JPH11109094A - Chemical decontamination method for equipment in nuclear power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce dose of radiation exposure in preparation work, shorten work time and obtain good decontamination effect by fixing a decontamination stage in the vicinity of decontaminating object, providing the stage with a locking point and circulating decontamination liquid. SOLUTION: In the case of decontamination by installing an insertion hose 15 for decontamination in a reactor recirculation pipe (a), a decontamination stage (d) is fixed by welding at the inlet/outlet of a recirculation pump (c), an insertion guide 13 is fixed to the stage and the insertion hose 15 installed by a spray nozzle 14 at the tip end along the guide is inserted into the range of decontaminating object in the pipe (a). A temporary hose 11 is connected to the insertion hose 15, which is connected to a chemical decontamination device 26. Also by doubly connecting from the locking point, a decontamination system is constituted, and the tip end of the insertion hose 15 is used as inlet and outlet of decontamination liquid to raise the efficiency of stirring and circulating the decontamination liquid so as to obtain good decontamination effect. The material of the insertion hose 15 is excellent chemical- resistant polyethylene and stainless steel wire is wound around so as to be self-supporting after inserting in the pipe (a).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a system decontamination of system pipes, pumps, valves, equipment, etc. installed in a nuclear power plant, and applies a chemical decontamination method to these decontamination objects. The present invention relates to a chemical decontamination method for equipment in a nuclear power plant.

[0002]

2. Description of the Related Art When chemical decontamination of equipment in a nuclear power plant, for example, a reactor recirculation (PLR) system pipe, the radiation exposure of workers is mainly reduced in accordance with improvement of the pipe or replacement work. It is applied to the reactor recirculation (PLR) system for the purpose. Therefore, when selecting the decontamination range of the decontamination target to be chemically decontaminated, it is largely dependent on improvement of the reactor recirculation system piping and the like and replacement work.

FIG. 14 shows a decontamination solution of a chemical decontamination apparatus in a case where chemical decontamination is performed on an object to be decontaminated, such as piping, valves, and pumps of a nuclear reactor recirculation system, among facilities in a nuclear power plant. It is an apparatus for circulating and a piping system diagram.

A general chemical decontamination apparatus is mainly composed of a chemical injection device 1, a circulating pump device 2, an electric heater device (heat exchanger) 3, an ultraviolet irradiation device 4, a decontamination solution capacity adjusting tank (surge). Tank) 5, a local exhaust device (demister) 6 including a mist separator, a hepa filter, and a blower, an ion exchange resin tower 7, and an auxiliary pump device 8. These devices are hereinafter referred to in the present specification. As a collective name, it will be referred to as a chemical decontamination device.

Next, a chemical decontamination method using the conventional chemical decontamination apparatus will be described. Reactor pressure vessel n (not shown) installed in dry well (D / W) in reactor containment vessel r
After cutting a part of the reactor recirculation pipe (a), the upper pipe part, and the residual heat removal pipe (b) of the reactor recirculation system (PLR), which are connection parts to other systems, to the many existing pipe cutting sections 9 Closing plate 10 with flange nozzle for chemical decontamination device 26
And a temporary hose 11 is connected to the connection closing plate to form a decontamination liquid circulation loop with the chemical decontamination device 26. A chemical decontamination agent is injected into the decontamination liquid circulation loop from the chemical liquid injection device 1, and chemical decontamination is performed collectively on the reactor recirculation system piping a, valves, pumps, and the like.

[0006]

In the conventional chemical decontamination method, when a decontamination liquid circulation loop is formed between the object to be decontaminated and the chemical decontamination apparatus, a large-diameter pipe or the like of existing equipment is cut off.
In addition, remodeling work such as welding work of the closing plate 10 for chemical decontamination was involved. These operations increase the radiation exposure of construction workers and increase the workload and time required for the work. Naturally, the reduction of the radiation exposure reduction effect in the entire construction including the remodeling and improvement work of existing facilities is reduced. There is a problem that causes the extension of the construction process.

[0007] When the number of decontamination objects is large and the area of the decontamination objects is large, the joints where the chemical decontamination devices are installed are concentrated in one place within the decontamination range. There are cases. However, in this case, for the decontamination target range in a place away from the joint, the decontamination liquid does not spread, or the stirring and exchange efficiency of the decontamination liquid deteriorates,
There is a problem that a sufficient decontamination effect cannot be obtained.

[0008] Further, when a system such as equipment, tanks and piping in a nuclear power plant is to be decontaminated, and a valve provided in the system is an interlocking part with a chemical decontamination device, It is necessary to prevent the decontamination solution from flowing into the one system that is not the decontamination target area from the joint. However,
In this case, there is a problem that only a necessary decontamination range cannot be isolated as a decontamination system.

[0009] For example, when a part of a system in a nuclear power plant filled with a coolant (water) having a high dose rate is chemically decontaminated, the coolant (water) of the entire system is completely used. The method of performing chemical decontamination by draining and attaching only the decontamination area by cutting and remodeling and attaching the decontamination solution circulation loop pipe was applied, but it took more time for all drainage, and the dose of circulating radiation There are issues such as an increase in the rate.

