JPS5887403A - Detector for falling of moving object - Google Patents

Abstract

PURPOSE:To enable the analyzing of the cause of abnormality in a nuclear reactor and a nuclear power generation plant by detecting and recording the falling order, falling speed or the like of control rods for a moving object at the abnormal situation, namely in the falling of the control rods. CONSTITUTION:Normally, a control rod driving shaft 2 penetrates into a winding element 1e, where A/D conversion circuits 7a-1 and 7b-1 both output '0'. When control rods begin falling, an inductance difference detecting circuit 4d outputs a signal as the driving shat 2 first leaves the winding element 1e and then, the winding element 1d while the output waveform is memorized with a memory device 8. Data about the control rods are memorized with the memory device 8 and recorded with a recorder 9. This facilitates the analysis of the cause of troubles from data concerning the falling of the control rods.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting a fall of a moving single object, and particularly to a device for detecting a fall of a tiljll rod in a nuclear reactor.

Conventionally, there have been devices of this type for detecting the position of a control rod as shown in FIGS. 1 and 1. 7th
In the figure, winding elements /a%/e, which are connected in parallel, are wound around the upper protrusion C of the high-pressure sealed vessel that houses the core of the nuclear reactor. A control rod drive shaft made of an expanded magnetic material is housed inside the protrusion C so as to be movable in the vertical direction as shown by the arrow 9. Below the control rod drive shaft is a moving object, that is, a control rod ( FjA (not shown) is attached and swayed. .

FIG. 1 shows a current circuit for detecting the position of the control rod by the signal from the winding group I shown in FIG. Haichi S element/
An inductance difference detection circuit that detects an inductance difference of a % / a, and a display screen that displays the position of the jFi control rod drive shaft, each of which has an inductance difference detection circuit 1 a % 41! Display element j connected to dL
a Contains 43 shifts.

Next, the operation will be explained.

Now, when the 1m111 rod drive shaft, which is a ferromagnetic material, is inserted into the winding element/a, the self-inductance of the winding fiI element/a increases, and an output is generated in the inductance difference detection circuit 4Ia, causing the display element! a lights up. Next, the control rod drive shaft is Volume Iv! When inserted into elements /a and /b, winding element /a
The self-inductance of both and /b increases, and the output of the inductance difference detection circuit u and la disappears, so the display element ja turns off.At the same time, the output of the inductance difference detection circuit is generated, so the display Element s1:l
lights up.

Similarly, when the control rod drive shafts are sequentially inserted into winding elements /c to /A, the inductance difference detection circuits start from C to #.
Output d is generated and display elements jc and ja light up in sequence.
Lights out. Also, when the control rod drive shaft is pulled out from the winding element /d to /a, the outputs of the inductance difference detection circuit d and a are generated sequentially in the same manner as when it is inserted, and the display element is j(1 The lights turn on and off in sequence from! to the turtle.

Generally, a nuclear reactor is provided with a plurality of control rods, and a control rod position detection value function as shown in Figure 1 is provided corresponding to each of the control rods. The steady position of the control rod is detected.

However, although the equipment shown in cause No. 1 detects the position of the control rod in the normal state, it does not have a function that enables analysis of the cause of an abnormality when an abnormality occurs. When an abnormality occurs in a nuclear reactor, a trigger signal is forcibly generated to cause all control rods to fall into the reactor, but if this falling condition can be detected and recorded, the cause of the abnormality can be analyzed. Very preferred above.

This was done in view of the above points, and by providing a means to detect and record the falling order and falling speed of each control rod as a falling state of a moving object, that is, a control rod, in the event of an abnormality. The purpose of this invention is to provide a moving object falling detection device that can analyze the causes of abnormalities in nuclear reactors, especially nuclear power plants.

Hereinafter, one embodiment of the hook of the present invention will be explained based on FIG. 3. In FIG. 3, the move addition/conversion circuit 7 &-/and ? b
-/ are connected to the outputs of the inductance difference detection circuits d and 41a shown in FIG. 1, respectively, and when these detection circuits are detecting the inductance difference, K"/"
Output the signal to the memory t. The memory device t stores AC/DO conversion circuits 7a and 7b corresponding to each of the n control rods.

......? It also receives the outputs of a-n and ri-b-n.

