Operation control method for preventing accidental short-period protection shutdown of reactor in power rising and falling process of sodium-cooled fast reactor

Abstract

The invention provides an operation control method for preventing accidental short-period protection shutdown of a reactor in a power rising and falling process of a sodium-cooled fast reactor, which comprises the following steps: increasing the power to an intermediate range of less than 100cps, and controlling reactivity introduced by continuous lifting of a single compensation rod to be 3pcm-5pcm; increasing the power until the intermediate range is greater than 100cps, and continuously increasing the rod position of the single compensation rod by not more than 10mm; checking whether a P signal is correctly triggered and related interlocking takes effect or not in a power increasing process; in the process of increasing the power by more than 10% Pn, the power increasing rate is controlled, and the power increased each time does not exceed 5% of the current reactor power Px; in the reactor power adjusting process, the adjusting rod is kept in the optimal adjusting area, the compensation rod is lifted in turn when the rod grid balancing operation is carried out, and the rod position of the compensation rod is lifted by 10 mm at most each time. According to the method, the technical problem of how to prevent accidental short-period protection shut-down of the reactor in the power rising and falling process of the sodium-cooled fast reactor is solved through research on a reactor start-stop and power rising and falling method.

Description

Technical Field

[0001] The present application belongs to the field of reactor technology, and specifically relates to an operation control method for preventing an unexpected short-cycle protection shutdown of a sodium-cooled fast reactor during power increase or decrease. Background Art

[0002] Energy development is an important issue that restricts the national economy and people's livelihood. Nuclear energy, as an advanced technology and clean energy, is an important part of ensuring my country's energy security. The continuous and safe development of advanced nuclear energy technology is the responsibility and mission entrusted to us by the times. Sodium-cooled fast reactor technology is currently the most widely used nuclear energy technology in the world, and it is also the focus of my country's fast reactor technology research for a long time. Due to the physical characteristics of fast neutron reactors, fast reactor technology can provide the possibility of fuel reuse, thereby improving the utilization rate of uranium. The development of fast reactor technology can greatly improve the utilization rate of uranium resources, solve the problem of uranium resource shortage, and solve the millennium of energy development.

[0003] The physical properties of fast neutron reactors are very different from those of thermal neutron reactors. The dynamic response speed of their prompt neutrons is faster than that of thermal neutron reactors, and their neutron detection performance and effect are more difficult than those of thermal neutron reactors. For example, the neutron count rate in the startup phase is extremely low, neutron detection can only be measured in one direction, and the range of neutron flux is larger, which increases the difficulty of reactivity control of fast neutron reactors.

[0004] At present, fast neutron reactors have not been able to carry out continuous power operation and normal fuel cycle due to various reasons. With the completion and commissioning of large-scale commercial fast reactors, it is a task that we must complete to operate fast reactors safely and stably. Based on the above reasons, how to prevent the reactor from unexpected short-cycle protection shutdown during the power increase and decrease process of sodium-cooled fast reactors has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present application is committed to providing an operation control method for preventing an unexpected short-cycle protection shutdown of a sodium-cooled fast reactor during power increase or decrease. By studying the reactor start-up and shutdown and power increase or decrease methods, combined with the physical characteristics of fast neutron reactors, the technical problem of how to prevent an unexpected short-cycle protection shutdown of a sodium-cooled fast reactor during power increase or decrease is solved.

[0006] The first aspect of the present application provides an operation control method for preventing an unexpected short-cycle protection shutdown of a sodium-cooled fast reactor during power increase or decrease, comprising: when the reactor reaches criticality, the regulating rod is lifted to 650mm, and the compensating rod is lifted to 30mm before the extrapolated critical rod position, and each time the compensating rod is lifted continuously, the continuous lifting of the compensating rod does not exceed 60mm, and the relative deviation of each compensating rod does not exceed 70mm; during the transition to reactor criticality, the extrapolated criticality is used, and the reactivity introduced by each lifting of the control rod is controlled at 3pcm-5pcm, and the waiting time after lifting the control rod shall not be less than 30s; lifting When the power is less than 100cps in the middle range, the reactivity introduced by a single compensation rod is controlled at 3pcm-5pcm; when the power is increased to more than 100cps in the middle range, the continuous increase of the single compensation rod shall not exceed 10mm, and the power shall continue to be increased after confirming that the power range nuclear power indication is stable for each increase of 1%Pn; during the power increase process, check whether the P signal is correctly triggered and the relevant lock is effective; during the power increase process above 10%Pn, control the power increase rate, that is, control the rate of introduction of reactivity, and each power increase shall not exceed the current reactor power P x 5%; during the reactor power adjustment process, keep the adjustment rod in the optimal adjustment area, and lift the compensation rods in turn when performing the balance rod grid operation, and the compensation rod position can be lifted by no more than 10mm each time.

[0007] In a specific implementation of the present application, during the power increase process, checking whether the P signal is correctly triggered and the related locking is effective includes:

[0008] When the intermediate range count rate is greater than 100cps, the P6 signal is triggered. If the P6 signal disappears during the power reduction process, it is confirmed that the source range short-cycle protection is activated.

[0009] When the mid-range count rate is greater than 160cps, the P8 signal is triggered and the source range short-period signal is bypassed;

[0010] When the power range power is greater than 5% Pn, the P9 signal is triggered. If the P9 signal disappears during the power reduction process, it is confirmed that the intermediate range short-cycle protection is activated.

[0011] When the power in the power range is greater than 10% Pn, the P10 signal is triggered and the short-period signal in the intermediate range is bypassed.

[0012] In a specific embodiment of the present application, the regulating rod is lifted to 650 mm when the reactor reaches criticality. Before that, the operation control method for preventing the reactor from unexpected short-cycle protection shutdown during the power increase or decrease of the sodium-cooled fast reactor also includes: confirming that the reactor is in a standard cold shutdown initial state, the shutdown circuit breaker has been reset, the main pump speed has been increased to 50% of the rated speed, the reactivity instrument and the nuclear measurement system are working normally, conducting a comprehensive inspection before starting the reactor, and setting critical control points.

[0013] In a specific embodiment of the present application, when the reactor reaches criticality, the regulating rod is lifted to 650 mm, and the compensating rod is lifted to 30 mm before the extrapolated critical rod position, and each time the compensating rod is lifted continuously, the lifting does not exceed 60 mm, and the relative deviation of each compensating rod does not exceed 70 mm, including:

[0014] After the critical control point is released, the safety rods and passive rods are lifted to the top of the reactor, and the regulating rods are lifted to 650 mm. At this time, the reactor is still in shutdown state, the subcriticality is deep, and the short-cycle protection is not effective.

[0015] Before lifting the compensation rod, calculate the critical rod position and lift the compensation rod cyclically to a position 30mm before the critical rod position. During the lifting process, ensure that the compensation rod position deviation is within 70mm and that each compensation rod is continuously lifted no more than 60mm to avoid introducing excessive reactivity at a single time.

[0016] In a specific embodiment of the present application, when the reactor reaches criticality, the regulating rod is lifted to 650mm, and the compensating rod is lifted to 30mm before the extrapolated critical rod position. The compensating rod is lifted continuously for no more than 60mm each time, and the relative deviation of each compensating rod does not exceed 70mm. Afterwards, the operation control method for preventing an unexpected short-cycle protection shutdown of the reactor during the power increase or decrease of the sodium-cooled fast reactor also includes: closely monitoring the reactor cycle during the process of lifting the control rod, and immediately stopping lifting the control rod when the reactor cycle is less than 100s, and inserting the control rod when necessary to avoid a short cycle.

[0017] In a specific embodiment of the present application, during the transition to reactor criticality, extrapolated criticality is used, and the reactivity introduced each time the control rod is lifted is controlled at 3pcm-5pcm, and the waiting time after lifting the control rod shall not be less than 30s, including: when the reactor continues to increase the power to transition to criticality, extrapolated criticality calculations are performed, and one-third of the reactivity deviation is added each time, and the operating personnel perform independent calculations, and the reactivity continuously introduced by a single control rod each time is controlled at 3pcm-5pcm.

[0018] In a specific embodiment of the present application, the power is increased to an intermediate range greater than 100cps, a single compensation rod is continuously raised by no more than 10mm, and the power is continued to be increased every time 1%Pn is increased, and the power range nuclear power indication is confirmed to be stable before the power is increased. Previously, the operation control method for preventing the reactor from unexpected short-cycle protection shutdown during the power increase and decrease of the sodium-cooled fast reactor also includes: when the source range count rate is greater than 100cps, the source range short-cycle protection is put into operation.

[0019] In a specific embodiment of the present application, the power is increased to an intermediate range greater than 100 cps, a single compensation rod is continuously increased by no more than 10 mm, and the power is continued to be increased after confirming that the power range and power indication are stable for each increase of 1% Pn, including:

[0020] Continue to increase the power. When the intermediate range count rate is greater than 100cps, the intermediate range short-cycle protection is activated. In this stage, the rate of introducing reactivity is controlled so that the reactor doubling cycle is stable at more than 300s, and the reactivity introduced at a single time does not exceed 5pcm. The cycle and reactivity changes are closely monitored. When the doubling cycle of a single channel reactor is less than 30s or the doubling cycle of a two-channel reactor is less than 60s and continues to decline, the control rod is immediately inserted to reduce the reactivity; after the intermediate range short-cycle protection is activated, the continuous movement of a single compensation rod does not exceed 10mm each time, and each time the power is increased by 1%Pn, the next increase is carried out after the reactor power and cycle are stable;

[0021] After the intermediate range short-cycle protection is put into use, the continuous movement of a single compensation rod shall not exceed 10 mm each time, and each time the power is increased by 1% Pn, the next increase shall be made after the reactor power and cycle are stable.

[0022] In a specific embodiment of the present application, during the process of increasing the power by more than 10% Pn, the power increase rate is controlled, and each power increase does not exceed the current reactor power Pn. x 5%; during the reactor power regulation process, the regulating rod is kept in the optimal regulation area, and the compensating rod is lifted in turn during the balance rod grid operation, and the position of the compensating rod is lifted by a maximum of 10mm each time. Previously, the operation control method for preventing the reactor from unexpected short-cycle protection shutdown during the power increase and decrease process of the sodium-cooled fast reactor also includes:

[0023] The reactor power is increased to 7% Pn. During the increase process, it is confirmed that when the intermediate range count rate reaches 160cps, the source range short-cycle protection bypass is activated, the P8 signal is triggered, and the source range detector is correctly cut off and shut down;

[0024] The reactor power is increased to 7% Pn and maintained there.

[0025] In a specific embodiment of the present application, during the process of increasing the power by more than 10% Pn, the power increase rate is controlled, and each power increase does not exceed the current reactor power Pn. x 5%; During the reactor power adjustment process, keep the adjustment rod in the optimal adjustment area, and lift the compensation rods in turn when performing the balance rod grid operation, and each time the compensation rod position is lifted by a maximum of 10mm, including:

[0026] The reactor power is increased to 10% Pn, and it is confirmed that the P10 signal is triggered, the intermediate range short-cycle protection has been bypassed, and the intermediate range detector is correctly cut off and shut down; check that the reactor power is slightly greater than 10% Pn, the relative power deviation of the power regulation system is less than or equal to 5% Pn, and there is no signal prohibiting the increase of the control rod, and put the regulating rod into automatic control;

[0027] Continue to increase the reactor power to 11.9% Pn, 28% Pn, 40% Pn, 50% Pn, 75% Pn, and 100% Pn, respectively. Each power platform corresponds to the commissioning of the three-circuit system equipment. During the operation, the feed water and steam of the three circuits may be disturbed, which in turn affects the sodium temperature of the first circuit and the reactivity. Therefore, during the operation, it is necessary to pay close attention to the changes in the reactor power and confirm that the regulating rod is operating normally. Secondly, each power increase controls the power increase rate, and the maximum single power does not exceed 5% Px, where Px is the current power of the reactor.

[0028] In a specific embodiment of the present application, during the process of increasing the power by more than 10% Pn, the power increase rate is controlled, and each power increase does not exceed the current reactor power Pn. x 5%; during the reactor power regulation process, the regulating rod is kept in the optimal regulation area, and the compensating rods are lifted in turn during the balanced rod grid operation, and the position of the compensating rod is lifted by a maximum of 10 mm each time. After that, the operation control method for preventing the reactor from unexpected short-cycle protection shutdown during the power increase and decrease process of the sodium-cooled fast reactor also includes:

[0029] During the process of reducing the power of the reactor from 100% Pn to 10% Pn, attention may be paid to the power disturbance caused by the three-circuit operation, while controlling the power reduction rate to ensure a smooth reduction in the reactor power;

[0030] When the power is reduced to 5% Pn, confirm that the P9 signal disappears, the intermediate range detector is in operation and working properly; when the power is reduced to the intermediate range of 100cps, confirm that the P6 signal disappears, the source range detector is in operation and working properly; when the source range count rate drops to 500cps, confirm that the in-core measurement system is in operation and working properly;

[0031] During the power raising and lowering process, it is necessary to balance the bar grid multiple times. When balancing the bar grid, the single movement of the compensation bar should not exceed 10mm to avoid excessive reactive fluctuations that trigger the protection signal.

[0032] Insert the safety rod to the bottom of the pile, insert the adjustment rod and compensation rod to the bottom of the pile, insert the passive rod to the bottom of the pile, then reduce the main pump speed to 25% of the rated speed, and conduct the final status inspection after the reactor is shut down.

[0033] The beneficial effects of the technical solution of the present application are: adopting a unique reactivity control scheme for large sodium-cooled fast reactors to ensure the safety of the core, achieve the technical effect of safely and stably starting and stopping the reactor, and also ensure the technical effect of smoothly increasing and decreasing the power of the unit. The embodiment of the present application is to prevent the reactor from unexpected short-cycle protection events during the power increase and decrease of large sodium-cooled fast reactors. The embodiment of the present application has been verified and improved through debugging, minor unit repairs, and major unit repairs, and through a variety of operation control methods, it has achieved safe and stable power increase and decrease of large sodium-cooled fast reactors. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The figure is a flow chart of an operation control method for preventing an unexpected short-period protection shutdown of a sodium-cooled fast reactor during power increase or decrease provided by an embodiment of the present application.

[0035] Figure 2 The figure is a simplified schematic diagram of the process of an operation control method for preventing an unexpected short-cycle protection shutdown of a sodium-cooled fast reactor during power increase or decrease provided by another embodiment of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] At least one embodiment of the present application provides an operation control method for preventing an unexpected short-cycle protection shutdown of a sodium-cooled fast reactor during a power increase or decrease process. The operation control method for preventing an unexpected short-cycle protection shutdown of a sodium-cooled fast reactor during a power increase or decrease process includes the following steps.

[0038] S1: When the reactor reaches criticality, the regulating rod shall be lifted to 650mm, and the compensating rod shall be lifted to 30mm in front of the extrapolated critical rod position. The continuous lifting of the compensating rod shall not exceed 60mm each time, and the relative deviation of each compensating rod shall not exceed 70mm.

[0039] S2: During the transition to reactor criticality, extrapolated criticality is used, and the reactivity introduced each time the control rod is lifted is controlled at 3pcm-5pcm, and the waiting time after lifting the control rod must not be less than 30s.

[0040] S3: Increase the power to less than 100cps in the middle range, and control the reactivity introduced by continuous increase of a single compensation rod to 3pcm-5pcm.

[0041] S4: Increase the power to a level greater than 100cps in the middle range. The continuous increase of a single compensation rod shall not exceed 10mm. For each increase of 1%Pn, confirm that the power range and power indication are stable before continuing to increase the power.

[0042] It should be noted that Pn represents the rated nuclear power.

[0043] S5: During the power increase process, check whether the P signal is correctly triggered and whether the related locking is effective.

[0044] It should be noted that the P signal is a permission signal.

[0045] S6: During the process of increasing power by more than 10% Pn, the power increase rate is controlled, and each power increase does not exceed the current reactor power P x 5% (ie 5%P x ); During the reactor power adjustment process, keep the adjustment rod in the optimal adjustment area, and lift the compensation rods in turn when performing the balance rod grid operation, and the compensation rod position is lifted by no more than 10mm each time.

[0046] It should be noted that when conducting reactivity operations and related tests, operations or work that affect reactivity changes should be avoided. When the reactor is critical or in the low-power operation stage, related work needs to consider risk factors such as electromagnetic interference to avoid generating interference signals to the nuclear measurement system. Secondly, reactivity operations must be permitted by the duty officer and carried out under the supervision of a senior operator. Controlling the rate of power increase is also controlling the rate of introducing reactivity.

[0047] For example, the optimal adjustment area of ​​the adjustment rod may be when the adjustment rod is located between 400 mm and 800 mm.

[0048] According to the technical solution provided in the embodiment of the present application, a unique reactivity control solution for large sodium-cooled fast reactors is adopted to ensure the safety of the core, achieve the technical effect of safely and stably starting and stopping the reactor, and also ensure the technical effect of smoothly raising and lowering the power of the unit. The embodiment of the present application is to prevent the reactor from unexpected short-cycle protection events during the power raising and lowering process of large sodium-cooled fast reactors. The embodiment of the present application has been verified and improved through debugging, minor repairs of the unit, and major repairs of the unit, and through a variety of operation control methods, the safe and stable power raising and lowering of large sodium-cooled fast reactors is achieved.

[0049] The embodiments of the present application, through the study of reactor startup and shutdown and power increase and decrease methods, combined with the physical characteristics of fast neutron reactors, establish an operation control technology for preventing accidental short-cycle protection shutdown of the reactor during power increase and decrease of a sodium-cooled fast reactor, thereby enabling large-scale sodium-cooled fast reactors to safely and stably perform mode conversions and avoid reactor short-cycle protection shutdown accidents.

[0050] In at least one embodiment of the present application, S5.1 to S5.4 are a specific implementation of the above S5.

[0051] S5.1: When the intermediate range count rate is greater than 100cps, the P6 signal is triggered. If the P6 signal disappears during the power reduction process, it is confirmed that the source range short-cycle protection is activated.

[0052] S5.2: When the mid-range count rate is greater than 160cps, the P8 signal is triggered and the source range short-period signal is bypassed.

[0053] S5.3: When the power range power is greater than 5% Pn, the P9 signal is triggered. If the P9 signal disappears during the power reduction process, it is confirmed that the intermediate range short-cycle protection is activated.

[0054] S5.4: When the power in the power range is greater than 10% Pn, the P10 signal is triggered and the short-period signal in the intermediate range is bypassed.

[0055] In at least one embodiment of the present application, S01 is included before S1.

[0056] S01: Confirm that the reactor is in the standard cold shutdown initial state, the shutdown circuit breaker has been reset, the main pump speed has been increased to 50% of the rated speed, the reactivity instrument and nuclear measurement system are working normally, conduct a comprehensive inspection before starting the reactor, and set the critical control point.

[0057] Specifically, before starting, stopping, or increasing or decreasing the power of the reactor, an initial status check is first performed to confirm that the conditions required for the reactor status transition are in place and that there is no work that may affect the unit status transition, including the availability of the reactivity instrument and the normal operation of the nuclear detection detectors inside and outside the reactor.

[0058] In at least one embodiment of the present application, S1.1 and S1.2 are a specific implementation of the above S1.

[0059] S1.1: After the critical control point is released, the safety rods and passive rods are lifted to the top of the reactor, and the regulating rods are lifted to 650mm. At this time, the reactor is still in the shutdown state, the subcriticality is deep, and the short-cycle protection is not effective.

[0060] S1.2: Before lifting the compensation rod, calculate the critical rod position and cyclically lift the compensation rod to a position 30mm before the critical rod position. During the lifting process, ensure that the compensation rod position deviation is within 70mm and that each compensation rod is continuously lifted by no more than 60mm to avoid introducing excessive reactivity at a single time.

[0061] In at least one embodiment of the present application, S11 is further included after the above S1.

[0062] S11: Closely monitor the reactor cycle during the process of lifting the control rods. When the reactor cycle is less than 100s, stop lifting the control rods immediately and lower the control rods when necessary to avoid short cycles.

[0063] In at least one embodiment of the present application, S2.1 is a specific implementation of the above S2.

[0064] S2.1: As the reactor continues to increase its power towards criticality, an extrapolated criticality calculation is performed, with one-third of the reactivity deviation added each time. The operator performs independent calculations, and the reactivity continuously introduced by a single control rod is controlled at 3pcm-5pcm each time.

[0065] It should be noted that the above reactivity-related operations must be permitted by the duty officer and carried out under the supervision of a senior operator.

[0066] In at least one embodiment of the present application, S31 is included before S4.

[0067] S31: When the source range count rate is greater than 100cps, the source range short-cycle protection is activated.

[0068] It should be noted that in S31, due to the low counting rate and large counting fluctuation range, a short-cycle shutdown signal may appear. In this stage, the rate control of introducing reactivity is kept stable within 300s when the reactor doubling period is stable, and the cycle and reactivity changes are closely monitored. When the doubling period of a single-channel reactor is less than 30s or the doubling period of a two-channel reactor is less than 60s and continues to decline, the control rod is immediately inserted to reduce the reactivity, and then the reactor power is gradually increased to 0.1% Pn. The primary circuit is maintained and the steam generator is operated with water. Since the core temperature changes due to the cooling of the three circuits, the reactivity changes. At this time, it is also necessary to pay close attention to the changes in the core reactivity.

[0069] In at least one embodiment of the present application, S4.1 and S4.2 are a specific implementation of the above S4.

[0070] S4.1: When the power continues to increase and the mid-range count rate is greater than 100cps, the mid-range short-cycle protection is put into operation. In this stage, the rate of introducing reactivity is controlled so that the reactor doubling cycle is stable at more than 300s, and the reactivity introduced at a single time does not exceed 5pcm. The cycle and reactivity changes are closely monitored. When the doubling cycle of a single channel reactor is less than 30s or the doubling cycle of a two-channel reactor is less than 60s and continues to decrease, the control rod is immediately inserted to reduce the reactivity.

[0071] In step S4.1, during this process, due to the low count rate and large count fluctuation range, a short-cycle shutdown signal may appear. Therefore, by controlling the rate of introducing reactivity within a small range at this stage, the reactivity introduced at a single time does not exceed 5pcm, and closely monitoring the cycle and reactivity changes, the control rod is immediately inserted to reduce the reactivity when necessary, thereby avoiding the occurrence of a short-cycle shutdown signal.

[0072] S4.2: After the intermediate range short-cycle protection is put into operation, the continuous movement of a single compensation rod shall not exceed 10 mm each time, and each time the power is increased by 1% Pn, the next increase shall be made after the reactor power and cycle are stable.

[0073] In at least one embodiment of the present application, the above-mentioned S6 also includes S51 and S52.

[0074] S51: The reactor power is increased to 7% Pn. During the increase process, it is confirmed that when the intermediate range count rate reaches 160cps, the source range short-cycle protection bypass is activated, the P8 signal is triggered, and the source range detector is correctly cut off and shut down;

[0075] S52: The reactor power is increased to 7% Pn and maintained.

[0076] In step S52, since the three loops are performing water-steam conversion operations, changes in the core reactivity can be closely monitored.

[0077] In at least one embodiment of the present application, the above S6.1 and S6.2 are a specific implementation of the above S6.

[0078] S6.1: Increase the reactor power to 10% Pn, confirm that the P10 signal is triggered, the intermediate range short-cycle protection has been bypassed, and the intermediate range detector has been correctly cut off and shut down; check that the reactor power is slightly greater than 10% Pn, the relative power deviation of the power regulation system is less than or equal to 5% Pn, there is no signal prohibiting the control rod from being raised, and the regulating rod is put into automatic control.

[0079] S6.2: Continue to increase the reactor power to 11.9% Pn, 28% Pn, 40% Pn, 50% Pn, 75% Pn, and 100% Pn, respectively. Each power platform corresponds to the commissioning of the three-circuit system equipment. During the operation, the feed water and steam of the three circuits may be disturbed, which will affect the sodium temperature of the first circuit and the reactivity. Therefore, during the operation, it is necessary to pay close attention to the changes in the reactor power and confirm that the regulating rod is operating normally. Secondly, each power increase controls the power increase rate, and the maximum single power does not exceed 5% Px, where Px is the current power of the reactor.

[0080] In at least one embodiment of the present application, S7 to S10 are also included after S6.

[0081] S7: During the process of reducing the power of the reactor from 100% Pn to 10% Pn, attention may be paid to the power disturbance caused by the three-loop operation, while controlling the power reduction rate to ensure a smooth reduction in reactor power.

[0082] S8: When the power is reduced to 5% Pn, it is confirmed that the P9 signal disappears, and the intermediate range detector is put into operation and works normally. When the power is reduced to the intermediate range of 100cps, it is confirmed that the P6 signal disappears, and the source range detector is put into operation and works normally. When the source range count rate drops to 500cps, it is confirmed that the in-core measurement system is put into operation and works normally.

[0083] S9: During the power raising and lowering process, it is necessary to balance the bar grid multiple times. When balancing the bar grid, the single movement of the compensation rod shall not exceed 10mm to avoid excessive reactive fluctuations triggering the protection signal.

[0084] S10: insert the safety rod to the bottom of the reactor, insert the regulating rod and the compensating rod to the bottom of the reactor, insert the passive rod to the bottom of the reactor, then reduce the main pump speed to 25% of the rated speed, and conduct the final status inspection after the reactor is shut down.

[0085] The above embodiments of the present application provide a reactor power up / down operation control scheme. In some embodiments, a reactivity detection and application scheme may be implemented before the reactor power up / down operation control scheme. The following examples are given in conjunction with the in-core nuclear measurement system and the out-of-core nuclear measurement system.

[0086] For the in-core measurement system, when the reactor is started or stopped, when the neutron flux is low (for example, the source range neutron count rate is less than 100cps) and the count rate measured by the external nuclear measurement system fluctuates greatly (such as the reactor doubling period fluctuates from ∞ to less than 30s), the in-core measurement system is used to monitor the neutron flux density in the reactor to prevent the accidental introduction of positive reactivity or excessive positive reactivity introduction rate (such as a single introduction of reactivity causing the reactor doubling period to be less than 30s). 2) When the reactor neutron count rate gradually increases to a point where there is a stable count to the external nuclear measurement system (greater than 100cps), closely monitor the changes in neutron flux and control the reactivity introduction to less than 30pcm. 3) During the critical and power-up stages of the reactor, use an external reactivity measurement instrument to measure and calculate the changes in reactivity in real time.

[0087] For the out-of-core nuclear measurement system, the measurement range of the linear current amplifier card of the out-of-core nuclear measurement power range is adjusted to 10 -11 A-10 -4 A. The measuring current is divided into seven levels, and the level can be switched automatically or manually without disturbance, ensuring that the changes in core reactivity can be reliably monitored during the reactor power increase process. 2) Signal interference shielding measures are added to the external nuclear measurement system to prevent short-term protection shutdown due to signal interference during the reactor power increase process.

[0088] It should be noted that the combination of the various technical features in the embodiments of the present application is not limited to the combination described in the embodiments of the present application or the combination described in the specific embodiments, and all technical features described in the present application can be freely combined or combined in any way unless there is a contradiction between them.

[0089] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the term "comprising" only indicates that the steps and elements that have been clearly identified are included, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0090] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An operation control method for preventing an unexpected short-period protection shutdown of a sodium-cooled fast reactor during power increase or decrease, characterized in that: include: When the reactor reaches criticality, the regulating rod shall be lifted to 650mm, and the compensating rod shall be lifted to 30mm before the extrapolated critical rod position. The compensating rod shall be lifted continuously by no more than 60mm each time, and the relative deviation of each compensating rod shall not exceed 70mm. During the transition to reactor criticality, the extrapolated criticality shall be used, and the reactivity introduced by each control rod lifting shall be controlled at 3pcm-5pcm, and the waiting time after lifting the control rod shall not be less than 30s. When the power is increased to less than 100cps in the middle range, the reactivity introduced by a single compensating rod shall be controlled at 3pcm-5pcm. When the power is increased to more than 100cps in the middle range, the rod position of a single compensating rod shall be lifted continuously by no more than 10mm, and the power shall continue to be increased after confirming that the power range nuclear power indication is stable after each 1%Pn increase. During the power increase process, check whether the P signal is correctly triggered and the relevant locking is effective. During the power increase process above 10%Pn, control the power increase rate, that is, control the rate of introducing reactivity, and each power increase shall not exceed the current reactor power P. x 5%; during the reactor power adjustment process, keep the adjustment rod in the optimal adjustment area, and lift the compensation rods in turn when performing the balance rod grid operation, and the compensation rod position can be lifted by no more than 10mm each time.

2. The operation control method according to claim 1, characterized in that: During the power increase process, check whether the P signal is correctly triggered and the related locking is effective, including: When the intermediate range count rate is greater than 100cps, the P6 signal is triggered. If the P6 signal disappears during the power reduction process, it is confirmed that the source range short-cycle protection is activated. When the mid-range count rate is greater than 160cps, the P8 signal is triggered and the source range short-period signal is bypassed; When the power range power is greater than 5% Pn, the P9 signal is triggered. If the P9 signal disappears during the power reduction process, it is confirmed that the intermediate range short-cycle protection is activated. When the power in the power range is greater than 10% Pn, the P10 signal is triggered and the short-period signal in the intermediate range is bypassed.

3. The operation control method according to claim 1, characterized in that: When the reactor reaches criticality, the regulating rod is lifted to 650mm. Previously, the operation control method for preventing accidental short-cycle protection shutdown of the reactor during power increase or decrease of the sodium-cooled fast reactor also included: confirming that the reactor is in the standard cold shutdown initial state, the shutdown circuit breaker has been reset, the main pump speed has been increased to 50% of the rated speed, the reactivity instrument and nuclear measurement system are working normally, conducting a comprehensive inspection before starting the reactor, and setting critical control points.

4. The operation control method according to claim 1, characterized in that: When the reactor reaches criticality, the regulating rod is lifted to 650mm, and the compensating rod is lifted to 30mm before the extrapolated critical rod position. Each time the compensating rod is lifted continuously, the lifting shall not exceed 60mm, and the relative deviation of each compensating rod shall not exceed 70mm, including: After the critical control point is released, the safety rods and passive rods are lifted to the top of the reactor, and the regulating rods are lifted to 650 mm. At this time, the reactor is still in shutdown state, the subcriticality is deep, and the short-cycle protection is not effective. Before lifting the compensation rod, calculate the critical rod position and lift the compensation rod cyclically to a position 30mm before the critical rod position. During the lifting process, ensure that the compensation rod position deviation is within 70mm and that each compensation rod is lifted continuously by no more than 60mm to avoid introducing excessive reactivity at a single time.

5. The operation control method according to claim 1, characterized in that: When the reactor reaches criticality, the regulating rod is lifted to 650 mm, and the compensating rod is lifted to 30 mm before the extrapolated critical rod position. The continuous lifting of the compensating rod each time does not exceed 60 mm, and the relative deviation of each compensating rod does not exceed 70 mm. Afterwards, the operation control method for preventing the reactor from unexpected short-cycle protection shutdown during the power increase and decrease of the sodium-cooled fast reactor also includes: During the process of lifting the control rods, the reactor cycle is closely monitored. When the reactor cycle is less than 100s, the lifting of the control rods is stopped immediately and the control rods are lowered if necessary to avoid short cycles.

6. The operation control method according to claim 1, characterized in that: When the power is increased to an intermediate range greater than 100cps, the continuous increase in the position of a single compensation rod shall not exceed 10mm, and the power shall continue to be increased after confirming that the power range nuclear power indication is stable every time the power is increased by 1%. Previously, the operation control method for preventing accidental short-cycle protection shutdown of the reactor during the power increase and decrease of the sodium-cooled fast reactor also included: when the source range count rate is greater than 100cps, the source range short-cycle protection is put into operation.

7. The operation control method according to claim 1, characterized in that: Increase the power to a level greater than 100cps in the middle range. The continuous increase of a single compensation rod shall not exceed 10mm. For each increase of 1%Pn, confirm that the power range and power indication are stable before continuing to increase the power, including: Continue to increase the power. When the intermediate range count rate is greater than 100cps, the intermediate range short-cycle protection is activated. In this stage, the rate of introducing reactivity is controlled so that the reactor doubling cycle is stable at more than 300s. The reactivity introduced at a single time does not exceed 5pcm. The cycle and reactivity changes are closely monitored. When the doubling cycle of a single channel reactor is less than 30s or the doubling cycle of two channels reactor is less than 60s and still continues to decline, the control rod is immediately inserted to reduce the reactivity. After the intermediate range short-cycle protection is activated, the continuous movement of a single compensation rod does not exceed 10mm each time, and each time the power is increased by 1%Pn, the next increase is carried out after the reactor power and cycle are stable. After the intermediate range short-cycle protection is put into use, the continuous movement of a single compensation rod shall not exceed 10 mm each time, and each time the power is increased by 1% Pn, the next increase shall be made after the reactor power and cycle are stable.

8. The operation control method according to claim 1, characterized in that: When the power is increased by more than 10% Pn, the power increase rate is controlled, and each power increase does not exceed the current reactor power P x 5%; during the reactor power regulation process, the regulating rod is kept in the optimal regulation area, and the compensating rod is lifted in turn during the balance rod grid operation, and the position of the compensating rod is lifted by a maximum of 10mm each time. Previously, the operation control method for preventing the reactor from unexpected short-cycle protection shutdown during the power increase and decrease process of the sodium-cooled fast reactor also includes: The reactor power is increased to 7% Pn. During the increase process, it is confirmed that when the intermediate range count rate reaches 160cps, the source range short-cycle protection bypass is activated, the P8 signal is triggered, and the source range detector is correctly cut off and shut down; The reactor power is increased to 7% Pn and maintained there.

9. The operation control method according to claim 1, characterized in that: When the power is increased by more than 10% Pn, the power increase rate is controlled, and each power increase does not exceed the current reactor power P x 5%; During the reactor power adjustment process, keep the adjustment rod in the optimal adjustment area, and lift the compensation rods in turn when performing the balance rod grid operation, and each time the compensation rod position is lifted by a maximum of 10mm, including: The reactor power is increased to 10% Pn, and it is confirmed that the P10 signal is triggered, the intermediate range short-cycle protection has been bypassed, and the intermediate range detector is correctly cut off and shut down; check that the reactor power is slightly greater than 10% Pn, the relative power deviation of the power regulation system is less than or equal to 5% Pn, and there is no signal prohibiting the increase of the control rod, and put the regulating rod into automatic control; Continue to increase the reactor power to 11.9% Pn, 28% Pn, 40% Pn, 50% Pn, 75% Pn and 100% Pn respectively. Each power platform corresponds to the commissioning operation of the three-circuit system equipment. The operation may cause water supply and steam disturbances in the three circuits, which in turn affect the sodium temperature of the first circuit and the reactivity. Therefore, pay close attention to the changes in reactor power during operation and confirm that the regulating rod is operating normally. Secondly, control the power increase rate each time the power is increased. The maximum single power shall not exceed 5% Px, where Px is the current power of the reactor.

10. The operation control method according to claim 1, characterized in that: When the power is increased by more than 10% Pn, the power increase rate is controlled, and each power increase does not exceed the current reactor power P x 5%; During the reactor power adjustment process, keep the adjustment rod in the optimal adjustment area, and lift the compensation rods in turn when performing the balance rod grid operation, and each time the compensation rod position is lifted by a maximum of 10mm. After that, it also includes: During the process of reducing the power of the reactor from 100% Pn to 10% Pn, attention may be paid to the power disturbance caused by the three-circuit operation, while controlling the power reduction rate to ensure a smooth reduction in the reactor power; When the power is reduced to 5% Pn, confirm that the P9 signal disappears, and the mid-range detector is in operation and working properly. When the power is reduced to the mid-range 100cps, confirm that the P6 signal disappears, and the source range detector is in operation and working properly. When the source range count rate drops to 500cps, it is confirmed that the in-core core measurement system is in operation and working normally; During the power raising and lowering process, it is necessary to balance the bar grid multiple times. When balancing the bar grid, the single movement of the compensation bar should not exceed 10mm to avoid excessive reactive fluctuations that trigger the protection signal. Insert the safety rod to the bottom of the pile, insert the adjustment rod and compensation rod to the bottom of the pile, insert the passive rod to the bottom of the pile, then reduce the main pump speed to 25% of the rated speed, and conduct the final status inspection after the reactor is shut down.

Images