JPS5929761B2 - Steam pressure control device during hot standby in nuclear power plants - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is particularly applicable to the wet standby state of a nuclear reactor plant (a state in which the reactor has stopped reacting but the coolant is still circulating and is waiting for the plant to restart), etc. The present invention relates to a device for controlling steam pressure in.

In a nuclear reactor plant, once the reactor and related equipment are completely stopped, it takes time to restart them.

In particular, in fast breeder reactors that use liquid metal as a coolant, various preparation work is required before restarting the coolant system, such as preheating the coolant system before introducing high temperature liquid metal into the coolant system. Unable to reboot quickly.

Therefore, if a restart is expected, the coolant must be circulated and the steam pressure maintained at a predetermined value even after the reactor output has been shut down, and the restart can be carried out promptly to meet plant demand. There is a need to.

The present invention has been made in order to satisfy the functions required for a nuclear reactor plant as described above.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an example of a nuclear couplant controlled by this embodiment, which cools the reactor core 3 into which the control rods 2 driven by the control rod drive device 1 are inserted, and heats up the nuclear reaction. The coolant that conveys the heat to the outside of the furnace circulates through a primary circulation system 6 that passes through an intermediate heat exchanger 4 and a circulation pump 5.

In the intermediate heat exchanger 4, the secondary coolant that has received heat from the coolant flowing through the primary circulation system 6 is divided into a superheater 7 and a reheater 8, joins together, flows through an evaporator 9, and is circulated. It passes through the pump 10, returns to the intermediate heat exchanger 4, and circulates through the secondary circulation system 11 consisting of the above-mentioned route during operation of the nuclear reactor.

The feed water given a lift by the feed water pump 12 flows through the steam-water circulation system 13, receives heat from the high temperature secondary coolant flowing through the secondary circulation system 11 in the evaporator 9, becomes steam, and is turned into steam in the superheater 7. It receives heat from the secondary coolant and becomes superheated steam.

Furthermore, it passes through the governor valve 14 to drive the (high pressure) turbine 15, and then enters the reheater 8 where it is heated by the secondary coolant, drives the (low pressure) turbine 16, and drives the condenser etc. (not shown). Then, it returns to the water supply pump 12.

Feed water or steam circulates through the steam-water circulation system 13 following the path during operation of the nuclear reactor.

In the wet standby state or transition thereto, the nuclear reaction within the reactor core 3 is stopped or is being stopped by the control rods 2, but the coolant is circulated through the primary circulation system 6 and the secondary circulation system 11, respectively. The feed water continues to be supplied to the evaporator 9.

FIG. 2 shows an embodiment of the invention.

As shown in FIG. 2, a steam-water separator 20 is installed between the evaporator 9 and the superheater 70 of the steam-water circulation system 13, and the air-water separator 20 is connected to a set water level via a subtractor 21. Signal generator 22
A water level detector 23 is provided which communicates with the water level.

The subtracter 21, the set water level signal generator 22, and the water level detector 23 form a water level discriminator of the steam/water separator 20.

A pressure detector 24 provided on the outlet side of the evaporator 9 of the steam-water circulation system 13 is connected to a steam pressure setting device 2 via a comparator 25.
6, while the comparator 25 is connected to the positive input terminal 2γa of the switch 27 and the negative input terminal 28b of the switch 28.

The output terminals of the switching devices 27 and 28 are connected to a PID controller 29.
, 30, respectively, and the PID controllers 29 and 30 respectively communicate with a steam bypass valve 31 provided between the steam separator 20 and the superheater T and a drain valve 32 of the steam separator 20. ing.

The negative input terminal 27b of the switch 21 is connected to a valve full-close signal generator 33, and the valve full-close signal generator 33, the switch 21, and the PID regulator 29 form a bypass valve controller. There is.

Similarly, a valve close signal generator 34, which is connected to the positive input terminal 28a of the switch 28, forms, together with the switch 28 and the PID regulator 30, a drain valve controller.

In this embodiment having the above-described configuration, the water level detector 23 detects the water level of the steam/water separator 20, and the detection signal is sent to the subtractor 21 as a water level setting signal of the setting water level signal generator 22. When the setting signal is larger than the detection signal, the output of the subtracter 21 connects the output terminals of the switches 27 and 28 to the positive input terminal 2γa.

28a, and when the other is small, the output terminal of the switch 27.28 is connected to the negative input terminals 27b and 28b.