A recording needle D is connected to the output shaft of the memory device t, and the contents of the memory device I are recorded under the control of the control circuit 10. Control 4I (c) path io is a good indicator for each of the n control rods! -/,...,! - receives signals from n, compares each of those signals with respective set position signals for n control rods set in setter l/, and stores in memory according to the result of the comparison. t and recorder!
To explain the only control rod drive shaft 2 in the above configuration, under normal conditions, the control rod drive shaft -
is inserted up to the winding element /e, so mc/DC
The conversion circuit ri a −/and ri ni +−/Il)g side is “0
1@ number is output. If the l1iI control rod starts to fall, the drive shaft will first turn Im! The inductance difference detection circuit 4I passes through the resistor /e and immediately after that passes through /d.
a instantaneously outputs an inductance difference detection signal, which is a DC conversion circuit? It appears as a pulse output of a-/. Similarly, the control rod then exits winding element 71;
Immediately after that, when /a is removed, the mu c/Da conversion circuit 71)-/ outputs a pulse. The memory WM1 stores a waveform W1 shown in FIG. 1 based on the pulse signals of both conversion circuits 7a-/ and RIb-/. In the reference figure, the horizontal axis shows the time t, and the vertical axis shows the voltage V. From this figure, at time 1a, the voltage V
It can be seen that the conversion circuit a-/ outputs a pulse, and at time tb, the conversion circuit b-/ outputs a pulse.

In the memory t, there are nine conversion circuits a corresponding to n other control rods.
-ko, rib-ko, ease, '711 nyγb-n
In addition, under the control of the control circuit 10, these signals are stored in the relationship of time versus voltage, and the memory is updated at a fixed time T (see Figure). do.

The control circuit 10 converts the steady position display signal of each drive shaft from the general @j-/~to1 into the set position signal (from the setter l/).
Individual setting positions are set for each control rod. ), when the steady position display signal becomes smaller than the set position signal, it is determined that the control rod has fallen, and data input is stopped to prevent new data from being written to the memory t. The contents of t are recorded on the recording needle t. Therefore, the recording needle t
An example of the entire recorded contents is as shown in the WJ reference.

Waveform v2. W, , . . . , Wn each represent the falling state of the n crane control rods. From this reference figure, the order in which each control rod falls can be determined, and for the type W1, the falling time (1b, -11) can be determined, and therefore the falling speed can be determined. By knowing the falling speed, it is possible to confirm the fall of each control rod and to know the state of the fall.

Nuclear reactor abnormalities can occur for various reasons, such as a failure in the control rod drive mechanism causing only a few control rods to fall, or an abnormality in the reactor power distribution, but in all cases, a trip signal is generated. Therefore, it is generally difficult and time-consuming to determine the cause of an accident after all the control rods have fallen. As explained above, this invention is configured to record the falling conditions such as falling time and falling order, so it is possible to shorten the time required to analyze the cause of a nuclear power plant shutdown due to a control rod falling accident, and to enable early recovery. Therefore, there is an effect that the operating rate of the nuclear power plant is improved.

Although the above embodiments have been shown to detect the falling of a control rod, this invention #i--generally applicable to monitoring the movement of a plurality of objects.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a part of a high-pressure tube closed vessel of a nuclear reactor, Fig. 1 is a circuit configuration diagram showing a conventional rounding device for detecting the position of control rods, and Fig. 3 is an embodiment of the present invention. A one-way circuit diagram showing an example of a fall detection device for a plow bar, and the second figure is a waveform diagram for explaining the operation of FIG. 3. In the figure, /a
4/・ is the winding IiI element, ko is the rod drive shaft (ferromagnetic material), 亨a-diaaFi inductance difference detection circuit, j-
-/~t-n is the display, t is the memory, the line recording needle is 10
is the control circuit. Agent Makoto Kuzuno - Party Figure 1

Claims (1)

[Claims] In order to detect the movement of each of a plurality of moving objects moving in the vertical direction, one piece is attached at the same time to each moving object and is placed at the top and bottom of the movement path of the nine ferromagnetic bodies. A first inductance difference detection path (b) for detecting the difference in inductance occurring between the I1m elements arranged at the top and the first inductance difference detection path arranged at the bottom of #i. The first inductance difference detection circuit detects the inductance difference that occurs between the two winding elements, and the inductance difference detection signals from the first and first inductance difference detection circuits are stored, and the inductance difference detection signals are stored at regular intervals. A memory device that updates the memory, which simultaneously stores all similar inductance difference detection signals corresponding to other moving objects, and a memory device that updates the memory in response to a signal indicating that the moving object is below a predetermined position. and a control circuit that controls to stop updating the memory of the device and to record the memory contents,
A moving object fall detection device characterized in that when the moving object falls, the falling state can be determined from the contents recorded under the control of the control circuit. Claim v5, wherein the falling state is the falling time of each moving object detected by pulsed signals from the first and first inductance difference detection circuits, and the falling order of all moving objects. 1.!J
The moving object falling detection device described above.