JPH0254520B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for cutting pipes connected to a reactor pressure vessel, specifically, a method for cutting pipes connected to a nuclear reactor pressure vessel, specifically, a shaped explosive is charged into the pipe to be cut, and the Neumann This relates to a method of cutting pipes using the effect.

Nuclear reactors currently used for power generation, etc. reach the end of their lifespan after about 30 years from the start of operation, and the methods of disposing of nuclear reactors that have reached the end of their lifespan include hermetic management, shielding and isolation, and dismantling and dumping. Demolition and scattering is considered desirable.

Therefore, the piping connected to the reactor pressure vessel usually has a nominal diameter of 1B to 30B.
The wall thickness is also greater than Sch80 (Schule 80). Furthermore, these pipes pass through the biological shielding wall, and when they are cut, they are planned to be cut between the reactor pressure vessel and the biological shielding wall.

However, since the surrounding space is extremely narrow and exposed, it is impossible for humans to directly cut the pipes.

Therefore, as a method for cutting the above-mentioned piping, a method of cutting from inside the piping by remote control from outside the biological shielding wall is considered to be promising.

In general, mechanical cutting methods can be considered for medium-diameter or large-diameter pipes, but for small-diameter pipes, the minimum nominal diameter is 1B, and for these small-diameter pipes, the usual cutting equipment is It is very difficult to charge and cut deep.

Furthermore, if there is a bent part in the pipe, it is nearly impossible to insert or operate cutting equipment, and at present, mechanical cutting methods cannot be applied.

The present invention has been made in response to such a situation, and is a generally drum-shaped molded product in which a V-shaped liner groove is formed on the circumferential surface and a detonator is laterally attached to the center of one or both end faces. The explosive is placed inside the pipe to be cut so that the center line of the shaped explosive matches the center line of the pipe, and the shaped explosive is detonated to cut the pipe to achieve the desired result. It has a purpose.

Generally, if a conical cavity is made on one side of a shaped explosive and detonated from behind the cavity,
A strong force is generated in the direction of the detonation. The effect of this conical cavity is called the Neumann effect, and the present invention provides a method for cutting the above-mentioned pipes using a shaped explosive that effectively utilizes the Neumann effect.

This cutting method using shaped explosives that utilizes the Neumann effect can sharply cut any desired location with a smaller amount of explosives than with normal explosives, and the shaped explosives can be easily and reliably loaded by remote control. Moreover, it has the advantage of being able to complete the cutting work in a short time by simultaneously detonating a large number of shaped explosives.

Conventional shaped explosives that have been put into practical use for cutting pipes include ring-shaped shaped explosives with a double V-shaped cross section, inside and outside, with a detonator attached to the inner periphery. All of these are used to cut pipes with a nominal diameter of 2B or more, and the space inside the pipe becomes smaller for pipes with a nominal diameter of less than 2B, so the shaped explosives with the above structure cannot cut the pipes. It's impossible.

In contrast, in the present invention, the detonator is attached laterally to the center of the end face of one or both sides of the shaped explosive, and the detonator is detonated from the lateral direction of the shaped explosive, thereby successfully exerting the same Neumann effect. It is something.

Thus, the present invention has established a method for cutting pipes that effectively utilizes the Neumann effect even for pipes with a nominal diameter of less than 2B connected to a reactor pressure vessel.

Furthermore, by making the gap between the V-shaped liner groove of the shaped explosive and the inner wall of the pipe airtight, the pipe can be cut even underwater.

Thus, according to the method of the present invention, the shaped explosive or the combination of the shaped explosive and the holder can be made very compact, so it can be used not only for piping with a nominal diameter of less than 2B.
This provides an extremely effective cutting method even for pipes with a nominal diameter of 2B or more.

The present invention will be specifically explained below with reference to embodiments shown in the drawings.

FIG. 1 shows a reactor pressure vessel system to which the cutting method of the present invention is applied, where 2 is a reactor pressure vessel, 3 is a biological shielding wall, 4 is a connection pipe to the reactor pressure vessel, and 5 is a pipe 4. Indicates the cutting position.

Therefore, as shown in Figure 2, a device supported by a suitable holder is mounted on a biological shielding wall so that the center axis of the pipe in which the roughly drum-shaped shaped explosive is to be cut coincides with the center line of the shaped explosive. 3 and charged into the deep part of the pipe 4, and after aligning the center plane of the peripheral V-shaped groove 7-1 of the shaped explosive 7 with the cutting position 5, the shaped explosive is detonated to bring the Neumann effect to the cutting position 5. exert,
At this point, pipe 4 is cut. 8 indicates the leg line.

The shape of the shaped explosive described above is illustrated in FIGS. 3 and 4.

In Fig. 3, a drum is surrounded by a V-shaped liner groove 7-2 made of a copper plate or the like in which a V-shaped groove 7-1 is formed, and covers 7-3 and 7-3' made of paper, plastic, etc. on both sides. A high explosive 7-4 is loaded in the shaped case, and a detonator 7-5 is attached to the center of the circle of one cover 7-3 by adhesive or other suitable means.

Also, in Figure 4, detonators 7-5, 7-5'
are attached to the covers 7-3, 7-3' on both sides, respectively, and the tips of the devices 7-5, 7-5' are attached to the covers 7-3, 7-3'.
3,7-3' and is inserted into the explosive 7-4.

Using the shaped explosive shown in Figs. 3 and 4 above, the materials, dimensions, and shapes are equivalent to those of cooling water pipes, steam pipes, monitor piping, etc. with nominal diameters of less than 2B and 2B or more, according to the embodiment of Fig. 2. Tests using tubes with a

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a nuclear reactor pressure vessel system to which the cutting method of the present invention is applied, Fig. 2 is an explanatory diagram showing an embodiment of the cutting method of the present invention, and Fig. 3 is a molding used in the cutting method of the present invention. In the illustrative views of the explosive, A is a longitudinal side view of the main part, B is a front view, and FIG. 4 is a longitudinal side view of the main part showing another example of the shaped explosive. 2... Reactor pressure vessel, 3... Biological shielding wall,
4...Connection pipe, 5...Planned cutting position, 6...Holder, 7...Shaped explosive, 7-1...V-shaped groove, 7-
2...V-shaped liner groove, 7-3...Cover, 7
-4... High explosive, 7-5... Detonator.

Claims (1)

[Claims] 1. When cutting the piping connected to the reactor pressure vessel, a V-shaped liner groove is formed on the circumferential surface, and a detonator is placed laterally in the center of one or both end faces. A roughly drum-shaped shaped explosive attached to the pipe is inserted into the pipe to be cut so that the center line of the shaped explosive coincides with the center line of the pipe, and the shaped explosive is marked and detonated. A nuclear reactor piping cutting method characterized by cutting the piping. 2. The method according to claim 1, in which piping between the reactor pressure vessel and the biological shielding wall, piping attached to reactor internals, or other piping contaminated with radioactivity is cut. 3 Claims 1 or 2, in which the gap between the peripheral liner of the shaped explosive and the inner wall of the pipe to be cut is airtight in air or water, and the shaped explosive is detonated to cut the pipe. The method described in section.