JPH0316636B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a nuclear fuel leakage inspection device.

Nuclear fuel in nuclear power plants is subjected to predetermined inspections during regular plant inspections, and if its soundness is confirmed, fuel with a low combustion rate is used again next time. Here, the nuclear fuel is inspected mainly for the presence of defects such as damage, and for the presence or absence of abnormalities in appearance. Among these methods, the method for testing the presence or absence of defects in nuclear fuel is generally called a shipping test, and two methods are currently in use: the gas circulation method and the water sample method. In both of these methods, the fuel to be inspected is isolated from the surrounding conditions of other fuels, etc., and a gas or water sample is analyzed, and whether radionuclides have increased from the background (normal state level) or not, the leakage of nuclear fuel is determined. This is to determine the presence or absence of.

Conventionally, for example, the gas circulation method has been carried out using an inspection apparatus as shown in FIGS. 1 and 2.

1 in FIG. 1 is a nuclear reactor vessel, and the reactor core 2 is loaded with nuclear fuel 3. On the other hand, 11 in the figure
1 is a nuclear fuel storage pit filled with water, and within this storage pit 11 is provided a shipping can 12 for storing nuclear fuel 3 and carrying out a shipping inspection. In addition, the storage pit 1
A crane 13 is movably provided on rails 14, 14. A shipping cap 15 is detachably fitted into the upper opening of the shipping can 12, as shown in FIG. A sample tube 16 is inserted into the shipping cap 15 and communicates with the upper opening of the shipping can 12 isolated by the shipping cap 15. An analysis section 17 is connected to the sample tube 16. A circulation pump 18 is connected to the analysis section 17, and a pipe 19 communicating with the lower part of the shipping can 12 is connected to the circulation pump 18.

Shipping inspection by the above-mentioned inspection device is performed as follows.

First, the nuclear fuel 3... loaded in the reactor core 2 is taken out from the reactor core 2, and is temporarily transferred to the nuclear fuel storage pit 11.
The fuel is stored in a nuclear fuel storage rack made of, for example, angle material. Next, the nuclear fuels 3 are moved one by one into the shipping can 12 by the crane 13 in order to carry out a shipping inspection. After this,
The circulation pump 18 is operated and a predetermined flow rate of gas (usually high-purity N ₂ gas) is supplied to the lower part of the shipping can 12 through the pipe 19, and the sample pipe 16, analysis section 17, circulation pump 18, and pipe 19 are sequentially connected. Circulate. At this time, if there is a defect in nuclear fuel 3,
Radioactive gas nuclides are diffused and accumulated in the gas.
Therefore, leakage of the nuclear fuel 3 can be detected by continuously analyzing the gas in the analysis section 17.

In the case of the water sample method, similar to the gas circulation method described above, the nuclear fuel 3 is stored in the shipping can 12 and isolated, and after a predetermined period of time, the water in the shipping can 12 is sampled to detect radionuclides in the water. The leakage of the nuclear fuel 3 is detected by analyzing and comparing it with the background.

However, in the conventional shipping inspection described above, as shown in FIG.
Since it is necessary to transfer the nuclear fuel to the shipping can 12 one by one and return it again, the operation becomes complicated, which is disadvantageous in terms of the reliability of handling nuclear fuel, and the inspection work time during periodic inspections is lengthened. be. Furthermore, since the shipping can 12 is provided within the nuclear fuel storage pit 11, the storage pit 11 becomes larger, which is disadvantageous in terms of equipment.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a nuclear fuel leakage inspection device that can reduce restrictions on equipment, improve reliability in handling nuclear fuel, and shorten inspection work time. It is something to do.

Hereinafter, an embodiment in which the present invention is applied to a nuclear fuel leakage inspection device using a water sample method will be described with reference to FIG.

In the figure, 21 is a nuclear fuel storage pit filled with water and selectively connected to the reactor vessel. Inside this storage pit 21, a large number of cylinders (cans) 22 in which nuclear fuel is individually housed are arranged vertically and horizontally in a regular grid pattern, forming a can-type nuclear fuel storage rack. Each of these cylindrical bodies 22 has a structure capable of surrounding the bottom and side surfaces of the nuclear fuel contained therein. A plurality of sealing parts 23 corresponding to each cylinder 22 are provided in the upper openings of more than ten of these cylinders 22.
The shipping caps 23 having a... are removably fitted at the same time, and each sealing portion 23a... cooperates with each of the corresponding ten or more cylinders 22... so as to define an individual isolated space. It's summery. This cap 23
is a rail 24 provided on the storage pit 21.
It is pulled up by a wire 26 from a crane 25 movably mounted above, and is simultaneously removably fitted into the upper openings of other cylindrical bodies 22 constituting the storage rack. More than ten flexible sample tubes 27 are inserted into the cap 23 and communicate with the upper openings of the respective isolated storage racks 22 in cooperation with the caps 23a. These sample tubes 27 have a length that can cover the entire area of the storage pit 21. Further, these sample tubes 27... are connected to a sampling device 28, and furthermore, the sampling device 28 is connected to a sampling device 28.
is connected to the analyzer 29.

