JPS5951391A - Reactor core state monitoring 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] [Technical field of invention] The present invention relates to a nuclear reactor core condition monitoring device.

[Technical Background of the Invention] Control rods are generally used in nuclear reactors such as boiling water reactors to control the output level. This control rod generally contains boron, which has a large neutron absorption cross section, and by inserting boron, a large amount of neutrons will be absorbed into this control rod, and the power distribution in the vicinity of this control rod will be significantly reduced.

Conversely, when a control rod is pulled out, the output of the part where the control rod was inserted increases significantly.

Therefore, in general, when operating the control rods, it is necessary to operate the control rods while monitoring so that the local change in power distribution due to the control rod operations does not exceed a predetermined value.

To this end, in a boiling water reactor, a local power range monitor is generally placed in the reactor core, and control rods are operated while monitoring readings from this local power range monitor.

For example, in a 110 MWe class boiling water reactor, 172 local power range monitors are placed in the reactor core. It is difficult to monitor.

Therefore, in the past, detailed power distribution calculations within the reactor core have been performed using a process computer based on the counts of the local power range monitors, thereby performing detailed monitoring of the reactor core.

However, when using a process computer in this way, for example, it takes about 3 minutes to calculate the output distribution Wl on the process computer, so the process computer needs to calculate the output distribution every time a control rod is operated. It is very difficult to calculate.

That is, when monitoring the core state based on power distribution calculations by a process computer, a very long time is required for control rod operations.

Therefore, in practice, control rod operations are performed in such a way that the output level is sufficiently lowered during control rod operation, and even if there is a local increase in output due to control rod withdrawal, the output does not exceed a predetermined value.

[Problems with back-up technology] However, when trying to perform load following operation according to a certain predetermined load request or control rod pattern conversion operation without drastically lowering the operating rate,
As mentioned above, it is impossible to sufficiently reduce the output level during control rod operation.

Therefore, there is a need for a nuclear reactor core condition monitoring device that can accurately monitor the core condition in a short period of time during operation of such a nuclear reactor.

[Object of the invention] The present invention has been made in response to such conventional circumstances,
For example, it is an object of the present invention to provide a nuclear reactor core state monitoring device that can accurately monitor the reactor core state in a short period of time, such as during load following operation where the output level cannot be lowered sufficiently during control rod operation.

[Summary of the Invention] In other words, the present invention provides a prediction device that predicts the pros and cons of a nuclear reactor operation plan by calculation using a physical model, a data file that stores the calculation results calculated by this prediction device, and a system that stores the calculation results in this data file. This is a nuclear reactor core condition monitoring device characterized by comprising a monitoring device that estimates the current power distribution within the core from the calculated results and plant data indicating the current state of the reactor.

[Embodiments of the invention] The following is an example in which the details of the present invention are shown in the drawings. It covers the explanation.

The figure shows a nuclear reactor core state monitoring device according to an embodiment of the present invention. This reactor core state monitoring device includes an input device 1, a prediction device 2, a physical model calculation device 3, and a data file 4.
and the monitoring device 5 constitute the main part.

That is, the input device 1 inputs an operation plan from an operator.

The prediction device 2 receives 41 operation pictures from the input device 1, and uses the physical model calculation device 3 to calculate the control rod pattern and power distribution to be realized during the operation based on this operation plan and the current core state.

Then, the prediction device 2 determines whether the driving plan can be executed without exceeding the limit based on the calculation result by the physical model calculation device 3, and outputs this to the output device 6.

Based on the information displayed on the output device 6, the operator operates the nuclear power generation plant 8 using the plant operation panel 7 if the operation inputted from the input device 1 is possible.・=4− In other words, this prediction device 2, based on the scheduled operation plan,
A control rod pattern and a power level are set, and the core flow rate level and in-core power distribution to achieve this are determined by the physical model calculation system N3, and it is checked whether the limiting conditions are satisfied.

The physical model calculation device 3 reads the constants necessary for calculating the coefficients of the neutron flux diffusion equation and the constants necessary for calculating the void distribution from the variable file 9, and reads the fuel burnup distribution etc. from the constant file 10, and calculates the neutron flux diffusion. Calculate the coefficients of the equation and use this to calculate the power distribution within the core.

The data file 4 stores the control rod patterns in the operation plan calculated by the prediction device 2 and the output level, flow rate level, output distribution, etc. for each control rod pattern.

The monitoring device 5 inputs plant data such as control rod patterns, local power range monitor readings, reactor core flow rate, reactor power level, etc. from the nuclear power plant 8, and also performs the same control as the current nuclear power plant 8 from the data file 4. Select the data corresponding to the bar pattern, correct it using the plant data, and estimate the output distribution.

That is, this monitoring device 5 inputs the output level and core flow m () in the same control rod pattern as the current nuclear power plant 8 from the data file 4, and estimates the power distribution using the output level and core flow rate. If the values are close to the current output level and core flow rate values, the estimated value of the local output area monitor calculated from the output distribution extracted from the data file 4 and the local output area monitor actually measured at the nuclear power plant 8. The output distribution extracted from the data file 4 is corrected so that the readings match. Therefore, with this monitoring device 5, the current output distribution can be accurately estimated in a short time.

On the other hand, this monitoring device 5 detects that the power level and core flow rate at the time when the power distribution should be estimated are significantly different from the power level and core flow rate obtained by the predictive calculation stored in the data file 4 to be used. If they are different, that is, if there is a large difference between the value of the local power range monitor predicted by the prediction device 2 and the value of the local power range monitor actually measured at the nuclear power plant 8, the value calculated by the physical model calculation device 3 The predicted output distribution is corrected using equation (1) described below, and the estimated value of the local output area monitor determined by this corrected output distribution matches the reading of the local output area monitor actually measured by the nuclear power plant 8. The prediction calculation results calculated by the prediction device 2 are corrected so as to be corrected.

P (x, y, z) = Pe (x, y, z)・p';'
D (z) /p, D (z)...
...(1) Here, P(X, V, Zl corrected output distribution Pe(x, y, z): Predicted output distribution P, D(z): One-dimensional output distribution corresponding to the predicted output distribution P, D(Z): Estimation at the point of time when estimation is to be made. The output distribution monitoring device 5 calculates a limiting condition based on the output distribution calculated in this way, and outputs the result. Note that Pd(7) is obtained by performing axial one-dimensional distribution calculation in the bank-like core state d5.

According to the reactor core condition monitoring device of the present invention described above, “the 11f constant value of the local power range monitor determined from the output distribution of the prediction calculation by the prediction device and the actual measurement by the nuclear power plant By correcting the predicted bundle so that the readings of the local power range monitors match, it is possible to estimate a highly accurate power distribution in a short time, and it is possible to estimate the power distribution with high accuracy in a short period of time. can be monitored.

[Brief explanation of drawings]

The figure is a block diagram showing a nuclear reactor core state monitoring device according to an embodiment of the present invention. 1......Input device 2...Prediction device 3...Physical model calculation device 4...
・・・・・・・・・Data file 5・・・・・・・・・
...Monitoring device' -45 8- 6,11...Output device 7...Plant operation panel 8...
・・・・・・・・・Nuclear power plant 9・・・・・・・・・
・・・・・・Variable file 10・・・・・・・・・・・・
Constant File Representative Patent Attorney Sasa Suyama - 9-10-

Claims (1)

[Claims] (1) A prediction device that predicts the pros and cons of a nuclear reactor operation plan by calculation using a real-time model, a data file that stores the calculation results calculated by this prediction device, and the calculation results stored in this data file and the current What is claimed is: 1. A nuclear reactor core condition monitoring device comprising: plant data indicating the condition of a nuclear reactor; and a monitoring device that estimates the current power distribution within the reactor core.