JPH0797298B2 - Temperature control device for sodium circulation system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device for controlling the sodium temperature in a sodium circulation system such as a fast breeder reactor. More specifically, the sodium circulation system is divided into a number of blocks. Then, electric heaters are installed in each of them, and the electric heaters are prioritized. On the other hand, the electric power is detected by directly detecting the system sodium temperature and turned on or off according to the deviation between the detected temperature and the control target temperature. The present invention relates to a temperature control device of a sodium circulation system configured to control a heat input amount by defining a heater.

[Prior Art] In a fast breeder reactor using metallic sodium as a coolant for a nuclear reactor, an electric heater is laid on the surface of preheated objects (various sodium devices and piping) to prevent freezing of the sodium circulation system. Then electricity is applied to preheat and keep the internal sodium.

Conventionally, for preheating control of system sodium during the reactor shutdown of a fast breeder reactor, a configuration has been adopted in which the sodium circulation system is divided into a number of blocks and each block is completely independent. That is, an electric heater and a thermocouple are laid on the surface of the preheated object that constitutes each block, and the control target temperature that is predetermined based on the signal of the thermocouple and the preheated object surface temperature of the block are compared. Based on the comparison result, the electric heater was turned on and off independently for each block, and the entire sodium circulation system was preheated and kept warm.

[Problems to be Solved by the Invention] However, the output signal from each thermocouple has a relative detection error due to an error of each thermocouple and a difference in the adhesion state to the surface of the preheated body. Therefore, even if the system sodium temperature is uniform, the difference between the control target temperature in each control block and the temperature detected by the thermocouple varies, and as a result, the temperature control target value of each control block varies. Therefore, there is a drawback that the temperature control of sodium cannot be performed with high accuracy.

By the way, in such a conventional technology, the control accuracy of the system sodium temperature is limited to about ± 10 ° C of the control target temperature, and high-precision sodium required for creating test conditions of the plant and checking and adjusting sodium equipment. Temperature control could not be realized at all.

Further, as described above, in some control blocks, the electric heater is turned on and off unnecessarily, which causes a problem of excessive power consumption.

The object of the present invention is to eliminate the drawbacks of the prior art as described above, and to control the system sodium temperature with high accuracy,
It is an object of the present invention to provide a temperature control device for a sodium circulation system, which can suppress the electric power consumption to a necessary minimum when the system sodium temperature is stable and unnecessary electric heaters are not turned on.

[Means for Solving Problems] In the present invention capable of achieving the above-mentioned object, a system in which sodium circulates is directly detected as a system sodium temperature and input to a temperature control system. A device that determines an electric heater that needs to be turned on and off based on an algorithm preprogrammed in a microcomputer according to the deviation between the control target temperature and the sodium temperature, and controls the deviation to a specified value or less.

The temperature control device of the sodium circulation system according to the present invention divides the sodium equipment and pipes constituting the sodium circulation system into a large number of blocks, and a large number of electric heaters laid on the surface of the sodium equipment and pipes for each block. , A number of switches connected to each electric heater to control their operation, a temperature detector for directly detecting the system sodium temperature, a control target temperature setting means, and a deviation between the detected temperature and the control target temperature. Deviation detecting means for determining the electric heaters, storage means for storing the priority order and turning-on / off states of a large number of electric heaters, and electric heaters to be turned on / off according to the output of the deviation detecting means and the contents of the storing means. It is provided with a switch selection means and a switch drive circuit for driving a corresponding switch according to the output of the switch selection means.

The temperature detector is installed at one location in the sodium circulation system. Regarding the priority of the electric heater, it is desirable that the block immediately after the temperature detector has the highest priority in the direction in which sodium flows, and that the priority gradually decreases toward the downstream side.

[Operation] The system sodium temperature is directly detected by the temperature detector. The deviation between the detected temperature and the control target temperature is obtained, and the turning on / off of the electric heater divided into blocks is controlled accordingly. When the detected temperature is lower than the control target temperature, the switch is controlled so as to turn on the electric heater having the highest priority among the electric heaters cut off at that time. When the detected temperature is higher than the control target temperature, the switch is controlled so as to cut off the electric heater having the lowest priority among the heaters that are currently turned on. In other cases, the on / off state of the electric heater is maintained as it is.

This makes it possible to control the amount of heat input to the sodium circulation system to the minimum necessary amount and to control the sodium temperature with high accuracy.

In particular, if the priority of the electric heater is set to be highest immediately after the temperature detector and lowest immediately before the temperature detector in the sodium flow direction, the local temperature change caused by turning on and off the electric heater is caused by the sodium flow. It is preferable in that it is made uniform by the stirring effect, the detected temperature can be stabilized, and more accurate temperature control can be performed.

[Embodiment] FIG. 1 is an explanatory view showing an embodiment of a temperature control device for a sodium circulation system according to the present invention. The sodium circulation system includes a main cooler 10, a main circulation pump 12, and an intermediate heat exchanger 14, which are connected by a pipe 16.
The outside of the pipe 16 and the like is covered with a heat insulating material 18.

Such a sodium circulation system is divided into a large number of blocks, and an electric heater 20 is laid on the surface of sodium equipment and piping in each block. Each electric heater 20 is equipped with a switch 22 for controlling the energization / interruption operation thereof,
It is connected to the power supply device 24 for the heater. Therefore each switch
By turning on / off the switch 22, the operation of the corresponding electric heater 20 can be controlled.

