CN214279616U - Prevent excessive nuclear power station protection system of steam generator - Google Patents

Abstract

The utility model discloses a nuclear power station protection system for preventing steam generator overflow, which comprises a steam generator, a primary loop system, a secondary loop system and a steam release valve, wherein the primary loop system and the secondary loop system are respectively connected with the steam generator; and the water level control unit is electrically connected with the water level monitoring sensor and the steam release valve and is used for controlling the opening of the steam release valve to discharge steam when the water level of the two-loop system in the steam generator rises to a first threshold value. The utility model discloses set up water level monitoring sensor and monitored two return circuit system's in the steam generator water level, risen to the first threshold value of settlement when the water level, steam release valve is opened in order to discharge steam in the control of water level control unit, and it is excessive that the below emission steam of this water level can not cause radioactive liquid, has ensured safe emission.

Description

Prevent excessive nuclear power station protection system of steam generator

Technical Field

The utility model belongs to the technical field of the nuclear power station protection, concretely relates to prevent excessive nuclear power station protection system of steam generator.

Background

In a nuclear power plant using high pressure safety injection, such as a CPR1000 nuclear power plant, a steam generator heat transfer tube rupture (SGTR) accident occurs, and then emergency shutdown and safety injection signals are triggered. At the moment, the emergency shutdown signal triggers the air inlet valve of the two-loop steam turbine to be closed, the pressure of the two loops rises, and the steam atmospheric emission system (GCTa) or the safety valve is triggered to be opened to be stabilized at a certain pressure value, so that the overlarge pressure value of the two loops is avoided. And the pressure drop of the primary circuit is maintained at a higher pressure value due to the flow injection of the high-pressure safety injection pressure head, namely, a larger pressure difference (before 2500 s) exists between the primary circuit and the secondary circuit, as shown in figure 1.

The primary circuit and the secondary circuit have larger pressure difference, which causes larger flow rate leaking from the primary circuit to the secondary circuit through the rupture heat transfer pipe, and the injection of the feed water side of the secondary circuit, thereby causing the secondary circuit to generate overflow high risk event. Once the overflow occurs in the two loops, the radioactive liquid in the first loop is released to the atmosphere through the damaged heat transfer tube, the two loops, the GCTa or the safety valve. The emission from a typical accident is shown in fig. 2, where the radioactive liquid directly to the environment results in a much higher radioactive equivalent than the same mass of radioactive vapor.

Therefore, it is desirable to avoid as much as possible the direct discharge of radioactive liquid due to the overflow of the two circuits.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a technical problem that will solve lies in, current nuclear power station system in the SGTR accident, may be to the problem of the radioactive liquid of outer discharge. In order to solve the technical problem, the utility model provides a prevent excessive nuclear power station protection system of steam generator, including steam generator, respectively with a loop system, two loop system that steam generator connects and be used for control the steam release valve of two loop system pressure still includes:

the water level monitoring sensor is used for monitoring the water level of the secondary loop system in the steam generator;

and the water level control unit is electrically connected with the water level monitoring sensor and the steam release valve and is used for controlling the opening of the steam release valve to discharge steam when the water level of the two-loop system in the steam generator rises to a first threshold value.

The nuclear power station protection system is characterized in that N steam generators are arranged, wherein N is an integer greater than or equal to 2;

each steam generator is connected in parallel in a loop system and a secondary loop system to respectively form N primary loop branches with the same pressure and N secondary loop branches with the same pressure;

each secondary circuit branch is correspondingly provided with a water level monitoring sensor and a steam release valve;

and the water level control unit is electrically connected with the water level monitoring sensor and the steam release valve of each secondary circuit branch and is used for controlling to open all the steam release valves to discharge steam when the water level of any one secondary circuit branch rises to a first threshold value.

The nuclear power station protection system is characterized in that three steam generators are arranged;

each of the three primary circuit legs includes a coolant flow inlet and a coolant flow outlet, the three primary circuit legs being in communication at the coolant inlet and in communication at the coolant outlet;

each two-loop branch comprises a water supply opening and a steam outlet, and the three two-loop branches are communicated at the water supply opening and communicated at the steam outlet.

