JPS59164981A - Control rod selective drive control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a method for automatically operating control rods during boosting of a reactor in a boiling water nuclear power plant while complying with the reactor water temperature rise rate. This invention relates to a control rod selection drive control device.

[Prior art]

In a boiling water nuclear power plant, it is necessary to operate the reactor to boost pressure when it is started up, and to reduce the pressure of the reactor when it is shut down.

In other words, when the reactor is started, the control rods are pulled out and the reactor is heated and the pressure is increased to the pressure at rated operation, but when the reactor is stopped, a cooling operation is performed at atmospheric pressure. It is something that exists.

However, in the conventional system, the pressure increase at the time of startup is performed manually by a skilled operator, and there is a problem in that the operation is carried out over a long period of time.

Figure 1 shows an overview of a boiling water nuclear power plant. In this way, to explain the conventional pressurization method, the decommissioning operator who starts up the reactor 3 selects a control rod and manually pulls out the control rod 4482 via the control rod drive control device 12 and control rod drive device 1. However, as a result of this withdrawal, the pressure of the reactor 3 is increased by the generated steam. This pressure increase is carried out with the regulator valve 5 and the bypass valve 4 closed, but it is important to note here that during the pressure increase period when the control rods 2 are withdrawn, the reactor water temperature is measured by the reactor water temperature detector 11. It is necessary to perform the withdrawal operation of the control rod 2 while monitoring the reactor water temperature. This is because, in order to ensure the soundness of the constituent materials of the nuclear reactor 3, a limit value is set for the rate of change in the coolant temperature within the reactor 3 during pressure increase and pressure reduction. Therefore, the operator must perform the withdrawal operation of the control rod 2 without deviating from the limit value. During the pressurization period, as the control rods 2 are withdrawn, the reactor water temperature T and therefore the reactor pressure P gradually rise as shown in FIG. It is necessary to raise the pressure while keeping it below the set pressure V PszT. The reason why the set pressure VPs''!:T is gradually updated as shown in Fig. 2 is to cope with the case where the control rod is pulled out excessively due to an operator's mistake.Reactor pressure P is constantly detected by the pressure detector 8, and the set pressure VPsE from the pressure setting device 9 is detected by the comparator 13.
It is compared with the signal corresponding to T, but due to excessive withdrawal of the control rod 2, the reactor pressure P becomes the set pressure VPsz
t or more, the pressure regulator 10 controls the bypass valve 4 to open based on the output of the comparator 13, thereby suppressing the rise in the reactor pressure P. As a result, the reactor water temperature T
This means that deviation from the rate of change limit value is prevented. Note that reference numerals 7 and 6 in FIG. 1 indicate the turbines 1 and 1, respectively. The condenser is shown.

In this way, increasing the reactor pressure at the time of reactor startup is almost always done manually by operators, and moreover, manual operations are repeated over a long period of time. It will be a heavy burden. ,ita,
Since the rate of increase in reactor water temperature during summer due to control rod withdrawal generally differs depending on the control rod, there are problems such as the need for skilled operators to raise the pressure of the reactor according to a fixed rate of increase in reactor water temperature. be.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a control rod drive control device that can automatically operate control rods during pressure increase in a nuclear reactor while observing the rate of increase in reactor water temperature.

[Summary of the invention]

For this purpose, the present invention, in principle, selects control rods sequentially in each control cycle and automatically performs a withdrawal operation on the selected control rod, but the amount of withdrawal at that time is controlled by the control rod. This is done based on the deviation between the target reactor water temperature for the cycle and the actual reactor water temperature at the beginning of the control cycle. In a highly desirable embodiment, only when the deviation is above a certain level, the control rod is first withdrawn by the standard amount in the early stage of the control cycle, and then further withdrawn in the latter stage of the control cycle so that the actual reactor water temperature becomes the target reactor water temperature. It looks like this.

[Embodiments of the invention]

The present invention will be explained below with reference to FIGS. 3 to 7.

