CN109524140B

CN109524140B - Nuclear power station primary loop abnormal state tracking and monitoring method and system

Info

Publication number: CN109524140B
Application number: CN201811324095.7A
Authority: CN
Inventors: 王振营; 黄宇; 龚铭游; 刘琉; 焦振营; 张建文
Original assignee: China General Nuclear Power Corp; China Nuclear Power Engineering Co Ltd; CGN Power Co Ltd; Shenzhen China Guangdong Nuclear Engineering Design Co Ltd
Current assignee: China General Nuclear Power Corp; China Nuclear Power Engineering Co Ltd; CGN Power Co Ltd; Shenzhen China Guangdong Nuclear Engineering Design Co Ltd
Priority date: 2018-11-08
Filing date: 2018-11-08
Publication date: 2020-04-17
Anticipated expiration: 2038-11-08
Also published as: CN109524140A

Abstract

The invention discloses a tracking and monitoring method and a system for an abnormal state of a loop of a nuclear power station. The method comprises the following steps: constructing a temperature and pressure operation limiting model in the loop abnormal state according to the operation characteristics and the operation limiting conditions in the loop abnormal state; selecting a corresponding loop temperature and pressure operation limiting model according to the loop main pump operation state, the executing accident operation regulation state and the P signal state; and acquiring the running state of the loop in the abnormal state, and adjusting the running strategy of the loop in real time according to the selected temperature and pressure running limit model of the loop in the abnormal state. The method and the system construct a temperature and pressure operation limiting model under the abnormal state of the primary circuit by combining the operation characteristics and the operation limiting conditions under the abnormal state of the primary circuit, can assist an operator to conveniently and intuitively monitor the operation state of the primary circuit during the execution of the accident operation regulation, timely adjust a proper operation strategy and stably retreat to a safe state.

Description

Nuclear power station primary loop abnormal state tracking and monitoring method and system

Technical Field

The invention relates to the technical field of nuclear power station safety, in particular to a method and a system for tracking and monitoring an abnormal state of a primary loop of a nuclear power station.

Background

A nuclear power plant is a large complex device composed of hundreds of systems, and is used for realizing the process of safely and controllably converting heat energy generated by nuclear fuel fission reaction into electric energy, and each system is endowed with specific functions, such as a chemical and volume control system for realizing the control of the water charge of a primary loop coolant and the functions of purification, chemical addition and the like of the primary loop coolant. The commissioning and decommissioning of these system functions requires that certain system operating conditions be observed, e.g. the residual heat removal system is allowed to connect and commission the circuit when the circuit pressure is below 32barg and the circuit temperature is below 120 ℃. In fact, the operation of the nuclear power plant requires compliance with a series of operating constraints, either determined by the operating conditions of the aforementioned systems, or deriving from specific requirements of the important plants (such as limiting the thermal stresses to which the reactor pressure vessel is subjected, the heating and cooling rates of the primary circuit must not exceed 56 ℃/h). Exceeding operational limits means that the nuclear power plant may be exposed to a risk of damage to system equipment or a potential safety risk.

The loop temperature and pressure operation limiting diagram under the normal operation state displays a series of operation boundaries during the normal operation of the unit in a graphic mode, is a convenient tool for tracking the operation state of the unit, and an operator can clearly and intuitively track the change path and trend of the loop parameter by using the loop temperature and pressure operation limiting diagram during the process of executing normal operation rules to control the start or stop of the unit, and is mature and widely applied to a nuclear power plant at present.

However, under a fault or accident condition (the reactor is in an emergency shutdown), the temperature and pressure operation limiting diagram of the primary circuit under the normal operation condition is no longer applicable, actually, the fault or accident condition is often accompanied by typical accidents such as important equipment fault or breach, and the system functions and the operation limiting conditions of the system which need to be used under the fault or accident condition are also greatly different from those under the normal operation condition. How to monitor the evolution trend of a loop parameter during the set withdrawal under the fault or accident condition becomes one of the problems of the nuclear power plant accident operation regulation design and the important attention of the human-computer interface design.

Disclosure of Invention

In order to solve the problems in the prior art, the embodiment of the invention provides a method and a system for tracking and monitoring an abnormal state of a primary loop of a nuclear power station. The technical scheme is as follows:

in one aspect, an embodiment of the present invention provides a method for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant, where the method includes:

constructing a temperature and pressure operation limiting model in the abnormal state of a primary loop of the nuclear power plant according to preset operation characteristics and operation limiting conditions in the abnormal state of the primary loop;

selecting a corresponding loop temperature and pressure operation limiting model according to the running state of a loop main pump of the nuclear power station, the running state of an executing accident operation rule and the state of a P signal, wherein the P signal is used for influencing the triggering condition of a safety injection system of the nuclear power station;

and acquiring the running state of a loop of the nuclear power station in the abnormal state, and adjusting the running strategy of the loop in real time according to the selected temperature and pressure running limit model in the abnormal state of the loop until the loop is stably withdrawn to the safe state.

In the method for tracking and monitoring an abnormal state of a loop of a nuclear power plant according to an embodiment of the present invention, the abnormal state includes: natural circulation conditions, fault conditions, and accident conditions that lose the forced circulation function.

