod drive mechanism housing 1 to be electrically driven. The control rod drive mechanism 24 is mounted. A control rod drive motor 5 is mounted on the lower end of the control rod drive mechanism housing 1 via a motor bracket 6, a shaft seal housing 7, and a control rod drive mechanism flange 8, and an electrically driven control rod drive mechanism 24 is configured. You.

FIG. 2 is a longitudinal sectional view of the plug. The in-core nuclear instrumentation monitor mounting flange 3 is attached to the in-core nuclear instrumentation monitor housing 2, and a plug 4 for water sealing is further attached. This plug 4 is a packing 10 for sealing the wall surface inside the reactor core instrumentation monitor housing 2.
And a shaft 9 that supports This shaft 9
Is mounted on the in-core nuclear instrumentation monitor mounting flange 3 via the holder 11. The nut 14 is tightened while fixing the shaft 9 so as not to rotate, the washer 13 and the collar 12 are moved, and the shaft 9 is pushed down, so that the packing 10 is contracted as shown by a two-dot chain line. The shrinkage of the packing 10 causes the core instrumentation monitor housing 2 in the furnace.
The bottom of the reactor pressure vessel can be water-sealed by contacting the inner wall.

The removal of the plug 4 is performed by
Perform the procedure in the reverse order of the installation. At this time, since the electrically driven control rod drive mechanism 24 is installed, remote control is required. The plug handling wrench required for this remote operation is shown in FIG. The plug handling wrench 22 has a double concentric structure of a shaft fixing wrench 20 and a nut rotating wrench 21. The shaft fixing wrench 20 includes a shaft socket 24 inserted into the tip of the shaft 9, a fixing rod 25 supporting the shaft socket 24, and a fixing handle 26 attached to the other end of the fixing rod 25. Similarly, the nut rotating wrench 21 includes a nut socket 27 inserted into the nut 14, a rotating rod 28 supporting the nut socket 27, and a rotating handle attached to the other end of the rotating rod 28.
Consists of 29. By configuring the plug handling wrench 22 in this manner, the nut 14 is loosened by the nut rotating wrench 21 while the shaft 9 is fixed by the shaft fixing wrench 20. The packing 10 is sufficiently extended and detached from the inner wall surface of the in-core nuclear instrumentation monitor housing 2, and the water seal state is released.

FIG. 4 is a structural view showing the plug removing wrench. The plug removal wrench 23 includes a holder socket 30 to be inserted into the holder 11, and a removal rod for supporting the holder socket 30.
31, a removal handle 32 attached to the other end of the removal rod 31
It is composed of By turning the plug removal wrench 23, the plug 4 released from the water-sealed state is
By rotating 11 and pulling it downward, it is removed from the in-core nuclear instrumentation monitor mounting flange 3. FIG. 5 is an installation process diagram showing an installation process of nuclear instrumentation equipment in a nuclear reactor. In this figure, the use period of the in-core nuclear instrumentation monitor mounting flange 3 and the plug 4 is shown.

Next, the operation of this embodiment having the above configuration will be described. A CRD closing flange 19 is attached to the lower end of the control rod drive mechanism housing 1. At the lower end of the in-core nuclear instrumentation monitor housing 2, an in-core nuclear instrumentation monitor mounting flange 3 is attached, and further, a plug 4 is attached, and the bottom of the reactor pressure vessel is water-sealed.

With the bottom of the reactor pressure vessel sealed with water, water is injected into the reactor pressure vessel, a primary water pressure test is performed, and a test run of the reactor pressure vessel water injection is performed. Of water is drained. The CRD closing flange 19 is removed from the control rod drive mechanism housing 1, and the electrically driven control rod drive mechanism 24 is installed. With the electric drive type control rod drive mechanism 24 attached, water is injected into the reactor pressure vessel and drained again after a fluid vibration test in the reactor.

After the drainage, the plug 4 is released from the water seal state using the plug handling wrench 22, and the plug 4 is remoted from the in-core instrumentation monitor mounting flange 3 using the plug removal wrench 23. Remove it. After removing the plug 4, a reactor core instrumentation monitor (not shown) is attached to the reactor core instrumentation monitor flange 3. After installing this in-core nuclear instrumentation monitor, water is again injected into the reactor pressure vessel and a secondary water pressure test is performed.

As described above, according to the present embodiment, from the stage immediately before the start of the on-site primary water pressure test of the reactor pressure vessel, the in-core nuclear instrumentation monitor mounting flange is attached to the in-core nuclear instrumentation monitor housing. Attach the plug to the inner core instrumentation monitor mounting flange and seal the inner wall of the reactor core instrumentation monitor housing. Thus, the bottom of the reactor pressure vessel is water-sealed. Thus, even in the state where the electrically driven control rod drive mechanism is installed, the in-core nuclear instrumentation monitor mounting flange and the in-core nuclear instrumentation monitor can be easily and reliably installed in the in-core nuclear instrumentation monitor housing.

[0021]

As described above, according to the method for installing nuclear instrumentation equipment in a nuclear reactor according to the present invention, the control rod drive mechanism of the electric drive type is attached to the lower part of the reactor pressure vessel, and the nuclear instrumentation monitor housing in the reactor is installed. The in-core nuclear instrumentation monitor can be installed in the in-core nuclear instrumentation monitor housing with high reliability even in the inaccessible state.

[Brief description of the drawings]

FIG. 1 is an external view showing an attached state of a plug according to a method of installing nuclear instrumentation in a nuclear reactor according to one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a detailed mounting state of the plug shown in FIG. 1;

FIG. 3 is a structural view showing a plug handling wrench.

FIG. 4 is a structural view showing a plug removal wrench.

FIG. 5 is an installation process diagram showing an installation process of nuclear instrumentation equipment in a nuclear reactor according to the present invention.

FIG. 6 shows an ICM to a nuclear instrumentation monitor housing of a reactor pressure vessel in which a conventional hydraulically driven control rod drive mechanism is implanted.
FIG. 3 is an external view showing a mounting state of a closing flange.

FIG. 7 is a side view showing the ICM closing flange shown in FIG. 6 in a partially cut-out state;

FIG. 8 is an installation process diagram showing a conventional installation process of nuclear instrumentation equipment in a nuclear reactor.

FIG. 9 shows an ICM to a nuclear instrumentation monitor housing at the bottom of a reactor pressure vessel in which a conventional electric control rod drive mechanism is implanted.
FIG. 3 is an external view showing a mounting state of a closing flange.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Control rod drive mechanism housing 2 ... Furnace nuclear instrumentation monitor housing 3 ... Furnace nuclear instrumentation monitor mounting flange 4 ... Plug 9 ... Shaft 10 ... Packing 24 ... Electric drive type control rod drive mechanism

Claims (1)

(57) [Claims] A step of attaching a flange for mounting an in-core nuclear instrumentation monitor to an in-core nuclear instrumentation monitor housing formed at a lower portion of a reactor pressure vessel; and a plug for sealing an inner wall surface of the in-core nuclear instrumentation monitor housing. A step of penetrating the reactor core instrumentation monitor mounting flange and mounting the bottom of the reactor pressure vessel with water, and injecting water into the reactor pressure vessel with the bottom of the reactor pressure vessel sealed. Performing a primary hydraulic pressure test, discharging the water in the reactor pressure vessel after the primary hydraulic pressure test, and installing an electrically driven control rod drive mechanism in the reactor pressure vessel, Removing the plug with the drive-type control rod drive mechanism installed; and, after removing the plug, installing the in-core nuclear instrumentation monitor through the in-core nuclear instrumentation monitor mounting flange. A method for installing nuclear instrumentation in a nuclear reactor.