JP2005227025A - Reactor power control method and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain reactor pressure and reactor water temperature at constant states during intervals of a raising process of temperature and pressure which is performed in a plurality of steps for reactor power control. <P>SOLUTION: In the reactor power control step, a terminal target reactor pressure is reached by setting individual intermediate target reactor pressures, repeating step by step temperature/pressure rising control and by operating control rods so as to maintain specific reactor water temperature variation rate and reaching the intermediate target reactor pressures. The control rods are to be operated when the difference between an insertion length and a withdrawal length of the control rods until reaching the target reactor pressure in the previous temperature/pressure rising process is within a set value range, after reaching the target reactor pressure in the previous temperature/pressure rising process between the previous process and the next process, and when the difference between a neutron flux detection value at the final control rod operation performed until reaching of the target reactor pressure in the previous temperature/pressure rising process, and a neutron flux detection value at a time elapsed for a certain time from the final control rod operation, is within a set value range. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to reactor power control, and in particular, to maintain a constant reactor pressure and reactor water temperature during each heating and boosting process performed in several stages when a boiling water reactor is started up. It relates to suitable reactor power control.

  The increase in output at the start-up of a boiling water nuclear power plant proceeds in the order of start-up → criticality → rated pressure reached → combined generator → rated output reached. Of these, the temperature rise and pressure increase process from the criticality of the reactor to the rated pressure is reached by operating the control rod (mainly pulling out the control rod) under the condition that the turbine bypass valve and main steam control valve are closed and steam does not flow out of the reactor ) While increasing the reactor pressure and reactor water temperature.

  In the temperature raising and pressure increasing process, the control rod is operated manually by the operator, or the control rod is automatically operated by the automatic output control device. In any operation, the reactor protection function such as the scram due to the rapid rise of the neutron flux does not operate, and the reactor water temperature change rate is set to a limit value (for example, 55 ° C.) in order to avoid the thermal shock of the equipment constituting the reactor. / H) It is a driving restriction to keep it below.

  Therefore, a method has been proposed in which the measured value of the reactor water temperature change rate is monitored and the control rod is operated based on the deviation between this measured value and the target value of the temperature change rate. However, with this method, the value of the neutron flux changes immediately according to the operation of the control rod, but there is a problem that the measurement of the reactor water temperature change rate involves a time delay. That is, in measuring the rate of temperature change, a time delay due to the heat transfer time from the fuel rod to the coolant in the core, a time delay due to the coolant flow time from the core to the temperature measurement point, and a measuring instrument that measures the reactor water temperature A time lag caused by the heat capacity of the thermocouple at, and a time lag caused by a certain time required to calculate the rate of temperature change from the measured temperature, and these time lags are on the order of several minutes. For this reason, even if the control rod is operated simply based on the deviation between the target value and the measured value of the reactor water temperature change rate, the operation of the control rod is delayed and it is difficult to maintain the reactor water temperature change rate at the target value. Become.

  In order to solve this problem, a method for controlling the slow reactor water temperature change rate in association with the fast response neutron flux, that is, calculating the target neutron flux to achieve the target reactor water temperature change rate, A method of controlling the reactor water temperature change rate by performing a control rod operation based on the deviation between the bundle and the measured value of the neutron flux has been proposed (for example, Patent Document 1).

  In addition, the temperature boosting process is usually performed in several stages, and the target reactor pressure (intermediate target reactor pressure) is set for each stage of the temperature boosting process in each stage. When the target reactor pressure is reached, the control rod operation is temporarily stopped there. During this shutdown, the equipment necessary for operating the reactor is started up and tested, and the operator is replaced. When these operations are completed, the operation proceeds to the next temperature raising and boosting stage. Then, the pressure of the reactor is increased to the final rated pressure by repeating such a temperature raising and pressure increasing process step by step.

  Regarding the reactor power control, in addition to Patent Document 1, examples disclosed in Patent Document 2 to Patent Document 6 are also known.

JP-A-9-145895 JP-A-5-150077 JP-A-5-209987 JP-A-10-39071 Japanese Patent Laid-Open No. 9-113683 JP-A 64-83190

  The conventional control method in the temperature raising and pressure increasing process is based on the premise that the temperature reactivity coefficient of the reactor water is negative. In other words, when the reactor pressure target value is reached for each temperature boosting step and the control rod operation is stopped, the reactor water temperature change rate settles around 0 ° C / h (hours), and the reactor pressure and reactor water temperature are near the target values. Is assumed to remain constant.

