JPS60149801A - Pre-treatment method on inspection of high-temperature liquid metal treating apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pretreatment method for inspecting high-temperature liquid metal handling equipment.

One type of high-temperature liquid metal handling equipment is a shell-and-tube heat exchanger. A conventional example of the shell-and-tube heat exchanger is explained with reference to FIG. 1. (1) shows the body of the shell-and-tube heat exchanger, (2) shows the sodium inlet pipe, (3) shows the sodium outlet nozzle, and (3) shows the sodium outlet nozzle. 4) is the water/steam inlet header, (5) is the downcomer pipe, and (6) is the downcomer pipe (5).
and the helical coil heat transfer tube, (7) is the helical coil heat transfer section, (8) is the riser tube, (9) is the steam outlet header, (11 is the steam system piping, (1) is the water Steam system piping, (13) is the discharge system nozzle, (13) is the outer cylindrical shroud, <14) is the inner cylindrical shroud, (15) (1,
6) is the tube plate, which is heated at high temperature in the reactor core) IJum (
High temperature liquid metal) is introduced into the shell-and-tube heat exchanger from the sodium inlet pipe (2) and guided to the helical coil heat transfer section (7). Here, the water side (inside the heat transfer tube)
(IJ descends while exchanging heat with IJ)
It is led out of the shell-and-tube type heat exchanger through the nozzle (3). On the other hand, the water side is divided into heat exchanger tubes from the water/steam inlet header (4) to the tube plate, and first, the outer shroud (131
and the shell (1), and after reaching the lower end, the downcomer pipe (
5) and the helical coil tube through the connecting part (6) to reach the helical coil heat transfer part (7). - This helical coil heat transfer section (power exchanges heat with the sodium side (shell side - outside the tube), and the steam is collected in the steam outlet header (9) via the riser pipe (8) and guided to the turbine system. It has become.

As mentioned above, the shell-and-tube heat exchanger of a liquid metal-cooled fast breeder reactor has liquid metal inside, which transfers heat. In addition to sodium, highly reactive liquid metals such as potassium or an alloy of sodium and potassium are also used as liquid metals, and during normal operation, the space containing these liquid metals is completely exposed to outside air. However, in the event of maintenance or an accident, it is necessary to open the equipment and inspect or replace the internal structure. Conventionally, this work was performed using the following steps. Ta. In the following explanation using sodium, first the sodium is discharged from the equipment that requires maintenance, then the temperature is lowered to solidify the sodium adhering to the outer surface of the internal structure, and then this Introduce a stabilizing gas that covers the outer surface of the sodium adhering to the inside of the device. Note that covering the outer surface here means, for example, introducing carbon dioxide gas (CO2 or CO) or oxygen 02 to cover the surface of sodium with substances that do not react even when exposed to air (Na2CO3, Na2CO3,
2O.

and others). After creating a layer that does not cause any problems even when exposed to the outside air, the internal structure is taken out and the necessary work is carried out. When introducing a stabilizing gas to cover the surface of the sodium adhering to the outer surface of the internal structure as described above, the temperature was not particularly controlled and was carried out at the natural temperature. For this reason, it does not mix with the cover gas (inert gas, eg A'r) inside the device and is not sufficiently distributed over the entire surface of the internal device. There was also the problem that it took a lot of time to cross.

To further explain this point using an example of working with force on a helical coil heat transfer section (helical coil heat transfer section),
First, by draining the loop, the sodium inside is discharged, and then the temperature is lowered below the sodium solidification temperature, and then stabilizing gas is introduced into the cover gas system to cover (immobilize) the sodium surface adhering to the internal equipment surface. (Introduced from the country into the interior. At this time, the temperature of the stabilizing gas introduced is not particularly controlled and is left to its own discretion. As mentioned above, the temperature of the stabilizing gas inside is
r) and does not sufficiently spread over the entire surface of the helical coil heat transfer section (7), which has a complex structure.

There was also the problem that it took a lot of time to cross.

The present invention addresses and solves the above-mentioned problems.Prior to internal inspection of high-temperature liquid metal handling equipment that receives high-temperature liquid alkali metal and has a cover gas space above the free liquid level, The purpose of this invention relates to a pretreatment method for inspecting high-temperature liquid metal handling equipment, which is characterized by discharging alkali metals, introducing a stabilizing gas with a different specific gravity from the cover gas, and discharging the cover gas. The stabilizing gas introduced into the device can be quickly and sufficiently distributed inside the device, such as the helical coil heat transfer part, which has a complex structure, and the liquid adhering to the surface can be quickly and sufficiently distributed. The present invention provides a pretreatment method for inspecting high-temperature liquid metal handling equipment that can stabilize the surface of alkali metals.