First, the configuration of an example of the control rod selection drive control device according to the present invention will be described. FIG. 3 shows its configuration. According to this, as in the conventional case, the selected control rod is enabled to be driven by the control rod drive control device 12 and the control rod drive device l. Therefore, each time a predetermined selection of control rods is made, the selected control rod is appropriately driven and controlled to achieve the intended purpose. The control rod selection device 13 is for selecting control rods in a predetermined order according to the control rod operation sequence, and the control rod selection is updated by a sequence progression permission command from the sequence control device 14. . Since the order in which the control rods will be pulled out before starting the power plant is known in advance through analysis, the selection rod selection device 13, the control rod drive control device 12, and the control rods are controlled by the sequence control device 14. The control rod to be withdrawn via the drive device 1 is selected. On the other hand, the sequence control device 14 drives the control rod selected to be pulled out. The sequence control device 14 determines the withdrawal amount for the selected control rod based on the deviation between the actual reactor water temperature from the reactor water temperature detector 11 and the target reactor water temperature, and then transfers the control rod to the control rod drive control device 12, This is the part from which the control rod is pulled out via the control rod drive device 1. Operator console 15
is used to instruct the start of automatic control rod withdrawal control, and in some cases, the target temperature increase rate used when calculating the target reactor water temperature in the sequence control device 14 is determined by this operator console. 15.

In the case of the present invention, control rods are generally selected and extracted as described in the summary of the invention, but in a more preferred embodiment, actual reactor water m
The extraction is performed only when the deviation between the temperature and the target reactor water temperature is above a certain level, and the extraction is performed in two stages. This is partly to suppress rapid changes in the actual reactor water filtration rate, but also to perform more fine control of the reactor water temperature.

Control in this manner will be specifically explained below. FIG. 4 shows how extraction is performed in one control cycle. According to this, if the deviation between the actual reactor water temperature and the target reactor water temperature exceeds a certain level, the currently selected control rod must be withdrawn, and the withdrawal is performed twice. ing. If the deviation is smaller than the constant value, the currently selected control rod will be withdrawn in the next control cycle.

If withdrawal is required, first time to.

Initial withdrawal by the standard withdrawal amount is performed during time 11, and as a result, the actual reactor water temperature T gradually rises, but the temperature change due to this temperature rise occurs at time t1 + "2", which is the temperature stabilization period. It is set to be settled between.

It is possible to know how much more the temperature rise due to this initial withdrawal is required to reach the target reactor water temperature in the later withdrawal period from time point '2'i13.

FIG. 5 shows a sequence control flow in a sequence control device for performing such extraction. For example, if one control cycle is 30 seconds, the sequence control is activated at 30 second intervals.

Note that FIG. 5 does not particularly show selection and updating of control rods.

It is sufficient that the control rods have been selected at least before the initial withdrawal, and the selection can also be updated based on the assumption that the control rods have been withdrawn in the previous control cycle. It is sufficient to do so until then.

According to the jitance control shown in Fig. 5, the target reactor water temperature T, 1lET [C] in the control cycle of the light tank immediately after startup is equal to the target temperature increase rate ΔTs+e t (C/) (r) and the reactor It is a trap that the elapsed time Στs [Hr] from the start of boosting is calculated by calculation.

T81? =ΔT ogt・ΣτK ... (
1) Next, this target reactor water temperature Ts! Actual reactor water temperature TTo(c
The deviation ΔT[tl:'] from l is calculated.

ΔT = T sit T Ha
”・ (2) This deviation ΔT is then the specified value ΔT
o, and it is determined whether or not the extraction is to be performed based on the comparison result. That is, if the deviation ΔT is less than the specified value ΔTo, the control rod is not pulled out in this control cycle, and the control rod selected in this control cycle is pulled out in the next control cycle. . Also, the specified value ΔT.

In the above cases, KnixvyWo is the control constant [l
1lec/bait], the standard pulling operation amount [fight], a pulling drive command is output for a time DEMwrti corresponding to the standard pulling operation amount W, and initial pulling is performed.

DEMwrti=KDRIV 0 Wo
... (3) Once this initial withdrawal is completed, time t
1 r "2 is considered to be a waiting period, but at time t2, the actual reactor water temperature 'rtz (cl) and the control gain constant are calculated by 1 [-] and the cine leg/extraction operation amount W, [mmE] Then, the latter-stage extraction is performed by outputting a extraction drive command for a time corresponding to this insufficient extraction operation amount W.

W'a: (K I ・Δ'r/(Tt+Tt
o) 1) Wo-(4) Although the present invention is as described above, in reality, from the viewpoint of fuel consumption balance, restrictions are placed on the amount of withdrawal of individual control rods, and it is still necessary to withdraw the control rods. If the control rod cannot be withdrawn before they meet, a problem will occur. This is because problems arise, such as the control cycle not being able to achieve the target reactor water temperature or making it difficult to increase the pressure at an optimal rate. On the other hand, considering that when a control rod is pulled out to its withdrawal limit, the next control rod is allowed to be pulled out immediately after that, it is possible to It is also possible to withdraw the next control rod to compensate for the shortage. FIG. 6 shows a case in which drawing is performed in this manner.