In the method for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant according to an embodiment of the present invention, when the abnormal state is a natural circulation condition, the model for limiting the operation of the primary loop in the abnormal state under the temperature and pressure includes: the system comprises a loop temperature and pressure operation limiting range, wherein the loop temperature and pressure operation limiting range is composed of a saturation curve of water in a loop, a loop pressure low limiting line, a loop pressure high limiting line, a loop steam generator primary side differential pressure limiting line, a loop steam generator secondary side differential pressure limiting line, a loop temperature limiting line, a loop voltage stabilizer safety valve setting value curve, a loop waste heat discharge system access temperature limiting line, a loop waste heat discharge system connection back pressure upper limit limiting line, a loop voltage stabilizer fluctuation pipe thermal stress limiting line and a loop minimum temperature limiting line.

In the method for tracking and monitoring an abnormal state of a primary circuit of a nuclear power plant according to an embodiment of the present invention, when the abnormal state is a fault condition, the model for limiting the operation of the primary circuit in the abnormal state under temperature and pressure includes: a return circuit temperature and pressure operation restriction range that constitutes by saturation curve, trouble operating mode restoration line, return circuit step-down operation suggestion line, return circuit step-down operation restriction line of a return circuit normal water, trouble operating mode restoration line includes: forbidding a boost line, a supercooling boundary limit line and a loop main pump limit line.

In the method for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant according to an embodiment of the present invention, when the abnormal state is an accident condition and the P signal is not valid, the operation restriction model for limiting the temperature and pressure in the abnormal state of the primary loop includes: a loop temperature and pressure operation limiting range is formed by a loop water saturation curve, a first operation lower limit limiting line, a first accident condition repairing limiting line, a first operation upper limit limiting line and a loop voltage stabilizer surge pipe thermal stress limiting line;

when the abnormal state is an accident condition and the P signal is effective, the temperature and pressure operation limiting model in the abnormal state of the primary circuit comprises the following steps: and the temperature and pressure operation limiting range of the loop is formed by a saturation curve of water in the loop, a second operation lower limit limiting line, a second accident condition repairing limiting line, a second operation upper limit limiting line and a pressure vessel thermal stress limiting line.

On the other hand, an embodiment of the present invention provides a system for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant, including:

the system comprises a construction module, a control module and a control module, wherein the construction module is used for constructing a temperature and pressure operation limiting model in a loop abnormal state according to preset operation characteristics and operation limiting conditions in the loop abnormal state of the nuclear power station;

the system comprises a selection module, a control module and a control module, wherein the selection module is used for selecting a corresponding loop temperature and pressure operation limiting model according to the operation state of a loop main pump of the nuclear power station, the state of an executing accident operation regulation and the state of a P signal, and the P signal is used for influencing the triggering condition of a safety injection system of the nuclear power station;

and the processing module is used for acquiring the running state of a loop of the nuclear power station in the abnormal state, and adjusting the running strategy of the loop in real time according to the selected temperature and pressure running limit model in the abnormal state of the loop until the loop is stably withdrawn to the safe state.

In the above system for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant according to an embodiment of the present invention, the abnormal state includes: natural circulation conditions, fault conditions, and accident conditions that lose the forced circulation function.

In the system for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant according to an embodiment of the present invention, when the abnormal state is a natural circulation condition, the model for limiting the operation of the primary loop in the abnormal state under the temperature and pressure includes: the system comprises a loop temperature and pressure operation limiting range, wherein the loop temperature and pressure operation limiting range is composed of a saturation curve of water in a loop, a loop pressure low limiting line, a loop pressure high limiting line, a loop steam generator primary side differential pressure limiting line, a loop steam generator secondary side differential pressure limiting line, a loop temperature limiting line, a loop voltage stabilizer safety valve setting value curve, a loop waste heat discharge system access temperature limiting line, a loop waste heat discharge system connection back pressure upper limit limiting line, a loop voltage stabilizer fluctuation pipe thermal stress limiting line and a loop minimum temperature limiting line.

In the system for tracking and monitoring an abnormal state of a primary circuit of a nuclear power plant according to an embodiment of the present invention, when the abnormal state is a fault condition, the model for limiting the operation of the primary circuit in the abnormal state under the temperature and pressure comprises: a return circuit temperature and pressure operation restriction range that constitutes by saturation curve, trouble operating mode restoration line, return circuit step-down operation suggestion line, return circuit step-down operation restriction line of a return circuit normal water, trouble operating mode restoration line includes: forbidding a boost line, a supercooling boundary limit line and a loop main pump limit line.