  However, fuels used in recent boiling water reactors have been increased in fuel burnup by increasing fuel enrichment in order to improve fuel economy. High burn-up fuel that burns fuel efficiently has been designed with the volume of the water region increased relative to the fuel volume. And about such high burn-up fuel, it has been found that there is a fuel in which the temperature reactivity coefficient of the reactor water may become positive when the reactor water temperature is low. A fuel having a positive reactor water temperature reactivity coefficient increases the neutron flux and the calorific value, so that when the reactor water temperature rises, positive reactivity is applied and the rate of neutron rise increases. As a result, the reactor water temperature change rate also increases.

  That is, when the temperature reactivity coefficient of reactor water is positive, the operation of the control rod is stopped until one temperature increase / decrease step that has reached the target reactor pressure is completed and the subsequent temperature increase / decrease step is started. In this state, the reactor water temperature change rate rises without being settled near 0 ° C./h, and the reactor pressure and the reactor water temperature that should be constant deviate greatly from the target values in the temperature raising and boosting process. In this case, even if the operator notices the rise in the reactor water temperature and responds by immediately inserting the control rod, the reactor water temperature reacts with a delay of a few minutes compared to the neutron flux, so the reactor for several minutes thereafter. The water temperature will continue to rise. As a result, it is necessary to insert control rods continuously in order to further suppress the neutron flux increase and the temperature change rate. However, it is expected that it is difficult to start up and test each device and change the operator while performing such work.

  The present invention has been made in the background as described above, and maintains the reactor pressure and the reactor water temperature in a constant state during each heating and boosting process performed in a plurality of stages. An object of the present invention is to provide a reactor power control method and apparatus capable of enabling it.

  For the above purpose, the present invention sets an intermediate target reactor pressure for each, and operates the control rod so as to reach the intermediate target reactor pressure while maintaining a predetermined reactor water temperature change rate. In the reactor power control method that allows the final target reactor pressure to be reached by repeating the step-up / step-up control that achieves During the process, after reaching the intermediate target reactor pressure in the preceding step-up temperature boosting process, until the intermediate target reactor pressure is reached in the preceding step-up temperature boosting process, Neutron flux detection when the difference between the insertion amount and the extraction amount is within the set value range, or during the last control rod operation performed until the intermediate target reactor pressure is reached in the heating and boosting process of the previous stage value When the difference of the neutron flux detection value at the time when a predetermined time has elapsed from the time the last control rod operation is in the range of set values, and characterized in that to perform the operation of the control rod.

  Further, in the present invention, in the reactor power control method as described above, A and B (where A <B) are set as set values relating to the difference between the insertion amount and the withdrawal amount of the control rod, and the neutron flux detection value is set. C and D (where C <D) are set as set values relating to the difference, and the difference between the insertion amount and the withdrawal amount of the control rod is in the range between the set value A and the set value B, or the neutron flux When the difference between the detected values is in the range between the set value C and the set value D, the control rod is inserted with a preset insertion amount, and the difference between the insertion amount of the control rod and the withdrawal amount is When it is in the range larger than the set value B or when the difference between the detected neutron flux values is in the range larger than the set value D, the reactor water temperature change rate is set to 0 ° C. per hour. The control rod so that the rate of change can be maintained And to perform the operation.

  Further, in the present invention, in order to apply to the reactor power control method as described above, a control setter after reaching the target pressure is provided, and in the control setter after reaching the target pressure, the insertion amount and the withdrawal amount of the control rod are set. A configuration in which at least one of an insertion / extraction comparator for obtaining a difference and a neutron flux comparator for obtaining a difference between the detected neutron flux values is provided to the reactor power control apparatus.

