A lead-cooled fast reactor system and control method

Abstract

A lead-cooled fast reactor system and control method. The system includes a core control system and a steam generator control system. Among them, the core control system includes the regulation of control rods and the regulation of the main pump speed, and the steam generator control system includes the regulation of the feed water flow rate. In the lead-cooled fast reactor core, the rod speed of the control rods is adjusted by simultaneously obtaining the power deviation and the coolant average temperature deviation. The speed of the main pump is adjusted by the feedback of the coolant flow rate. In the once-through steam generator, the feed water flow rate is adjusted by using the feedforward plus cascade control method to control the steam pressure. The present invention provides a control strategy and method for a lead-cooled fast reactor system, which improves the automation level of the lead-cooled fast reactor, greatly reduces the burden on the operating personnel, and enables the lead-cooled fast reactor to have better dynamic response quality and obtain ideal regulation characteristics.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear reactor engineering, and in particular relates to a lead-cooled fast reactor system and a control method. Background Art

[0002] Lead-cooled Fast Reactor (LFR) refers to a fast neutron reactor that uses liquid lead or lead-bismuth alloy cooling, adopts a closed fuel cycle, has good nuclear waste transmutation and nuclear fuel proliferation capabilities, as well as high safety and economy, and will have broad development space in the future. It has the characteristics of supplying the power demand of the small grid market, can be used as a small distributed power generation, and can also be used to produce other energy sources, including hydrogen and drinking water.

[0003] BREST-0D-300 is a lead-cooled fast reactor designed by Russia's NIKIET company, with a design power of 300MWe, and its main purpose is to generate electricity. The power control system of the BREST-0D-300 reactor currently available adopts a power feedback control method. The deviation between the power set value and the actual value is adjusted by the PID controller to adjust the control rod position, change the core reactivity, and thus achieve closed-loop control of the reactor power. ALFRED is a small (300MWth) pool-type lead-cooled fast reactor. Its control scheme is to control the power by adjusting the control rods, control the steam generator pressure by adjusting the turbine inlet valve, and adopt a combined feedforward-feedback scheme to control the lead temperature at the steam generator outlet by adjusting the feedwater mass flow rate.

[0004] CLEAR-IA is a modular heavy metal-cooled fast neutron reactor that is being independently designed and developed in my country. It has a design rated thermal power of 10MWth and is a miniaturized experimental reactor device. The primary loop of the reactor operates in a natural circulation mode. Under steady-state conditions, the reactor power remains constant, the natural circulation flow rate also remains constant, and the steady-state temperature parameters of the core and the primary loop remain unchanged corresponding to the power level. When the power changes (such as a power step), the reactor power automatic control system first changes the rod position of the regulating rod group in the core according to the power change, thereby stabilizing the reactor power at a new level.

[0005] The above three are different control methods for different lead-cooled fast reactors, each with its own advantages and disadvantages, but relatively speaking, the structure is simple and the adjustment time is long. Therefore, it is very necessary to propose a control strategy for the lead-bismuth fast reactor system to better meet the operation control requirements of the lead-cooled fast reactor. Summary of the invention

[0006] In order to overcome the deficiencies of the above-mentioned existing technologies, the object of the present invention is to provide a lead-cooled fast reactor system and a control method, which control the pressure at the outlet of the steam generator by the feed water flow rate, introduce the signal of the main steam valve opening degree when adjusting the feed water flow rate, so that the response of the steam pressure is faster, enabling it to maintain the stable operation of the lead-cooled fast reactor and having good load tracking ability.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A lead-cooled fast reactor system includes a core part I and a steam generator part II;

[0009] The core part I includes a lead-cooled fast reactor core 3, a main pump 4, a power controller 7, a temperature controller 8, and a coolant flow rate controller 9;

[0010] The input signals of the lead-cooled fast reactor core 3 are respectively the control rod speed signal 18 and the coolant inlet flow rate signal 19; the output signals of the lead-cooled fast reactor core 3 are respectively the reactor power signal 11, the coolant outlet flow rate signal 12, and the coolant core outlet temperature signal 13; the input signal of the main pump 4 is the rotation speed signal output from the coolant flow rate controller 9, and the output signal of the main pump 4 is the coolant inlet flow rate signal 19;

[0011] The reactor power signal 11 is sent to the power controller 7;

[0012] The control rod speed signal 18 is obtained by adding the two signals from the power controller 7 and the temperature controller 8;

[0013] The steam generator part II includes a once-through steam generator 1, a feed water system 2, a pressure controller 5, and a feed water flow rate controller 6;

[0014] The input signals of the once-through steam generator 1 are respectively the feed water flow rate signal 10, the coolant outlet flow rate signal 12, the coolant core outlet temperature signal 13, and the main steam valve opening degree signal 14, and the output signals of the once-through steam generator 1 are the feed water valve outlet pressure signal 15, the coolant core inlet temperature signal 16, and the steam pressure signal 17; the input signals of the feed water system 2 are the feed water valve outlet pressure signal 15 and the rotation speed signal output from the feed water flow rate controller 6, and the output signal of the feed water system 2 is the feed water flow rate signal 10;

[0015] The steam pressure signal 17 is sent to the pressure controller 5 after deviation from the reference steam pressure signal 23; the signal output from the pressure controller 5 is added to the main steam valve opening degree signal 14 to obtain the reference feed water flow rate signal 24, and the reference feed water flow rate signal 24 is sent to the feed water flow rate controller 6 after deviation from the water flow rate signal 10;

[0016] After averaging the coolant core outlet temperature signal 13 and the coolant core inlet temperature signal 16, the deviation from the reference coolant average temperature signal 22 is sent to the temperature controller 8 of the core part I.

[0017] The coolant flow controller 9, the pressure controller 5, and the flow controller 6 all select proportional-integral controllers.

[0018] Based on the above control method for a lead-cooled fast reactor system, it includes the following steps:

[0019] Step 1: When it is necessary to step from 100% full power to 90% full power, the main steam valve opening signal 14 is provided by the secondary circuit, the reference steam pressure signal 23 remains constant, the reference power signal 20 drops from 100% to 90%, and the reference coolant flow signal 21 and the reference coolant average temperature signal 22 are obtained from the corresponding power signals; according to the reactor power signal 11 output by the lead-cooled fast reactor core 3, the deviation from the reference power signal 20 is obtained and sent into the power controller 7.

[0020] Step 2: Obtain the coolant core outlet temperature signal 13 and the coolant core inlet temperature signal 16. After averaging the two, the deviation from the reference coolant average temperature signal 22 is obtained and sent into the temperature controller 8.

[0021] Step 3: Obtain the signals output by the power controller 7 and the temperature controller 8. After adding the two signals, the control rod speed signal 18 is obtained and input into the lead-cooled fast reactor core 3 system.

[0022] Step 4: Obtain the deviation between the coolant inlet flow signal 19 and the reference coolant flow signal 21, send it into the coolant flow controller 9 and output the main pump speed signal, and then input it into the main pump 4.

[0023] Step 5: After obtaining the deviation between the steam pressure signal 17 and the reference steam pressure signal 23, send it into the pressure controller 5.

[0024] Step 6: After adding the main steam valve opening signal 14 and the signal output by the pressure controller 5, the reference feedwater flow signal 24 is obtained, forming a cascade control system formed by the series connection of the pressure controller 5 and the flow controller 6.

[0025] Step 7: After obtaining the deviation between the feedwater flow signal 10 and the reference feedwater flow signal 24, send it into the feedwater flow controller 6 and obtain the rotational speed signal of the feed pump, and then input it into the feedwater system 2.

[0026] In Step 1, the power controller 7 is composed of a phase correction link and a differential lag link. The controller expression of the phase correction link is The controller expression of the differential lag link is K, α, and τ in the formula are all parameters of the controller in the s domain, and n is the order of phase correction.

[0027] In step 2, the temperature controller 8 is composed of a phase correction network.

[0028] In step 3, the control rod speed signal 18 adjusts the proportion between power feedback and temperature feedback by adjusting the parameters of the power controller 7 and the temperature controller 8.

[0029] The present invention has the following advantages:

[0030] (1) By controlling the pressure at the outlet of the steam generator through the feed water flow rate, the steam pressure at the outlet of the steam generator is ensured to return to the initial value. At the same time, the actual values of the key parameters of the system do not exceed the corresponding safety limits, greatly reducing the disturbance to the steam generator and the reactor system and ensuring the safety of the unit.

[0031] (2) When adjusting the feed water flow rate, the signal of the main steam valve opening is introduced, so that the feed water flow rate does not have to wait until the steam pressure changes to start adjusting, making the response of the steam pressure faster and the overshoot smaller.

[0032] (3) The control rod is a way to control the reactor power. In the present invention, the adjustment of the control rod speed is jointly controlled by power feedback and the average coolant temperature feedback. Therefore, in addition to having good control characteristics for the reactor power, the present invention also takes into account the adjustment of the average coolant temperature, greatly ensuring the safety of the unit. Brief Description of the Drawings

[0033] Figure 1 It is a schematic diagram of the control system of the present invention.

[0034] Figure 2 It is the control result of the relative nuclear power.

[0035] Figure 3 It is the control result of the steam generator pressure.

[0036] Figure 4 It is the control result of the core inlet temperature.

[0037] Figure 5 It is the control result of the core outlet temperature.

[0038] Reference numerals in the figure: I - core part; II - steam generator part; 1 - once-through steam generator; 2 - feedwater system; 3 - lead-cooled fast reactor core; 4 - main pump; 5 - pressure controller; 6 - feedwater flow controller; 7 - power controller; 8 - temperature controller; 9 - coolant flow controller; 10 - feedwater flow signal; 11 - reactor power signal; 12 - coolant outlet flow signal; 13 - coolant core outlet temperature signal; 14 - main steam valve opening signal; 15 - feedwater valve outlet pressure signal; 16 - coolant core inlet temperature signal; 17 - steam pressure signal; 18 - control rod speed signal; 19 - coolant inlet flow signal; 20 - reference power signal; 21 - reference coolant flow signal; 22 - reference average coolant temperature signal; 23 - reference steam pressure signal; 24 - reference feedwater flow signal. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] See Figure 1 A lead-cooled fast reactor system includes a core part I and a steam generator part II;

[0041] The core part I includes a lead-cooled fast reactor core 3, a main pump 4, a power controller 7, a temperature controller 8, and a coolant flow controller 9;

[0042] The input signals of the lead-cooled fast reactor core 3 are respectively the control rod speed signal 18 and the coolant inlet flow signal 19; the output signals of the lead-cooled fast reactor core 3 are respectively the reactor power signal 11, the coolant outlet flow signal 12, and the coolant core outlet temperature signal 13; the input signal of the main pump 4 is the rotational speed signal output from the coolant flow controller 9, and the output signal of the main pump 4 is the coolant inlet flow signal 19;

[0043] The reactor power signal 11 is sent to the power controller 7;

[0044] The control rod speed signal 18 is obtained by adding the two signals from the power controller 7 and the temperature controller 8;

[0045] The steam generator part II includes a once-through steam generator 1, a feedwater system 2, a pressure controller 5, and a feedwater flow controller 6;

[0046] The input signals of the described once-through steam generator 1 are respectively the feedwater flow signal 10, the coolant outlet flow signal 12, the coolant core outlet temperature signal 13, and the main steam valve opening signal 14. The output signals of the once-through steam generator 1 are the feedwater valve outlet pressure signal 15, the coolant core inlet temperature signal 16, and the steam pressure signal 17. The input signals of the feedwater system 2 are the feedwater valve outlet pressure signal 15 and the rotational speed signal output by the feedwater flow controller 6. The output signal of the feedwater system 2 is the feedwater flow signal 10;

[0047] The steam pressure signal 17 is sent to the pressure controller 5 after deviation from the reference steam pressure signal 23. The signal output by the pressure controller 5 is added to the main steam valve opening signal 14 to obtain the reference feedwater flow signal 24. The reference feedwater flow signal 24 is sent to the feedwater flow controller 6 after deviation from the water flow signal 10;

[0048] After averaging the coolant core outlet temperature signal 13 and the coolant core inlet temperature signal 16, the deviation from the reference coolant average temperature signal 22 is sent to the temperature controller 8 of the core part I.

[0049] All of the above input signals indicate an impact on the relevant object, and all output signals are obtained from relevant signals of relevant sensors.

[0050] Based on the above control method of a lead-cooled fast reactor system, when it is necessary to step from 100% full power to 90% full power, the main steam valve opening signal 14, the reference power signal 20, the reference coolant flow signal 21, the reference coolant average temperature signal 22, and the reference steam pressure signal 23 will change first. Among them, the main steam valve opening signal 14 is provided by the secondary circuit, the reference steam pressure signal 23 remains constant, the reference power signal 20 drops from 100% to 90%, and the reference coolant flow signal 21 and the reference coolant average temperature signal 22 are obtained from the corresponding power signals. The specific steps are as follows:

[0051] Step 1: According to the reactor power signal 11 output by the lead-cooled fast reactor core 3, obtain its deviation from the reference power signal 20 and send it to the power controller 7;

[0052] Step 2: Obtain the coolant core outlet temperature signal 13 and the coolant core inlet temperature signal 16. After averaging the two, obtain their deviation from the reference coolant average temperature signal 22 and send it to the temperature controller 8;

[0053] Step 3: Obtain the signals output by the power controller 7 and the temperature controller 8, add the two signals to obtain the control rod speed signal 18, and input it into the lead-cooled fast reactor core 3 system; among them, the control rod speed signal 18 includes the signals output by the power controller 7 and the temperature controller 8. Therefore, in addition to having good control characteristics for the reactor power, it also takes into account the regulation of the average temperature of the coolant, greatly ensuring the safety of the unit.

[0054] Step 4: Obtain the deviation between the coolant inlet flow signal 19 and the reference coolant flow signal 21, send it into the coolant flow controller 9, output the main pump speed signal, and input it into the main pump 4.

[0055] Step 5: After obtaining the deviation between the steam pressure signal 17 and the reference steam pressure signal 23, send it into the pressure controller 5.

[0056] Step 6: Add the main steam valve opening signal 14 and the signal output by the pressure controller 5 to obtain the reference feedwater flow signal 24; among them, the main steam valve opening signal 14 will start to change before the steam pressure signal changes, so that the reference feedwater flow does not have to wait until the steam pressure changes to start adjusting. Therefore, the main steam valve opening signal 14 is introduced as a feedforward signal to make the regulation response of the steam pressure faster and the overshoot smaller.

[0057] Step 7: After obtaining the deviation between the feedwater flow signal 10 and the reference feedwater flow signal 24, send it into the feedwater flow controller 6, obtain the speed signal of the feed pump, and input it into the feedwater system 2. Among them, using the feedwater flow signal 10 to regulate the steam pressure signal 17 is direct and rapid, with a faster response time, greatly reducing the disturbance to the steam generator and the reactor system.

[0058] In Step 1, the power controller 7 is composed of a phase correction link and a derivative lag link. The controller expression of the phase correction link is The controller expression of the derivative lag link is The derivative lag link therein can solve the steady-state deviation problem during power regulation. The K, α, and τ in the formula are all parameters of the controller in the s domain, and n is the order of phase correction.

[0059] In Step 2, the temperature controller 8 is composed of a phase correction network, and the reference coolant average temperature signal 22 is given by relevant reactor calculations or specifications.

[0060] In Step 3, the control rod speed signal 18 is determined by power feedback and temperature feedback. When adjusting the control rod, both the power of the reactor and the average temperature of the coolant in the reactor are considered. The proportion between power feedback and temperature feedback can be adjusted by adjusting the parameters of the power controller 7 and the temperature controller 8.

[0061] In step 4, the coolant flow controller 9 adopts a proportional-integral controller.

[0062] In step 5, the pressure controller 5 adopts a proportional-integral controller.

[0063] In step 7, the flow controller 6 adopts a proportional-integral controller.

[0064] Related systems such as the once-through steam generator 1, the feedwater system 2, the lead-cooled fast reactor core 3, and the main pump 4 are adjusted to a certain extent.

[0065] The above process is continuously carried out to adjust each parameter to the corresponding reference value or stable value. Taking one lead-cooled fast reactor as an example, at 10 seconds, the lead-cooled fast reactor steps from 100% full power to 90% full power, and the dynamic response results of the lead-cooled fast reactor are as Figures 2 - 5 shown. Figure 2 The control result of the relative nuclear power, Figure 3 is the control result of the steam generator pressure, Figure 4 is the control result of the core inlet temperature, Figure 5 is the control result of the core outlet temperature. It can be seen from the figure that after being controlled by the control method of the present invention, the adjustment time of each parameter of the lead-cooled fast reactor is short, the overshoot is small, and the control effect is good.

[0066] As a fourth-generation advanced nuclear reactor system, the lead-cooled fast reactor of the present invention has no case of grid-connected power generation at present, and its various control strategies are all in the design verification stage. However, the core control system of the present invention includes the adjustment of control rods and the adjustment of the main pump speed, and the steam generator control system includes the adjustment of the feedwater flow. In the lead-cooled fast reactor core, the rod speed of the control rod is adjusted by simultaneously obtaining the power deviation and the average coolant temperature deviation; the main pump speed is adjusted by the feedback of the coolant flow. In the once-through steam generator, the feedwater flow is adjusted by using the feedforward plus cascade control method to control the steam pressure. The present invention provides a control strategy and method for a lead-cooled fast reactor system, improves the automation level of the lead-cooled fast reactor, greatly reduces the burden on operating personnel, and enables the lead-cooled fast reactor to have better dynamic response quality and obtain ideal adjustment characteristics.