In the system for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant according to an embodiment of the present invention, when the abnormal state is an accident condition and the P signal is not valid, the operation restriction model for limiting the temperature and pressure in the abnormal state of the primary loop includes: a loop temperature and pressure operation limiting range is formed by a loop water saturation curve, a first operation lower limit limiting line, a first accident condition repairing limiting line, a first operation upper limit limiting line and a loop voltage stabilizer surge pipe thermal stress limiting line;

The technical scheme provided by the embodiment of the invention has the following beneficial effects:

the method comprises the steps of constructing a temperature and pressure operation limiting model under a loop abnormal state by combining operation characteristics and operation limiting conditions under the loop abnormal state of the nuclear power station, drawing a loop temperature and pressure operation limiting diagram under a natural circulation working condition, a fault working condition and an accident working condition, constructing a loop operation state automatic tracking method under the fault and accident working condition based on the operation limiting diagrams, utilizing the loop state automatic tracking method after the accident, assisting an operator to conveniently and intuitively monitor the operation state of a loop during the execution of an accident operation rule, tracking the evolution process and trend of the loop state, timely adjusting a proper operation strategy according to the accident operation rule when the operation point is in different regions, enabling the loop state to be always under monitoring, and stably withdrawing to a safe state.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a flowchart of a method for tracking and monitoring an abnormal state of a loop of a nuclear power plant according to a first embodiment of the present invention;

FIG. 2 is a temperature and pressure operating limit diagram for a loop under natural circulation conditions in accordance with an embodiment of the present invention;

FIG. 3 is a temperature and pressure operating limit diagram for a circuit under fault conditions in accordance with an embodiment of the present invention;

FIG. 4 is a graph illustrating the operating limits of circuit temperature and pressure during an accident condition when P26 is not active, according to an embodiment of the present invention;

FIG. 5 is a graph illustrating the operating limits of the circuit temperature and pressure during an accident condition when P26 has been enabled in accordance with an embodiment of the present invention;

FIG. 6 is a schematic diagram of a loop temperature and pressure operating limit map selection logic according to one embodiment of the present invention;

fig. 7 is a schematic structural diagram of a system for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant according to a second embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example one

An embodiment of the present invention provides a method for tracking and monitoring an abnormal state of a loop in a nuclear power plant, and referring to fig. 1, the method may include:

and step S11, constructing a temperature and pressure operation limiting model in the loop abnormal state according to the preset operation characteristics and operation limiting conditions in the loop abnormal state of the nuclear power station.

In this embodiment, the operation restriction conditions refer to various restriction requirements to be observed during the operation of the nuclear power plant, and these restriction conditions may be derived from requirements on unit safety, operation of important equipment, restriction on system operation, and the like. Violations of operational constraints mean that the plant may be at risk for safety, unexpected shutdown, and equipment damage. The main equipment of a circuit includes: the device comprises a main pump, a reactor core, a pressure vessel, an evaporator, a pressure stabilizer and the like.

In this embodiment, the concept of the loop temperature and pressure operation limiting map may be extended to the abnormal state to form a loop temperature and pressure operation limiting model in the abnormal state.

Specifically, the abnormal state may include: natural circulation conditions, fault conditions, and accident conditions that lose the forced circulation function.

In this embodiment, natural circulation refers to the situation where all reactor coolant pump (main pump) circuits will establish natural circulation due to head differences in steam generator and core placement, leading out a shutdown resulting in loss of forced circulation of the core. The fault conditions cover typical nuclear power plant faults such as loss of power or control power, unavailability of system functions due to a certain equipment fault, and the like.

Further, when the abnormal state is a natural circulation condition, the temperature and pressure operation limiting model in the abnormal state of the loop comprises: the system comprises a loop temperature and pressure operation limiting range, wherein the loop temperature and pressure operation limiting range is composed of a saturation curve of water in a loop, a loop pressure low limiting line, a loop pressure high limiting line, a loop steam generator primary side differential pressure limiting line, a loop steam generator secondary side differential pressure limiting line, a loop temperature limiting line, a loop voltage stabilizer safety valve setting value curve, a loop waste heat discharge system access temperature limiting line, a loop waste heat discharge system connection back pressure upper limit limiting line, a loop voltage stabilizer fluctuation pipe thermal stress limiting line and a loop minimum temperature limiting line.

In this embodiment, when the loop loses the forced circulation (for example, all the main pumps are shut down due to loss of power outside the plant), the heat of the core is mainly led out through the steam generator by the natural circulation, the loop temperature and pressure operation limiting diagram under the normal operation condition is no longer applicable, and the loop temperature and pressure operation limiting diagram under the natural circulation condition needs to be constructed by considering the characteristics of the natural circulation so as to assist the operator to track the unit operation state under the natural circulation condition.

The maximum value of the temperature of the coolant at the core outlet, T RIC max, is selected as a representative loop temperature, and the loop pressure measuring channel, P RCP, installed on the main pipeline is selected as a representative loop pressure. Taking a certain pressurized water reactor nuclear power unit as an example, a loop temperature and pressure operation limiting diagram under the natural circulation working condition is drawn, as shown in fig. 2. The individual limiting lines in the figure are illustrated as follows:

A) the method comprises the following steps Saturation curve of water in circuit

B) The method comprises the following steps Loop pressure right (low) limiting line

And (3) selecting a certain supercooling margin (such as a margin of 20 ℃) relative to the saturation curve as a basis for determining a pressure right limit line of the primary circuit, so as to ensure that the error of a measuring channel cannot cause the loss of a cooling boundary. At low pressure, the chosen supercooling margin (20 ℃) is not able to guarantee that the supercooling margin is not lost due to excessive measurement errors, and therefore the curve is modified at low pressure to guarantee that the supercooling margin is not lost.