In addition, the decontamination liquid level in the chemical decontamination apparatus is higher than the decontamination liquid level within the decontamination range in the decontamination target equipment, and decontamination to another system branched from the decontamination target. In the case where it is impossible to implement a liquid outflow prevention measure, there is a problem that it is difficult to perform chemical decontamination while circulating the decontamination solution in a well-balanced manner while limiting only the decontamination target range.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to remodel a large-scale existing facility for a decontamination target of a facility in a nuclear power plant, for example, a system pipe, a valve, a pump, a device, and the like. Without the existing flange seat, system piping, drain, vent pipes and other small-diameter pipes, make arrangements with the chemical decontamination equipment to form a decontamination liquid circulation loop,
It is an object of the present invention to provide a chemical decontamination method for a facility in a nuclear power plant, which can reduce a radiation exposure dose in a chemical decontamination preparation operation and shorten the operation time by the circulation loop of the decontamination liquid. Another object of the present invention is to provide a chemical decontamination method for equipment in a nuclear power plant, which can appropriately perform isolation of a decontamination range, circulation of a decontamination solution, and agitation operation to obtain a good decontamination effect.

[0012]

According to the first aspect of the present invention, a decontamination solution from a chemical decontamination device is circulated to a decontamination object of a facility in a nuclear power plant, and the decontamination object is chemically decontaminated. In the chemical decontamination method of a facility in a nuclear power plant equipped with a circulation loop of the dyeing liquor, an existing flange is used as a decontamination seat or a decontamination seat is attached near the decontamination object, and these decontamination seats are attached. It is characterized in that an attachment portion for engaging with the chemical decontamination device is provided, and the decontamination liquid is circulated through the object to be decontaminated.

According to the first aspect of the present invention, in the connection between the decontamination target of the facility in the nuclear power plant and the chemical decontamination device, the decontamination target can be removed without extensive cutting / welding remodeling work on the decontamination target. Perform a decontamination solution circulation loop between the chemical decontamination equipment and the decontamination seat, instrumentation piping, drain piping, or valve that is within the range or connected to the decontamination target. be able to.

According to a second aspect of the present invention, a hose insertion guide is connected to the connecting portion, and a decontamination insertion hose previously connected to the chemical decontamination apparatus is connected via the hose insertion guide.
It is characterized in that it is inserted into the object to be decontaminated.

According to the second aspect of the present invention, the connection with the chemical decontamination apparatus is performed from the connecting portion of the first aspect. In the decontamination area far from the joint, the efficiency of stirring and replacing the decontamination solution is poor,
A sufficient decontamination effect cannot be obtained. The means to improve this is
A hose insertion guide is connected to the joint according to claim 1, and a decontamination insertion hose connected to the chemical decontamination apparatus is inserted into the object to be decontaminated via the hose insertion guide, near an end of an arbitrary decontamination range. And a decontamination liquid circulation loop capable of inflow / outflow of the decontamination liquid can provide a sufficient decontamination effect.

According to a third aspect of the present invention, a decontamination liquid jet nozzle is connected to the joining portion, and the decontamination liquid is jetted from the nozzle to the decontamination object to chemically decontaminate the decontamination object. It is characterized by doing.

According to the third aspect of the present invention, the hose insertion guide and the decontamination insertion hose are used in a situation where it is difficult to apply the decontamination insertion hose in addition to the decontamination target in the state of the second aspect. The decontamination is performed without connecting the decontamination hose to the end of any decontamination range by connecting the jet injection nozzle connected to the chemical decontamination device with a temporary hose to the joint of claim 1 A sufficient decontamination effect can be obtained by forming a decontamination liquid circulation loop capable of stirring and replacing the decontamination liquid within the range.

According to a fourth aspect of the present invention, there is provided an existing valve provided near the object to be decontaminated with an attachment portion for engaging with the chemical decontamination apparatus, opening a valve cover of the valve and removing a valve body. It is characterized in that a fitting jig provided with a system isolation mechanism adapted to a box shape is inserted.

According to the invention of claim 4, when the system-constituting valves at both ends of the arbitrary decontamination range of the facility in the nuclear power plant to be decontaminated are to be joined with the chemical decontamination device, the valve is formed in a valve box shape. A circulation loop is configured by using a coupling jig equipped with a combined system isolation mechanism, and a chemical decontamination can be performed by isolating the decontamination area without causing the decontamination solution to flow out to another system. .

According to a fifth aspect of the present invention, there is provided an assembly in which the valve cover is opened and the valve body is removed at the connection portion with the valve, and a system isolation mechanism and a hose insertion guide mechanism adapted to the shape of the valve box are provided. The jig is used to insert the decontamination insertion hose into the decontamination object.

According to the invention of claim 5, when only the system-constituting valve at one of both ends of the arbitrary decontamination range of the facility in the nuclear power plant to be decontaminated can be connected to the chemical decontamination apparatus, The decontamination system can be isolated by closing the system-constituting valve on the other side of the decontamination jig and the decontamination system according to the invention of claim 4, but the decontamination is far away from the chemical decontamination device connection valve. For parts, the efficiency of agitation and exchange of the decontamination solution is poor,
A sufficient decontamination effect cannot be obtained.

For this reason, an attachment jig having a system isolation mechanism adapted to the shape of the valve box is provided with a decontamination hose insertion guide function similar to that of the second aspect, so that an arbitrary decontamination range can be extended to the vicinity of the end. A sufficient decontamination effect can be obtained by arranging a decontamination hose, forming a decontamination liquid circulation loop capable of inflow / outflow of the decontamination liquid, and performing chemical decontamination.

According to a sixth aspect of the present invention, there is provided a joint unit in which a valve cover is opened and a valve body is removed at a joint portion with the valve, and a system isolation mechanism and an injection nozzle mechanism adapted to a valve box shape are provided. It is characterized by using a tool.

According to the invention of claim 6, similarly to the above, only one of the system constituent valves can be connected to the chemical decontamination device, and the liquid circulation within the decontamination range can be performed by the method of claim 5. If this cannot be done accurately, use a jig with a system isolation mechanism and injection nozzle mechanism that matches the shape of the valve box, and configure a circulation loop with chemical decontamination equipment and hoses to perform chemical decontamination. Accordingly, a sufficient decontamination effect equivalent to the method of inserting the decontamination insertion hose into the decontamination object can be obtained.

A seventh aspect of the present invention is characterized in that a closing plug is attached to the decontamination insertion hose to limit a decontamination range of the object to be decontaminated. According to the invention of claim 7, decontamination is performed on valves, decontamination seats, strainer removal parts, nozzles in equipment and the like in the system configuration within an arbitrary decontamination range of the facilities in the nuclear power plant to be decontaminated. A closing plug provided with a hose for circulating the liquid and having improved ease of handling is attached to the opening. This forms a decontamination liquid circulation loop,
Chemical decontamination can be performed by isolating only the decontamination area without causing the decontamination solution to flow out to other systems.

The invention according to claim 8 is a system wherein the level of the decontamination liquid within the decontamination range of the object to be decontaminated is lower than the level of the decontamination liquid in the chemical decontamination apparatus, and the systems are open to each other. The decontamination solution is circulated and the decontamination solution is circulated by limiting the decontamination range of the object to be decontaminated by providing the decontamination solution circulation and liquid level monitoring control functions.

When the level of the decontamination liquid in the decontamination apparatus is higher than the level of the decontamination liquid in the decontamination range and the elevations are different when each is opened to the atmosphere, the decontamination liquid is properly circulated. It is difficult.

According to the invention of claim 8, as means to be solved, a capacitance type water level meter for monitoring the level of the decontamination liquid in the object to be decontaminated, an MO valve linked to the water level meter, decontamination when power is lost A chemical decontamination solution circulation loop equipped with an electromagnetic valve and the like to prevent liquid backflow ensures that even if decontamination in the decontamination system is impossible, outflow of decontamination solution to other systems is reliably prevented and removed. Chemical decontamination can be performed by limiting only the dyeing target range.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a chemical decontamination method for equipment in a nuclear power plant according to the present invention will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1 (a) is for explaining the first embodiment of the present invention, and schematically shows a plurality of joints in which an object to be decontaminated is a reactor recirculation system of a nuclear power plant. FIG. 1B is a layout view of the connecting portion shown, and FIG. 1B shows the connecting portion in FIG. In FIG. 1, an existing decontamination seat d provided near a reactor recirculation pump c to be decontaminated and a reactor recirculation pipe are provided at an interface with the chemical decontamination apparatus 26 shown in FIG. A small-diameter pipe such as a drain line e, a recirculation pump inlet / outlet vent line f and a recirculation pump inlet / outlet drain line g is used as a main line for decontamination liquid injection and discharge, and a temporary hose 11 having a temporary flange 12 is connected thereto. Perform chemical decontamination work. This temporary hose 11 is connected to a chemical decontamination device 26 as shown in FIG.

According to this embodiment, it is possible to reduce the cutting work and the welding work of the fitting closing plate 10 shown in FIG. Further, as another connection part, the pipes, pumps and valves of the recirculation system are also injected by injecting and discharging the decontamination liquid from the pipes of the recirculation pump inlet / outlet valve vent line f and the recirculation pump inlet / outlet drain line g. Chemical decontamination can be performed collectively.

FIG. 2 is a diagram showing a decontamination system in the first embodiment in the case where the area to be decontaminated is defined by the hatched recirculation pipe header h. The purpose of this construction is to chemically remove radioactive products in the recirculation pipe in advance as a measure to reduce the radiation exposure in the replacement of the discharge pipe section a of the reactor recirculation system.

In FIG. 2, the configuration of the circulation loop in the decontamination target area of the hatched portion provided to the reactor recirculation pipe a is the difference between the vertical section of the external riser pipe i above the recirculation pipe header h. The riser instrumentation pipe j having a small diameter for pressure measurement is cut, and the cut portion is welded to the joint d with the chemical decontamination device 26 and the temporary flange 12 to serve as an inlet for the decontamination liquid. The outlet of the decontamination solution uses all the joints shown in FIG. 1 shown above, and a circulation loop with the chemical decontamination device 26 is connected to the temporary hose 11.
Connect with.

