JPS6224757B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] [Field of Industrial Application] The present invention relates to a method for hydraulic pressure testing and cleaning of main steam system and water supply system piping in the construction of a nuclear power plant.

(Prior Art) Hereinafter, a conventional piping hydraulic pressure test and cleaning method for the reactor main steam system and water supply system piping will be described with reference to FIGS. 1 and 2.

In FIG. 1, a shield wall 13 is arranged around the reactor containment vessel 9. As shown in FIG. A reactor pressure vessel 8 is housed in this reactor containment vessel 9, and this reactor pressure vessel 8 is a reactor pressure vessel pedestal (hereinafter abbreviated as RPV pedestal) 1.
Supported by 2. The main steam generated in the reactor pressure vessel 9 is guided from the main steam system pipes 1 and 14 to a turbine (not shown) via a main steam isolation valve 4 and a third main steam isolation valve 5. The main steam led to the turbine is condensed in a condenser (not shown) and becomes condensed water. This condensate is transferred to water supply system piping 1
5, 2, and is led into the reactor pressure vessel 8 via the water supply system isolation valve 3. Then, the condensate is pressurized from the recirculation system piping 10 via the recirculation system pump 11, flows from the bottom to the top inside the reactor pressure vessel 8, becomes main steam again, and is converted into the main steam system piping 1. It is designed to be guided by. Here, referring to FIG. 2, a conventional hydraulic pressure test method using blind caps for main steam system piping and water supply system piping will be described.

In Fig. 2, according to the conventional construction method, the construction of the main steam system piping 1, 14 and the water supply system piping 2, 15 progresses, and when the area near the nozzle of the reactor pressure vessel 8 is completed, it will be possible to withstand the specified pressure. Attach the prepared blind cap 6. Quantity: 1 to 4 main steam system piping
ke, 6 blind caps 6 for water supply system piping 2, total 10 caps 6
Install. The water supply system piping 2 can be tested for water pressure at this point, but the main steam system piping 14 can be tested for water pressure after a special jig 17 is installed to stop the isolation valve 4. After these preparations are completed, a hydraulic test will be carried out. Two water pressure tests, the welding inspection pressure test and the pre-use pressure test, will be witnessed by government agencies, and the main steam system and water supply system will be witnessed four times.
In preparation for this, water pressure tests are conducted at least twice each in-house and at the customer's site, so eight hydraulic pressure tests are conducted on just these two systems (main steam system and water supply system). Each time this water pressure test is conducted, the temperature of the piping must be raised to the specified temperature in order to confirm the minimum operating temperature stipulated in the Electrical Technology Regulations of the Japan Electric Association. For this purpose, house boiler steam is injected, but inspections will not be possible unless proper circulation methods are used. Once the water pressure test is completed in this way, preparations for the next step, pipe cleaning, begin. That is, cleaning the piping involves injecting water or a solution of chemicals in water into the piping, creating a circulation loop around the piping to be cleaned, and circulating the solution to clean the piping. During this cleaning, there was no need to consider the pressure of the piping, and the cleaning work was performed by temporarily installing piping for only the cleaning route.

(Problems to be Solved by the Invention) With the above configuration, the conventional piping water pressure testing and cleaning methods have the following problems.

First, as shown in FIG. 1, there is a problem with the position of the piping within the containment vessel. In other words, since equipment, piping, support ducts, electrical conduit cables, and instrumentation piping will be installed and construction work within the narrow containment vessel, pressure testing and cleaning of the main piping will take place during the peak of nuclear power plant construction. Due to the current period, repeated simultaneous work poses problems in construction management, safety management, and quality control, making it extremely difficult. Secondly, it is difficult to raise the temperature, which is a condition for piping water pressure testing. In other words, in order to confirm the minimum operating temperature stipulated in the Electrical Engineering Regulations of the Japan Electric Association, the temperature of the piping is raised to the specified temperature, but the diameter of the piping is large (24 inches for the main steam system and 20 inches for the water supply system). In order to raise the temperature of this pipe, boiler steam is passed through the pipe to raise the temperature, but according to the conventional method described above, boiler steam is introduced from a branch pipe separated from the main pipe and the circulation time takes more than 10 hours. . In addition, because the pipe diameter is large and the pipe route is long, it is difficult to maintain the specified temperature, and the number of pipe water pressure checks required at least three times: in-house confirmation, user confirmation, and government office confirmation.If you take into account the preparation tools and personnel required for this, the total number of This improvement has reached 1,000 man-hours and is an essential condition for plant construction. Third, the conventional method described above requires strict design for manufacturing and installing blind caps that are attached to large-diameter pipes, and requires sufficient care in installation management (damaging the main pipe). Similar precautions are required for pipe water pressure and restoration work after cleaning is completed.