C) The method comprises the following steps Left (high) limiting line for loop pressure

The basis of the limit line is to avoid the risk of brittle fracture caused by pressure-bearing thermal shock which can be born by the reactor pressure vessel after the accident (if the supercooling boundary is limited to be lower than 140 ℃, and the coolant supercooling degree exceeds the value, the primary circuit is considered to be extremely supercooled, and the reactor pressure vessel has the risk of brittle fracture).

D and E): primary/secondary side differential pressure limiting line of primary loop steam generator

Under the natural circulation condition, the temperature of the cold pipe section is approximately equal to the temperature of the secondary side coolant of the steam generator, the secondary side coolant of the steam generator is generally in a saturated state, and the saturated temperature depends on the pressure of the steam generator.

In the natural circulation state, the temperature difference between the cold pipe section and the hot pipe section depends on the residual heat power level, which is related to factors such as initial power, shutdown time and burnup, so that the temperature difference is different in different states. However, in general, the temperature difference does not exceed a certain limit (e.g., 25 ℃).

Here, two steam generator primary/secondary differential pressure limit lines are drawn, corresponding to the case of a heat pipe section/cold pipe section temperature difference of 0 ℃ and a certain limit (e.g. 25 ℃), respectively, which delimit a region (region 2 in fig. 2) in which it is necessary to check that the steam generator primary/secondary differential pressure is below a certain design limit (e.g. 110 bar).

F and G): temperature limiting line of loop

The temperature of the cold pipe section is lower than the saturation temperature corresponding to the safety valve setting value of the steam generator (for example, the setting pressure of the safety valve of the steam generator is 89barG, and the corresponding saturation temperature is 303 ℃). Considering that the temperature difference between the hot and cold pipe sections does not generally exceed a certain limit (e.g. 25 ℃), there is also an upper limit for the maximum core outlet temperature (303 ℃ +25 ℃ ═ 328 ℃). These two temperature limits define a region 3 within which region 3 an operator should check that the steam generator pressure is below the steam generator safety valve setting to prevent the risk of the steam generator safety valve opening.

H) The method comprises the following steps Setting value curve of safety valve of loop voltage stabilizer

The regulator safety valve setting defines the maximum pressure of the primary circuit. For a typical pressurized water reactor nuclear power plant, safety valves with different three-level setting values are generally installed (for example, the setting values of the safety valves of a three-level voltage stabilizer of a certain nuclear power plant are 171barA, 174barA and 177barA respectively).

I) The method comprises the following steps Temperature limiting line for connecting loop waste heat discharge system

The limit line is determined by the allowable access temperature (e.g. 120 ℃) of the residual heat removal system.

J) The method comprises the following steps Pressure upper limit limiting line after connection of waste heat discharge system in loop

The limit line is determined based on the maximum pressure allowed after the waste heat removal system is connected (e.g., 31 barg).

K) The method comprises the following steps Thermal stress limiting line of loop voltage stabilizer surge tube

The limit line is determined according to the temperature difference between two ends of the fluctuation tube of the voltage stabilizer allowed by design so as to limit the thermal stress on the fluctuation pipeline (for example, the temperature difference between two ends of the fluctuation tube cannot exceed 180 ℃). This curve also serves as the lower limit for region 1, in which region 1 the operator should check that the stabiliser is in the water physical state.

L): lowest temperature limiting line of loop

The limit is determined by the risk of boron crystallisation at low temperatures (e.g. 10 c is chosen as the lower temperature limit of the primary loop to prevent the risk of boron crystallisation at boron concentrations above 2000 ppm).

Further, when the abnormal state is a fault condition, the temperature and pressure operation limiting model under the abnormal state of the loop comprises the following steps: by a return circuit temperature and the pressure operation restriction range that the saturation curve of a return circuit normal water, trouble operating mode restoration line, a return circuit step-down operation prompt line, a return circuit step-down operation restriction line constitute, trouble operating mode restoration line includes: forbidding a boost line, a supercooling boundary limit line and a loop main pump limit line.

In this embodiment, the fault condition covers some typical nuclear power plant faults such as loss of power or control power, unavailability of system functions due to a certain equipment fault, and the like. Under the fault working condition, the cooling state of the reactor core is not deteriorated, and special safety facility investment is not needed. The aim of the fault working condition operation is to stabilize the state of the unit, repair the power supply or the fault equipment as soon as possible, control the unit in a way as close to normal operation as possible, enable the unit to recover normal operation as soon as possible, or guide an operator to enable the unit to retreat to a predefined retreat mode, and avoid the deterioration of the unit state and further guide the unit to the accident working condition.

