JP2011208960A - Method for monitoring withdrawal of control rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for monitoring the withdrawal of control rods which decreases constraints on the operation of a reactor, and further reduces the sudden change in a thermal margin caused by an erroneous withdrawal of control rods around rated power.SOLUTION: When the reactor power P on the selection of the withdrawal of selected control rods withdrawn continuously is a set reactor power Por lower (S3) and (P+γ(a power increase limit range)) is Por lower (S5), (P+γ) is set at the maximum value (RBL' value) of a reactor power increase (S6). Since reactor power (P+γ) is reactor power P, the reactor power Pis set as the RBL' value. When S5 is "No", Pis set at the RBL's value (S7). When S3 is "Yes", (P+α(a power increase limit range)) is set at the RBL' value (S4). γ and α have the relation of γ>α. As to the selected control rods, consecutive withdrawal is continued in the relation of RBL'≤RBM (control rod withdrawal monitoring output) and consecutive withdrawal is discontinued in the relation of RBL'≤RBM.

Description

  The present invention relates to a control rod withdrawal monitoring method, and more particularly to a control rod withdrawal monitoring method suitable for application to a boiling water reactor.

  A conventional control rod withdrawal monitoring system has a control rod withdrawal monitoring device and a control rod operation monitoring device. The control rod withdrawal monitoring device may increase the output in the vicinity of the control rod due to excessive withdrawal of the selected control rod, and the thermal margin of the fuel rod, that is, the minimum critical power ratio (MCPR) may be less than the safety critical value. LPRM signal, which is a neutron detection signal, regarding the neutron flux in the core detected by a plurality of local output region monitors (hereinafter referred to as “LPRM”) that are equally arranged in the core, The core flow signal from the core flow detector installed in the control rod, and the control rod position signal output from the control rod operation monitoring device (hereinafter referred to as RC & IS or RMCS. In this specification, only RC & IS is described) To monitor the control rod pull-out operation.

  When a control rod to be operated is selected, the control rod pull-out monitoring device inputs a position signal of the selected control rod from RC & IS and selects an LPRM signal around the selected control rod for monitoring the control rod. Based on the selected LPRM signal, the control rod withdrawal monitoring device obtains a control rod withdrawal monitoring output (hereinafter referred to as RBM value) which is a reactor output used for control rod withdrawal monitoring. The control rod withdrawal monitoring device inputs a core flow rate signal that is an output of the core flow rate detector, and outputs a control rod withdrawal prevention setting output (hereinafter referred to as RBL value) as a function of the core flow rate based on this signal. Ask. The control rod pull-out monitoring device compares the calculated RBM value and RBL value with a comparator. If the RBM value rises due to excessive pulling of the control rod due to an operator's erroneous operation and reaches the RBL value, the control rod pulls the control rod to RC & IS. Outputs a pull-out prevention signal. RC & IS stops the operation of pulling out the control rod by the control rod driving device when the control rod withdrawal prevention signal is inputted. By stopping the control rod extraction operation, excessive control rod extraction is prevented, so that the fuel rod can be kept sound. The control rod pull-out monitoring device has a plurality of RBL values (usually three). The control rod pull-up monitoring device changes the RBL value to a higher level according to the request of the operator or the RBL value setup function of the control rod pull-out monitoring device. It has the function of excluding bar pullout prevention.

  Japanese Patent Application Laid-Open Nos. 57-136197 and 2000-162356 describe the control rod pull-out monitoring device described above.

  A conventional control rod pull-out monitoring device has a plurality (usually three) of RBL values with the core flow rate as a variable. These RBL values are set in the vicinity of the rated power of the nuclear reactor and are fixed unless there is a change request from the operator. In the conventional control rod pull-out monitoring device, the RBL value is set in the vicinity of the rated output, so if an excessive control rod pull-out operation occurs due to an operator's mistaken operation or the like with the reactor power being low. Even if there is a margin in the RBM value, the change in the thermal margin increases depending on the state of the fuel assembly in the core. For this reason, it may be considered that some of the fuel rods become thermally severe.

  In order to solve such a problem, Japanese Patent Laid-Open No. 2008-256548 discloses a pull-out prevention generated when the minimum limit power ratio at the time of pulling out the control rod from the core is equal to or lower than the minimum limit power ratio set value. Control rod withdrawal monitoring system for stopping the withdrawal of the control rod based on any one of the withdrawal prevention signals generated from the signal and the neutron detection signal output from the neutron detection signal output from the local output region monitor disposed in Has proposed.

JP 57-136197 A JP 2000-162356 A JP 2008-256548 A

  The control rod pull-out monitoring system described in Japanese Patent Application Laid-Open No. 2008-256548 also has a plurality of RBL values (usually three) with the core flow rate as a variable. These RBL values are set in the vicinity of the rated power of the nuclear reactor and are fixed values unless requested to be changed by the operator. If the control rod withdrawal monitoring system is within the range of the RBL value, the control rod can be continuously withdrawn. However, from the viewpoint of protecting the fuel rods included in the fuel assembly loaded in the reactor core, there is a demand to limit the amount of control rod extraction to a smaller width near the rated output and to reduce the change in thermal margin. there were. In Japanese Patent Application Laid-Open No. 2008-256548, when the reactor power exceeds the output set value (for example, 95% output), the continuous withdrawal of the control rod is stopped, and the control rod is pulled out by a notch operation or a step operation. ing.

  In order to cope with the above requirement, when the width of the RBL value is set to a fixed value smaller than the conventional setting width (a fixed value that narrows the interval between levels A, B, and C in FIG. 6 described later). The inventors have found that a new problem arises that restrictions on the operation of the reactor become large. For this reason, the inventors have recognized that it is necessary to implement a control rod withdrawal monitoring system that enables continuous withdrawal of control rods that can reduce the restrictions on reactor operation and thermal margin. It was.

  An object of the present invention is to provide a control rod withdrawal monitoring method that can reduce the restrictions on the operation of a nuclear reactor and further reduce the change width of the thermal margin due to erroneous withdrawal of the control rod near the rated output.

The feature of the present invention that achieves the above-described object is that, in the power region below the set reactor power, which is a reactor power lower than the rated power of the reactor, the atoms that are raised by the continuous extraction of the control rod from the reactor core. When the reactor power is less than or equal to the upper limit of the first reactor power set based on the reactor power and the first power increase limit at the time of starting the withdrawal of the control rod, the continuous withdrawal of the control rod is continued.
In the power region exceeding the set reactor power, the reactor power that is increased by the continuous withdrawal of the control rod from the core is the second that is smaller than the reactor power at the start of the withdrawal of the control rod and the first power increase limit width. When the second reactor power upper limit set based on the power increase limit width is exceeded, the continuous withdrawal of the control rod is prevented.

  In the power region exceeding the set reactor power, the reactor power that is increased by the continuous withdrawal of the control rod from the core is the second that is smaller than the reactor power at the start of the withdrawal of the control rod and the first power increase limit width. When the upper limit of the second reactor power set based on the power increase limit is exceeded, the continuous pulling of the control rod is prevented, so the reactor power output by the continuous pulling of the control rod in the power range exceeding the set reactor power The increase width can be made smaller than the increase width of the reactor power due to the continuous pulling of the control rod in the power region below the set reactor power. For this reason, it is possible to increase the reactor power by continuously pulling out the control rods in an output region exceeding the set reactor power, and it is possible to reduce restrictions on the operation of the reactor. In addition, the increase in reactor power due to continuous extraction of control rods in the power region exceeding the set reactor power can be reduced, so the change in thermal margin due to erroneous extraction of control rods near the rated output of the reactor The width can be further reduced.