  In the present invention, the control rod is operated in accordance with the determination based on the operation amount of the control rod or the change state of the neutron flux between one temperature raising and pressure raising process and the subsequent temperature raising and pressure raising process. Therefore, according to the present invention, since the reactor water temperature reactivity coefficient is positive, it is possible to effectively prevent an increase in reactor pressure and reactor water temperature that may occur after the temperature rise and pressure control is stopped. The plant can be started more smoothly and the burden on the operator can be reduced.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 shows a configuration of a reactor power control apparatus according to an embodiment. The reactor power control device includes a main body control device 1 and a measurement system. The measurement system includes a reactor pressure detection system, a reactor water temperature detection system, and a neutron flux detection system.

  The reactor pressure detection system calculates a reactor pressure value according to a pressure sensor 11 that detects a reactor pressure through a main steam pipe connected to the reactor 10, and a signal from the pressure sensor 11, and controls it. Reactor pressure detection means comprising a pressure detector 2 that outputs to the apparatus 1 is included.

  The reactor water temperature detection system calculates the reactor water temperature according to a signal from the thermocouple 15 that detects the reactor water temperature in the pipe connected to the reactor 10 and the thermocouple 15, and supplies it to the main body control device. 1 includes a reactor water temperature detecting means constituted by a temperature detector 3 that outputs to 1.

  The neutron flux detection system detects a neutron flux in the core 12 of the nuclear reactor 10, counts the number per unit time, and outputs a neutron flux detection signal as a neutron flux detection means. 13 is included. The neutron flux detection system converts the output signal from the neutron flux detector 13 to a neutron flux level (level indicating the ratio between the detected value of the neutron flux and the rated output of the core =% rating) and the time of the neutron flux. It includes a neutron flux monitor 4 that calculates the reactor cycle, which is an index representing the rate of change, and outputs them to the main body control device 1.

  The main body control device 1 includes a control rod automatic controller 8, a control setting device 9 after reaching the target pressure, and a target setting device 17, and also includes a CRT 6 and an operation panel 7.

  The control rod automatic controller 8 incorporates a control logic to be described later, and outputs a control rod withdrawal command or insertion command to the control rod drive controller 5 at an appropriate timing according to the control logic. For this purpose, the control rod automatic controller 8 includes the reactor water temperature detected by the temperature detector 3, the neutron flux level and reactor cycle output from the neutron flux monitor 4, and the reactor pressure target value fetched from the target setter 17. And the reactor water temperature change rate target value are input.

  The control rod drive controller 5 is a device that controls the control rod drive device 16, and controls the control rod drive device 16 based on a control rod drive signal (insertion command or extraction command) output from the main body control device 1. A rod drive signal is output. Further, a control rod drive state (control rod insertion, control rod pulling out, control rod operation completion, current position of control rod) signal is output to the main body control device 1.

  The control rod drive device 16 is a device that drives insertion or extraction of the control rod 14 with respect to the core 12. The control rod drive device 16 drives insertion or extraction of the control rod 14 by water pressure or electric power. The control rod 4 is inserted into the core 2 or pulled out from the core 2 in accordance with the signal from.

  The control setter 9 after reaching the target pressure is an element that characterizes the present invention, and incorporates a control logic to be described later. In accordance with the control logic, a certain temperature increase and pressure increase process and a subsequent temperature increase and pressure increase process are performed. Generate commands necessary for control rod operation during the interval. Specifically, the neutron flux level from the neutron flux monitor 4, the control rod drive signal from the control rod automatic controller 8, and the target reactor pressure arrival signal from the control rod automatic controller 8 are input signals, and the neutron flux The state of the reactor water temperature reactivity coefficient is determined for each level and control rod drive signal. When it is determined that the temperature reactivity coefficient of the reactor water is a small positive value, a control rod insertion request and a reactor cycle monitoring signal after reaching the target are output to the control rod automatic controller 8. On the other hand, if the reactor water temperature reactivity coefficient is determined to be a large positive value, the constant value control, which is a command for controlling the reactor pressure and reactor water temperature after reaching the target reactor pressure, to be constant The signal is output to the target setting unit 17.