The explanation will be as follows with reference to FIG.

In other words, Fig. 6 (→ shows the withdrawal/insertion limits at the axial position of the control rod at coordinate positions is 0 to 120 Wan, and that for YK is 40 to 160 Wan.Here, for example, when the axial position of X is Own, the amount of withdrawal is calculated by equation (4). Assuming that is calculated as 100mm, the control cycle will be completed after the thing related to X is pulled out 100 times after that.
No problems will occur. However, if the allowable range for pulling out items related to X is θ~50 as shown in Figure 6(b), then items related to It will become.

In such a case, it is sufficient to select the control rod related to Y to be selected next within the control cycle, and then draw out the shortfall of 50 mn.

Figure 7 (→ indicates the actual reactor water temperature T when controlled in this way.
However, the problem here is that simply pulling out a single KY by 50 m will not necessarily achieve the target reactor water temperature T[IET in that control cycle, and in some cases This means that a non-negligible error δ may occur. This is because the withdrawal amount of 100 rrrm is obtained by calculating the amount related to X, but not the amount related to 1 in D and Y. In order to eliminate the error δ, for example, when the selection of the control rod related to Y is updated, it is possible to multiply the deficiency by a correction coefficient. If the amount of extraction becomes less than the initial shortage due to this correction, and if the amount exceeds that amount and extraction cannot be performed within the control cycle, the control cycle is extended until the necessary time t3'. can also be considered.

In the next control cycle, things related to Y may be handled in the same way as things related to X. In addition to the control rod selection order, the control rod operation sequence also includes withdrawal/insertion limits for individual control rods, but when controlling as described above, there are It is necessary to make the necessary communications.

Although the present invention is as described above, the actual reactor water temperature is
It is also possible to obtain the output of the pressure detector shown in the figure by converting it into the saturated vapor pressure temperature.

〔Effect of the invention〕

As explained above, in the present invention, control rods are sequentially selected in each control cycle, and when the selected control rods are automatically pulled out, the actual reactor water temperature at the beginning of the control cycle is Withdrawal is performed based on the deviation from the target reactor water temperature assigned to that control cycle. Therefore, according to the present invention, it is possible to automatically operate the control rods during pressure increase in the reactor while observing the rate of increase in the reactor water temperature.

[Brief Description of the Drawings] Fig. 1 is a diagram showing an outline of a boiling water nuclear power plant, Fig. 2 is a diagram for explaining the atomic r pressurization method according to the prior art, and Fig. 3 is a diagram showing the outline of a boiling water nuclear power plant. FIG. 4 is a diagram showing the configuration of an example of the control rod drive control device according to the present invention together with peripheral devices.
FIG. 5 is a diagram showing a control rod drive control method in a preferred embodiment, and FIG. 5 is a diagram showing a sequence control flow for implementing the control method. FIGS.
Figures 7(a) and 7(b), which are diagrams for explaining the control rod withdrawal operation when the withdrawal tolerance range is set, are diagrams showing the withdrawal operation when multiple control rods are withdrawn within the same control cycle. It is a diagram for explaining the method. l... Control rod drive device, 2... Control rod, 3... Nuclear reactor, 11... Reactor water temperature detector, 12... Control rod drive control device, 13... Control rod selection Device, 14...Sequence control device. Agent Patent Attorney Masami Akimoto Figure 1 Figure t2 Figure 3 Tea 4 Figure 5 (B No. 7 Cα Ji (b)

Claims (1)

[Claims] (1) Each of the plurality of control rods inserted into the reactor core
A control rod selection drive control device that allocates the ttlJ control cycle, selects the control rods in a predetermined order and for each control cycle, and then drives the control rods to pull out the control rods is used to directly or indirectly obtain control rods at the initial stage of each control cycle. A withdrawal amount control means that calculates the withdrawal amount of the control rod based on the deviation between the water temperature and the target reactor water temperature assigned in advance to the control cycle, and issues a withdrawal drive command; The control rod selection means updates the control rods to a predetermined value. Control rod selection drive control device. 2. The withdrawal amount control means performs withdrawal control of a certain amount at the beginning of the control cycle only when the deviation between the actual reactor water temperature and the target reactor water temperature is above a certain level, and controls the withdrawal amount by the increase in the reactor water temperature due to the control. The control according to claim 1, wherein the control rod is extracted after determining the amount of withdrawal required in the latter half of the same control cycle, and the control rod selection means is instructed to update the selected control rod. Rod selection drive control device.