The nuclear power plant protection system, wherein the water level control unit is further configured to close all the steam release valves when the water level of the two-circuit system drops to a second threshold, and the first threshold is greater than the second threshold.

Implement the embodiment of the utility model provides a, following beneficial effect has: the utility model discloses set up water level monitoring sensor and monitored two return circuit system's in to steam generator water level, when the water level rose to the first threshold value of settlement, "SGa water level height" signal triggered, water level control unit control was opened the steam release valve in order to discharge steam, and the following discharge steam of this water level can not cause radioactive liquid excessive, has ensured safe emission, has overcome current nuclear power station system in the SGTR accident, owing to there is not the water level control can be the problem of external discharge radioactive liquid.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a graph comparing pressure values of a first circuit system and a second circuit system in the event of a burst accident of a heat transfer tube of a steam generator.

Fig. 2 is a graph comparing the discharge amount of the two cases of discharging gas and discharging liquid.

Fig. 3 is a schematic structural diagram of a nuclear power plant protection system for preventing an overflow of a steam generator according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a nuclear power plant protection system for preventing the steam generator from overflowing according to the second embodiment of the present invention.

Detailed Description

The following description of the embodiments refers to the accompanying drawings, which are included to illustrate specific embodiments in which the invention may be practiced.

Referring to fig. 3, a nuclear power station protection system for preventing a steam generator from overflowing includes a steam generator 1, a loop system 2, a secondary loop system 3, a steam release valve K, a water level monitoring sensor 4, and a water level control unit 5. The coolant (cooling water) in the primary loop system 2 flows through the reactor to generate high-temperature and high-pressure steam, heat energy is brought into the steam generator 1 to heat the water in the secondary loop system 3 to generate steam, and the steam enters a steam turbine through the secondary loop to generate electricity (the part does not relate to the invention point and is not shown in the figure). The water level monitoring sensor 4 is used for monitoring the water level of the two-loop system in the steam generator 1; the water level control unit 5 is electrically connected to the water level monitoring sensor 4 and the steam release valve K, and is configured to control the steam release valve K to open to discharge steam when the water level of the two-circuit system 3 in the steam generator 1 rises to a first threshold (upper water level limit), and further, to close the steam release valve K to stop discharging steam when the water level falls to a set second threshold (lower water level limit).

Specifically, when a heat transfer pipe of the steam generator 1 is broken (SGTR), an emergency shutdown is triggered, an air inlet valve (not related to the invention point, not shown in the figure) of a steam turbine of the two-circuit system 3 is triggered to be closed, the pressure in the two-circuit system 3 is gradually increased, and when the pressure in the two-circuit system 3 reaches a set value (about 7.85MPa), a steam atmosphere exhaust system (GCTa) or a steam release valve K is opened to exhaust gas outwards, so that overpressure is avoided. In the prior art, because a water level signal is not adopted for protection, the water level can overflow along with the opening of the steam release valve K when exceeding a certain position. And the utility model discloses in, set up water level monitoring sensor 4 and monitored two loop system's in steam generator 1 water level, when the water level rose to the first threshold value of settlement, "SGa water level is high" signal trigger, steam release valve K was opened in order to discharge steam in the control of water level control unit 5, and it is excessive that the below emission steam of this water level can not cause radioactive liquid, has ensured safe emission. Further, as the steam is discharged, when the water level is lowered to a set second threshold value, and a "SG water level low" signal is triggered, the water level control unit 5 controls to close the steam release valve K, stopping the discharge of the steam.