  The target setter 17 is a means for setting the target reactor pressure and the target reactor water temperature change rate. The setting operation is performed by the operator through the operation panel 7. The reactor pressure target value and the reactor water temperature change rate target value set by the target setting unit 17 are input to the control rod automatic controller 8. Here, the target reactor pressure is set for each heating and boosting process divided into a plurality of stages, and the target reactor pressure set in the final heating and boosting process is the final target reactor pressure. Become. For example, 1.0 MPa is set as the target reactor pressure in each stage. On the other hand, the target reactor water temperature change rate is set to 20 ° C./h, for example, so that the limit value (for example, 55 ° C./h) of the reactor water temperature change rate can be observed in each temperature increase / pressurization process. However, when a constant value control signal is input from the control setter 9 after reaching the target pressure, the reactor water temperature change rate target value is automatically changed to 0 ° C./h, and the target reactor pressure is set as described later. Is automatically changed to, for example, 10 MPa, which is a sufficiently large value with respect to the actual reactor pressure.

  The display device 6 is one of interface means between the main body control device 1 and an operator. This display device 6 displays the temperature change rate target value and the actual temperature change rate side by side, or displays the target time variation of the reactor water temperature and the time variation of the actual reactor water temperature as a graph. . The neutron flux level, the reactor cycle, or the reciprocal of the reactor cycle is also displayed as a trend, and the current position of the control rod is also displayed.

  The operation panel 7 is another interface means between the main body control device 1 and the operator, and is configured as a console on the control operation panel. As described above, the operator sets the target reactor pressure and the target reactor water temperature change rate through the operation panel 7.

  Below, the specific content of the reactor power control by the main body control apparatus 1 is demonstrated. 2 to 4 show the configuration of the control logic in the control setter 9 after reaching the target pressure. After the target pressure is reached, the control logic of the control setter 9 indicates that the temperature reactivity coefficient of the reactor water is positive during the period from the end of one temperature increase / decrease process to the start of control in the next temperature increase / decrease process. Therefore, the control logic performs control to prevent the reactor pressure and the reactor water temperature from rising. There are two types of control depending on the magnitude of the reactor water temperature reactivity coefficient.

  Specifically, the value of the reactor water temperature reactivity coefficient is determined by the following equations (1) to (4), and the control method after reaching the reactor pressure target is set. That is, if Equation (1) or Equation (3) is established, it is determined that the temperature reactivity coefficient of the reactor water is a small positive value. In this case, a control rod insertion command is issued to the main body control device 1, and in response to this, the main body control device 1 inserts control rods in units of preset insertion amounts. This is the first control method. On the other hand, if Equation (2) or Equation (4) is satisfied, it is determined that the temperature reactivity coefficient of the reactor water is a large positive value. In this case, a constant value control signal is output to the target setter 17, and the target water temperature change rate target value is automatically set to 0 ° C./h by the target setter 17, and this target reactor water is set. Control that maintains the rate of temperature change is performed by the main body control device 1. This is the second control method.

  A in the formulas (1) to (4) is a setting value set as, for example, A = (− 1) × (20% of the amount of control rod drawing), and B is a setting set as B = 0, for example. C is a set value set as, for example, C = (− 1) × (20% of the neutron flux at the time of the last control rod operation), and D is set as D = 0. These setting values A, B, C, and D are assumed to satisfy the relationship of Expression (5). In addition, the “certain time” in the expressions (2) and (3) is a time set as an appropriate time for determining the change state of the neutron flux, and for example, a time of 10 minutes is set. The “target reactor pressure” in the formula (1) and the formula (2) is a target reactor pressure set for each heating and boosting process, and “the last performed” in the formula (3) and the formula (4). The “control rod operation” is a control rod operation performed at the end of each temperature raising / pressurizing process.

A ≦ Control rod insertion amount until reaching the target reactor pressure−Pullout amount ≦ B (1)
B <Amount of control rod inserted until the target reactor pressure is reached minus the amount of withdrawal (2)
C ≦ neutron flux after a certain time from the last control rod operation−neutron flux at the last control rod operation ≦ D (3)
D <Neutron flux after a certain time since the last control rod operation-Neutron flux at the last control rod operation (4)
A <B and C <D (5)

  The control logic of FIG. 2 is a control logic for the first control method. This control logic is configured by combining a control logic based on Expression (1) and a control logic based on Expression (3). The control logic based on the formula (1) has a drawing amount memory 21, an insertion amount memory 22, and a first insertion / withdrawal comparator 23, and uses a control rod drive signal 20 from the main body control device 1 as an input signal. The withdrawal amount memory 21 receives the control rod drive signal 20 as an input, and operates the control rod that is performed from the start of the control of one temperature raising and boosting process until reaching the target reactor pressure in the temperature raising and boosting process. The amount of pulling out is stored so as to be sequentially added, and the stored amount of control rod drawing is output to the insertion / drawing comparator 23. Similarly, the insertion amount memory 22 receives the control rod drive signal 20 as an input, and the control rod drive signal 20 is controlled from the start of the control of one temperature raising and boosting process until the target reactor pressure is reached in the temperature raising and boosting process. The insertion amount in the operation is stored so as to be sequentially added, and the stored control rod insertion amount is output to the insertion / withdrawal comparator 23. The insertion / withdrawal comparator 23 is set with Expression (1) and its set values A and B, and whether or not Expression (1) is satisfied with respect to the withdrawal amount from the withdrawal amount memory 21 and the insertion amount from the insertion amount memory 22. Is determined each time one control rod operation is completed, and if the expression (1) is satisfied, an ON signal is output to the OR circuit 28, and if the expression (1) is not satisfied, the OR circuit 28 is output. Outputs an off signal.

  On the other hand, the control logic based on the equation (3) has a neutron flux memory 25, a time delay timer 26, and a first neutron flux comparator 27, and a control rod drive signal 20 from the main body control device 1 and a neutron flux monitor. 4 is used as an input signal. The neutron flux memory 25 receives the neutron flux level 24 and the control rod drive signal 20 as inputs, takes in the neutron flux level 24 when the control rod is driven, and outputs it to the neutron flux comparator 27. The time delay timer 26 receives the control rod drive signal 20 as an input, and outputs an ON signal to the neutron flux comparator 27 when the control rod is driven with a delay of a set time (10 minutes in the above example) from the drive point. To do. The neutron flux comparator 27 is set with equation (3) and its set values C and D. When an ON signal is input from the time delay timer 26, the neutron flux level from the neutron flux memory 25, that is, the control rod Is compared with the neutron flux level 24 directly input from the neutron flux monitor 4, that is, the neutron flux level when the control rod is delayed by a set time from the time when the control rod is driven. ) Is output to the OR circuit 28, and when the expression (3) is not satisfied, an OFF signal is output to the OR circuit 28.

  The OR circuit 28 outputs an ON signal when the insertion / extraction comparator 23 is ON or the neutron flux comparator 27 is ON, that is, outputs information indicating that Expression (1) or Expression (3) is satisfied to the AND circuit 30 and inserts it. When both the drawing comparator 23 and the neutron flux comparator 27 are off, an off signal is output to the AND circuit 30. The AND circuit 30 receives the output of the OR circuit 28 and the target reactor pressure arrival signal 29, and outputs an ON signal only when both are ON. In other words, the AND circuit 30 receives the target reactor pressure arrival signal 29 that is output when the target reactor pressure is reached in one heating and boosting process, and the formula (1) or the formula ( An ON signal is output on condition that 3) is satisfied. Therefore, if the output of the AND circuit 30 is on, since the equation (1) or the equation (3) is established in a state where the target reactor pressure is reached and the temperature increase / decrease control is stopped, It is determined that the temperature reactivity coefficient is a small positive value. In this case, a control rod insertion request 32 and a furnace cycle monitoring signal 31 after reaching the target are output.

  The control rod insertion request 32 is input to the control rod automatic controller 8 in FIG. The control rod automatic controller 8 has the control logic configuration shown in FIG. 6, and if the control rod insertion request 32 is input to the control rod motion determination unit 65 and the control rod drive is permitted, the insertion command 73 is given. Is output to the control rod drive controller 5, and the control rod is inserted with a predetermined insertion amount accordingly. The above is the control by the first control method.

