JPS59126294A - Relaxation device for horizontal pipe temperature distribution of fast breeder - 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 [Technical Field of the Invention] The present invention relates to a horizontal pipe temperature 1 degree distribution relaxation device for a ρj fast breeder reactor.

[Technical Summary of the Invention] FIG. 1 shows a liquid metal cooled fast breeder reactor, and in the figure, reference numeral 1 indicates a reactor vessel.

A reactor core 3 supported by a core support plate 2 is disposed within the reactor vessel 1 . A fixed plug 4 is inserted into the upper opening of the reactor vessel 1, and a rotary plug 5 is inserted into a through hole formed in the fixed plug 4. This rotary plug 5 has an eccentric through hole bored therein.
A core upper structure 6 is inserted into this through hole. A reactor vessel inlet nozzle pipe 7 is opened at the lower side of the reactor vessel 1, and a reactor vessel outlet nozzle pipe 8 is opened at the upper side.

In the liquid metal cooled fast breeder reactor configured as described above, the reactor vessel 1 contains liquid gold B9 made of, for example, liquid metal sodium, and the reactor vessel 1 includes reactor vessel inlet nozzle piping. The relatively low temperature liquid metal 9 flowing in from the reactor core 3 obtains thermal energy through nuclear fission, and then flows out from the reactor vessel outlet nozzle pipe 8.

[Problems with the Background Art] However, in the liquid metal cooled fast breeder reactor configured as described above, if the reactor is tripped, for example, the liquid metal in the upper reactor blennium will flow as indicated by the broken line a in FIG. As shown in Figure 2, due to the difference in density caused by the temperature difference in the liquid metal, the liquid metal is divided into a hot upper region and a cold lower region C, and due to the difference in buoyancy between them, the two form a layer without mixing, and this layered In this state, it flows out through the so-called hot leg piping, such as the furnace vessel outlet nozzle piping 8.

That is, generally after a reactor trip, the coolant flow rate is supplied by pony motor operation, so that the rated flow rate is approximately 1
0%, but the flow velocity in the hot leg piping is also about 10%, and considering the volume of the upper furnace brenum, the liquid metal that forms a layer for a considerable period of time enters the hot leg piping such as the furnace vessel outlet nozzle piping 8. There will be an influx. In such a case, non-uniform temperature distribution occurs along the circumferential direction of the hot leg piping, which may damage the hot leg piping.

For example, in a power-generating fast reactor, the temperature at the furnace outlet is 530°C and the temperature at the furnace inlet is approximately 400°C, assuming the coolant is in the rated state.
For example, stainless steel is used for cooling system piping and equipment. However, the lower limit of creep occurrence for stainless steel is 425°C, and hot leg piping and equipment are used within the temperature range where creep occurs. In order to prevent progression, it is required to eliminate tensile, compressive, shearing, residual, and other stresses as much as possible, as well as to eliminate as much as possible the causes of these stresses, such as thermal shock.

[Object of the invention] The present invention has been made in response to such conventional circumstances,
Eliminate non-uniform temperature distribution in the circumferential direction of hot leg piping caused by the layering phenomenon of liquid metal during a nuclear reactor trip.
The health of hot leg piping.

The present invention aims to provide a horizontal piping temperature distribution relaxation device for a fast breeder reactor that can be maintained.

[Summary of the Invention] That is, the present invention provides a cooling means for cooling the upper part of a horizontal pipe of a primary liquid metal system that circulates liquid metal in a nuclear reactor vessel, and a cooling means that measures the temperature of the upper and lower parts of the horizontal pipe, respectively. Temperature signals indicating the temperatures at the upper and lower portions of the horizontal pipe are inputted from the temperature measuring means and the cap U1 measuring means, respectively, and when the difference between the two exceeds a predetermined constant value, the cooling means is activated. There is a horizontal piping temperature distribution relaxation device C for a fast breeder reactor, which is characterized by comprising a liquid metal temperature control device.

[Embodiment 1 of the Invention] The details of the present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 2 shows the primary liquid metal system of a liquid metal cooled fast breeder reactor, and in the figure, reference numeral 20 indicates the primary liquid metal system. This primary liquid metal system 20 is provided to transfer the nuclear energy generated in the reactor to the intermediate heat exchanger 21 via liquid metal, and is connected to the primary system piping 22 that circulates the liquid metal in the reactor. are the primary system pump 2 in order from the upstream.
3. An intermediate heat exchanger 21 and a check valve 24 are provided.

In the example shown in this figure, the reactor vessel 1 and the primary system pump 23 are connected by Botleg piping consisting of two horizontal piping 25.26 and two vertical piping 27.28. In the example shown in this figure, the primary system pump 23 and the intermediate heat exchanger 21 are connected by hot leg piping consisting of two horizontal piping 29, 30 and two vertical piping 31, 32.

Figures 3 and 4 are horizontal piping 25.26 shown in Figure 2.
．． 29.30 shows the horizontal piping 25, and in the figure, the reference numeral 25 indicates the horizontal piping.

A heat insulator 33 is disposed along the concave edge of the horizontal pipe 25, and near the top of the horizontal pipe 25, a cooling pipe 35 is provided with an on-off valve 34 that penetrates the heat insulator 33 and runs approximately parallel to the horizontal pipe 25. is installed. Temperature measurement means 3 each consisting of a thermometer are in contact with the outer periphery of the upper and lower parts of the horizontal pipe 25.
6.37 is provided, and the temperature measuring means 36 provided above the horizontal pipe 25 is thermally isolated from the cooling pipe 35.

In FIG. 3, reference numeral 38 indicates a liquid metal temperature control device, and this liquid metal temperature control device 38 is connected to the horizontal pipe 25.
Temperature measuring means 36.37 arranged at the upper and lower parts of the
Temperature signals S1 and S2 are respectively inputted from the temperature signals S1 and S2, and when the difference between the two exceeds a certain value set in advance in this liquid metal temperature control device 3B, the on-off valve 3 disposed in the cooling pipe 35 is activated.
4 is opened to allow the refrigerant to flow into the cooling pipe 35.

Note that the constant value preset in the liquid metal temperature control device 38 is determined to be equal to the temperature difference between the upper, pipe temperature, and lower pipe temperature of the horizontal pipe 25 when a stratification phenomenon occurs in the horizontal pipe 25. There is.

In the horizontal pipe 25 configured as described above, when the reactor trips, due to the stratification phenomenon of the liquid metal in the reactor vessel 1, as shown in FIG. The low-temperature liquid metal flows into the upper side of the horizontal pipe 25 in a layered manner as shown by the symbol e, but the temperature of the low-temperature liquid metal d and The temperature of the high-temperature liquid metal e is always measured by the temperature measuring means 3.
6.37, and when the difference between the two exceeds a predetermined constant value due to the occurrence of the stratification phenomenon, the liquid metal temperature control device 38 turns on/off the opening/closing valve 34 of the cooling pipe 35.
is opened, and the cooling medium flows through the cooling pipe 35.

Therefore, the high-temperature liquid metal e flowing in the upper part of the horizontal pipe 25 due to the stratification phenomenon is cooled by the refrigerant flowing in the cooling pipe 35, and its temperature decreases to almost the same as the low-temperature liquid metal d flowing in the lower part of the horizontal pipe 25. Traditionally, it is cooled to the same temperature.
The non-uniform humidity distribution in the circumferential direction that occurs in hot leg piping such as the horizontal piping 25 can be completely eliminated, and the thermal shock given to various equipment, piping, etc. installed downstream of this piping can be significantly reduced. be able to.

Note that when the temperatures of the liquid metal flowing in the upper and lower parts of the horizontal pipe 25 are approximately equal, the temperature measuring means 36
．． 37 to the liquid metal temperature control device 38 becomes within a predetermined constant value, and the liquid metal temperature control device 38 controls the cooling piping 35.
The open valve 34 disposed in the cooling pipe 35 is opened, and the flow of the cooling medium to the cooling pipe 35 is stopped.

``Effects of the Invention'' As described above, according to the horizontal pipe temperature distribution relaxation device for a fast breeder reactor of the present invention, for example, the non-uniform circumferential temperature distribution of hot leg piping due to the stratification phenomenon during a reactor trip can be alleviated. Since the piping in which the invention is implemented, the problem a) can be completely eliminated, and a safer liquid metal cooled fast breeder reactor with improved hot leg piping integrity can be provided.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing a conventional liquid metal cooled fast breeder reactor, Figure 2 is a piping system diagram showing the liquid metal system of the fast breeder reactor, and Figure 3 is the horizontal piping of the fast breeder reactor of the present invention. A longitudinal sectional view showing an embodiment of the temperature distribution relaxation device, FIG. 4 is a TV shown in FIG. 3.
- It is a cross-sectional view along the IV line. 1......Reactor vessel 25...
・・・・・・Horizontal piping 33-・・・・・・・・・・・・
Heat insulation material 35...... Cooling piping 36.37...
・Temperature measurement means 38・・・・・・・・・Liquid metal temperature control device Patent attorney Satoshi Suyama - Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) A cooling means for cooling the upper part of the horizontal piping of the primary liquid metal system that circulates liquid metal in the reactor vessel, a temperature measuring means for measuring the temperature of the upper and lower parts of the horizontal piping, and a liquid metal temperature control device that inputs temperature signals indicating the temperatures at the upper and lower portions of the horizontal pipe from the temperature measuring means, and operates the cooling means when the difference between the two exceeds a predetermined constant value of 110; A horizontal piping temperature distribution relaxation device for a fast breeder reactor, which is characterized by: