JPS6086446A - Immersion testing method in liquid sodium - Google Patents

Abstract

PURPOSE:To perform a corrosion test while preventing dislodging, etc. of metallic test pieces by bending a straight pipe at every insertion of a plate-shaped holder riveted with the test piece into the pipe to prevent the holder from moving, forming the bent body in such a way and passing liquid Na into the pipe. CONSTITUTION:A rivet 13 is further spot-welded 18 to a plate-shaped holder 14 which is riveted 13 with a test metallic piece 12 and such holders 14 are inserted by each piece into a straight pipe 11 and the pipe is bent at every insertion until, for example, six pieces of the holders are inserted into the pipe and a hexagonal bent body 10 is thus manufactured in a test for corrosion of a metallic material, the deposition condition of a radioactive material, etc. by Na for atomic reactor coolant. Liquid Na is admitted into the body 10 from one end 15 and is discharged from the other end 16 to perform long-term continuous immersion test. The dislodging and damage of the test piece 12 are thus prevented. The body 10 is cut and removed upon end of testing and the corrosion condition, etc. are observed. The immersion test of high reliability is thus made possible.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention involves immersing a test piece of metal, etc., in liquid metal sodium used as a coolant for fast breeder nuclear reactors to prevent corrosion or corrosion of the test piece. This article relates to an immersion test method in liquid sodium for investigating the state of deposition of radioactive substances.

[Technical background of the invention and its problems] When examining the deposition state of radioactive substances by immersing a thin plate-like test piece of metal material in liquid sodium, chemically highly active sodium adheres to the test piece. In addition, because the radioactive material may sink, it is necessary to quickly remove the test piece in a sealed container such as a glove pouch and analyze it without damaging the test piece.

In addition, in order to eliminate coolant leakage accidents in fast breeder reactors, etc., the immersion test container with the test piece attached is of a welded structure, and the welded portion of the container is inspected using X-rays, He leak testers, etc. I need to do that.

A conventional immersion test method in liquid sodium will be explained with reference to FIGS. 1 to 3.

FIG. 1 shows radioactive substances such as Mn-54 and C.

This is an example in which a thin metal plate was used as a test piece for the purpose of investigating how a nuclear reactor such as -60 behaves in the coolant of a high-speed TA reactor. In FIG. 1, a sleeve-shaped holder 3 is placed in a cylindrical container 2 to which the upper M1 is hermetically welded, and its both ends are fixed with nuts 5 to a shaft 4 suspended from the upper M1. Holder 3
A test piece 6 is attached to the side surface of the test piece with screws 7, as shown enlarged in FIGS. 2 and 3. Further, an inlet pipe 8 for flowing liquid sodium into the container 2, and an outlet pipe 9 at the lower end of the container 2 are provided on the upper side surface of the container 2, respectively. Inlet piping 8 and outlet piping 9
is connected to the main loop, not shown. However,
According to the test method using the above-mentioned immersion test device, sodium as the test fluid is flowed into the container 2 from the inlet pipe 8, and radioactive substances in the sodium are deposited on the test piece 6 without flushing out the test piece 6. . The fluid flowing in contact with the test piece 6 returns to the main loop through the outlet pipe 9.

After the sodium flows for a certain period of time 1), the sodium is drained into a sodium drain tank (not shown), and the sodium in the container 2 is caused to flow out of the container 2.

After cooling the container 2 to room temperature, the container 2 is cut in an airtight glove box and the holder 3 is taken out.

Wash the sodium adhering to the holder 3 with alcohol or the like, and remove the test piece 6 using the screw 7. The removed test piece 6 is analyzed for various purposes. FIGS. 2 and 3 are enlarged views of the mounting portion of the test piece 6 on the holder 3, respectively. Test piece 6 is screw 7
It is fixed to the holder 3 by.

As mentioned above, in the conventional immersion test method, since the apparatus itself has a welded structure, inspection by X-ray, 1-18 leak test, etc. is required. In addition, the test piece 6 is fixed to the holder 3 with screws 7, but there is a risk that the screws 7 may loosen or come off during long-term immersion tests. 7 and the test piece 6 would flow into the main loop, clogging the piping on the way, which would lead to a serious accident in the main loop. Further, when taking out the test piece 6, it is necessary to cut the container 2, remove the holder 3, and remove the screw 5, which poses a problem in handling.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and it does not require inspection of welded parts by X-ray, He leak tests, etc. Another object of the present invention is to provide a highly reliable method for immersion testing in liquid sodium, in which there is no risk of detachment of attached parts, etc., and in which test pieces can be easily taken out.

[Summary of the Invention] The present invention involves riveting a test piece [a plate-shaped holder is inserted into a straight pipe vibrator and bent, and then plate-shaped holders substantially similar to those described above are sequentially inserted into each one. The vibrator is bent to form a folded body according to the length of each plate-shaped holder so that each plate-shaped holder does not move, and liquid sodium is poured into the folded body from one end of the folded body. This is a test method for immersion in a liquid, which is characterized by flowing out from the other end of a curved body.

[Embodiment of the Invention] An embodiment of the method of the present invention will be described below with reference to FIGS. 4 to 7.

In this example, radioactive substances such as Mn-54 and Co-60 in sodium as a coolant for fast breeder reactors are used.
We will explain the immersion test method using a thin metal plate as a test piece in order to investigate the behavior of .

FIG. 4 is a front view of the folded body 10 used in the method of the present invention, and FIG. 5 is a side view thereof. In FIGS. 4 and 5, the bending body 10 is constructed by inserting a plate-shaped holder 14 in which a test piece 12 is fixed with rivets 13 into a straight pipe vibrator 11, bending it according to its length, and then A plurality of plate-shaped holders 14 similar to those described above are sequentially inserted into the vibrator 11 one by one and bent to form a hexagonal shape and a coiled shape as shown in FIG. Then, the pipe 11 is bent so that one end becomes the liquid sodium inflow pipe 15 and the narrow end becomes the outflow pipe 16.