  The furnace cycle monitoring signal 31 after reaching the target is input to the gate circuit 36 in the control logic shown in FIG. The control logic of FIG. 3 works after the control rod insertion request 32 is output after the target reactor pressure is reached and the control rod is inserted, and has an auxiliary function to the control logic of FIG. That is, when the control rod insertion request 32 is output after the equations (1) and (3) are satisfied after the target reactor pressure is reached, the control rod is inserted with a preset insertion amount accordingly. When the neutron flux tends to increase, the control logic shown in FIG. 2 is complemented by outputting a control rod insertion request 32. Specifically, the reciprocal number of the furnace cycle is calculated by the reciprocal calculator 34 from the furnace cycle measurement value 33 obtained by the neutron flux monitor 4, and the reciprocal number of the furnace cycle is compared with the set value by the furnace cycle reciprocal comparator 35. Here, the reactor cycle is the time when the neutron flux is about 2.72 times (more precisely, the base e times the natural logarithm). For example, a set value of 0.00167 (corresponding to a furnace cycle of 600 seconds) is set in the furnace cycle reciprocal comparator 35. Then, this set value is compared with the reciprocal furnace cycle reciprocal from the reciprocal calculator 34. If the reciprocal furnace cycle reciprocal is equal to or greater than the set value, the neutron flux tends to increase and the furnace cycle reciprocal comparator 35 is turned on. If the gate circuit 36 is connected by the input of the furnace cycle monitoring signal 31 after reaching the target, a control rod insertion request 32 is output.

  The control logic of FIG. 4 is a control logic for the second control method. This control logic is basically the same as the control logic of FIG. The difference is that the control logic of FIG. 2 has determined the expressions (1) and (3), but the determination is based on the expressions (2) and (4) and the fixed value control signal after reaching the target. 44 is output. Hereinafter, the control logic for the second control method will be described focusing on the control contents different from the control logic for the first control method. The second insertion / withdrawal comparator 40 corresponds to the first insertion / withdrawal comparator equation 23, and the equation (2) and its set value B are set, and the second neutron flux comparator 41 is: This corresponds to the first neutron flux comparator 27, and formula (4) and its set value D are set. An ON signal is sent to the OR circuit 42 when the insertion / extraction comparator 40 determines that the expression (2) is satisfied and when the neutron flux comparator 41 determines that the expression (4) is satisfied. The OR circuit 42 outputs an ON signal to the AND circuit 43 when one of the input values from the insertion / extraction comparator 40 and the neutron flux comparator 41 is ON. When both the input value from the OR circuit 42 and the target reactor pressure arrival signal 29 are ON, that is, the AND circuit 43 reaches the target reactor pressure and the control of the temperature raising and boosting process is stopped. ) Or equation (4) is established, and when it is determined that the temperature reactivity coefficient of the reactor water is a large positive value, the fixed value control signal 44 after reaching the target is output to the target setting unit 17 in FIG.

  As shown in FIG. 5, the target setting unit 17 is a target setting circuit for setting the target reactor pressure and the target reactor water temperature change rate inputted through the operation panel 7 at the start of control of the temperature raising and boosting process at a certain stage. After checking the upper limit and the lower limit at 52, the target reactor pressure 53 and the target reactor water temperature change rate 54 are set and output to the control rod automatic controller 8 of FIG. Then, when the post-target constant value control signal 44 is input after the temperature raising and boosting process at that stage is completed, the target setting circuit 52 automatically sets a predetermined target value instead of the target value input on the operation panel. To set. The target value is set to a target reactor pressure 53 that is sufficiently large with respect to the actual reactor pressure, for example, 10 MPa, and there is no increase in the reactor water temperature as the target reactor water temperature change rate 54. A condition of 0 ° C./h is set.

  As shown in FIG. 6, the control rod automatic controller 8 is configured so as to increase the temperature of the reactor up to the target reactor pressure 53 while maintaining the target reactor water temperature change rate 54. Control rod operation is commanded by proportional-integral operation with feedback of reactor water temperature change rate and neutron flux. When the actual reactor pressure 69 becomes higher than the target reactor pressure 53, the pressure comparator 70 outputs an OFF signal to turn off the gate circuit 64, and the output of the proportional integrator 62 is sent to the control rod operation determiner 65. Do not communicate, do not perform control rod movement. In this state, the fixed value control signal 44 after reaching the target in FIG. 4 is output, the target reactor pressure 53 is set to a sufficiently large value (10 MPa in the above example) by the target setting circuit 52 in FIG. When the rate of change 54 is set to 0 ° C./h, the pressure comparator 70 outputs an ON signal, whereby the output of the proportional integrator 62 is transmitted to the control rod operation determiner 65, and the reactor water temperature change rate is set to 0. The proportional integration operation is performed so as to maintain the temperature at ° C./h, and the insertion command 73 is continuously output. The above is the control by the second control method.