  Preferably, the atoms that rise by continuous drawing of the control rod that raises the reactor power below the first reactor power upper limit set by the first power increase limit width with the reactor power at the start of pulling out the control rod as a base point. When the reactor power reaches the set reactor power, the control rod is prevented from being continuously pulled out, and in the power range exceeding the set reactor power, the reactor rises by restarting the continuous drawing of the control rod that has been continuously pulled out. When the output exceeds the upper limit of the second reactor power set based on the reactor power at the time of restarting the continuous withdrawal of the control rod and the second power increase limit, the continuous withdrawal of the control rod that has resumed the continuous withdrawal is prevented. It is desirable.

  The reactor power that rises due to the continuous withdrawal of the control rod that increases the reactor power below the upper limit of the first reactor power set by the first power increase limit width based on the reactor power at the start of the control rod withdrawal. When the set reactor power is reached, continuous pulling of the control rod is prevented, so that the reactor output is less than the set reactor output and the reactor output near the set reactor output (for example, slightly less than the set reactor output) Even when the control rod is continuously pulled out in a state where the reactor power is low, the continuous withdrawal of the control rod is prevented when the reactor power reaches the set reactor power. Further, in the region where the reactor power exceeds the set reactor power, the reactor power reaches the second power increase limit width that is smaller than the first power increase limit width, with the set reactor power as a base point. Continuous withdrawal of control rods is allowed. However, when the reactor power exceeds the second power increase limit width based on the set reactor power, the continuous pulling out of the control rod is again prevented, and the second power increase limit width based on the set reactor power is increased. It is possible to prevent an increase in reactor power that exceeds that. For this reason, the variation width of the thermal margin in the high power region exceeding the set reactor power can be further reduced.

  According to the present invention, it is possible to reduce restrictions on the operation of the nuclear reactor and further reduce the change width of the thermal margin due to erroneous pulling of the control rod near the rated output.

It is a block diagram of the control-rod extraction monitoring system used for the control-rod extraction monitoring method of Example 1 which is one preferable Example of this invention. It is a flowchart which shows the process in the control rod extraction monitoring system at the time of extraction of the selection control rod in Example 1 centering on the process performed with the control rod extraction monitoring auxiliary | assistance apparatus shown in FIG. It is explanatory drawing which shows the driving | operation area | region of BWR in the control rod pull-out monitoring method of Example 1. FIG. It is an explanatory view showing the reactor power increase restriction width α in the output region exceeds the set reactor power P ₀ in the control rod withdrawal monitoring method of Example 1. Is an explanatory view showing a pull-out operation of the selection control rods in the output region exceeds the set reactor power P ₀ the following output area and set the reactor power P ₀ in the control rod withdrawal monitoring method of Example 1. It is explanatory drawing which shows the continuous extraction operation | movement of the selection control rod in a prior art example and Example 1. FIG. It is a block diagram of the control-rod extraction monitoring system used for the control-rod extraction monitoring method of Example 2 which is another Example of this invention. It is a flowchart which shows the process in the control rod extraction monitoring system at the time of extraction of the selection control rod in Example 2 centering on the process performed with the control rod extraction monitoring auxiliary | assistance apparatus shown in FIG. It is explanatory drawing which shows the driving | operation area | region of BWR in the control rod pull-out monitoring method of Example 2. FIG. It is an explanatory view showing the reactor power increase restriction ratio β in the output region exceeds the set reactor power P ₀ in the control rod withdrawal monitoring method of Example 2. Is an explanatory view showing a pull-out operation of the selection control rods in the output region exceeds the set reactor power P ₀ the following output area and set the reactor power P ₀ in the control rod withdrawal monitoring method of Example 2.

  Examples of the present invention will be described below.

  A control rod pull-out monitoring method according to Embodiment 1, which is a preferred embodiment of the present invention, will be described with reference to FIGS.

  First, an outline of a boiling water reactor (BWR) to which the control rod withdrawal monitoring system 1 is applied will be described. The nuclear reactor 16 includes a nuclear reactor pressure vessel 17, a core (not shown) loaded with a plurality of fuel assemblies 18, and a plurality of control rods 19. Four fuel assemblies 18 surround one control rod 19. The reactor core is disposed in the reactor pressure vessel 17, and the control rod 19 is inserted between adjacent fuel assemblies 18 loaded on the reactor core. Each control rod 19 is separately connected to a control rod drive mechanism (hereinafter referred to as CRD) 12. The CRD 12 is installed in a control rod drive mechanism housing (not shown) attached to the bottom of the reactor pressure vessel 17 and performs an operation of inserting the control rod 19 into the core and an operation of extracting the control rod 19 from the core. . A plurality of LPRM assemblies 22 including four local output region monitors (hereinafter referred to as LPRMs) 21 arranged in the axial direction of the core interferes with the operation of the control rod 19 between the fuel assemblies 18 in the core. It is placed in a position that does not become LPRM21 is a neutron detector. These LPRM assemblies 22 are arranged at positions that are to be subjected to 1/4 rotation in the core. A core flow rate detector 20 is installed in the reactor pressure vessel 17.

  As shown in FIG. 1, a control rod pull-out monitoring system 1 used in the control rod pull-out monitoring method of this embodiment includes a control rod pull-out monitoring device (hereinafter referred to as RBM) 2, a control rod pull-out monitoring auxiliary device 3, and a control rod. An operation monitoring device (hereinafter referred to as RC & IS) 10 and a control rod drive auxiliary board 11 are provided.

  The wirings 23-1 to 23-n connected to each LPRM 21 one by one are connected to the RBM 2 and the average output area monitor (hereinafter referred to as APRM) 13. The core flow rate detector 20 is connected to the RBM 2 by a wiring 36. The control rod pull-out monitoring auxiliary device 3 is connected to the RBM 2 by the wiring 38 and further connected to the RC & IS 10 by the wiring 41. An operation panel 14 having a display device 15 is connected to the control rod pull-out monitoring auxiliary device 3 by wiring 40. RC & IS 10 is also connected to operation panel 14 by wires 44 and 46. The control rod drive auxiliary board 11 is connected to the RC & IS 10 by the wiring 42 and is connected to the CRD 12 by the wiring 43.

  A control rod pull-out monitoring method of the present embodiment performed using the control rod pull-out monitoring system 1 will be described below.

  When the BWR is activated, the control rod 19 is pulled out of the core by the operation of the CRD 12 and changes from the subcritical state to the critical state. Thereafter, the reactor power is increased to the rated output through a temperature raising and pressure increasing process in which the control rod 19 is further pulled out. When the control rod 19 is pulled out, the control rod drawing information of the control rod drawing sequence is sequentially displayed on the display device 15 of the operation panel 14. The control rod extraction information regarding the control rods 19 to be extracted (hereinafter referred to as selection control rods) 19 includes position information of the selection control rods 19 in the core cross section and information on the set extraction amount. Based on the control rod extraction information displayed on the display device 15, the operator inputs the position information and the set extraction amount information on the cross section of the selected control rod 19 to be extracted next from the operation panel 14 (step S 1 ( (See FIG. 2)). By inputting these pieces of information, a control rod extraction command 53 for the CRD 12 that operates the corresponding selection control rod 19 is output from the operation panel 14. The control rod extraction command 53 includes the position information of the selected control rod 19 and the set extraction amount information. A control rod extraction command 53 is input to the control rod extraction monitoring auxiliary device 3 via the wiring 40, and is input to the RC & IS 10 via the wiring 44.

  The RC & IS 10 having received the control rod extraction command 53 outputs a control rod continuous extraction request signal 58 for the selected control rod 19 to the control rod drive auxiliary board 11 (step S13 (see FIG. 2)). The control rod continuous extraction signal 61 output from the control rod drive auxiliary board 11 based on the control rod continuous extraction request signal 58 drives the CRD 12 that operates the selection control rod 19 designated by the position information. As a result, the selection control rod 19 is extracted from the core by the set extraction amount. The pulling amount of the selected control rod 19 can be grasped based on the position of the control rod in the core axis direction detected by the control rod position detector 24 provided in the CRD 12. The position of the control rod 19 in the core axis direction detected by the control rod position detector 24 is input to the RC & IS 10.

  In the process of increasing the reactor power, the reactor power is increased by pulling out the selection control rod 19. In particular, the output increases in the four fuel assemblies 18 adjacent to the selection control rod 19.

  During the operation of the BWR, cooling water is supplied to the core to cool each fuel rod included in the fuel assembly 18. The flow rate of cooling water supplied to the core is controlled by a recirculation pump (not shown) (or an internal pump) and detected by the core flow rate detector 20. The core flow rate detector 20 that has detected the coolant flow rate outputs a core flow rate signal 51 to the wiring 36. This core flow rate signal 51 is input to the RBM 2. The cooling water is heated by the heat generated by the nuclear fission of the nuclear fuel material contained in each fuel rod, and a part of the cooling water becomes steam. This steam is guided to a turbine (not shown) by a main steam pipe (not shown) connected to the reactor pressure vessel 27.

  Each LPRM 21 provided in each LPRM assembly 22 arranged in the core is generated by nuclear fission of nuclear fuel material contained in the fuel assembly 18 by pulling out the selection control rod 19 from the core after the start of the BWR. The detected neutron flux is detected, and a detection signal (hereinafter referred to as LPRM signal) of this neutron flux is output. LPRM signals (neutron detection signals) 50-1 to 50-n output from the respective LPRMs 21 are input to the RBM 2 through the wirings 23-1 to 23-n, and are connected to the wirings 23-1 to 23-n and the wiring 37. And input to the APRM 13. The APRM 13 calculates the reactor power by averaging the LPRM signals 50-1 to 50-n.

  In the RBM 2, when the selection control rod 19 is excessively pulled out due to an erroneous operation on the operation panel 14 of the operator or the like, and the increase in the output of the fuel assembly 18 positioned around the selection control rod 19 increases, In order to ensure the thermal margin of the aggregate 18, it has a function of preventing the selection control rod 19 from being pulled out. Therefore, the RBM 2 inputs the LPRM signals 50-1 to 50-n through the wirings 23-1 to 23-n and the core flow rate signal 51 through the wirings 36. The RBM 2 uses the corresponding LPRM signal among the LPRM signals output from the LPRMs 21 existing in the LPRM aggregate 22 located around the selection control rod 19 in order to monitor the pulling of the selection control rod 19. To calculate the RBM value (step S14 (see FIG. 2)).

  Specifically, the LPRM signal selection unit (not shown) of the RBM 2 has four LPRM sets adjacent to the selection control rod 19 when the selection control rod 19 is located in the center of the core. When the selection control rod 19 is located in the periphery of the core, the LPRM signals 50 output from a total of 16 LPRMs 21 existing in the body 22 are three adjacent to the selection control rod 19. Alternatively, the LPRM signals 50 output from all LPRMs 21 existing in the two LPRM aggregates 22 are selected from the LPRM signals 50-1 to 50-n. The LPRM signal selection unit calculates the RBM value using the input core flow signal 36 and all the selected LPRM signals 50. The calculation of the RBM value is performed every calculation cycle of the LPRM signal selection unit, and the RBM value is updated with the newly calculated RBM value.

  When the RBM value reaches the RBL value by the extraction operation of the selection control rod 19, the RBM 2 outputs a control rod extraction prevention signal 55 for the rod block to the control rod extraction monitoring auxiliary device 3 through the wiring 38. This control rod withdrawal prevention signal 55 is transmitted to the corresponding CRD 12 via the control rod withdrawal monitoring auxiliary device 3, the RC & IS 10 and the control rod drive auxiliary board 11. The corresponding CRD 12 prevents the selection control rod 19 from being pulled out.

  The RBM 2 has a plurality of RBL values (usually three). That is, these are three control rod pull-out prevention setting lines (RB lines), specifically, three lines of a positive RB line A, an intermediate RB line B, and a low RB line C, and each RBL determined by the core flow rate. Value. The operator has a function of changing the RBL value to a higher RBL value in response to an RBL value setup request input from a man-machine interface (hereinafter referred to as MMI) provided on the operation panel 14. For this reason, when the RBM value reaches the RBL value and the selection control rod 19 is prevented from being pulled out, the setup request is used to set up the upper RBL value (for example, the intermediate RB line B is set up as the positive RB line A). ) To prevent the selection control rod 19 from being pulled out. However, the highest RBM value (the RBM value of the positive RB line A) cannot be set up. This RBL setup function is an extended function of RBM2. By monitoring the RBM value and the core flow rate signal 51 by the LPRM signal processing unit of the RBM 2, the RBM 2 can also perform RBL setup by itself without the operator's operation from the MMI. Further, when the reactor power drops when the control rod 19 is inserted into the core, the RBM 2 monitors the RBM value and the core flow rate signal 51, sets the RBL value itself, and changes the RBL value to the lower RBL value. (For example, the intermediate RB line B can be changed to the low RB line C).

An example of the BWR operation region in this embodiment is shown in FIG. 3 as a relationship between the core flow rate and the reactor power. In FIG. 3, the set reactor power P ₀ is lower than the rated power and is a reactor power threshold value at which the continuous pulling of the selection control rod 19 is stopped. That is, when the reactor power obtained by the APRM 13 exceeds the set reactor power P ₀ during the continuous pulling operation of the selection control rod 19, when the reactor power reaches the set reactor power P ₀ , The continuous pulling of the selection control rod 19 is stopped.

α% and γ% indicate the increase limit of the reactor power, and α <γ. The reactor power increase limit width γ% is set to be equal to or greater than the increase width of the reactor power that increases at the maximum extraction amount among the extraction amounts of the selected control rods 19 set in the control rod extraction sequence. In this embodiment, the reactor power increase limit width γ% is set to the increase width of the reactor power that increases with the maximum extraction amount. In the present embodiment, the reactor power increase limit width α% is 5%, and as shown in FIG. 4, by the continuous drawing of the selection control rod 19 in the reactor power region exceeding the set reactor power P _0. Applies to increased output. Incidentally, in the configuration reactor power P ₀ the following reactor power region, for increased output by continuous withdrawal of the selected control rod 19, the reactor power rises limited width gamma% is applied. The set reactor power P ₀ in the present embodiment is, for example, 95%.

  As described above, based on the control rod continuous extraction request signal 58 for the selection control rod 19 output from the RC & IS 10, the selection control rod 19 is extracted from the core, so that the reactor output increases. LPRM signals 50-1 to 50-n respectively output from LPRMs 21 included in each LPRM aggregate 22 are input to APRM 13. The APRM 13 averages the LPRM signals 50-1 to 50-n to obtain the reactor power, and outputs this reactor power to the wiring 39. The reactor power output from the APRM 13 is input to the control rod withdrawal monitoring auxiliary device 3. The APRM 13 constantly receives the LPRM signals 50-1 to 50-n to obtain the reactor power.

Control part of the selection control rod 19 which is set with a stick sequence, for example, shown in FIG. 5, the reactor power P ₁ of the reactor power P ₂ set withdrawal amounts set selected control rod 19A to increase to , selected reactor power P ₂ of the reactor power P ₃ to the set withdrawal amounts set selected control rods 19B to increase, and that is set withdrawal amounts to increase the reactor power P ₃ to reactor power of 100% has been set Assume control rod 19C.

  The function of the control rod pull-out monitoring auxiliary device 3 used in the control rod pull-out monitoring system 1 of this embodiment will be described with reference to FIG. 2, taking the output increase shown in FIG. 5 as an example. The control rod pull-out monitoring auxiliary device 3 executes each process of steps S2 to S9 surrounded by a one-dotted line in FIG. Each process of steps S10 to S13 shown in FIG. 2 is executed by RC & IS10.

  A control rod extraction command 53 for the selected control rod 19A output from the operation panel 14 is input to the control rod extraction monitoring auxiliary device 3 and the RC & IS 10. The RC & IS 10 outputs a control rod continuous drawing request signal 58 relating to the selected control rod 19A to the control rod drive auxiliary board 11 (step S13). The CRD 12 that operates the selection control rod 19A is driven by the output of the control rod continuous extraction request signal 58, and the selection control rod 19A is continuously extracted from the core.

Reactor output P at the time of selection of the drawing control rod is input (step S2). The reactor power P ₁ input from APRM13 at the time when the control rod withdrawal instruction 53 for the selected control rod 19A is input to the control rod withdrawal monitoring aid 3 (withdrawal beginning of the control rods), atomic during withdrawal control rod selection The furnace power is P. It is determined whether the reactor power P is less than or equal to the set reactor power P ₀ (step S3). Since the reactor power P ₁ is equal to or less than the set reactor power P ₀ (see FIG. 5), the determination in step S3 is “No”. Therefore, it is determined whether or not the reactor power (P + γ) is equal to or lower than the set reactor power P ₀ (step S5). As shown in FIG. 5, since the reactor power P ₂ that is the reactor power (P ₁ + γ) is equal to or lower than the set reactor power P ₀ , the determination in step S5 is “Yes”. Next, the reactor power (P + γ) is set to a reactor power increase upper limit (reactor power upper limit) (hereinafter referred to as RBL ′ value) (step S6). Since the reactor power (P ₁ + γ) is the reactor power P ₂ , the reactor power P ₂ is set as the RBL ′ value.

It is determined whether the RBM value is equal to or greater than the RBL ′ value (step S8). The RBM value obtained by the RBM 2 when the selection control rod 19A is continuously pulled out is input to the control rod pull-out monitoring auxiliary device 3 through the wiring 38 as an RBM signal. As described above, the RBM value is obtained using the corresponding LPRM signal among the LPRM signals output from the LPRMs 21 existing in the LPRM aggregate 22 located around the selection control rod 19A in the RBM2. (Step S14). As the selection control rod 19A is pulled out, the output rises around the fuel assembly 18 existing around the selection control rod 19A, and the RBM value obtained by RBM2 also increases. However, the selection control rod 19A is controlled by the rods period until withdrawal is withdrawn to the withdrawal amount set in the sequence, it is lower than the reactor power P ₂ RBM value is RBL' value obtained in RBM2. For this reason, the determination in step S8 is “No”.

  When the determination in step S8 is “No”, the control rod pull-out monitoring auxiliary device 3 does not do anything with the determination result and continues the current state. In response to the determination in step S8, the control rod pull-out monitoring auxiliary device 3 outputs a selection control rod continuous pull-out prevention signal 56 as described later only when “Yes”. In FIG. 2, “No” is entered for the determination in step S <b> 8 in order to make the explanation about the operation of the BWR easier to understand. Also, “No” is entered for the determination in step S12 for the same reason.

  If the determination in step S8 is “No”, in other words, if the determination in step S8 is not “Yes”, the selection control rod 19A is continuously pulled out. A position signal 66 of the selected control rod 19A in the core axis direction, which is detected every moment by the control rod position detector 24 provided in the CRD 12, is input to the RC & IS 10 by the wiring 47. The RC & IS 10 determines whether or not the selection control rod has been pulled out (step S12). Based on the input position signal 66 of the selection control rod 19A, it is determined whether or not the extraction amount of the selection control rod 19A has reached the set extraction amount included in the control rod extraction command 53 for the selection control rod 19A. When the extraction amount of the selection control rod 19A is not the set extraction amount, the determination in step S12 is “No”. When the determination in step S12 is “No”, the RC & IS 10 does nothing with the determination result and continues the current state. That is, the continuous pulling of the selection control rod 19A and the determination in step S8 are continuously performed.

If the pulling operation of the selection control rod 19A is continued, the determination in step S12 will be “Yes”. When the determination in step S <b> 12 is “Yes”, the RC & IS 10 outputs a drawing stop request signal 59 to the control rod drive auxiliary board 11. The control rod drive auxiliary board 11 that has received the withdrawal stop request signal 59 outputs a withdrawal stop signal 62 to the CRD 12 that operates the selection control rod 19A. The CRD 12 operating the selection control rod 19A stops the extraction of the selection control rod 19A based on the extraction stop signal 62. At this time, the selection control rod 19A is pulled out from the core by a set pulling amount. When the determination in step S12 is “Yes”, an extraction completion signal indicating “extraction of the selection control rod 19A” is output from the RC & IS 10 to the operation panel 12 through the wiring 45. This extraction completion signal is displayed on the display device 15. When the selection control rod 19A is pulled by a set withdrawal amount, the reactor power rises to reactor power P _2.

  The operator who has viewed the display of the pull-out completion signal of the selection control rod 19A, based on the control rod pull-out information displayed on the display device 15, positions information on the core cross section of the next selection control rod 19B to be pulled out and the setting pull-out. Quantity information is input from the operation panel 14. The control rod extraction command 53 for the selected control rod 19B output from the operation panel 14 is input to the control rod extraction monitoring auxiliary device 3 and the RC & IS 10 as in the case of the selected control rod 19A. Since RC & IS10 outputs a control rod continuous drawing request signal 58 relating to the selection control rod 19B to the control rod drive auxiliary board 11 (step S13), the CRD 12 for operating the selection control rod 19B is driven, and the selection control rod 19B continues from the core. Pulled out.

In step S2, the reactor power P ₂ input from APRM13 at the time when the control rod withdrawal command 53 is input to the control rod withdrawal monitoring auxiliary device 3 to the selected control rod 19B, and the reactor power P during withdrawal control rod selection To do. Since reactor power P ₂ is equal to or smaller than the set reactor power P ₀ (see FIG. 5), the determination in step S3 is "No", the determination in step S5 is performed. Since the reactor power (P ₂ + γ) is the reactor power P ₃ and exceeds the set reactor power P ₀ (see FIG. 5), the determination in step S5 becomes “No”. Therefore, the set reactor power P ₀ is set to the RBL ′ value (step S7). If the reactor power P ₂ is equal to or lower than the set reactor power P _{0 and} the determination in step S5 is “No”, the reactor power is set to the set reactor power P ₀ while the selection control rod 19B is being pulled out. Indicates that there is a possibility of reaching.

Reactor power is increased by pulling out the selection control rod 19B. A new RBM value obtained by the RBM 2 is input to the control rod withdrawal monitoring auxiliary device 3. In step S8, since lower than the set reactor power _{P 0} RBM value is RBL' value, the determination in step S8 becomes "No". Since the determination in step S12 executed in RC & IS10 is also “No”, the continuous pulling of the selection control rod 19B is continuously performed in the same manner as the selection control rod 19A. When RBM value obtained by RBM2 elevated reactor power further becomes set reactor power P ₀ by withdrawal of the selected control rods 19B, the determination in step S8 is "Yes".

  Continuous withdrawal of the selection control rod is prevented (step S9). Since the determination in step S8 is “Yes”, the control rod withdrawal monitoring auxiliary device 3 outputs the continuous withdrawal prevention signal 56 of the selected control rod 19B to the RC & IS 10. The RC & IS 10 outputs a continuous drawing prevention request signal 60 based on the continuous drawing prevention signal 56. The control rod drive auxiliary board 11 receives the continuous pulling prevention request signal 60 and outputs a continuous pulling stop signal 63 to the CRD 12 that operates the selection control rod 19B. The CRD 12 that operates the selection control rod 19B prevents the selection control rod 19B from being drawn based on the continuous drawing / drawing stop signal 63.

  The RC & IS 10 having received the continuous withdrawal prevention signal 56 determines whether or not the withdrawal of the selected control rod has been completed (step S10). Based on the input position signal 66 of the selection control rod 19B, it is determined whether or not the extraction amount of the selection control rod 19B has reached the set extraction amount included in the control rod extraction command 53 for the selection control rod 19B. When the extraction amount of the selection control rod 19A is not the set extraction amount, the determination in step S10 is “No”. If the determination in step S10 is “Yes”, the RC & IS 10 outputs an extraction completion signal indicating “extraction completion of the selection control rod 19B” to the operation panel 14. This extraction completion signal is displayed on the display device 15.

  Since the determination in step S10 is “No”, the RC & IS 10 outputs the continuous pulling stop information and the information indicating that the selection control rod pulling incomplete in step S11 to the operation panel 14 via the wiring 46. When the determination in step S10 is “No”, the RC & IS 10 uses the position signal 66 of the selected control rod at the time when the continuous extraction of the corresponding selected control rod is stopped to determine the set withdrawal amount for the selected control rod. Of these, the amount of extraction that remains without being extracted (hereinafter referred to as the remaining amount of extraction) is calculated. Specifically, the pulling remaining amount for the selection control rod 19B is obtained. The RC & IS 10 outputs the information indicating that the selection control rod is not yet drawn, including the remaining amount of drawing. Information indicating the continuous withdrawal cancellation information regarding the selection control rod 19B and information indicating that the selection control rod withdrawal is not completed, including the remaining withdrawal amount, transmitted to the operation panel 14 is displayed on the display device 15.

  The operator sees these pieces of information displayed on the display device 15 and recognizes that the continuous pulling of the selection control rod 19B has been prevented and that the selection control rod 19B is being pulled out. For this reason, the operator inputs the position information of the selection control rod 19B and the extraction remaining amount which is the extraction amount on the operation panel 14. From the operation panel 14, a control rod extraction command 53 including position information for the selected control rod 19 </ b> B and the remaining amount of extraction is input to the control rod extraction monitoring auxiliary device 3 and the RC & IS 10.

The RC & IS 10 outputs a control rod continuous extraction request signal 58 for the selected control rod 19B to the control rod drive auxiliary board 11 based on the control rod extraction command 53 (step S13). For this reason, the extraction of the selection control rod 19B is resumed. The control rod withdrawal command 53 control rod withdrawal monitoring auxiliary device 3 to the selected control rods 19B, again, the reactor power P ₀ inputted from APRM13 at the time of the input and reactor power P during withdrawal control rod selection (Step S2). Since reactor power P is a reactor power P _0, the determination in step S3 is "Yes". Next, (P + α)% is set to the RBL ′ value (step S4). In step S4, (P ₀ + α)% is set to the RBL ′ value. Here, the reactor power increase limit width α% is, for example, 5%. The determination in step S8 is performed using (P ₀ + α)% as the RBL ′ value. At this time, since the RBM value input from the RBM 2 is smaller than (P ₀ + α)%, the determination in step S8 is “No”, and the continuous withdrawal prevention signal 56 is not output from the control rod withdrawal monitoring auxiliary device 3. As a result, the continuous pulling of the selection control rod 19B is continued.

While the selection control rod 19B is being continuously pulled out, in RC & IS10, the process of step S12 is performed. Based on the input position signal 66 of the selection control rod 19B, it is determined whether or not the remaining amount of the selection control rod 19B has been extracted. When the determination in step S12 is “Yes”, the selection control rod 19B has been pulled out by the amount remaining. Reactor power is raised to reactor power P ₃ (see FIG. 5).

  When the determination in step S <b> 12 is “Yes”, the RC & IS 10 outputs a drawing stop request signal 59 to the control rod drive auxiliary board 11. As a result, the drive of the CRD 12 for operating the selection control rod 19B is stopped, and the pulling out of the selection control rod 19B is stopped. When the determination in step S <b> 12 is “Yes”, an extraction completion signal indicating “extraction completion of the selection control rod 19 </ b> B” is output from the RC & IS 10 to the operation panel 12, and this extraction completion signal is displayed on the display device 15.

The operator who has viewed the display of the pull-out completion signal of the selection control rod 19B, based on the control rod pull-out information displayed on the display device 15, positions information on the core cross-section of the next selection control rod 19C to be pulled out and the setting pull-out. Quantity information is input from the operation panel 14. The setting withdrawal amount information, the reactor power is a pull-out amount of the selected control rod 19C to increase the reactor power P ₃ up to the rated output of 100%. The control rod extraction command 53 for the selected control rod 19C output from the operation panel 14 is input to the control rod extraction monitoring auxiliary device 3 and the RC & IS 10 as in the case of the selected control rod 19A. The RC & IS 10 outputs a control rod continuous extraction request signal 58 relating to the selection control rod 19C to the control rod drive auxiliary board 11 (step S13), so that the CRD 12 for operating the selection control rod 19C is driven and the selection control rod 19C is extracted from the core. It is burned.

In step S2, the reactor power P ₃ inputted from APRM13 at the time when the control rod withdrawal command 53 is input to the control rod withdrawal monitoring auxiliary device 3 to the selected control rod 19C, and the reactor power P during withdrawal control rod selection To do. Since the reactor power P ₃ exceeds the set reactor power P ₀ (see FIG. 5), the determination in step S3 is “Yes”, and (P ₃ + α)% is set to the RBL ′ value in step S4. The The determination in step S8 is performed using (P ₃ + α)% as the RBL ′ value. At this time, since the RBM value input from the RBM 2 is smaller than (P ₃ + α)%, the determination in step S8 is “No”, and the continuous withdrawal prevention signal 56 is not output from the control rod withdrawal monitoring auxiliary device 3. As a result, the continuous pulling of the selection control rod 19B is continued.

  In RC & IS10, the process of step S12 is performed. Based on the input position signal 66 of the selection control rod 19C, it is determined whether the set extraction amount for the selection control rod 19C has been extracted. When the determination in step S12 is “Yes”, the selection control rod 19C has been pulled out by the set pulling amount. Reactor power increases to 100% rated power.

  When the determination in step S <b> 12 is “Yes”, the RC & IS 10 outputs a drawing stop request signal 59 to the control rod drive auxiliary board 11. As a result, the drive of the CRD 12 that operates the selection control rod 19C is stopped, and the pulling out of the selection control rod 19B is stopped. When the determination in step S <b> 12 is “Yes”, an extraction completion signal indicating “extraction completion of the selection control rod 19 </ b> C” is output from the RC & IS 10 to the operation panel 12, and this extraction completion signal is displayed on the display device 15.

  The BWR is operated at a rated output of 100% by the above pulling operation of the selection control rod.

If the operator mistakenly sets the pulling amount set for the selection control rod 19C to such a pulling amount that the reactor power becomes P ₄ exceeding (P ₃ + α)%. At this time, since the determination in step S8 is “Yes”, the continuous withdrawal prevention signal 56 is output from the control rod withdrawal monitoring auxiliary device 3, and the continuous withdrawal of the selected control rod 19C is prevented.

The main points of continuous drawing of the selected control rod in the control rod drawing monitoring method of this embodiment will be described with reference to FIG. In the operation of the selection control rod in the conventional example, as shown on the left side of FIG. 6, the selection control rod can be continuously pulled out regardless of the reactor power. In the control rod withdrawal monitoring method of this embodiment, the reactor output (hereinafter referred to as the selected control rod) when the selected control rod is selected, that is, when the control rod withdrawal command 53 for the selected control rod is output from the operation panel 14. Reactor power at the time of selection (reactor power at the time of selection) is lower than the set reactor power P ₀ which is the threshold of the reactor power to stop the continuous pulling of the selected control rods, or exceeds the set reactor power P ₀ The operation of the selection control rod differs depending on the output.

When the reactor power P when the selected control rod is selected is equal to or less than the set reactor power P ₀ , for example, when the reactor power P when the selected control rod is selected is the level C nuclear power shown in FIG. , when raising the reactor power from nuclear output P to (P + gamma)%, the range of (P + gamma)% does not exceed the set reactor power P _0, to permit continuous withdrawal of the selected control rods. When the reactor power P when the selected control rod is selected exceeds the set reactor power P ₀ , for example, when the reactor power P when the selected control rod is selected is the level B nuclear power shown in FIG. In this case, the continuous pulling out of the selected control rod is permitted in the range of the reactor power from the nuclear power P to (P + α)%. When the reactor power by withdrawal of the selected control rod is increased beyond a set reactor power P ₀ is the time when the reactor power becomes set reactor power P _0, stops the continuous withdrawal of the selected control rod To do. In the case of raising the reactor power by extracting the selected control rod by the remaining withdrawal amount with respect to the selected control rod, after the continuous withdrawal of the selected control rod is stopped at the set reactor power P ₀ , the set reactor power P If it is within the range from ₀ to (P + α)%, continuous pulling of the selection control rod is permitted.

In the present embodiment, in the power range exceeding the set reactor power P ₀ , the reactor power that rises due to the continuous withdrawal of the selected control rod 19 from the core, the control rod withdrawal command 53 for this selected control rod 19A is the control rod withdrawal. Reactor power increase limit width narrower than reactor power P and reactor power increase limit width γ (first power increase limit width) at the time of input to the monitoring auxiliary device 3 (at the time when the selection control rod 19 starts to be pulled out) When the RBL ′ value set based on α (second output increase limit width) is exceeded, the continuous pulling of the selection control rod 19 is prevented, so that the selection control rod 19 in the output region exceeding the set reactor power P ₀ is selected. that the rise of the reactor power by continuous withdrawal is made smaller than increase the width of the reactor power by continuous withdrawal of the selected control rod 19 in the set reactor power P ₀ the following output region That. For this reason, it is possible to increase the reactor power by continuously pulling out the selection control rod 19 in an output region exceeding the set reactor power P ₀ , thereby reducing restrictions on the operation of the reactor. In addition, since the increase in the reactor power due to the continuous pulling of the selection control rod 19 in the output region exceeding the set reactor power P ₀ can be reduced, the selection near the rated output (100% output) of the reactor 16 is possible. The change width of the thermal margin due to erroneous pulling out of the control rod 19 can be further reduced.

In this embodiment, even if the reactor power P at the time when the control rod withdrawal command 53 is input to the control rod withdrawal monitoring auxiliary device 3 (control rod withdrawal start time) is equal to or less than the set reactor output P ₀ (P + α). ) If the percentage exceeds the set reactor power P ₀ , the set reactor power P ₀ is set to the RBL ′ value, so if the reactor power P is less than the set reactor power P ₀ , the set reactor power P Even when the selective control rod 19 is continuously pulled out while the reactor power is close to ₀ , the reactor power increase limit width γ% from the reactor power P at the start of the continuous pulling of the selective control rod 19 The increase in reactor power can be prevented. Therefore, it is possible to further reduce the variation width of the thermal margin at high output region exceeds the set reactor power P ₀ (e.g., near the rated output of reactor 16).

In the present embodiment, the selected control rod 19 is continuously pulled out in a state where the reactor power P when the control rod withdrawal command 53 is input to the control rod withdrawal monitoring auxiliary device 3 is equal to or less than the set reactor power P _0. When (P + γ)% exceeds the set reactor power P ₀ , the selected control rod 19 is increased when the reactor power that rises due to continuous withdrawal of the selected control rod 19 reaches the set reactor power P _0. Of continuous drawing is prevented. The pulling remaining amount of the selected control rod 19 from which the continuous pulling is prevented is obtained based on the position signal output from the control rod position detector 24 and displayed on the display device 15. For this reason, in order for the operator to pull out the selection control rod 19 for which continuous pulling has been stopped, only the remaining amount of extraction, the position information of this selection control rod 19 and the set extraction amount (removal remaining amount) to the operation panel 14 are extracted. Input can be performed easily.

In Japanese Patent Application Laid-Open No. 2008-256548, even if the core is in a state where a sufficient thermal margin is secured at a set reactor power (for example, 95%) or more, the control rod is continuously drawn at the set reactor power. Stopped. The increase of the reactor power exceeding the set reactor power is performed by a notch operation or a step operation of the control rod. On the other hand, in this embodiment, even when the reactor power increases beyond the set reactor power P ₀ , the control rod 19 is continuously pulled out within a preset power increase limit within a range in which a thermal margin is secured. It is possible, and the operability of the control rod operation in the high output region is excellent.

  Here, the continuous pulling of the control rod is a control rod pulling operation performed in a state where the control rod pulling mode is set to “continuous pulling” in the RC & IS 10 for controlling the control rod pulling. Specifically, in this continuous pulling mode, while the operator pushes the control rod pulling button provided on the operation panel 14, the control rod continuous pulling signal 58 is output from the RC & IS 10, and the control rod 19 is continuously moved from the core. Pulled out. The control rod notch operation (or step operation) is set by the operator from the operation panel 14 and is performed by the control rod extraction operation performed in the state where the control rod extraction mode is set to “notch operation (or step operation)” in the RC & IS 10. is there. In this case, every time the control rod is pulled out from the core by one notch (or one step), the operator needs to press a control rod pull-out button provided on the operation panel 14. Note that the influence on the thermal margin of the fuel rods included in the fuel assembly 18 is noticeable when the control rods 19 are continuously pulled out (in a short time). The notch operation (or step operation) is an operation that has no influence on the thermal margin because judgment and operation by the operator is involved every time the button provided on the operation panel 14 is operated. These two are properly used for control rod operation.

An arbitrary output level can be set as the set reactor output P ₀ , and by setting the output increase limit width α according to the set reactor output P ₀ , the same effect as the above embodiment can be obtained. I can expect.

  A control rod pull-out monitoring method according to Embodiment 2, which is another embodiment of the present invention, will be described with reference to FIGS.

  As shown in FIG. 7, a control rod pull-out monitoring system 1A used in the control rod pull-out monitoring method of the present embodiment uses the control rod pull-out monitoring auxiliary device 3 as a control rod in the control rod pull-out monitoring system 1 used in the first embodiment. It has the structure replaced with the drawing monitoring auxiliary device 3A. Other configurations of the control rod pull-out monitoring system 1A are the same as those of the control rod pull-out monitoring system 1. The control rod pull-out monitoring auxiliary device 3A executes each process in the range surrounded by the one-dot chain line shown in FIG. The processing executed by the control rod pull-out monitoring auxiliary device 3A is changed from the processing executed by the control rod pull-out monitoring auxiliary device 3 to steps S4A, S5A, and S6A. It is processing. The processes other than steps S4A, S5A, and S6A executed by the control rod withdrawal monitoring auxiliary device 3A are the same as the processes other than steps S4, S5, and S6 executed by the control rod withdrawal monitoring auxiliary device 3.

An example of the BWR operation region in this embodiment is shown in FIG. 9 in terms of the relationship between the core flow rate and the reactor power. Similar to the first embodiment, when the reactor power reaches the set reactor power P ₀ , the continuous withdrawal of the selected control rod is stopped. In this embodiment, the reactor power increase limit ratios β and δ are used instead of the reactor power increase limit widths α% and γ%. β and δ have a relationship of β <δ. The reactor power increase limit ratio β is, for example, 1.05, and, as shown in FIG. 10, with respect to the output increase due to continuous pulling of the selected control rod in the reactor power region exceeding the set reactor power P _0. Applied. Incidentally, the reactor power increase limit ratio δ is applied to the power increase caused by the continuous pulling of the selected control rod in the reactor power region where the set reactor power P _{0 is} lower. The reactor power increase limit ratio δ is the reactor power obtained by multiplying the reactor power P at the time of selection of the selected control rod by δ% of the withdrawal amount of each selected control rod 19 set in the control rod withdrawal sequence. Of these, it is set so that it will be more than the reactor power after rising at the maximum extraction amount. In this embodiment, the reactor power increase limit ratio δ is, for example, selected from the reactor power obtained by multiplying the reactor power P at the time of selection of the selected control rod by δ% in the control rod drawing sequence. It is set so that the reactor power after reaching the maximum pull-out amount of the pull-out amount of the control rod 19 is obtained. The set reactor power P ₀ in the present embodiment is, for example, 95%.

  The control rod pull-out monitoring method of the present embodiment will be described with reference to FIGS. 8 and 11 for portions different from those of the first embodiment. Selection control rods 19A, 19B, and 19C are used as selection control rods.

  A control rod extraction command 53 for the selected control rod 19A is input from the operation panel 14 to the control rod extraction monitoring auxiliary device 3A and RC & IS10. The CRD 12 for operating the selection control rod 19A is driven by the control rod continuous pull-out request signal 58 for the selection control rod 19A output from the RC & IS10. Thereby, the selection control rod 19A is pulled out from the core.

Reactor power P ₁ is a reactor power P becomes, the determination in step S3 becomes "No". Since (P ₁ × δ) is equal to or less than the set reactor power P ₀ , the determination in step S5A is “Yes”. For this reason, (P ₁ × δ)% is set as the RBL ′ value (step S6A). The determination in step S8 is performed with (P ₁ × δ) as the RBL ′ value. Since the determination in step S8 is “No”, the control rod withdrawal monitoring auxiliary device 3A does not output the continuous withdrawal prevention signal 56 of the selected control rod 19A, and the continuous withdrawal of the selected control rod 19A is continuously performed. When the determination in step S12 is “Yes”, the extraction of the selection control rod 19A is stopped.

Thereafter, a control rod extraction command 53 for the selected control rod 19B is input from the operation panel 14 to the control rod extraction monitoring auxiliary device 3A and the RC & IS 10. Then, the selection control rod 19B is pulled out. In the control rod withdrawal monitoring auxiliary devices 3A, the reactor power P ₂ at the time of inputs the control rod withdrawal instruction 53 for the selected control rod 19B, are reactor power P during withdrawal control rod selection (step S2). Step S3, the determination of S5A is "No", the setting reactor power _{P 0} is set to RBL' value (step S7). The determination in step S8 is performed setting the reactor power _{P 0} as RBL' value. Since the determination in step S8 is “No”, the control rod withdrawal monitoring auxiliary device 3A does not output the continuous withdrawal prevention signal 56 of the selected control rod 19A, and the continuous withdrawal of the selected control rod 19A is continuously performed. Eventually, as in the first embodiment, the determination in step S12 becomes “Yes”. For this reason, the control rod extraction monitoring auxiliary device 3A outputs a continuous extraction prevention signal 56 for the selection control rod 19A (step S9), and the continuous extraction of the selection control rod 19B is stopped.

Since the selection control rod 19B has not been pulled out to the set extraction amount, after the continuous extraction of the selection control rod 19B is stopped, the control rod extraction command 53 for the selection control rod 19B is again sent from the operation panel 14 to the operation panel. 14 is input again to the control rod pull-out monitoring auxiliary device 3A and RC & IS10. For this reason, the selection control rod 19B is continuously drawn out until the reactor power increases to (P ₀ + β)%.

The control rod withdrawal instruction 53 for the selected control rod 19B is a control rod withdrawal monitoring aid 3, again, the reactor power P ₀ inputted from APRM13 as it is entered, the reactor power P during withdrawal control rod selection (Step S2). Since the determination in step S3 is “Yes”, (P ₀ × β)% is set to the RBL ′ value (step S4A). The determination in step S8 is performed using (P ₀ × β) as the RBL ′ value. Since the determination in step S8 is “No”, the control rod withdrawal monitoring auxiliary device 3A does not output the continuous withdrawal prevention signal 56 of the selected control rod 19B, and the continuous withdrawal of the selected control rod 19B is continued. Eventually, as in the first embodiment, when the selection control rod 19B is pulled out by the remaining amount, the determination in step S12 becomes “Yes”. For this reason, the extraction of the selection control rod 19B is stopped.

  From the operation panel 14, a control rod extraction command 53 for the selected control rod 19 </ b> C is input from the operation panel 14 to the control rod extraction monitoring auxiliary device 3 </ b> A and the RC & IS 10. For this reason, the selection control rod 19C is continuously drawn out until the reactor power rises to the rated power (100% power) as in the first embodiment.

The reactor power P ₃ inputted from APRM13 When control rod withdrawal instruction 53 for the selected control rod 19C is input to the control rod withdrawal monitoring aid 3, and reactor power P during withdrawal control rod selection (step S2 ). Since the determination in step S3 is “Yes”, (P ₃ × β)% is set to the RBL ′ value (step S4A). The determination in step S8 is performed with (P ₃ × β) as the RBL ′ value. Since the determination in step S8 is “No”, the control rod withdrawal monitoring auxiliary device 3A does not output the continuous withdrawal prevention signal 56 for the selected control rod 19C, and the continuous withdrawal of the selected control rod 19C is continued. Eventually, as in the first embodiment, when the selection control rod 19C is pulled out by the remaining amount, the determination in step S12 becomes “Yes”. For this reason, the extraction of the selection control rod 19C is stopped.

  The present embodiment can obtain each effect produced in the first embodiment.

  DESCRIPTION OF SYMBOLS 1,1A ... Control rod drawing monitoring system, 2 ... Control rod drawing monitoring device (RBM), 3, 3A ... Control rod drawing monitoring auxiliary device, 10 ... Control rod operation monitoring device (RC & IS), 11 ... Control rod drive auxiliary board , 12 ... Control rod drive mechanism (CRD), 13 ... Average power range monitor (APRM), 14 ... Control panel, 15 ... Display device, 16 ... Reactor, 17 ... Reactor pressure vessel, 18 ... Fuel collection specific, DESCRIPTION OF SYMBOLS 19 ... Control rod, 20 ... Core flow rate detector, 21 ... Local output area monitor (LPRM), 24 ... Position detector.

Claims (10)

In the power region below the set reactor power, which is the reactor power lower than the rated power of the reactor, the reactor power that rises due to the continuous withdrawal of the control rod from the reactor core is When the reactor power in is below the first reactor power upper limit set by the first power increase limit width from the reactor power as a base point, the continuous pulling of the control rod is continued,
In the power region exceeding the set reactor power, the reactor power that is increased by the continuous withdrawal of the control rod from the core is the first power increase limit width based on the reactor power at the start of the withdrawal of the control rod. A control rod withdrawal monitoring method, wherein continuous withdrawal of the control rod is prevented when a second reactor power upper limit set with a narrower second power increase limit width is exceeded. Increased by continuous extraction of the control rod that raises the reactor power below the first reactor power upper limit set by the first power increase limit width with the reactor power at the starting point of the control rod drawing start as a base point When the reactor power reaches the set reactor power, the continuous withdrawal of the control rod is prevented,
In the power region exceeding the set reactor power, the reactor power that is increased by resuming the continuous drawing of the control rod for which the continuous drawing has been stopped is the reactor power when the continuous drawing of the control rod is resumed and the second 2. The control rod withdrawal monitoring method according to claim 1, wherein when the second reactor output upper limit set based on an output increase limit width is exceeded, continuous withdrawal of the control rod that has resumed the continuous withdrawal is prevented. 3. Based on the neutron detection signal output from the neutron detector arranged in the core of the nuclear reactor, in the control rod withdrawal monitoring device, the atoms used in the determination of the prevention of withdrawal of the control rod arranged in the core and withdrawn from the core Find the control rod withdrawal monitoring output that is the furnace output,
When the reactor power at the time of starting drawing of the control rod continuously drawn from the core is equal to or lower than the set reactor power that is lower than the rated power of the reactor, the control rod to be continuously drawn The reactor power obtained based on the reactor power at the start of drawing and the first power increase limit width is set as the first reactor power upper limit,
The first control rod extraction monitoring output obtained by the control rod extraction monitoring device when the control rod is continuously extracted in an output region below the set reactor output is the first reactor output upper limit. When it is less than, continue the continuous withdrawal of the control rod,
When the reactor power at the time of starting drawing of the control rod to be continuously drawn exceeds the set reactor power, the reactor power at the time of starting drawing of the control rod to be continuously drawn and the first The reactor power obtained based on the second power increase limit width narrower than the power increase limit width is set as the second reactor power upper limit,
The second control rod withdrawal monitoring output obtained by the control rod withdrawal monitoring device when the reactor power rising due to continuous withdrawal of the control rod exceeds the set reactor power is the second atom A control rod withdrawal monitoring method, wherein continuous withdrawal of the control rod is prevented when a furnace output upper limit is exceeded. The reactor power obtained on the basis of the reactor power and the first power increase limit width at the time of starting drawing of the control rod continuously drawn in an output region below the set reactor power is the set reactor power. When exceeding, set the set reactor power to the first reactor power upper limit,
When the first control rod withdrawal monitoring output reaches the first reactor output upper limit which is the set reactor output, the continuous withdrawal of the control rod is prevented,
The second control rod extraction monitoring output obtained when the reactor power that rises after restarting the continuous extraction of the control rod that has stopped the continuous extraction exceeds the set reactor output is the control rod 4. The control according to claim 3, wherein when the second power output upper limit set based on the reactor power at the time of resuming continuous pulling and the second power increase limit is exceeded, continuous pulling of the control rod is prevented. Bar pull-out monitoring method. In the power region below the set reactor power, which is the reactor power lower than the rated power of the reactor, the reactor power that rises due to the continuous withdrawal of the control rod from the reactor core is When the reactor power and the first power output upper limit ratio set below the first reactor power upper limit is less than or equal to the upper limit of the first reactor power, the continuous withdrawal of the control rod,
In the power region exceeding the set reactor power, the reactor power that is increased by the continuous withdrawal of the control rod from the core is smaller than the reactor power at the start of the withdrawal of the control rod and the first power increase limit ratio. A control rod withdrawal monitoring method, wherein when a second reactor power output upper limit set based on a second power increase limit ratio is exceeded, continuous withdrawal of the control rod is prevented. Increased by continuous extraction of the control rod that raises the reactor power below the upper limit of the first reactor power set based on the reactor power and the first power increase limitation ratio at the time of starting the extraction of the control rod When the reactor power reaches the set reactor power, the continuous withdrawal of the control rod is prevented,
In the power region exceeding the set reactor power, the reactor power that is increased by resuming the continuous drawing of the control rod for which the continuous drawing has been stopped is the reactor power when the continuous drawing of the control rod is resumed and the second 6. The control rod withdrawal monitoring method according to claim 5, wherein when the second reactor output upper limit set based on an output increase restriction ratio is exceeded, continuous withdrawal of the control rod that has resumed the continuous withdrawal is prevented.   The remaining drawing amount of the control rod that has been prevented from being continuously drawn when the reactor power that is increased by the continuous drawing becomes the set reactor power, The control rod pull-out monitoring method according to claim 2 or 6, wherein the control rod pull-out monitoring method is obtained based on a position of the core in the axial direction and the obtained remaining pull-out amount is displayed on a display device. Based on the neutron detection signal output from the neutron detector arranged in the core of the nuclear reactor, in the control rod withdrawal monitoring device, the atoms used in the determination of the prevention of withdrawal of the control rod arranged in the core and withdrawn from the core Find the control rod withdrawal monitoring output that is the furnace output,
When the reactor power at the time of starting drawing of the control rod continuously drawn from the core is equal to or lower than the set reactor power that is lower than the rated power of the reactor, the control rod to be continuously drawn The reactor power obtained based on the reactor power at the start of the extraction and the first power increase limit ratio is set to the first reactor power upper limit,
The first control rod extraction monitoring output obtained by the control rod extraction monitoring device when the control rod is continuously extracted in an output region below the set reactor output is the first reactor output upper limit. When it is less than, continue the continuous withdrawal of the control rod,
When the reactor power at the time of starting drawing of the control rod to be continuously drawn exceeds the set reactor power, the reactor power at the time of starting drawing of the control rod to be continuously drawn and the first The reactor power obtained based on the second power increase limit ratio that is smaller than the power increase limit ratio is set to the second reactor power upper limit,
The second control rod withdrawal monitoring output obtained by the control rod withdrawal monitoring device when the reactor power rising due to continuous withdrawal of the control rod exceeds the set reactor power is the second atom A control rod withdrawal monitoring method, wherein continuous withdrawal of the control rod is prevented when a furnace output upper limit is exceeded. The reactor power obtained on the basis of the reactor power and the first power increase restriction ratio at the time of starting drawing of the control rod continuously drawn in an output region below the set reactor power is the set reactor power. When exceeding, set the set reactor power to the first reactor power upper limit,
When the first control rod withdrawal monitoring output reaches the first reactor output upper limit which is the set reactor output, the continuous withdrawal of the control rod is prevented,
The second control rod extraction monitoring output obtained when the reactor power that rises after restarting the continuous extraction of the control rod that has stopped the continuous extraction exceeds the set reactor output is the control rod 11. The control according to claim 10, wherein when the reactor power exceeds the second reactor power upper limit set based on the reactor power at the time of resuming continuous withdrawal and the second power increase limit, the control rod is prevented from being continuously drawn. Bar pull-out monitoring method.   The control rod at the time point when the continuous pulling is prevented is set to the remaining pulling amount of the control rod that is prevented from being continuously pulled out when the reactor power that is increased by the continuous drawing reaches the first reactor power upper limit. 10. The control rod pull-out monitoring method according to claim 4, wherein the remaining pull-out amount obtained is determined on a display device based on a position of the core in the axial direction.

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