The maximum value of the core outlet coolant temperature T RIC max is selected as a representative loop temperature, and the loop pressure measurement channel pcrcp installed in the heat pipe section is selected as a representative loop pressure. Taking a certain pressurized water reactor nuclear power unit as an example, a loop temperature and pressure operation limiting diagram under a fault working condition of the pressurized water reactor nuclear power unit is drawn, and is shown in fig. 3. The individual limiting lines in the figure are illustrated as follows:

A) the method comprises the following steps Saturation curve of primary loop water

B) The method comprises the following steps Fault condition repair limiting line

The basis of the fault condition repairing limit line is as follows: as long as the operating pressure remains above this, there is no requirement to perform operations related to restoring subcooling. The fault condition repairing limiting line consists of the following parts:

boost prohibition limit (limit line upper part): if the pressure exceeds the pressure limit value, the pressure of the loop is boosted, so that the operation state point cannot return to the range limited by the middle limit line and the left limit line;

supercooling boundary limit (limit line middle): the limit value is determined according to the right boundary line of the primary circuit temperature and pressure operation limiting diagram under the normal operation condition, and certain allowance is considered (for example, the right boundary line of the primary circuit temperature and pressure operation limiting diagram under the normal operation condition takes the supercooling degree of 40 ℃, the allowance of 10 ℃ is considered, and the basis for determining the fault condition repairing limiting line is the supercooling degree of 50 ℃);

primary-circuit main-pump limiting line (lower limiting line): the part limit line is determined based on certain conditions that need to be met to ensure operation of the main pump, including the main pump NPSH limit line, the minimum pressure requirement for operation of the main pump (e.g., 24barA), etc.

C) The method comprises the following steps Loop voltage reduction operation prompt wire

The purpose of the limit line is to prompt the operator not to take too aggressive a depressurization operation near the end of the depressurization sequence to avoid eventual guidance to the contingency operating regime. The limiting line is determined according to the fault working condition repairing limiting line, and a certain allowance (for example, the allowance of 10 ℃ is considered, and the determination of the middle limiting line is based on the supercooling degree of 60 ℃).

D) The method comprises the following steps A loop step-down operation restriction line

The purpose of this limit line is to give a limiting condition for the buck operation. It is a compromise that allows depressurization as quickly as possible while maintaining sufficient saturation margin (to avoid steering to accident regime operation). The limit line is determined according to the maximum temperature difference (such as 110 ℃) of the temperature difference between two ends of the fluctuation tube of the voltage stabilizer given in the class II transient analysis applicable to the stress analysis of the fluctuation tube of the voltage stabilizer.

Further, when the abnormal state is an accident condition and the P signal is not valid, the temperature and pressure operation limiting model in the abnormal state of the primary circuit comprises: a loop temperature and pressure operation limiting range is formed by a loop water saturation curve, a first operation lower limit limiting line, a first accident condition repairing limiting line, a first operation upper limit limiting line and a loop voltage stabilizer surge pipe thermal stress limiting line;

when the abnormal state is an accident condition and the P signal is effective, the temperature and pressure operation limiting model under the abnormal state of the loop comprises the following steps: and the temperature and pressure operation limiting range of the loop is formed by a saturation curve of water in the loop, a second operation lower limit limiting line, a second accident condition repairing limiting line, a second operation upper limit limiting line and a pressure vessel thermal stress limiting line.

In the embodiment, the primary circuit temperature and pressure operation limiting map under the accident condition is mainly suitable for the situation that the core cooling state is not deteriorated, and is used for assisting an operator to track the change trend of primary circuit parameters during the transition period from the accident operation regulation to the cold shutdown, and the triggering of special safety facilities such as a safety injection system and the like is avoided as much as possible in the process.

Considering that the environment in the containment vessel may be deteriorated under the accident condition, the pressure parameter is the absolute pressure of a primary loop: PHL (loop relative pressure measured by heat pipe section) + pcon (containment pressure). The core outlet coolant temperature maximum value, T RIC max, is selected as a representative primary loop temperature.

Taking a certain pressurized water reactor nuclear power unit as an example, a loop temperature and pressure operation limiting diagram in the non-effective and effective states of the allowing signal P26 is drawn (after the allowing signal P26 is effective, the triggering condition of the safe injection signal is switched to low loop water level of the heat pipe section from loss of the saturation margin of the coolant of the heat pipe section). The operating limits of circuit temperature and pressure during an accident condition when P26 is not active are shown in FIG. 4. The individual limiting lines in the figure are illustrated as follows:

B) The method comprises the following steps First operation lower limit line

The operation lower limit line is composed of the following parts:

high-temperature high-pressure part: the basis for this determination is to avoid the occurrence of a too low saturation margin in the heat pipe section while rapidly depressurizing the circuit, so that the safety injection signal is triggered by the loss of the heat pipe section coolant saturation margin. Thus, the limit line is based on a threshold determination that the protection system triggers a safe injection signal;

a low-pressure low-temperature part: the determined basis is the lower limit of the operating pressure interval (e.g., 27bara) maintained to ensure operation of the main pump.

C) The method comprises the following steps Accident condition repair limiting line

The accident condition repairing limiting line comprises the following parts:

high-pressure high-temperature part: this part is based on the lower limit line of operation under high temperature and high pressure conditions, and takes a certain margin (e.g., 10 ℃).