  As described above, in the present invention, the positive and negative values of the reactor water temperature reactivity coefficient are distinguished, and the control method is changed in accordance with this. This means that the control rod should not be operated as much as possible when one stage of the temperature increase / decrease process is completed and various devices are activated, tested, or the operator is changed during the next temperature increase / decrease process. It is considered that it is desirable. That is, under the condition that the positive value of the reactor water temperature reactivity coefficient is small and the rise of the reactor water temperature is not expected to be so rapid, the control rod can be inserted by a single insertion with a preset insertion amount. Only reduce the operation frequency of the control rod. On the other hand, under conditions where the positive value of the reactor water temperature reactivity coefficient is large and a rapid rise in the reactor water temperature is predicted, emphasis is placed on preventing the reactor water temperature from rising, and a target reactor water temperature change rate of 0 ° C / h is set. The control to maintain is performed.

  FIG. 7 shows the result of evaluating the effect when the first control method in the above embodiment is applied by simulation. The reactor in the initial stage of the critical process of the boiling water reactor and the temperature boosting The change in water temperature and reactor water temperature change rate is shown. Here, the target reactor pressure in the temperature raising / pressurizing process is set to 0.38 MPa, and the target reactor water temperature change rate is set to 30 ° C./h. The initial reactor water temperature is 85 ° C., and the reactor water temperature reactivity coefficient is slightly positive when the temperature is 180 ° C. or lower, and negative when the temperature is higher than 180 ° C. As a result of the evaluation, the target reactor pressure was reached in about 8500 seconds, and the control rod was repeatedly withdrawn and inserted from the start of control until the target reactor pressure was reached. Has reached. Curves 76 and 78 are evaluation results of the reactor water temperature and reactor water temperature change rate when the present invention is not applied, respectively, and the control rod operation is not performed after reaching the target reactor pressure, so the reactor water temperature change rate is increased. However, the reactor water temperature has risen considerably. This is because the temperature reactivity coefficient of the reactor water is positive, so that the neutron flux increases due to the temperature rise, which further contributes to the temperature rise. In an actual reactor, if the reactor water temperature change rate exceeds a certain set value (for example, 55 ° C / h), an alarm is generated, so the operator manually operates the control rod. In order to suppress it, it is assumed that considerable control rod operation is required, and it is difficult to judge the amount of control rod insertion. On the other hand, curves 77 and 79 show the evaluation results of the reactor water temperature and the reactor water temperature change rate when the present invention is applied, and control that the reactor water temperature reactivity coefficient is a small positive value after reaching the target pressure. Judgment is made by the setting device 9, and the control rod is inserted immediately after reaching the target reactor pressure, and the control cycle is inserted again because the reactor cycle is less than 600 seconds at about 9500 seconds. By inserting these control rods The reactor water temperature and the reactor pressure after reaching the target reactor pressure are stabilized without increasing the reactor pressure. From this result, the effectiveness of the present invention can be confirmed.

  FIG. 8 shows a result of evaluating by simulation the effect when the second control method in the above embodiment is applied. Like FIG. 7, the critical process and the temperature increase / decrease of the boiling water reactor are shown. Shows the changes in the reactor water temperature and the reactor water temperature change rate in the initial stage. Here, the target reactor pressure in the temperature raising / pressurizing process is set to 0.38 MPa, and the target reactor water temperature change rate is set to 30 ° C./h. The initial reactor water temperature is 70 ° C., and the temperature reactivity coefficient of reactor water is a large positive value when the temperature is 180 ° C. or lower, and a negative value when the temperature is higher than 180 ° C. As a result of the evaluation, the target reactor pressure was reached in about 10800 seconds, and the temperature reactivity coefficient of the reactor water was a large positive value. Therefore, the insertion of control rods continued from the start of the temperature boost control to the target reactor pressure. The result was done. Curves 80 and 82 are evaluation results of the reactor water temperature and reactor water temperature change rate when the present invention is not applied, respectively, and the control rod operation is not performed after reaching the target reactor pressure, so the reactor water temperature change rate is increased. The reactor water temperature is also increasing at an accelerated rate. On the other hand, curves 81 and 83 are the evaluation results of the reactor water temperature and the reactor water temperature change rate when the present invention is applied, and the control setting after reaching the target pressure indicates that the reactor water temperature reactivity coefficient is a large positive value. As soon as the reactor pressure is reached, the control rod is continuously inserted as constant control of the reactor water temperature with the target reactor water temperature change rate set to 0 ° C./h immediately after reaching the target reactor pressure. The temperature has settled without significantly increasing. From this result, according to the present invention, even if the temperature reactivity coefficient of reactor water is a large positive value, it is possible to keep the reactor pressure and reactor water temperature constant after reaching the target reactor pressure. I can confirm.