Next, the pretreatment method for inspection of high-temperature liquid metal handling equipment according to the present invention will be explained with reference to the embodiment shown in Figs. 2 and 3. (1)
is the shell of the shell-and-tube heat exchanger, (2) is the sodium inlet pipe, (3) is the sodium outlet nozzle, (force is the helical coil heat transfer part, zero country is the outer cylindrical shroud,
(1 is the inner cylindrical shroud, (11 is the stabilizing gas supply system, (2 is the stabilizing gas supply system (11 is the temperature control device (cooler or heater), +211 is the stop valve, and is the stabilizing gas supply system. By making the gas temperature higher or lower than the temperature of the gas (Ar) inside the device, a boundary layer with a different specific gravity is created between the stabilizing gas to be introduced and the cover gas inside the device. In order to control the temperature of the stabilizing gas introduced into the equipment, a temperature regulating device (a condenser) is installed in the stabilizing gas supply system α1. In the case of introduction, a temperature control device (a) is not required.It is also possible to control the temperature of stable Ipigas inside the device.

High-temperature liquid metal handling equipment (e.g. shell-and-tube heat exchangers) accepts high-temperature liquid alkali metals (sodium, potassium, alloys of sodium and potassium, etc.), and a cover gas space is formed above the free liquid surface. has been done. When inspecting the inside of this high-temperature liquid metal handling equipment, first discharge the alkali metal inside, then introduce a stabilizing gas at a predetermined temperature with a specific gravity different from that of the cover gas into the inside from the stabilizing gas supply system (I9). Then, the cover gas is discharged, creating a density difference between the two gases as described below, and suppressing the mixing of the gases.Figure 2.6 shows the case where a low-temperature stabilizing gas is introduced. Gas has a heavy specific gravity,
Helical coil heat transfer section (force rises evenly from bottom to top between each heat transfer tube.

On the other hand, the cover gas is discharged to the outside of the shell (1) from a gas exhaust system provided at the upper part of the shell (1), so that the cover gas and the stabilizing gas do not mix significantly. The above is for introducing a low-temperature stabilizing gas, but the same applies when introducing a high-temperature stabilizing gas.The stabilizing gas introduced from the top of the device passes through the cover gas inside the device from top to bottom. Push it down and it will fill the device. However, in this case, a gas exhaust system is provided at the bottom of the shell (1), and the low-temperature cover gas is discharged from this exhaust system to the outside of the shell (1). The difference in specific gravity (density) between the Naori bar gas and the stabilizing gas varies depending on the type of both gases, but typical examples are as follows. (1) Cumming gas is Ar and stabilizing gas is CO2
In this case, the cover gas Ar in the equipment has a temperature of 50
If it is C, the specific gravity is 1.511. <gl&, if the temperature of the introduced stabilizing gas CO2 is 20C, the specific gravity is 1.8
4 to 9/nl", and the difference in specific gravity between the two gases is 0.33 kg/nl.
rr? It is. In this case, it is preferable to warm up the device a little and introduce stabilizing gas at about the above temperature. (II) When the cover gas is Ar and the stabilizing gas is 02, the cover gas Ar in the device has a specific gravity of 1 if its temperature is 80c.
．． 66 kg/rIIs, the introduced stabilizing gas 02 has a specific gravity of 1.21 if its temperature is 5 DC! ? /rrl
'Then, the difference in specific gravity between both gases is 0.45 kl? /rn'
It is. In this case, it is preferable to raise the temperature of the stabilizing gas 02 to be introduced.

The pretreatment method for inspection of high-temperature liquid metal handling equipment according to the present invention is, as described above, for internal inspection of high-temperature liquid metal handling equipment in which a high-temperature liquid alkali metal is received and a cover gas space is formed above the free liquid surface. Prior to this, the liquid alkali metal inside is discharged, and a stabilizing gas with a specific gravity different from that of the cover gas is introduced into the interior, and the cover gas is discharged. It has the effect of being able to quickly and sufficiently spread the heat to a complex helical coil heat transfer section, etc., and stabilizing the surface of the liquid alkali metal adhering to the surface.

Although the present invention has been described above with reference to embodiments, it goes without saying that the present invention is not limited to such embodiments, and that various design modifications can be made without departing from the spirit of the present invention. .

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional side view showing high-temperature liquid metal handling equipment, Figure 2
The figure is an explanatory diagram showing one embodiment of the pretreatment method for inspection of high-temperature liquid metal handling equipment according to the present invention, and FIG. 3 is an enlarged explanatory diagram thereof. (1) - (161... High-temperature liquid metal handling equipment (shell and tube type heat exchanger), Kanji... Stabilizing gas supply system. Sub-agent: Patent attorney Shige Okamoto, 3 people outside the kiln Figure 1

Claims (1)

[Claims] Prior to internal inspection of high-temperature liquid metal handling equipment that receives high-temperature liquid alkali metal and forms a cover gas space above the free liquid surface, the internal liquid alkali metal is discharged,
A pretreatment method for inspecting high-temperature liquid metal handling equipment characterized by introducing a stabilizing gas with a different specific gravity from the cover gas into the interior and discharging the cover gas.