In the present invention, a temperature detector 26 for directly detecting the system sodium temperature is provided in such a sodium circulation system. This temperature detector 26 is a thermocouple in this embodiment,
It is inserted so that the heat insulating material 18 and the pipe 16 are penetrated and the tip portion thereof reaches the inside of the sodium flow path.

The output from the temperature detector 18 is sent to a temperature controller mainly composed of a microcomputer to control each switch 22.

In this embodiment, the analog temperature signal from the temperature detector 26 is
The digital temperature signal is converted by the A / D converter 30 and input to the deviation detecting means 32. The deviation detecting means 32 finds the deviation between the temperature signal and the control target temperature set by the control target temperature setting means 34. Then, the result is sent to the switch selection means 36, and the switch to be driven is selected according to the information from the storage means 38 that stores the priority order of the electric heaters and the ON / OFF state, and a signal is sent to the switch drive circuit 40. Is sent to control turning on / off of a predetermined switch 22.

In the storage means 38, the priority order of the electric heaters is set and held as described above. In the case of this embodiment, if sodium flows in the circulation system as indicated by arrow A in FIG.
The electric heater provided in the block immediately after the block in which the temperature detector 26 is installed (here, the electric heater 20a installed in the main cooler 10) has the highest priority, and then the electric heater 2
The order of priority becomes lower in the order of 0b, 20c, ..

The flow chart of the control algorithm pre-programmed in the microcomputer is shown in FIG. The temperature detector 26 detects the inlet temperature of the main cooler 10 as a representative temperature of system sodium. Compare this with the control target temperature, and if the detected temperature is lower than the control target temperature,
The electric heater with the highest priority is selected from among the electric heaters that are cut off at that time, and the switch is turned on. On the contrary, if the detected temperature is higher than the control target temperature, the electric heater having the lowest priority among the electric heaters turned on at that time is shut off. In other cases, the on / off state of the electric heater is maintained as it is.

In this way, according to the present invention, it is possible to appropriately control the heat input amount into the sodium circulation system. In addition, because the electric heater with a high priority is set high immediately after the temperature sensor installation location in the sodium flow direction,
Stirring effect occurs in the process of sodium flow, temperature change rarely directly affects the detection temperature, and the detection temperature is stabilized.

By the way, according to the present invention, the control accuracy of the system sodium temperature can be kept within ± 1 ° C. of the control target temperature.
Therefore, specifically, for example, good temperature controllability was verified in a leak test of the entire containment vessel, which requires temperature control with high accuracy as a test condition. Further, it is sufficiently applicable to nuclear characteristic tests such as control rod calibration in which sodium temperature conditions are strictly controlled and stroke adjustment of control rod drive mechanism.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to such a configuration. In the above embodiment, the control is performed by software by the microcomputer, but the control device may be configured by hardware. In that case, the detected temperature signal, the control target temperature, and the like can be processed in analog.

[Effects of the Invention] The present invention is directed to a system in which sodium circulates as described above, and directly detects the temperature of the temperature control system by using the circulating sodium temperature, and determines the difference between the control target temperature and the detected temperature. And turn on the electric heater according to the operating status and priority.
Since an electric heater that needs to be cut off is defined and the deviation is controlled to a specified value, it is possible to perform temperature control with high accuracy and eliminate unnecessary power consumption.

In other words, in the conventional temperature control, the temperature signal from the thermocouple provided on the pipe surface of each block was received, and the electric heater was turned on and off completely independently for each block, so the sodium temperature in the system is highly accurate. It was difficult to control, but in the present invention, the sodium temperature is directly detected at one point in the sodium circulation system, and it is decided to turn on / off the electric heater of each block based on a predetermined priority order. Various controls can be realized.

Further, in the present invention, the amount of heat input in the circulation system is entirely controlled, so that the sodium temperature is stabilized at the control target temperature. When the system sodium temperature is stable, there is no need to turn on or off the electric heater unnecessarily, and the saturation control is substantially achieved. Therefore, there is an effect of eliminating unnecessary power consumption.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a temperature control device for a sodium circulation system according to the present invention, and FIG. 2 is a flow sheet showing an algorithm of its operation. 10 …… Main cooler, 12 …… Main circulation pump, 14 …… Intermediate heat exchanger, 16 …… Piping, 18 …… Heat insulation material, 20 …… Electric heater,
22 …… switch, 24 …… power supply, 26 …… temperature detector,
34: control target temperature setting means, 32: deviation detection means, 36
...... Switch selection means, 38 ...... electric heater priority order and storage means for turning on and off, 40 ...... switch drive circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Mitsuaki Sato, 4002, Narita-cho, Oarai-cho, Higashi-Ibaraki-gun, Ibaraki Prefecture Inside the Oarai Engineering Center, Reactor and Nuclear Fuel Development Corporation (56) Reference JP-A-52-145691 (JP) , A) JP-A-56-9811 (JP, A) JP-A-62-168359 (JP, A)

Claims (1)

[Claims] 1. A sodium equipment or pipe forming a sodium circulation system is divided into a large number of blocks, and each block is connected to an electric heater installed on the surface of the equipment or the pipe and connected to each electric heater. Switch for controlling the operation of the system, a temperature detector for directly detecting the system sodium temperature at one point in the sodium circulation system, a control target temperature setting means, and a deviation detection for obtaining a deviation between the detected temperature and the control target temperature. Means, storage means for storing the priority order and turning-on / off states of a large number of electric heaters, and switch selecting means for determining the electric heaters to be turned on / off according to the output of the deviation detecting means and the contents of the storing means. A switch drive circuit for driving a corresponding switch according to the output of the switch selection means. Degree control device.