  Since the reactor water temperature reactivity coefficient is positive, the present invention can effectively prevent an increase in reactor pressure and reactor water temperature that may occur after the temperature rise and pressure boost control is stopped. Can be performed more smoothly, and the burden on the operator can be reduced. Therefore, the present invention can be widely used as useful for nuclear power plants.

It is a figure which shows the structure of the nuclear reactor power control apparatus by one Embodiment. It is a figure which shows the structure of the control logic regarding the 1st control system in the control setter after target pressure arrival. It is a figure which shows the structure of the control logic of the control rod insertion request | requirement based on a furnace cycle. It is a figure which shows the structure of the control logic regarding the 2nd control system in the control setter after target pressure arrival. It is a figure which shows the structure of a target setting device. It is a figure which shows the structure of the control logic in a control rod automatic controller. It is a figure which shows the example which evaluated the effect of this invention regarding the reactor water temperature and the reactor water temperature change rate. It is a figure which shows the other example which evaluated the effect of this invention regarding the reactor water temperature and the reactor water temperature change rate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body control apparatus 2 Pressure detector 3 Temperature detector 4 Neutron flux monitor 5 Control rod drive controller 8 Control rod automatic controller 9 Control setting device 10 after reaching target pressure Reactor 11 Pressure sensor 13 Neutron flux detector 14 Control rod 16 Control rod drive device 17 Target setter 21 Extraction amount memory 22 Insertion amount memory 23 First insertion / extraction comparator 25 Neutron flux memory 27 First neutron flux comparator 40 Second insertion / extraction comparator 41 Second neutron Bundle comparator

Claims (3)

An intermediate target reactor pressure is set for each of them, and the temperature rising and boosting control is performed step by step to operate the control rod so as to reach the intermediate target reactor pressure while maintaining a predetermined reactor water temperature change rate. In the reactor power control method designed to reach the final target reactor pressure by repeating
After reaching the intermediate target reactor pressure in the preceding heating and boosting process between a certain heating and boosting process in the subsequent stage, and in the preceding heating and boosting process, When the difference between the insertion amount of the control rod and the withdrawal amount until reaching the intermediate target reactor pressure is within the set value range, or the intermediate target reactor pressure is reached in the temperature raising and boosting process of the previous stage When the difference between the detected neutron flux at the time of the last control rod operation and the detected neutron flux at the time when a predetermined time has elapsed from the last control rod operation is within the set value range, A reactor power control method characterized in that an operation is performed.   A and B (where A <B) are set as the set values regarding the difference between the insertion amount and the withdrawal amount of the control rod, and C and D (where C <D) are set as the set values regarding the difference between the detected neutron flux values. When the difference between the insertion amount and the withdrawal amount of the control rod is in the range between the setting value A and the setting value B, or the difference between the detected neutron flux values is the difference between the setting value C and the setting value D. The control rod is inserted with a preset insertion amount when the difference is between the insertion amount of the control rod and the extraction amount within a range larger than the set value B or the detected neutron flux value If the difference is greater than the set value D, the reactor water temperature change rate is set to 0 ° C. per hour, and the control rod is operated so that the reactor water temperature change rate can be maintained. Reactor power control method according to claim 1 . A reactor power control device used in the reactor power control method according to claim 1 or 2,
A control setter after reaching the target pressure is provided, and the control setter after reaching the target pressure obtains the difference between the insertion / withdrawal comparator for obtaining the difference between the insertion amount and the withdrawal amount of the control rod and the detected value of the neutron flux. A reactor power control device provided with at least one of the neutron flux comparators.

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