A low-pressure low-temperature part: the part is determined based on a fault working condition repairing limit line, and a certain allowance (such as an allowance of 4 bar) is considered, so that enough operation space is reserved, the supercooling degree repairing operation under the fault working condition can be executed, and the part does not need to be directly guided to the fault working condition after the fault working condition is successfully repaired.

D) First operation upper limit limiting line

The operation upper limit limiting line is composed of the following parts:

high-pressure high-temperature part: the limit curve is determined based on the lower limit of operation under the same conditions, and a certain margin (such as a margin of 45 ℃) is added.

A low-pressure low-temperature part: the basis for this determination is the upper limit of the operating pressure interval (e.g., 29bara) maintained to ensure operation of the main pump.

E) The method comprises the following steps Thermal stress limiting line of loop voltage stabilizer surge tube

The limit line is determined according to the temperature difference between two ends of the fluctuation tube of the voltage stabilizer allowed by design so as to limit the thermal stress on the fluctuation pipeline (for example, the temperature difference between two ends of the fluctuation tube cannot exceed 180 ℃).

The primary circuit temperature and pressure operating limit map for the accident condition with P26 enabled is an extension of the primary circuit temperature and pressure operating limit map for the accident condition with P26 disabled, as shown in fig. 5. The individual limiting lines in the figure are illustrated as follows:

B) The method comprises the following steps Second operation lower limit line

The operation lower limit line is composed of the following parts:

high-pressure high-temperature part: this portion takes over the low pressure and low temperature portion of the lower limit of operation limit line when P26 is not active until a low temperature (e.g., 55℃.) and reduced pressure condition is reached.

A low-temperature and low-pressure part: this is partly given by the temperature (e.g. 55 c) condition of the final target cold shut-down condition.

C) The method comprises the following steps Second accident condition repairing limiting line

The accident condition repairing limiting line comprises the following parts:

high-pressure high-temperature part: the limit line is a compromise between limiting the high temperature and high pressure portion of the line at the lower limit of operation and maintaining a sufficient saturation margin. In the low-pressure state, a large margin is taken relative to the saturation curve (for example, a margin of 20 ℃) due to a large measurement error.

A low-pressure low-temperature part: temperatures below 100 c at atmospheric pressure ensure that saturation does not occur, taking into account a certain margin (e.g. 20 c) the limit line is a vertical straight line (80 c).

D) Second operation upper limit limiting line

The operation upper limit limiting line is composed of the following parts:

high-pressure high-temperature part: the limit curve is determined based on the high temperature and high pressure portion of the operation lower limit line, and a certain margin (for example, a margin of 35 ℃) is considered.

A low-temperature and low-pressure part: in this region, the upper limit pressure of the target is determined mainly based on the following factors: it should be above the pressure defined by the lower limit of operation limit line and low enough so that the circuit can be considered almost fully depressurized.

E) The method comprises the following steps Thermal stress limiting line of loop pressure vessel

The limit line is determined to avoid the risk of brittle fracture (e.g., limit supercooling below 140 ℃) due to pressure-bearing thermal shock that the reactor pressure vessel may be subjected to after an accident.

In the embodiment, reasonable monitoring parameters are selected, the operation limiting boundary under the fault or accident condition is determined based on the monitoring parameters, and in order to ensure the consistency with normal operation, a primary circuit temperature and pressure operation limiting diagram under the fault or accident condition is respectively drawn. The state point of the loop at each moment can be automatically recorded and displayed on the loop temperature and pressure operation limiting diagram under the fault or accident condition, so that an operator can be assisted to conveniently monitor the operation state of the loop during the execution of the accident operation regulation, the evolution path and the trend of the loop parameter are tracked, the operation strategy is timely changed when the operation point exceeds the operation boundary defined by the loop temperature and pressure operation limiting diagram, the adverse effect on the operation of a system and equipment is reduced as much as possible, and the unit can be stably withdrawn to the safe state within the range defined by the loop temperature and pressure operation limiting diagram.

Step S12, selecting a corresponding primary circuit temperature and pressure operation limiting model according to the operating state of the primary circuit main pump of the nuclear power plant, the state of the accident operation procedure being executed, and the state of the P signal (i.e. the above mentioned P26 signal) for influencing the triggering condition of the safety injection system of the nuclear power plant.

In this embodiment, the accident operation rule is a file written in the form of sequential instructions, and is used to guide an operator to control the unit under the fault condition and the accident condition, so that the unit is withdrawn and stabilized in a safe shutdown state. Due to the difference of the operation targets, the accident operation regulations can be divided into accident operation regulations under the fault working condition (the target is to stabilize the unit or withdraw the unit, and recover the unit operation as soon as possible after fault repair) and accident operation regulations under the fault working condition (the target is to recover and maintain the reactor core to be cooled for a long time and avoid the reactor core to be molten).

In this embodiment, the loop temperature and pressure operating limit maps applicable to the current conditions are selected based on the conditions of the main pump operating conditions, the process conditions, and the P signal (i.e., the P26 signal) conditions. The logic is shown in fig. 6, and is specifically explained as follows:

-selecting a loop temperature and pressure operation restriction map for natural circulation conditions if a fault or accident condition accident operation regime is in execution requiring stabilization at current conditions and the main pump has been shut down;

-selecting a fault condition primary circuit temperature and pressure operation limit map if a fault condition contingency operation schedule is in execution, not requiring stabilization in a current state (pullback), or requiring stabilization in a current state but with the main pump in operation;

-if the accident operating regime is being executed, requiring no stabilization in the current state (pullback), or requiring stabilization in the current state but with the main pump operating, selecting the corresponding accident condition circuit temperature and pressure operating limit map, depending on whether the P26 signal is in effect or not;

and directly exiting if neither the fault condition nor the accident condition accident operation regime is being executed.

And step S13, acquiring the running state of the primary loop of the nuclear power station in the abnormal state, and adjusting the running strategy of the primary loop in real time according to the selected temperature and pressure running limit model in the abnormal state of the primary loop until the primary loop is stably withdrawn to the safe state.

In the embodiment, the temperature and pressure parameters of the primary circuit, which are required for describing the operating state of the primary circuit after a fault or an accident, are mainly collected, and the temperature and pressure parameters mainly include a primary circuit pressure pcrp (gauge pressure), a heat pipe section pressure pihl (gauge pressure), a containment pressure pcon, a reactor core outlet coolant temperature trinc, and the like. In practical application, redundant measurement channels are mostly configured for temperature and pressure parameters (typical nuclear power plants are generally 4 rows of redundant), and the signal processing module processes the pressure and temperature signals acquired by the signal acquisition module, including identifying and eliminating invalid measurement channels.

In general, about 20 thermocouples are arranged at the core outlet of the nuclear power plant to measure the distribution of the core outlet coolant temperature trinic, and the signal processing module calculates the maximum value of the core outlet coolant temperature trincmax according to the thermocouple measurement signals. The signal processing module simultaneously executes simple operation, such as calculating the absolute pressure P HL + PCON of the primary circuit required by the accident working condition primary circuit temperature and pressure operation limiting diagram. In order to avoid the influence of factors such as possible instrument drift table and the like, the signal processing module selects the second largest value of the redundant channel as a parameter representing the actual state of the loop.

In this embodiment, the method for tracking and monitoring the abnormal state of the primary loop of the nuclear power station firstly represents various operation limiting conditions in the form of temperature and pressure operation limiting diagrams by combining the characteristics of unit operation under the fault working condition and the accident working condition, draws the primary loop temperature and pressure operation limiting diagrams under the natural circulation working condition, the fault working condition and the accident working condition, and constructs the automatic tracking method of the primary loop operation state under the fault and the accident working condition based on the operation limiting diagrams. The automatic tracking method for the loop state after the accident can assist an operator to conveniently and intuitively monitor the running state of the loop during the execution of the accident running rule, track the evolution process and the trend of the loop state, and adjust a proper running strategy in time according to the accident running rule when running points are located in different areas, so that the loop state is always under monitoring and is stably withdrawn to a safe state.

The embodiment of the invention constructs a temperature and pressure operation limiting model under the abnormal state of the primary circuit of the nuclear power station by combining the operation characteristics and the operation limiting conditions under the abnormal state of the primary circuit, draws a natural circulation working condition, a fault working condition and a primary circuit temperature and pressure operation limiting diagram under the accident working condition, constructs an automatic tracking method of the operating state of the primary circuit under the fault and accident working condition based on the operation limiting diagrams, and utilizes the automatic tracking method of the state of the primary circuit after the accident to assist an operator to conveniently and intuitively monitor the operating state of the primary circuit during the execution of the accident operation regulation, track the evolution process and trend of the state of the primary circuit, and timely adjust a proper operation strategy according to the accident operation regulation when the operating point is in different areas, so that the state of the primary circuit is always monitored and is stably withdrawn to.

Example two

An embodiment of the present invention provides a system for tracking and monitoring an abnormal state of a primary loop of a nuclear power plant, where the method described in the first embodiment is executed, and referring to fig. 7, the system may include: a building module 100, a selecting module 200 and a processing module 300.

The building module 100 is configured to build a temperature and pressure operation restriction model in a loop abnormal state according to preset operation characteristics and operation restriction conditions in the loop abnormal state of the nuclear power plant.

A selection module 200 for selecting a corresponding primary circuit temperature and pressure operating limit model based on a primary circuit main pump operating condition of the nuclear power plant, an ongoing accident operating procedure condition, and a P signal condition, the P signal (i.e. the above mentioned P26 signal) being used to influence the triggering conditions of the nuclear power plant safety injection system.

In this embodiment, the loop temperature and pressure operating limit maps applicable to the current conditions are selected based on the conditions of the main pump operating conditions, the process conditions, and the P signal (i.e., the P26 signal) conditions. The logic is as follows:

And the processing module 300 is configured to acquire an operating state of a primary loop of the nuclear power plant in an abnormal state, and adjust an operating strategy of the primary loop in real time according to the selected temperature and pressure operation restriction model in the abnormal state of the primary loop until the primary loop is stably withdrawn to a safe state.