Referring to fig. 4, a schematic diagram of a nuclear power plant protection system for preventing overflow of steam generators according to a second embodiment of the present invention includes three steam generators a/B/C, each steam generator is connected in parallel in a loop system and a secondary loop system to form three primary loop branches and three secondary loop branches, specifically AI1, BI1, and CI1, which are connected to each other and are coolant inlets of a primary loop, AO1, BO1, and CO1 which are connected to each other and coolant outlets of a primary loop. AI2, BI2, CI2 communicate, are supplied water by same feed pump, for the water supply mouth of two return circuits, AO2, BO2, CO2 communicate, for the steam outflow of two return circuits, guarantee that the pressure of two return circuits is unanimous in three steam generator, all are connected to the steam turbine. Three branches in the second loop are correspondingly provided with a water level monitoring sensor 4 and a steam release valve K; and a water level control unit 5 electrically connected with each water level monitoring sensor 4 and the steam release valve K, and controlling the steam release valves K of the three branches to be opened to discharge steam when the water level of the two branches rises to a first threshold value when any steam generator heat transfer pipe is broken. Except for a damaged branch, the exhaust of a perfect branch steam atmospheric emission system (GCTa) is beneficial to improving the cooling and pressure reduction efficiency and avoiding the overflow of radioactive liquid.

The above is explained by taking three branches as an example, so that the explanation can be performed, and the technical scheme of two or more branches is obtained, which is not repeated herein.

The steam release valve K may be opened and closed several times before operator intervention; when an operator starts to act, the damaged SG can be manually isolated, the opening setting value of the steam release valve K is increased to 9.0MPa abs, and the steam is exhausted through a perfect branch GCTa to cool a primary loop; and closing the high-pressure safety injection to reduce the pressure of the primary circuit, and stopping primary and secondary leakage by spraying through the pressure stabilizer after the high-pressure safety injection pump stops.

As can be seen from the above description, compared with the prior art, the beneficial effects of the utility model reside in: the water level monitoring sensor 4 is arranged to monitor the water level of the two-loop system in the steam generator 1, when the water level rises to a set first threshold value and a 'SGa water level high' signal is triggered, the water level control unit 5 controls to open the steam release valve K to discharge steam, the discharge steam below the water level can not cause the overflow of radioactive liquid, the safe discharge is ensured, the problem that the radioactive liquid can be discharged outwards due to the fact that no water level monitoring exists in the SGTR accident of the existing nuclear power station system is overcome.

The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the scope of the invention, which is defined by the appended claims.

Claims (4)

1. A nuclear power station protection system for preventing a steam generator from overflowing comprises the steam generator, a primary loop system, a secondary loop system and a steam release valve, wherein the primary loop system, the secondary loop system and the steam release valve are respectively connected with the steam generator, the steam release valve is used for controlling the pressure of the secondary loop system, and the nuclear power station protection system is characterized by further comprising:

the water level monitoring sensor is used for monitoring the water level of the secondary loop system in the steam generator;

and the water level control unit is electrically connected with the water level monitoring sensor and the steam release valve and is used for controlling the opening of the steam release valve to discharge steam when the water level of the two-loop system in the steam generator rises to a first threshold value.

2. The nuclear power plant protection system according to claim 1, wherein the number of the steam generators is N, N being an integer of 2 or more;

each steam generator is connected in parallel in a loop system and a secondary loop system to respectively form N primary loop branches with the same pressure and N secondary loop branches with the same pressure;

each secondary circuit branch is correspondingly provided with a water level monitoring sensor and a steam release valve;

and the water level control unit is electrically connected with the water level monitoring sensor and the steam release valve of each secondary circuit branch and is used for controlling to open all the steam release valves to discharge steam when the water level of any one secondary circuit branch rises to a first threshold value.

3. The nuclear power plant protection system of claim 2, wherein there are three steam generators;

each loop leg includes a coolant flow inlet and a coolant flow outlet, the three loop legs communicating at the coolant flow inlet and communicating at the coolant flow outlet;

each two-loop branch comprises a water supply opening and a steam outlet, and the three two-loop branches are communicated at the water supply opening and communicated at the steam outlet.

4. The nuclear power plant protection system of claim 1 or 2, wherein the water level control unit is further configured to close all the steam release valves when the water level of the two-circuit system falls to a second threshold, the first threshold being greater than the second threshold.

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