As a result, the decontamination liquid can be circulated to both systems of the reactor recirculation pipe a having two AB systems.
In addition, the recirculation pipe a 'on the inlet side where chemical decontamination is not performed shown on the left side in FIG. 2 is closed by a recirculation pump inlet valve, and a replenishment water pump (MUWP) water sealing operation of pouring pure water into the inlet pipe. In addition, it is possible to prevent the decontamination agent from diffusing due to a valve sheet leak.

FIG. 3 illustrates a second embodiment according to the present invention, in which a decontamination insertion hose 15 is inserted into a reactor recirculation pipe a for chemical decontamination. Is shown. That is, in FIG. 3, a decontamination seat d is attached to the entrance of the recirculation pump c by welding, an insertion guide 13 is attached to the decontamination seat d, and a spray nozzle made of polyethylene is attached to the distal end along the insertion guide 13. A decontamination insertion hose 15 of an arbitrary length equipped with 14 is inserted into the decontamination area to be decontaminated in the reactor recirculation pipe a.

The decontamination insertion hose 15 attached to the decontamination seat d via the insertion guide 13 is attached, the temporary hose 11 is connected to the decontamination insertion hose 15, and the temporary hose 11 is connected to the chemical decontamination device 26. Connect to Further, a decontamination system is constructed by combining and connecting the connection parts described in FIG. 2, and the tip of the decontamination insertion hose 15 is used as an inlet or an outlet for the decontamination liquid, and the decontamination liquid within the decontamination range is used. A good decontamination effect can be obtained by increasing the agitation and circulation efficiency. In addition, v in FIG. 3 has shown the decontamination liquid water level in the reactor recirculation piping a.

FIG. 4A is an enlarged view of the spray nozzle 14, the decontamination insertion hose 15 and the decontamination seat d in FIG. 3, and FIGS. 4B and 4C are enlarged views of the insertion guide 13. Is shown. The material of the decontamination insertion hose 15 is a polyethylene material having excellent chemical resistance. After the decontamination insertion hose 15 is inserted into the reactor recirculation pipe a, the decontamination insertion hose 15 is inserted in a vertical portion of the pipe. Stainless steel wire 15 to be free standing
a is wound around the outer surface of the insertion hose 15 for decontamination.

Also, a screw is attached to the tip of the insertion hose 15 for decontamination.
The spray nozzle 14 attached at 14a is formed of a polyethylene material in order to ensure soundness within the decontamination target range, and is passed and inserted by a valve or the like in the middle of the insertion path within the decontamination target range. It has a spindle-like sharp shape in order to improve the performance. Lower end flange 15b for insertion hose 15 for decontamination
And the lower end flange portion 15b is connected to the decontamination seat d.

Further, the insertion guide 13 shown in FIGS. 4 (b) and 4 (c) is made of stainless steel, and has a flange portion 13a for engaging with the decontamination seat d for the reactor recirculation system and a lower end flange of the insertion hose 15 for decontamination. In addition to a flange 13b for connecting to the portion 15b, a joint 13c for measuring the level of the decontamination liquid in the reactor recirculation pipe (in the decontamination target) is also provided.

FIG. 5 (a) is for explaining the third embodiment of the present invention. When the object to be decontaminated is a reactor recirculation pipe a, the reactor recirculation pipe a Within decontamination target
17 shows an example in which a jet injection nozzle 16 for jetting a decontamination liquid to decontaminate the pipe 17 is provided with the pipe a. FIG.
(B) is an enlarged view of (a) in which the jet injection nozzle 16 is attached to the pipe a. The jet injection nozzle 16 is connected to the chemical decontamination device 26 by the temporary hose 11.

In this case, as shown in FIG. 5 (b), after the connection with the chemical decontamination device 26 is modified into a flange connection (capped in some power plants), the jet injection nozzle 16 Is attached to the center of the decontamination target 17, connected to the chemical decontamination device 26, and the decontamination liquid is jetted from the jet injection nozzle 16 to perform chemical decontamination.

According to the present embodiment, since the connection with the chemical decontamination device 26 in the decontamination range 17 is close,
In the case where a sufficient decontamination effect cannot be obtained, or even when the decontamination insertion hose 15 shown in FIG. 4 is applied, a U-turn event of the decontamination insertion hose 15 within the decontamination range 17 may occur. In some cases, the decontamination solution can be stirred and circulated to the vicinity of the end of the decontamination range, and a sufficient decontamination effect can be obtained.

FIG. 6 (a) shows a fourth embodiment of the present invention, in which a valve of a reactor residual heat (remaining heat) removal system (RHR) is provided with a valve fitting jig having a system isolation mechanism. It describes a chemical decontamination method for decontaminating strains. FIG.
(A) shows a line configuration centering on a heat exchanger k of a residual heat removal system in a nuclear power plant.