Fourth, due to the number of water pressure tests mentioned above, the required number of days and hours will increase, and there will be no time for final seam welding to the pressure vessel nozzle, which is a critical path in power plant construction, which may lead to construction confusion. Ta.

The present invention eliminates the above-mentioned problems, takes into account the simplification of work procedures, the improvement of quality, and the improvement of construction management, and provides a construction method that satisfies the specified specifications for pipe water pressure and pipe cleaning. The purpose is to provide.

[Structure of the invention]

(Means for Solving the Problems) A feature of the present invention is a piping jig manufactured to meet specifications for performing piping water pressure tests and piping cleaning as a substitute for blind caps on piping for water supply systems and main steam systems. This is a method in which the pipes are welded to the water supply system and main steam system piping. When manufacturing this piping jig, it goes without saying that it must satisfy the pipe wall thickness to withstand pressure (water pressure) as required for this piping, and since it will be constructed in a narrow space inside the containment vessel, the designer The project will be designed and constructed based on these instructions.

(Example) An example of the present invention will be described below with reference to FIG. In FIG. 3, the same parts as in FIGS. 1 and 2 are designated by the same reference numerals, and the explanation of the structure of the parts will be omitted. As shown in FIG. 3, the piping jig is installed using the piping diagram and piping jig installation diagram that have been designed by the designer in advance about one month before the piping water pressure test or piping cleaning.
In this case, the work is inside the containment vessel 9, and the piping for the main steam system and water supply system is Class 1 piping, and as it is extremely important piping, great care must be taken in construction when connecting it to the main pipe, etc. At the same time, safety precautions are necessary. As described above, the reactor containment vessel 9 is a very narrow space because various piping, supports, iron structures, air conditioning ducts, electrical conduits, etc. are arranged inside the reactor containment vessel 9. Once the detailed route design of the main steam system piping 14 and water supply system piping 15 to be placed here is finalized,
Based on this, the design of the piping jig 20 is started. This will be manufactured by arranging materials and considering the wall thickness to withstand the pressure of the water pressure test, in accordance with the main steam system and water supply system piping design. The completion date is set to be one month before the completion of the main steam system and water supply system. In other words, the main steam system piping 1, 14 was prepared one month before the piping water pressure test and was not yet completed.
and a piping jig 2 prepared with water supply system piping 2, 15
0 to complete the pipe water pressure test and pipe cleaning preparations. Once the preparations are complete, a water pressure test will be carried out on the piping. Water is sent from the water supply system piping 15 to the main steam system piping 18 using a pump (not shown), and the water is filled with water, and the pressure is increased using a compressor (not shown) prepared elsewhere. In addition, take the test. In addition, work to raise the temperature in piping condition tests (Electrical Engineering Regulations)
JEAL-4206), in which the water supply system piping 15 and the main steam system piping 14 are connected by a piping jig 20, so that the boiler steam can be easily raised to a specified temperature by circulating it. The number of water pressure tests is the same as in the conventional example, but it can be significantly improved by preparing for the water pressure test. The pipe cleaning process continues after the water pressure test is completed, but cleaning can be carried out using the same circulation route. After this is completed, the piping jig is removed and final welding to the pressure vessel is performed.

〔Effect of the invention〕

As explained above, according to the method of the present invention, it is possible to significantly shorten the process of pipe hydraulic pressure testing, pipe cleaning, and final pipe welding to the pressure vessel, which are currently critical paths in nuclear power plant construction. I can do it.

[Brief explanation of the drawing]

Figure 1 is a side view of the reactor containment vessel showing the main steam system piping and water supply system piping inside the reactor containment vessel in a nuclear power plant, and Figure 2 is a schematic diagram showing the water pressure test method for piping in a nuclear power plant. System diagram, FIG. 3 is a schematic system diagram showing a method for testing and cleaning piping in a nuclear power plant according to an embodiment of the present invention. 1, 14... Main steam system piping, 2, 15... Water supply system piping, 3... Water supply system isolation valve, 4... Main steam isolation valve, 5...
Main steam third isolation valve, 8...Reactor pressure vessel, 9...Reactor containment vessel, 20...Piping jig.

Claims (1)

[Claims] 1. Main steam system piping and water supply system piping located in a nuclear power plant are connected to withstand a predetermined water pressure test pressure, and the water pressure test and cleaning work of the main steam system and water supply system piping are performed simultaneously and sequentially. Nuclear power plant piping testing and cleaning methods.