JPH0458913B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Field of Application> The present invention relates to an apparatus used for measuring the temperature coefficient of a moderator, which is carried out as part of a core characteristic investigation carried out in a nuclear reactor start-up test, periodic test, etc. <Conventional technology> Conventionally, one method for determining reactor reactivity is to convert the minute current obtained from a neutron flux detector installed in or near the reactor core into voltage using a current amplifier, and then solve the dynamic characteristic equation. Used as an input signal for the reactor reactivity meter, the obtained reactivity is recorded on the Y axis of the XY record, and the temperature signal from the moderator thermometer is adjusted to the measurement temperature range on the other X axis. Connect and record. Next, a method for determining the desired moderator temperature coefficient from the reactivity trace recorded in this manner will be described. FIG. 4 shows the change in reactivity (A) with respect to the change in moderator temperature (B) recorded by the XY recorder mentioned above, and the change in reactivity accompanying the change in moderator temperature in the core is recorded as the slope of this trace. The change in reactivity per unit temperature obtained from this slope is called the isotemperature coefficient, and is the sum of the moderator temperature coefficient and the Doppler temperature coefficient. Therefore, the desired moderator temperature coefficient is determined by manually subtracting the Doppler temperature coefficient from this isotemperature coefficient. As described above, in the prior art, when determining the slope from a trace, the slope of the trace is determined by manual processing after the measurement in a predetermined measurement temperature range is completed. Therefore, it takes time to obtain results, and manual processing is cumbersome. Processing work is also required to prepare the measured values in a predetermined recording format, Table 1.