The case of chemically decontaminating the RHR heat exchanger k and its surrounding pipes as an object of decontamination will be described as an example. The existing first and second valves 1 and 2 at both ends of an arbitrary decontamination range will be described. The valve lid of the valve m is removed and opened, and a valve fitting jig having a system isolation mechanism adapted to various valve box shapes is attached to the valve box, and this valve fitting jig is connected to the chemical decontamination device 26. Decontamination within the target decontamination range. The decontamination liquid within the decontamination area is circulated using the valve fitting jig as an inlet and an outlet for the decontamination liquid.

FIG. 6B shows a partition plate w in a valve box u as an example of a valve fitting jig after removing a valve lid and a valve body in the first and second valves 1 and 2 of the RHR system. Is attached, the insertion hose 15 for decontamination is inserted into the opposite side of the partition plate w, and a decontamination system for isolating the system is shown.

According to the present embodiment, the inside of the decontamination area is isolated by providing the RHR valve with the valve joining jig,
Chemical decontamination can be performed by preventing the decontamination solution from flowing into another system from the R valve.

FIG. 7 (a) shows a case where RH is used in FIG. 6 (a).
A structural diagram of a globe valve s and a globe valve s for connecting a chemical decontamination device 26 to the globe valve using a globe valve for the R valve is shown. FIGS. 7 (b) and 7 (c) are structural views in which the check valve connecting jig 19 is attached to the check valve t.

Each of the connecting jigs 18 and 19 has a closing plate 20 which matches with the valve seat.
To isolate the system. The joining jig lids 18a and 19a adapted to the shape of the valve bonnet are provided with an joining nozzle 22 for chemical decontamination and a decontamination system water drain and vent nozzle 23. Incidentally, reference numeral 22a denotes a connection nozzle flange.

FIG. 8 shows a fifth embodiment of the present invention, in which the valve cover of the check valve t is removed, the fitting jig cover 19a is attached, and the system isolation and decontamination inserts are adjusted to the shape of the valve box. 3 shows the structure of a check valve coupling jig 19 to which a hose 15 is inserted. An insertion guide 13 is attached to the connection jig cover 19a of the check valve connection jig 19, and a decontamination insertion hose 15 is inserted from the insertion guide 13 along the insertion guide 13 to the vicinity of the end of an arbitrary decontamination range. Insert up to.

Insertion hose for decontamination attached to decontamination seat d
15 and the chemical decontamination device 26 are connected by the temporary hose 11, the decontamination liquid is jetted from the end of the insertion hose 15 for decontamination into the decontamination range, and the decontamination connected to the valve fitting jig lid 19a. The decontamination liquid is discharged from a drain pipe attached to the decontamination object or the like provided near the system water drainage nozzle 23 and the check valve t to stir and circulate the decontamination liquid within the decontamination range. .

According to this embodiment, only the system-constituting valve at one end of the arbitrary decontamination range can be connected to the chemical decontamination device (can be opened), and the other device connection part is close to one place. However, even when it is not possible to circulate the decontamination solution in the entire decontamination range, the decontamination solution can be efficiently stirred,
A sufficient decontamination effect can be obtained. FIG. 9 is a view showing a structure of a valve fitting jig according to a sixth embodiment of the present invention, in which a system isolation and injection nozzle mechanism combined with a valve box shape is combined.

In the present embodiment, the decontamination insertion hose 15 is not suitable for the object to be decontaminated under the same conditions for decontamination as in the fifth embodiment. When the insertion hose 15 for decontamination is large enough to make a U-turn inside the decontamination object, a check jig for a check valve having a system isolation mechanism and a jet injection nozzle 16 according to the shape of the valve box u 19
And the chemical decontamination device 26.

The jet injection nozzle 16 is connected to the distal end of the insertion guide 13, injects decontamination liquid from the jet injection nozzle 16, and drains the decontamination system water connected to the connection jig lid 19a. The decontamination liquid is discharged from a drain pipe attached to the decontamination object and the like provided near the nozzle 23 and the check valve t to stir and circulate the decontamination liquid within the decontamination range.

According to the present embodiment, the decontamination solution within the decontamination range can be efficiently stirred and circulated, and the decontamination effect equivalent to the method of inserting the decontamination insertion hose into the decontamination range. Can be obtained.

FIG. 10 shows a seventh embodiment of the present invention. That is, in FIG. 10, an L-shaped pipe 25 having a closing plug 24 attached to the distal end thereof is inserted into a valve box u, and the temporary hose 11 is connected to a flange 25a of the pipe 25. The temporary hose 11 is connected to a chemical decontamination device 26.
A vent pipe 25b and a compressed air intake / exhaust pipe 25c are connected to the pipe 25.

In an object to be decontaminated in a facility in a nuclear power plant, valves, decontamination seats provided at both ends of the decontamination object range,
A closed plug (air tight plug) 24 made of cylindrical hollow rubber is inserted into the opening of the strainer removal section, nozzle inside the equipment, etc., and compressed air (up to 5 kg / cm ² ) is supplied from the compressed air intake / exhaust port 25. .