A nuclear fuel leak test using the water sample method using the above-mentioned apparatus is carried out as follows.

First, after storing the nuclear fuel 30 from the core of the reactor into each cylinder 22 constituting the can-type nuclear fuel storage rack, the shipping caps 23 are simultaneously fitted into the upper openings of more than ten of the cylinders 22. In cooperation with the sealing portions 23a of the caps 23, the ten or more cylindrical bodies 22 are individually isolated. Next, water is sequentially sampled by the sampling device 28 through the sample tubes 27 from each of the cylindrical bodies 22 separated by the caps 23a constituting the cap 23, and analyzed by the analyzer 29. And if the radionuclides increase compared to the background,
Leakage of nuclear fuel 30... can be detected. When the shipping inspection for the first ten or more nuclear fuels 30 is completed, the crane 25 moves the cap 23 and simultaneously inserts the cap 23 into the upper opening of the other ten or so cylinders 22 that make up the storage rack. The cylindrical bodies 22 are fitted into the cap 23 and attached to the cap 23.
Isolate in a... and conduct a shipping inspection in the same way.

However, according to the above-mentioned inspection apparatus, a plurality of sealing parts 2 corresponding to each cylinder 22 are formed in the upper openings of more than ten cylinders 22 constituting the can-type nuclear fuel storage rack.
By simultaneously fitting the shipping caps 23 having the cylinders 3a, it is possible to conduct a shipping inspection of the nuclear fuel 30 while keeping each cylinder body 22 individually isolated. Therefore, there is no need to provide a separate shipping can inside the nuclear fuel storage pit as in the past, and the storage pit can be made smaller, which is advantageous in terms of equipment. In addition, since the work of transporting nuclear fuel stored in the nuclear fuel storage rack one by one to the shipping can is eliminated, it not only greatly contributes to improving the reliability of handling nuclear fuel, but also significantly reduces the time required for nuclear fuel leakage inspection. It also greatly contributes to reducing the amount of time required for periodic plant inspections.

In addition, if the analysis of sample water is automated in the above-mentioned inspection device, and ten or more bottles of water can be analyzed sequentially, the working time can be further shortened.

Furthermore, by providing a circulation control pump that circulates gas and a gas pipe connected to the circulation pump and communicating with the lower part of the can-type nuclear fuel storage rack, the present invention can be similarly applied to nuclear fuel leakage inspection using the gas circulation method.

Further, the shipping cap is not limited to one capable of inspecting ten or more vessels as in the above embodiment, but the number of vessels that can be inspected can be increased or decreased depending on the operability of the crane, the sampling device, etc.

As detailed above, according to the present invention, it is possible to provide a nuclear fuel leakage inspection device that can improve reliability in handling nuclear fuel and significantly shorten inspection work time without being subject to equipment restrictions. It is.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing a conventional nuclear fuel leakage inspection device, FIG. 2 is a side view of the same device, and FIG. 3 is a side view showing a nuclear fuel defect inspection device in an embodiment of the present invention. 21...Nuclear fuel storage pit, 22...Cylinder body, 2
3... Shipping cap, 23a... Crowning section,
24...Rail, 25...Crane, 26...Wire, 27...Sample tube, 28...Sampling device, 29...Analyzer, 30...Nuclear fuel.

Claims (1)

[Claims] 1. A containment chamber filled with water and selectively connected to the reactor vessel, and a large number of regularly spaced cylinders vertically and horizontally provided within the containment chamber, individually containing nuclear fuel, and surrounding the bottom and sides of the nuclear fuel. The nuclear fuel storage rack is installed vertically and the upper openings of a plurality of cylinders are removably fitted at the same time, corresponding to each cylinder and working together to create individual isolated spaces. A cap having a plurality of caps defining a plurality of caps, a plurality of sample tubes communicating with an upper opening of each cylinder isolated by the cap of the cap, and an analyzer coupled to the sample tubes. A nuclear fuel leakage inspection device characterized by comprising: