JPH0679704B2 - Reactor system piping cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for cleaning a pipe of a nuclear reactor system installed in a nuclear power plant or the like, and particularly to a main steam pipe and a condensate water supply pipe. Related to the pipe cleaning method.

(Prior Art) A piping system of a reactor system connected to a reactor pressure vessel is generally configured as illustrated in FIG. That is, the steam generated in the reactor pressure vessel 1 passes through the main steam pipe 2 and is introduced into a steam turbine for driving a generator (not shown) to rotate the steam turbine, and then the condenser 3 disposed immediately below the steam turbine 3. It is condensed inside and becomes condensed water. Condensate condensed in the condenser 3 is transferred by the condensate system pump 4 and the condensate water supply pump 5 through the condensate water supply pipe 6.
It is returned to the reactor pressure vessel 1 again via the feed water heater 7. Therefore, the main steam system and the condensate water supply system piping form a circulation flow path around the reactor pressure vessel 1. Therefore, for both the main steam system and the condensate water supply system, the pipes are cleaned at the same time after the assembly is completed.

Then, when the cleaning operation is performed, a bypass is appropriately used for a device that is not preferable to pass the cleaning liquid with a device interposed in the circulation flow path, or a temporary bypass pipe is installed to bypass the device. , Forming a circulation channel. For example, around the steam turbine, a turbine bypass pipe 10 that branches from the primary side of the main steam stop valve 8 and reaches the condenser 3 directly via the turbine bypass valve 9 is used as a circulation passage for the cleaning liquid.

Further, equipment such as the condensate water supply pump 5 which is structurally difficult to clean forms a bypass by the bypass temporary pipe 12. On the other hand, the main steam pipe 2 around the reactor pressure vessel 1 and the condensate water supply pipe 6 are connected by a temporary piping 13 for communication without passing through the reactor pressure vessel 1. That is,
Main steam pipe 2 and condensate water supply pipe 6 are reactor pressure vessels 1.
The final spool pipe constituting the part to be connected with is temporarily connected with the pipe removed.

As described above, the main steam pipe 2 and the condensate water supply pipe 6 are connected by means such as forming a temporary bypass pipe to form a circulation flow path.

Next, the operation of cleaning the circulation channel will be specifically described.

First, after confirming by various pipe inspections that there are no defects such as leaks in the piping that constitutes the circulation flow path, the cleaning liquid prepared by the cleaning device 14 is transferred through the temporary water injection piping 15, and inside the circulation flow path. Inject.

Here, as shown in FIG. 3, the cleaning device 14 includes a chemical dissolution tank 17 for storing a cleaning chemical by dissolving it in pure water,
A pure storage tank 18 for storing pure water serving as a solvent for the drug,
A chemical injection pump 19 for injecting a chemical solution into pure water, a mixing heater 20 for uniformly mixing the chemical solution and pure water, and a cleaning liquid pump 21 for transferring a cleaning liquid prepared by uniform mixing.
Composed of and. The cleaning liquid passes through the temporary pipe 15 for water injection,
As shown in FIG. 2, it is injected into the circulation passage from the bonnet portion of the outlet check valve 16 arranged on the secondary side of the condensate system pump 4.

The injected cleaning liquid is circulated in the circulation flow path by the condensate system pump 4 to clean and remove the adhered substances such as scale and oil adhered to the inner wall of the pipe. After the cleaning operation is continued for a predetermined time, the used cleaning liquid remaining in the system when the system reaches the specified cleaning degree is the temporary pipe for discharge connected to the main steam stop valve 8.
It is discharged through 22 and is introduced into the processing device 23 as shown in FIG. The processing device 23 first uses the used cleaning liquid in the neutralization tank 24.
After the neutralization treatment at, the scale component and the like are precipitated and separated in the precipitation tank 25, and only clear water is discharged out of the system.

After the above cleaning work is completed, the bypass temporary pipe 12, the water injection temporary pipe 15, the discharge temporary pipe 22, and the communication temporary pipe 13 that constitute the circulation channel of the cleaning liquid are removed, and the reactor pressure vessel 1 and 4 final spool pipes of main steam pipe 2
After assembling the six final spool pipes of the condensate water supply pipe 6 and the respective attached pipe supports at regular positions and attaching them by welding and joining, the pressure resistance test of the reactor pressure vessel 1 to be carried out in the next inspection step is performed. Continue preparation work such as boundary composition.

(Problems to be Solved by the Invention) In the conventional pipe cleaning method, the main steam pipe and the condensate water supply pipe are connected to each other by a temporary pipe for communication before the final spool pipe is formed, Since the circulation passage was formed, the final spool pipe could not be attached until the circulation cleaning work was completed. The final spool pipe constitutes a connection part with the reactor pressure vessel of the main steam pipe and the condensate water supply pipe, and its installation must be completed before carrying out the pressure resistance test of the reactor pressure vessel. By the way, the final spool piping has four systems for main steam piping, while there are six systems for condensate water supply piping, and when the piping stand and support attached are included, the amount of work required from assembly to welding is enormous. Therefore, there was a tendency for the recovery period after the pipe cleaning work to be prolonged. Further, since the boundary is not formed unless the welding of the final spool pipe is completed, the pressure resistance test of the reactor pressure vessel cannot be performed. Therefore, there is a problem in that the lengthening of the recovery period lengthens the critical path for plant construction.

The present invention has been devised to solve the above problems, and a method for cleaning the piping of a reactor system that can shorten the construction period of the entire plant by shortening the recovery period after the pipe cleaning work. The purpose is to provide.

[Structure of Invention]

(Means for Solving the Problems) In the reactor system pipe cleaning method according to the present invention, the final spool pipe constituting the portion where the main steam pipe and the condensate feedwater pipe are combined with the reactor pressure vessel is pre-reacted with the reactor pressure. While connecting to the vessel, the opening of the main steam pipe joined to the reactor pressure vessel is connected so as to communicate with each other by a temporary pipe installed inside the reactor pressure vessel, and the relief safety valve base of the main steam pipe is connected. And the non-return valve of the condensate water supply pipe at the inlet of the reactor pressure vessel are connected by a temporary pipe to connect the main steam pipe and the condensate water supply pipe in an annular shape to form a circulation passage for the cleaning liquid, and then the cleaning liquid. Is injected into the circulation channel, and the cleaning liquid is circulated for a predetermined time.

(Operation) According to the pipe cleaning method of the above configuration, the final spool pipes of both the main steam pipe and the condensate water supply pipe that form the piping system around the reactor pressure vessel are joined in advance to the reactor pressure vessel, In this state, the main steam pipe and the condensate water supply pipe are connected by a temporary pipe to form an annular circulation flow path,
The recovery work after the completion of the predetermined circulation cleaning work is greatly simplified as compared with the conventional method. That is, assembling and welding of the final spool pipe is not required, the recovery work is completed by removing only a small number of temporary pipes, and it is easy to immediately shift to the pressure resistance test of the reactor pressure vessel.

Further, since the openings of the main steam pipes joined to the reactor pressure vessel are connected to each other by the temporary pipes arranged in the reactor pressure vessel so that they communicate with each other, the main cleaning liquid becomes a pair. The area to be cleaned can be expanded by circulating the steam in the final spool piping of the steam piping.

(Embodiment) Next, one embodiment of a method for cleaning a pipe of a reactor system according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a system diagram showing an example of a piping configuration for carrying out the method of the present invention. The same elements and parts as those in the conventional example shown in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

The pipe system to be cleaned by the method of the present invention is a main steam pipe final spool pipe 26 joined to the reactor pressure vessel 1,
Isolation valves 28 and 29 installed inside and outside the wall of the reactor containment vessel 27
, Main steam pipe 2, main steam stop valve 8, turbine bypass valve 9, condenser 3, condensate system pump 4, feed water heater 7, condensate feed water pump 5, condensate system check valve 31. It is an annular circulation flow path formed by. The condensate water supply system stop valve 32 provided at the inlet of the reactor pressure vessel 1 of the condensate water supply pipe 6 is closed.

After the secondary side of the condensate system check valve 31, the piping system up to the reactor pressure vessel was previously flushed and cleaned at the factory,
Exclude from cleaning by the on-site cleaning liquid.

In addition, a bypass is formed by the temporary pipe 12 for equipment such as the condensate water supply pump 5 that is difficult to clean among the circulation flow paths.

Further, in order to form the circulation flow path after the main steam pipe final spool pipe 26 and the condensate water supply pipe final spool pipe 33 are welded and joined to the reactor pressure vessel 1, the main steam pipe 2
The pipe base 34 of the steam relief safety valve and the bonnet part of the condensate system check valve 31 are connected by a temporary pipe 35.

Further, the openings of the main steam pipes joined to the reactor pressure vessel 1 are connected to each other so as to communicate with each other by temporary pipes 36 arranged in the reactor vessel.

In this way, after connecting the main steam system and the condensate water supply system in an annular shape to form a circulation flow path for cleaning, perform an airtight test etc. to confirm that there are no leak points in the piping system and proceed to cleaning work. .

The procedure of the cleaning work is as follows. First, the cleaning liquid prepared in the cleaning device 30 shown in FIG. 3 is transferred by the cleaning liquid pump 21, and is injected into the circulation flow path from the outlet check valve 16 to supply the cleaning liquid into the flow path. Fill up. The injected cleaning liquid is circulated in the circulation passage by the condensate system pump 4 to clean the inner surface of the pipe. The cleaning liquid used for circulation cleaning until a predetermined cleaning degree is discharged through the temporary discharge pipe 22 and neutralized and precipitated by the processing device 23 shown in FIG. Is discharged.

After completion of the cleaning work, temporary pipes for bypass 12, which formed a circulation flow passage for the cleaning liquid, temporary pipe for water injection 15, temporary pipe for discharge 22, temporary pipes 35, 36 around the reactor pressure vessel, etc. And attach the bonnet of the condensate check valve 31. Then, the recovery work is completed by mounting the blind plate 34 of the steam relief valve, and the pressure resistance test of the reactor pressure vessel can be carried out immediately.

That is, according to the method of the present invention, the final spool pipes of the main steam system and the condensate water supply system, which are required during the pressure resistance test of the reactor pressure vessel, are joined to the reactor pressure vessel in advance, and the cleaning work is performed in that state. Is carried out. And the recovery work after cleaning does not include the assembly and welding of the final spool pipe,
Since the restoration work is completed with only a small amount of work for removing the temporary piping, the pipe cleaning process including the restoration work is greatly shortened.

Further, since the opening of the main steam pipe joined to the reactor pressure vessel is connected to each pair by a temporary pipe, the cleaning liquid also flows into the final spool pipe of the main steam pipe. Therefore,
The piping region to be cleaned is expanded as compared with the conventional method, and the piping system with higher cleanliness can be obtained.

〔The invention's effect〕

According to the reactor system pipe cleaning method of the present invention, since the final spool pipe is joined to the reactor pressure vessel in advance and the cleaning work is performed in this state, the recovery work after the cleaning work is temporarily performed. Only the removal of piping. Therefore, as compared with the case where the final spool pipe is assembled and welded after removing the temporary pipe as in the conventional method, the recovery work process is greatly simplified, and the construction period of the nuclear power plant is greatly shortened.

In addition, since the opening of the main steam pipe joined to the reactor pressure vessel is connected to each pair by temporary pipe, the cleaning liquid also flows into the final spool pipe of the main steam pipe, expanding the pipe area to be cleaned. It

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a piping system for carrying out the pipe cleaning method according to the present invention, FIG. 2 is a system diagram showing a piping system for carrying out a conventional pipe cleaning method, and FIG. 3 is a cleaning system. FIG. 4 is a system diagram showing the configuration of the device, and FIG. 4 is a system diagram showing the treatment device of used cleaning water. 1 ... Reactor pressure vessel, 2 ... Main steam pipe, 3 ... Condenser, 4 ... Condensate system pump, 5 ... Condensate feed pump, 6 ...
… Condensed water supply piping, 7 …… Supply water heater, 8 …… Main steam stop valve, 9 …… Turbine bypass valve, 10 …… Turbine bypass piping, 12 …… Bypass temporary piping, 13 …… Communication temporary piping , 14 …… Cleaning device, 15 …… Temporary piping for water injection, 16 ……
Outlet check valve, 17 …… chemical dissolution tank, 18 …… pure water storage tank, 19 …… chemical injection pump, 20 …… mixing heater, 21
...... Cleaning liquid pump, 22 …… Temporary pipe for discharge, 23 …… Treatment device, 24 …… Neutralization tank, 25 …… Precipitation tank, 26 …… Main steam piping final spool piping, 27 …… Reactor containment vessel, 28,29 ……
Isolation valve, 30 ... Water heater, 31 ... Condensation system check valve, 32 ...
… Condensed water supply stop valve, 33 …… Condensed water supply piping Final spool piping, 34 …… Steam relief safety valve base, 35,36 …… Temporary piping.

Claims (1)

[Claims] 1. A main steam pipe and a condensate water supply pipe are joined to a reactor pressure vessel in advance while connecting a final spool pipe constituting a portion where the main steam pipe and the condensate water supply pipe are joined to the reactor pressure vessel, and an opening of the main steam pipe joined to the reactor pressure vessel. Parts are connected so that they can communicate with each other through temporary piping installed in the reactor pressure vessel, and the relief safety valve base of the main steam piping and the check valve of the condensate water supply piping at the inlet of the reactor pressure vessel are connected. After connecting the main steam pipe and the condensate water supply pipe in an annular shape by connecting with a temporary pipe to form a circulation channel of the cleaning liquid, the cleaning liquid is injected into the circulation channel, and the cleaning liquid is circulated for a predetermined time. A characteristic method for cleaning the piping of a reactor system.