The closing plug 24 is formed of a cylindrical hollow body made of a chemical resistant silicone rubber. Therefore, when the compressed air is supplied, the closing plug 24 expands and can seal the existing pipe without damaging it. The inflow and outflow of the chemical decontamination liquid is performed from a pipe portion 25a passing through the center of the hollow body connected to the chemical decontamination apparatus, and the decontamination liquid is circulated from the joints at both ends in the decontamination range.

According to the present embodiment, the various openings to be decontaminated can be easily connected to the chemical decontamination apparatus.
Chemical decontamination can be performed by isolating only the decontamination area without causing the decontamination solution to flow out to other systems.

FIG. 11 shows a method of performing chemical decontamination using the closing plug 24 shown in the sixth embodiment in which a decontamination liquid is circulated in order to explain a seventh embodiment of the present invention. ing. When decontaminating the entire recirculation pipe connected to the reactor pressure vessel n (including the jet pump riser pipe in the reactor), the recirculation pipe inlet nozzle o in the reactor pressure vessel n and the jet pump infrent mixer are used. After the removal, the closing plug 24 shown in FIG. 10 is attached to each of the openings p and connected to the chemical decontamination device 26 installed on the operating floor 36 to circulate the decontamination liquid.

In addition, depending on the installation location conditions of the chemical decontamination apparatus, the chemical decontamination apparatus is installed on a lower floor in the reactor building,
The connection with the chemical decontamination apparatus is performed using the decontamination seat d shown in FIG. 1 below the recirculation pipe. In this case, the recirculation pipe inlet nozzle o in the reactor pressure vessel n and the opening p after removing the jet pump inflation mixer are directly connected by a closing plug jig.

According to the present embodiment, the coolant (water) in the reactor pressure vessel n having a high dose rate is completely drained, and recirculation is performed without cutting or modifying the recirculation pipe as a connection. The entire pipe (including the jet pump inside the reactor) can be isolated, and chemical decontamination can be performed, so that the drainage time of the reactor pressure vessel can be eliminated and measures can be taken to prevent an increase in the environmental radiation dose rate.

FIG. 12 is a layout diagram for explaining the eighth embodiment of the present invention when chemical decontamination is performed by opening two places having different elevations to the atmosphere. In this construction, as a measure to reduce radiation exposure when inspecting the reactor recirculation pump outlet valve, chemical decontamination of the reactor recirculation pump and inlet / outlet valve before inspection can be performed to reduce the environmental dose rate.

Therefore, the decontamination range of the reactor recirculation pipe
27 is sufficient that the valve / pump is submerged in the chemical decontamination solution, and the shaded area in the figure is the decontamination range. Chemical decontamination equipment 26
Will be installed on the first floor of the reactor building due to the vacant area in the power plant, and will inevitably be higher than the highest liquid level in the decontamination area 27. In such a case, a booster pump 28 for pushing up the decontamination liquid in the pipe to the chemical decontamination device 26 is installed near a decontamination seat d (not shown) provided below the reactor recirculation pipe a. did.

FIG. 13 shows a decontamination system flow for explaining the decontamination liquid level control method in the eighth embodiment described in FIG. A hose insertion guide 13 is attached to one of the decontamination seats d of the flange type attached to the reactor recirculation pipe a, and an insertion hose 15 for decontamination is inserted into the recirculation pipe a along the insertion guide 13, and a vertical pipe is inserted. The decontamination insertion hose 15 is started up to an arbitrary range inside.

Thereafter, the decontamination insertion hose 15, the booster pump 28, the solenoid valve 32, the MO valve 31, the chemical injection device 1 of the chemical decontamination device, the ultraviolet irradiation device 4, the decontamination solution capacity adjusting tank 5, the circulation pump device 2, an electric heater 3, a first flow control valve 34, a temporary hose 11, an MO valve 31, and a solenoid valve 32 are connected in sequence, and finally connected to the other decontamination seat d to form a circulation system. The line configuration is such that the decontamination liquid also flows to the small-diameter line of the recirculation pump inlet / outlet drain line g.

Next, the chemical decontamination system configuration and the decontamination liquid level control method will be specifically described. Pure water is poured from the chemical injector 1 into the decontamination system, and the booster pump is constructed by a valve configuration in which the ultraviolet irradiation device 4, the cartridge filter 29 for collecting undissolved clad, and the ion exchange resin tower 7 are bypassed.
28 and the circulation pump device 2 are started. At this time, the operation is performed without bypassing to the decontamination liquid volume adjustment tank 5, and the decontamination liquid level in the pipe a of the reactor recirculation system and the liquid level in the decontamination liquid volume adjustment tank 5 are booster pumps. The balance is adjusted by adjusting the flow rates of the circulation pump device 2 and 28.

The balance is implemented by adjusting the opening of a first flow control valve 34 provided on the outlet side of the circulation pump device 2. When the balance of the main circulation flow rate of the decontamination system is stabilized, the electric heater device 3 is activated, the temperature is raised to a predetermined liquid temperature, and chemical injection is started from the chemical liquid injector 1 into the decontamination system to start chemical decontamination. It is the beginning of dyeing.