Claims

1. A lead-cooled fast reactor system includes a core part (I) and a steam generator part (II); characterized in that, The core part (I) includes a lead-cooled fast reactor core (3), a main pump (4), a power controller (7), a temperature controller (8) and a coolant flow controller (9); The input signals of the lead-cooled fast reactor core (3) are respectively the control rod speed signal (18) and the coolant inlet flow signal (19); the output signals of the lead-cooled fast reactor core (3) are respectively the reactor power signal (11), the coolant outlet flow signal (12) and the coolant core outlet temperature signal (13); the input signal of the main pump (4) is the rotation speed signal output from the coolant flow controller (9), and the output signal of the main pump (4) is the coolant inlet flow signal (19); The reactor power signal (11) is sent to the power controller (7); The control rod speed signal (18) is obtained by adding the two signals by the power controller (7) and the temperature controller (8); The steam generator part (II) includes a once-through steam generator (1), a feed water system (2), a pressure controller (5) and a feed water flow controller (6); The input signals of the once-through steam generator (1) are respectively the feed water flow signal (10), the coolant outlet flow signal (12), the coolant core outlet temperature signal (13) and the main steam valve opening signal (14), and the output signals of the once-through steam generator (1) are the feed water valve outlet pressure signal (15), the coolant core inlet temperature signal (16) and the steam pressure signal (17); the input signal of the feed water system (2) is the feed water valve outlet pressure signal (15) and the rotation speed signal output from the feed water flow controller (6), and the output signal of the feed water system (2) is the feed water flow signal (10); The steam pressure signal (17) is sent to the pressure controller (5) after deviation from the reference steam pressure signal (23); the signal output from the pressure controller (5) is added to the main steam valve opening signal (14) to obtain the reference feed water flow signal (24), and the reference feed water flow signal (24) is sent to the feed water flow controller (6) after deviation from the water flow signal (10); After the coolant core outlet temperature signal (13) and the coolant core inlet temperature signal (16) are averaged, the deviation from the reference coolant average temperature signal (22) is sent to the temperature controller (8) of the core part (I).

2. A lead-cooled fast reactor system according to claim 1, characterized in that, The coolant flow controller (9), the pressure controller (5) and the flow controller (6) all adopt proportional-integral controllers.

3. The control method of a lead-cooled fast reactor system according to claim 1, characterized in that, Including the following steps: Step 1: When it is necessary to step from 100% full power to 90% full power, the main steam valve opening signal (14) is provided by the secondary loop, the reference steam pressure signal (23) remains constant, the reference power signal (20) drops from 100% to 90%, and the reference coolant flow signal (21) and the reference coolant average temperature signal (22) are derived from the corresponding power signal; according to the reactor power signal (11) output by the lead-cooled fast reactor core (3), obtain the deviation between it and the reference power signal (20) and send it into the power controller (7); Step 2: Obtain the coolant core outlet temperature signal (13) and the coolant core inlet temperature signal (16). After averaging the two, obtain the deviation between it and the reference coolant average temperature signal (22) and send it into the temperature controller (8); Step 3: Obtain the signals output by the power controller (7) and the temperature controller (8). After adding the two signals, obtain the control rod speed signal (18) and input it into the lead-cooled fast reactor core (3) system; Step 4: Obtain the deviation between the coolant inlet flow signal (19) and the reference coolant flow signal (21), send it into the coolant flow controller (9) and output the main pump speed signal and then input it into the main pump (4); Step 5: After obtaining the deviation between the steam pressure signal (17) and the reference steam pressure signal (23), send it into the pressure controller (5); Step 6: The main steam valve opening signal (14) is added to the signal output by the pressure controller (5) to obtain the reference feedwater flow signal (24), forming a cascade control system formed by the series connection of the pressure controller (5) and the flow controller (6); Step 7: After obtaining the deviation between the feedwater flow signal (10) and the reference feedwater flow signal (24), send it into the feedwater flow controller (6) and obtain the feed pump speed signal and then input it into the feedwater system (2).

4. A control method for a lead-cooled fast reactor system according to claim 1, characterized in that, It includes the following steps: In Step 1, the power controller (7) is composed of a phase correction link and a differential lag link. In Step 1, the power controller 7 is composed of a phase correction link and a differential lag link. The controller expression of the phase correction link is The controller expression of the differential lag link is In the formula, K, α, and τ are all parameters of the controller in the s domain, and n is the order of phase correction.

5. A control method for a lead-cooled fast reactor system according to claim 1, characterized in that It includes the following steps: In Step 2, the temperature controller (8) is composed of a phase correction network combination.

6. A control method for a lead-cooled fast reactor system according to claim 1, characterized in that, It includes the following steps: In Step 3, the control rod speed signal (18) adjusts the proportion between the power feedback and the temperature feedback by adjusting the parameters of the power controller (7) and the temperature controller (8).

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