F and G): temperature limiting line of loop

L): lowest temperature limiting line of loop

B) The method comprises the following steps First operation lower limit line

The operation lower limit line is composed of the following parts:

The accident condition repairing limiting line comprises the following parts:

D) First operation upper limit limiting line

The operation upper limit limiting line is composed of the following parts:

B) The method comprises the following steps Second operation lower limit line

The operation lower limit line is composed of the following parts:

The accident condition repairing limiting line comprises the following parts:

D) Second operation upper limit limiting line

The operation upper limit limiting line is composed of the following parts:

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

It should be noted that: when the primary loop abnormal state tracking and monitoring system for the nuclear power plant provided in the above embodiment implements the primary loop abnormal state tracking and monitoring method for the nuclear power plant, only the division of the above functional modules is used for illustration, and in practical application, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the equipment is divided into different functional modules, so as to complete all or part of the above described functions. In addition, the system for tracking and monitoring the abnormal state of the primary loop of the nuclear power plant provided by the embodiment and the embodiment of the method for tracking and monitoring the abnormal state of the primary loop of the nuclear power plant belong to the same concept, and specific implementation processes are detailed in the method embodiment and are not described herein again.

It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A nuclear power station primary loop abnormal state tracking and monitoring method is characterized by comprising the following steps:

acquiring the running state of a loop of the nuclear power station in an abnormal state, and adjusting the running strategy of the loop in real time according to the selected temperature and pressure running limit model of the loop in the abnormal state until the loop is stably withdrawn to a safe state;

the abnormal state includes: natural circulation conditions, fault conditions, and accident conditions that lose the forced circulation function.

2. The method of claim 1, wherein the loop abnormal state temperature and pressure operating limit model comprises, when the abnormal state is a natural circulation condition: the system comprises a loop temperature and pressure operation limiting range, wherein the loop temperature and pressure operation limiting range is composed of a saturation curve of water in a loop, a loop pressure low limiting line, a loop pressure high limiting line, a loop steam generator primary side differential pressure limiting line, a loop steam generator secondary side differential pressure limiting line, a loop temperature limiting line, a loop voltage stabilizer safety valve setting value curve, a loop waste heat discharge system access temperature limiting line, a loop waste heat discharge system connection back pressure upper limit limiting line, a loop voltage stabilizer fluctuation pipe thermal stress limiting line and a loop minimum temperature limiting line.

3. The method of claim 1, wherein the loop abnormal state temperature and pressure operating limit model comprises, when the abnormal state is a fault condition: a return circuit temperature and pressure operation restriction range that constitutes by saturation curve, trouble operating mode restoration line, return circuit step-down operation suggestion line, return circuit step-down operation restriction line of a return circuit normal water, trouble operating mode restoration line includes: forbidding a boost line, a supercooling boundary limit line and a loop main pump limit line.

4. The method of claim 1, wherein the loop abnormal condition temperature and pressure operating limit model comprises, when the abnormal condition is an accident condition and the P signal is not active: a loop temperature and pressure operation limiting range is formed by a loop water saturation curve, a first operation lower limit limiting line, a first accident condition repairing limiting line, a first operation upper limit limiting line and a loop voltage stabilizer surge pipe thermal stress limiting line;

5. The utility model provides a nuclear power station return circuit abnormal state tracking monitoring system which characterized in that includes:

the processing module is used for acquiring the running state of a loop of the nuclear power station in an abnormal state, and adjusting the running strategy of the loop in real time according to the selected temperature and pressure running limit model of the loop in the abnormal state until the loop is stably withdrawn to a safe state;

6. The system of claim 5, wherein the loop abnormal state temperature and pressure operating limit model comprises, when the abnormal state is a natural circulation condition: the system comprises a loop temperature and pressure operation limiting range, wherein the loop temperature and pressure operation limiting range is composed of a saturation curve of water in a loop, a loop pressure low limiting line, a loop pressure high limiting line, a loop steam generator primary side differential pressure limiting line, a loop steam generator secondary side differential pressure limiting line, a loop temperature limiting line, a loop voltage stabilizer safety valve setting value curve, a loop waste heat discharge system access temperature limiting line, a loop waste heat discharge system connection back pressure upper limit limiting line, a loop voltage stabilizer fluctuation pipe thermal stress limiting line and a loop minimum temperature limiting line.

7. The system of claim 5, wherein the loop abnormal state temperature and pressure operating limit model comprises, when the abnormal state is a fault condition: a return circuit temperature and pressure operation restriction range that constitutes by saturation curve, trouble operating mode restoration line, return circuit step-down operation suggestion line, return circuit step-down operation restriction line of a return circuit normal water, trouble operating mode restoration line includes: forbidding a boost line, a supercooling boundary limit line and a loop main pump limit line.

8. The system of claim 5, wherein the loop abnormal condition temperature and pressure operating limit model comprises, when the abnormal condition is an accident condition and the P signal is not asserted: a loop temperature and pressure operation limiting range is formed by a loop water saturation curve, a first operation lower limit limiting line, a first accident condition repairing limiting line, a first operation upper limit limiting line and a loop voltage stabilizer surge pipe thermal stress limiting line;