During the chemical decontamination, according to the steps of the chemical decontamination method, the ion exchange resin tower 7
The operation valves of the decontamination system are moved, for example, by performing in-serving of the ion exchange resin in the reactor, the flow rate balance is lost, the decontamination liquid level in the reactor recirculation pipe a rises, and the branch of the residual heat removal system pipe b The decontamination solution may flow out to the line.

Therefore, the level of the decontamination liquid level is as shown in FIG.
The first and second flow control valves 34 and 35 are monitored while monitoring the liquid level by a water level meter 30 for taking out and measuring the decontamination liquid from a nozzle having a flange portion 13a branched from the hose insertion guide 13 shown in FIG. Operate to control the liquid level. If this control does not prevent the decontamination solution from flowing out,
The MO valve 31 having a function interlocked with the water level gauge 30 is closed at an arbitrary set value, and the inflow of the decontamination solution can be stopped.

Further, as a safety measure, in consideration of the case where the power supply to the booster pump 28, the recirculation pump device 2 and the like is cut off or stopped, and the decontamination liquid flows into the recirculation pipe side which is low in layout, An electromagnetic valve 32 having a function of closing when power is lost is installed at a low position in the circulation line of the decontamination system.

Finally, after the decontamination is completed, the decontamination system water is extracted by the drain pump 33 with the drain line g of the recirculation pump as the main line, and the insoluble matter is removed by the cartridge filter 29. Release to the existing drain funnel q in the drainage system.

According to this embodiment, the level of the decontamination liquid in the chemical decontamination apparatus 26 is higher than the level of the decontamination liquid in the decontamination range, and even when the elevation is different when each is opened to the atmosphere. In addition, it is possible to reliably prevent the decontamination solution from flowing out to another system, and to appropriately perform the decontamination solution circulation processing.

[0072]

According to the present invention, the following effects can be obtained. (1) Chemical decontamination of facilities in nuclear power plants, which could not be performed unless existing facilities such as large-diameter pipes were cut or otherwise modified before decontamination, can now be performed with minimal modification Thus, a significant reduction in work load can be achieved. (2) Reduce the exposure of construction workers during decontamination preparation work;
In addition to shortening the period for remodeling the entire equipment, economic benefits can be achieved.

(3) The chemical decontamination liquid can be isolated only within the decontamination target area, and the decontamination liquid can reliably and safely be prevented from flowing out to other systems that are not decontamination targets, and good decontamination can be achieved. Work results can be obtained. (4) A good decontamination effect can be obtained for a decontamination site where circulation of the decontamination solution was not possible.

[Brief description of the drawings]

FIG. 1 (a) is a layout view of a joint with a chemical decontamination apparatus in a first embodiment of a chemical decontamination method for equipment in a nuclear power plant according to the present invention, and FIG. The side view which shows the connection state of a fitting part.

FIG. 2A is a piping diagram showing a state in which an instrumentation line, a decontamination seat and the like according to a second embodiment of the present invention are incorporated, and FIG. 2B is an enlarged view of a portion A in FIG. FIG.

FIG. 3 is a perspective view showing a state in which an insertion hose for decontamination is attached to a reactor recirculation pipe in FIGS. 1 (a) and 2 (a).

4 (a) is an external view partially showing the insertion hose for decontamination in FIG. 3; FIG. 4 (b) is an external view showing an insertion guide for engaging with the insertion hose for decontamination; FIG. 2 is an external view of the insertion guide in FIG.

FIG. 5A is an external view showing a state in which a jet nozzle for decontamination is inserted into a water level gauge seat according to the third embodiment of the present invention, and FIG. FIG. 2 is an external view showing a state of connection to a dyeing apparatus.

FIG. 6 (a) is a piping diagram showing an existing facility line to be decontaminated in a fourth embodiment of the present invention, and FIG. 6 (b) is a longitudinal sectional view showing first and second valves in FIG. .

FIG. 7 (a) is a diagram showing R in the fourth embodiment of the present invention.
FIG. 4B is a longitudinal sectional view showing a state in which a ball valve is used as an HR system valve and a metal alloy tool is attached to the ball valve, and FIG. Vertical sectional view showing, (c)
FIG. 4B is a longitudinal sectional view of FIG.

FIG. 8A shows a fifth embodiment of the present invention.
FIG. 4 is a longitudinal sectional view showing a state in which a valve fitting jig with a decontamination insertion hose mechanism is attached to a valve box, and FIG. 4B is a longitudinal sectional view of FIG.

FIG. 9A shows a sixth embodiment of the present invention.
FIG. 4B is a longitudinal sectional view showing a state in which a valve fitting jig with a decontamination spray nozzle mechanism is attached to a valve box, and FIG. 4B is a longitudinal sectional view of FIG.

FIG. 10 is a longitudinal sectional view partially showing a state in which a hollow body closing plug is mounted on a valve box in a seventh embodiment of the present invention.

FIG. 11 is a piping diagram for explaining a decontamination method using a plug for closing a hollow body in a seventh embodiment of the present invention.

FIG. 12 is a layout configuration diagram of a chemical decontamination apparatus according to an eighth embodiment of the present invention.