FIG. 6 is a front view showing an example in which the test piece 12 is fixed to the plate-like holder 14 with a rivet 13, and FIG.
FIG. 2 is an enlarged sectional view showing a state in which a test piece 12 and a plate-shaped holder 14 are inserted and fixed so as not to move. That is, as is clear from FIG. 7, the rivet 13 is inserted into the through hole 17 provided in the center of the plate-shaped holder 1/I, and the test piece 12 is welded by hot welding 1 on the back surface of the holder 14.
8. Further, the inflow pipe 15 and the outflow pipe 16 of the bent body 10 are connected to a sodium main loop system (not shown). Sodium, which is the fluid to be tested, flows into the bent body 10 from the inlet pipe 15,
It flows in contact with the 12 surfaces of the test piece. Since the pipe 11 is formed into a polygonal coil shape, the holder 14 is not washed away by the sodium flow, and the radioactive substance in the sodium adheres to the surface of the test piece 12. The sodium passed through the test piece 12 is returned to the main loop through the outlet pipe 16. After the sodium movement is carried out for a certain period of time, the sodium is drained into a sodium drain tank (not shown), and the sodium in the bent body 10 is caused to flow out of the pipe 11.

After cooling the folded body 10 to room temperature, the folded body 10 is cut with a pipe cutter or the like in an airtight glove box, and the holder 14 is taken out. Clean the metal adhering to the holder 11 with alcohol or the like. To remove the test piece 12 from the boulder 14, use a pallet (concave steel) 19 as shown in FIGS. 8 and 9.
The test piece 12 can be easily removed. That is, place the holder 14 of test piece 1' 2 (=J) on one pallet as shown in Figure 9, and place 13 points on rivet 1.
A punch 20 or the like is brought into contact with the weld 18 surface, and the rivet 13 is knocked off by striking with a hammer or the like. Since the rivet 13 is spot welded 18, it can easily come off and not be knocked down.

The test piece 12 thus removed is analyzed for various purposes.

As mentioned above, in the immersion test method according to the present invention, the bent body 10, which is the immersion container, is formed by bending the pipe 11, so there is no welded part, so the leakage test of the welded part is conducted. There is no need to conduct an inspection. In addition, since the test piece is fastened to the beam scraper 1 by point welding on the boulder, there is no risk of the test piece becoming loose and falling off, unlike screw fastening, even during long-term tests. . Furthermore, since the bent body is made of pipe, it can be easily cut with a pipe cutter or the like, and the test piece can be removed from the holder using concave steel. By using a pallet punch, the test piece can be easily removed without damaging it.

[Effects of the Invention] According to the present invention, since there is no welded part in the piping that prevents the flow of liquid sodium, there is no need for inspection such as a leak test.
Furthermore, since there are no threaded parts, the test piece will not fall off even during long-term tests, making it extremely reliable. Furthermore, it is possible to provide a method for immersion testing in liquid sodium that allows the test piece to be quickly and easily removed from the holder without damaging the surface of the test piece, and has less influence on analysis during removal.

Note that the shape of the bent body can be arbitrarily determined depending on the shape of the plate-shaped holder, and is not limited to a hexagonal shape or a coil shape. Further, the number of holders is not limited depending on the bending length of the pipe.

[Brief explanation of drawings]

Figures 1 to 3 are for explaining the conventional example. Figure 1 is a vertical cross-sectional view without showing the main body of the immersion test device, and Figure 2 is a vertical cross-sectional view showing an enlarged view of the main parts of Figure 1. A top view, FIG. 3 is a sectional view taken along arrow A-A in FIG. 2, and FIGS. 4 to 9 are for explaining an example of the test method according to the present invention.
Fig. 4 is a front view, Fig. 5 is a side view, Fig. 6 is an enlarged plan view of the holder shown in Fig. 4, and Fig. 7 is an enlarged view taken in the direction of arrow B-B in Fig. 4. 8 is a perspective view showing pallets 1~ used for disassembling test pieces, and Figure 9 is a test piece holder placed on pallets 1~ in Figure 8 without being knocked off with a bonder. It is a sectional view showing a state. 1... Top lid 2... Cylindrical container 3... Holder 4... Shaft 5... Nut 6... Test piece 7... Screw 8... Inlet piping 9... Outlet Piping 10...Bending body 11...Pipe 12...Test piece 13...Rivet 14...Plate holder 15...
Inflow pipe 16...Outflow pipe 17...Through hole 18
...Scorched welding 19...Pallet 20...Punch Application agent Patent attorney Kikuchi Part 5 Part 1 Lean clause 4 @ i Fig. 6 Fig. 2 Fig. 6 Fig. 9

Claims (3)

[Claims] (1) After inserting a plate-shaped holder to which the test piece is riveted into a straight pipe and bending it, insert plate-shaped holders almost similar to the above and sequentially insert each plate-shaped holder into each inserted plate-shaped holder. bending the pipe to form a bent body so that each plate-like holder does not move according to its length;
A method for immersion testing in liquid sodium, characterized in that liquid sodium flows in from one end of the bent body and flows out from the narrow end of the bent body. (2) The immersion test method in liquid sodium according to claim 1, wherein the bent body is formed into a polygonal coil or spiral. (3) Claim 1, characterized in that the test piece is riveted to a plate-shaped holder and welded by boiling.
Immersion test method in liquid sodium as described in section.