Since the thermal output of the core 3 decreases or becomes zero during the wet standby state and transition thereto, if the water supply to the evaporator 9 is kept constant, the evaporator 9
The dryness of the outlet steam decreases and it begins to become wet, and as a result, the water level in the steam-water separator 20 rises as shown in the opening of FIG. 3, and exceeds the set water level when a predetermined time T has elapsed.

Therefore, within time T, the output of the subtracter 21 connects the output terminals of the switching devices 27 and 28 to the positive input terminal 27a.

28a.

Therefore, the set pressure of steam in the comparator 25 is set constant as shown in FIG.
A deviation output obtained by comparing the steam pressure detected by the pressure detector 24 is input to the PID controller 29, and after being subjected to proportional differentiation and integration, the valve opening degree of the steam bypass valve 31 is adjusted to make the steam pressure match the set pressure.

In other words, when the detected steam pressure is greater than the set pressure,
The output of PID regulator 29 increases and steam bypass valve 31
Increase the valve opening to remove more steam and lower the steam pressure to the set pressure.

On the other hand, when the steam pressure is lower than the set pressure, the output of the PID regulator 29 decreases, the valve opening of the steam bypass valve 31 is reduced, and the steam pressure is raised to the set pressure.

The changes in the set pressure, steam pressure, output of the PID regulator 29, and valve opening degree of the steam bypass valve 31 described above are shown in curves a, b, c, and d in FIGS. 3C and 2, respectively.

In order to make it easier to understand the aforementioned phenomenon, the curves c, d
Although it is overdrawn, it is actually a minute change.

During the change, the PID controller 30 is activated by the valve fully closed signal generator 3.
4, the drain valve 32 is closed.

After time T has elapsed, the sign of the output of the subtractor 21 is reversed, so the PID regulator 29 is connected to the valve fully closed signal generator 33, the steam bypass valve 31 is closed, and the PID regulator 3
0 is connected to the comparator 25, and the valve opening degree of the drain valve 32 is adjusted by the deviation output of the comparator 25, the water level in the steam-water separator 20 is raised and lowered, and the steam pressure is made equal to the set pressure.

Changes in the output of the PID regulator 30 and the opening degree of the drain valve 32 are shown by curves e and f in FIG. 3E.

As described above, according to this embodiment, since the steam pressure at the outlet of the evaporator 9 is maintained at a predetermined set pressure, the time required for restarting the plant can be significantly shortened.

As described above in detail in connection with the embodiments, the present invention includes:
It is installed in a steam-water circulation system that corresponds to the heat medium system passing through the nuclear reactor and includes an evaporator, a steam-water separator, and a superheater. a drain valve controller that adjusts the opening degree of a drain valve of the steam water separator; and a valve opening degree of a steam bypass valve connected to the water level discriminator and disposed between the steam water separator and the superheater. and a steam pressure discriminator including a pressure detector connected to the bypass valve controller and the drain valve controller and provided at the evaporator outlet during wet standby of the atomic coupler. According to the present invention, the steam pressure control device controls the steam pressure at the outlet of the evaporator by appropriately selecting the drain valve and the steam bypass valve according to the water level of the steam separator and adjusting their valve opening degrees. Since it can be held at a predetermined value during wet standby or transition to it, the time required to restart a nuclear reactor plant can be greatly reduced, allowing the plant to be restarted quickly and adapted to meet plant demand. can be met.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a system diagram of an atomic couplant controlled by an embodiment of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention,
FIG. 3 A, 2, C, 2 and H are explanatory views of the operation of the embodiment of the present invention. 3... Core, 6... Primary circulation system, 7.
...Superheater, 9...Evaporator, 11...
...Secondary circulation system, 13...Steam-water circulation system,
20...Steam water separator, 21...Subtractor, 22...Setting water level signal generator, 23...
...Water level detector, 24...Pressure detector, 25.
... Comparator, 26 ... Steam pressure setting device,
27, 28...Switcher, 29.30...
・PID controller, 31...Steam bypass valve, 3
2... Drain valve, 33, 34... Valve fully closed signal generator.

Claims (1)

[Claims] 1 Corresponding to the heat medium system passing through the reactor, a steam-water circulation system including an evaporator, a steam-water separator, and a superheater is provided, and is connected to the water level discriminator of the steam-water separator and the water level discriminator. A drain valve controller that adjusts the opening degree of a drain valve of the air/water separator, and a valve opening of a steam bypass valve connected to the water level discriminator and disposed between the air/water separator and the superheater. and a vapor pressure discriminator including a pressure detector connected to the bypass valve controller and the drain valve controller and provided at the evaporator outlet. Coplant's wet standby steam pressure control device.