FIG. 13 is an apparatus and piping system diagram for explaining the chemical decontamination system in FIG.

FIG. 14 (a) is an apparatus and piping diagram for explaining a conventional chemical decontamination method for equipment in a nuclear power plant, and (b).
FIG. 3 is a vertical cross-sectional view showing a state in which a connection closing plate is welded to a riser instrumentation pipe in (a).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Chemical liquid injection device, 2 ... Circulation pump device, 3 ... Electric heater device, 4 ... Ultraviolet irradiation device, 5 ... Decontamination solution capacity adjustment tank, 6 ... Local exhaust device, 7 ... Ion exchange resin tower 8 ... Auxiliary pump , 9 ... existing pipe cutting part, 10 ... closing plate, 11 ...
Temporary hose, 12 ... Temporary flange, 13 ... Insertion guide, 14 ...
Spray nozzle, 15 ... Insertion hose for decontamination, 15a ... Stainless steel wire, 16 ... Jet injection nozzle, 17 ... In the object to be decontaminated, 18 ... Jig for globe valve, 19 ... Joint for check valve jig,
19a: lid of joining jig, 20: closing plate, 21: fastening bracket, 22
... Nozzle for connection, 23 ... Nozzle for draining and venting, 24 ...
Closing plug (air tight plug), 25 ... L-shaped pipe,
25a: Flange, 25b: Vent pipe, 25c: Compressed air intake / exhaust port, 26: Chemical decontamination device, 27: Decontamination range, 28: Booster pump, 29: Cartridge filter, 30: Water level gauge, 31
... MO valve, 32 ... solenoid valve, 33 ... drain pump, 34 ... first flow control valve, 35 ... second flow control valve, 36 ... operation floor, a ... reactor recirculation piping, b ... residual heat removal System piping, c: Reactor recirculation pump, d: decontamination seat, e: Reactor recirculation pipe drain line, f: Recirculation pump inlet / outlet vent line, g: Recirculation pump inlet / outlet drain line, h ...
Recirculation pipe header, i: external riser pipe, j: riser instrumentation pipe, k: residual heat removal system heat exchanger, l: first valve,
m: second valve, n: reactor pressure vessel, o: recirculation pipe inlet nozzle, p: jet pump riser pipe opening, q ...
Existing drain funnel, r: reactor containment vessel, s: globe valve, t: check valve, u: valve box, v: decontamination liquid surface, w: partition plate.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hitoshi Sakai 8 Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa Prefecture Inside the Toshiba Yokohama Office (72) Inventor Ichiro Inami 8 Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa Company Toshiba Yokohama Office

Claims (8)

[Claims] 1. A nuclear power plant having a decontamination solution circulation loop for circulating a decontamination solution from a chemical decontamination apparatus to an object to be decontaminated in a facility in a nuclear power plant to chemically decontaminate the decontamination object. In the chemical decontamination method of equipment, an existing flange is used as a decontamination seat or a decontamination seat is attached near the object to be decontaminated, and an attachment part for attaching the decontamination seat to the chemical decontamination device is provided on these decontamination seats. And circulating the decontamination solution to the decontamination object, a chemical decontamination method for equipment in a nuclear power plant. 2. A hose insertion guide is connected to the connection portion, and a decontamination insertion hose connected in advance to the chemical decontamination device is inserted into the decontamination object via the hose insertion guide. The method for chemical decontamination of equipment in a nuclear power plant according to claim 1, wherein: 3. A decontamination liquid jet nozzle is connected to the connection portion, and the decontamination liquid is jetted from the nozzle to the decontamination object to chemically decontaminate the decontamination object. The method for chemical decontamination of equipment in a nuclear power plant according to claim 1. 4. An existing valve is provided in the vicinity of the decontamination object with an attachment portion for engaging with the chemical decontamination apparatus, and the valve cover is opened and the valve body is removed to match the shape of the valve box. 2. The method for chemical decontamination of equipment in a nuclear power plant according to claim 1, wherein an attachment jig provided with a system isolation mechanism is inserted. 5. A connecting jig having a system isolation mechanism and a hose insertion guide mechanism adapted to a valve box shape by opening the valve lid and removing a valve body at a connection portion with the valve. 5. The method according to claim 4, wherein the insertion hose for decontamination is inserted into the object to be decontaminated. 6. A connecting jig having a system isolation mechanism and an injection nozzle mechanism adapted to a valve box shape by opening the valve lid and removing a valve body at a connection portion with the valve. The method for chemical decontamination of equipment in a nuclear power plant according to claim 4, characterized in that: 7. The chemical decontamination method of a nuclear power plant facility according to claim 1, wherein a closing plug is attached to the decontamination insertion hose to limit a decontamination range of the decontamination object. . 8. A system in which the level of the decontamination liquid within the decontamination range of the object to be decontaminated is lower than the level of the decontamination liquid in the chemical decontamination apparatus, and the systems are open to each other. The facility in a nuclear power plant according to claim 1 or 4, wherein a circulating solution and a liquid level monitoring control function are provided to limit only a decontamination range of the object to be decontaminated and circulate the decontamination solution. Chemical decontamination method.