【table】

[Table] <Problems to be solved by the invention> In the prior art, moderator temperature coefficient measurement, which is determined by manual processing, involves a lot of trouble in order to obtain the results. Time was needed. It is an object of the present invention to provide a moderator temperature coefficient measuring device for a nuclear reactor that can quickly solve these problems. <Means for Solving the Problems> Therefore, the moderator temperature coefficient measurement device of the present invention is an atomic moderator that solves the dynamic characteristic equation by converting the current obtained from the neutron flux detector installed in or near the reactor core into a voltage. In a nuclear reactor equipped with a reactor reactivity meter, a moderator average temperature meter, and a control rod position indicator, (a) means for detecting the position of the control rods, (b) means for detecting the reactivity of the reactor, (c) ) Means for detecting the moderator temperature; (d) Means for storing the control rod position, reactivity and moderator temperature as well as the design value of the Doppler temperature coefficient; (e) Means for detecting the same control rod position from the above storage means. A method for calculating the isotemperature coefficient by performing regression calculation from the reactivity and the moderator temperature at intervals where the temperature change of the moderator is equal, and calculating the moderator temperature coefficient from the isotemperature coefficient and the Doppler temperature coefficient. ) A means of continuously plotting the relationship between reactivity and moderator temperature on an XY recorder. (g) Means for sequentially displaying the above-mentioned memorized numerical values and calculation results. (H) A means for printing out the results once the measurement in the scheduled temperature range is completed; <Example> Hereinafter, the moderator temperature coefficient measuring device for a nuclear reactor of the present invention will be described in detail based on the accompanying drawings. FIG. 1 is a block diagram showing the function implementation means of the measuring device of the present invention, and FIG. 2 is a block diagram showing the structure of an embodiment of the measuring device of the present invention. 4 is a flowchart showing processing steps performed by the measuring device of the present invention, and FIG. 4 is a graph of reactivity versus moderator temperature drawn by the plotting device. The reactor is equipped with a reactor reactivity meter 1 that converts the current obtained from a neutron detector 1a installed in or near the core to a voltage to solve a dynamic characteristic equation, and generates a signal of reactivity. is supplied. Furthermore, signals for control rod position are supplied to the apparatus of the present invention from a control rod position indicator 2 of a control rod drive device (not shown), and signals for moderator temperature are supplied from a moderator average thermometer 3. The signal of the moderator average thermometer 3 is A/D
The signal from the reactor reactivity meter 1 is converted by the serial interface 5.
Further, the signal from the control rod position indicator 2 passes through an A/D converter or a pulse counter 6, and is supplied to the CPU 8 via an I/O port 7. There are two types of control rod position indicators 2, one that emits analog signals and one that emits pulse signals, but the one that emits pulse signals is more accurate. This pulse transmission signal is divided into a control rod withdrawal signal and a control rod insertion signal. Pulse signals are transmitted independently at the time of each withdrawal and insertion, and the pulses of this withdrawal and insertion are sent to a pulse counter 6.
The position of the control rod is determined by integrating the two types of pulses and subtracting the two types of pulses. The CPU 8 is connected to a RAM 9 and an external storage device 10, and performs processing in the following steps. When the moderator temperature changes, the core reactivity changes due to the temperature coefficient specific to the core. For example, this change in reactivity changes linearly within a temperature change range of about 2℃, so it is a small temperature change (about 0.01℃).
The temperature and reaction rate at each time are measured, plotted in the drawing device 14 of the XY recorder, stored in the external storage device 10, and a regression calculation is performed to calculate the isotemperature coefficient. The moderator temperature coefficient is calculated based on the design value of the Doppler temperature coefficient stored in the external storage device 10. In addition, if the control rod position changes during the measurement (due to neutron flux adjustment during the measurement), data during this time can be deleted to enable measurement of the moderator temperature coefficient at the same control rod position. As for the processing results, when several points of data are collected after the start of measurement, the moderator temperature coefficient is displayed on the display device 1.
2 and when the specified measurement is completed,
As before, the measurement results as shown in Table 1 are printed on the printing device 13.
Output to. The processing procedure is shown in FIG. This figure shows a case where the control rod position indicator 2 emits pulses. First, in the initialization 21 part, the initial control rod position is updated. In step 22, it is determined whether the minute temperature has changed, and if yes, in step 23, it is determined that the control rod position has changed. If no, step 24
(as shown in Figure 3, each measurement point 14 of the zigzag
a) and regression calculations (plotting is performed by the drawing device 14 and regression calculations by the CPU 8), and in step 26, parameters and calculation results are stored externally and displayed on the display device 12. Next, in step 27, it is determined whether the measurement is completed, and if Yes, in step 28, the measurement results are printed and plotted (printing is done by the printing device 13, and plotting is done by the plotting device 14. point 14
A straight line 14b) connecting points a is performed. No on step 22
Or, if Yes in step 23, that is, if the moderator temperature is not changing or the control rod position is changing, the drawing and regression calculation processes are not performed. If the measurement is not completed at step 27 (No), return to step 22 and repeat. <Effects of the Invention> The nuclear reactor moderator temperature coefficient measuring device described in detail above has the following effects. Since real-time processing is performed and design values and measured values can be compared immediately after the test is completed, processing time can be significantly shortened, and labor savings and reactor operating rates can be improved. In the processing procedure, regression calculations are performed at intervals when a slight change in moderator temperature occurs, so even if the rate of change in moderator temperature changes during measurement, the process can be performed accurately. can. Since the measuring device can be made smaller, it can be used in test locations such as central control rooms. For this reason,
It is possible to reduce the number of testers and data organizers.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the means for realizing functions by the moderator temperature coefficient measuring device of the present invention, and FIG. 2 is a block diagram showing the structure of an embodiment of the measuring device of the present invention.
FIG. 3 is a flowchart showing processing steps by the measuring device of the present invention, and FIG. 4 is a graph of reactivity versus moderator temperature drawn by the plotting device. 1... Reactor reactivity meter, 1a... Neutron flux detector, 2... Control rod position indicator, 3... Moderator average temperature meter, 4... A/D converter, 5... Serial interface, 6...A/D converter or pulse counter, 7, 11...I/O port, 8...CPU, 9...RAM, 10...external storage device, 12...display device, 13...printing device, 14...Drawing device.

Claims (1)

[Scope of Claims] 1. A reactor reactivity meter, moderator average temperature meter, and control rod position indicator that converts the current obtained from a neutron flux detector installed in or near the reactor core into voltage to solve a dynamic characteristic equation. (a) means for detecting the position of the control rods, (b) means for detecting the reactivity of the reactor, (c) means for detecting the temperature of the moderator, and (d) the above control rods. (e) means for storing the position, reactivity, and moderator temperature as well as the design value of the Doppler temperature coefficient; A method for calculating an isotemperature coefficient by performing regression calculation from temperature, and calculating a moderator temperature coefficient from this isotemperature coefficient and Doppler temperature coefficient; (g) means for sequentially displaying the memorized numerical values and calculation results; and (h) means for printing the results when the measurement in the scheduled temperature range is completed. Furnace moderator temperature coefficient measuring device.