DD250201B5 - METHOD FOR EVALUATING THE FUNCTIONING OF CONTROL ELEMENTS - Google Patents

Description

used according to the invention as a start pulse for the recording or Zeitmeßeinrichtung. Since the motor operates by its design so that 3-phase three-phase current is applied to the stator at the intended rotational movement, the falling movement of the cassette via the rotor rotation induced in the stator and thus in each power supply line of the motor-an AC voltage. Their period is defined via the translation of the drive motor defined with a change in height of the control cassette and their frequency is also defined as linked to the instantaneous speed.

According to the invention, this induction voltage is detected and provided the individual zero crossings of the voltage with time stamps.

The total fall time is determined by determining the time for as many zero crossings of the voltage as corresponds to the fall distance of the control element.

In order to evaluate the case, each number of a zero crossing of the induced voltage associated with the corresponding Fallwegstrecken and the timestamps are compared, so that one obtains the path-time course of the case or from the time difference between two zero crossings and the corresponding fixed distance to known Determines the instantaneous speed and this faced the corresponding Fallwegstrecken, so as to obtain the speed-travel course of the case.

The assessment of the case is carried out in particular on the basis of the speed-distance curve and the total time of the fall, in that disturbances in the case can be read directly from the diagram by greatly reducing the speed at the desired grinding points.

embodiment

The invention will be explained in more detail below using an exemplary embodiment. In the attached figure show the

Fig. 1: the time course of the induced voltage

Fig. 2: a pattern of the table to be set up

3 shows three examples of speed-distance diagrams, wherein FIG. 3a shows the desired course, FIG. 3b too large a fall time due to a too low falling speed and FIG. 3c a too large a fall time due to terminals of the control element at the height coordinate I _k represent.

Nuclear reactors have as accidental protection u. a. via a fast retraction of absorber rods (control elements) into the splitting zone,

i. a. by falling due to their own weight, the ability to shut down the chain reaction taking place in the reactor. The case times to be observed are prescribed at a certain interval so that the reactor is switched off quickly enough, but also damage due to falling too fast is avoided.

In older control element designs, a drop is achieved in that the mechanical connection between the control element drive and the rack of the control element is released by notching the rack pinion, so that the control element can fall.

Newer designs have a simpler gear and allow falling of the control elements by the fact that at the stator of - provided with a permanent magnet rotor - motor of the control element drive applied DC voltage (holding voltage) is switched off. As a result, the magnetic field built up in the stator, which prevents the rotor from rotating by default, collapses and the rotor can move freely, so that it is idling and is turned over by the falling due to its weight control element.

To explain must be added that a defined change in position of the control element is achieved in that the stator is not charged with DC but with three-phase current, the rotor follows this rotating field and the transmission of the control element drive converts the rotational movement in a height position change of the control element.

As far as the construction of the control element drives. For the evaluation of rule elements, two properties are significant: the fall time of the rule element and its velocity path diagram in the case.

These two properties can be determined as follows: Since the falling of the control element initiates a shutdown of the holding voltage on the stator of the motor of the control element drive, a registration process is started by switching off by z. B. the voltage is continuously monitored.

Since the control element is rigidly coupled to the drive motor via the gearbox, on the one hand each rotor rotation of the motor can be assigned a defined distance of the height change, on the other hand causes the rotating rotor but that the drive motor operates as a generator, so that in the stator of the motor 3- Phase three-phase current is induced, the individual phases can be tapped for each other as AC voltage (Fig. 1), wherein a period of the AC voltage correspond to one revolution of the rotor and thus the defined path.

During the started registration process, each period of the induced alternating voltage, which is determined via the zero-crossing determination of the alternating voltage, is now assigned in the form of a table (see Fig. 2) the times which have elapsed since the holding voltage was switched off. The individual zero crossings are then assigned to them corresponding Regelelementfallstrecken and according to the known physical relationship

ν = ΔΙ / Δΐ

the instantaneous speeds v, where ΔΙ represent the path of the control element from zero crossing to zero crossing and At the time measured for this.

From this table can then be taken in a simple manner, the fall time as the time at which the distance covered 1 corresponds to the target fall distance l _{s of} the control element.

The speed-distance diagram is determined such that the distance traveled 1 is plotted as abscissa and the instantaneous velocity ν as ordinate.

Among other things, it can be determined from the speed-distance diagram whether the case of the control element is running properly (FIG. 3a), whether the speed z. B. too small (Fig. 3 b), which leads to an excessive case time, or whether the falling time is too large, because the control element as a result of jamming at the height coordinate l _k (Fig. 3 c) locally too small Speed has.

Accordingly, the person skilled in the art may initiate measures for remedying the causes if necessary.

Claims (1)

Method for evaluating the operation of control elements of nuclear reactors on the determination of the falling time and the falling speed of these control elements, characterized in that is used to determine the falling time and the falling speed which is formed by falling movement of the control elements on the stator of the motor of the control elements induction voltage, with the switching off of the holding voltage of the registration process is initiated and then each period of the induced AC voltage, which is determined via a zero crossing determination of the AC voltage, the times are assigned, which have elapsed since the stop voltage, then the individual zero crossings are assigned to them corresponding Regelelementfallstrecken and determines the instantaneous speed in a known manner, finally from the individual case times and the individual instantaneous speeds, the total case time and the Geschwindigkeitsverl ascertained and used for evaluating the operation of the control elements, wherein the registration process after passing a certain number of zero crossings, which corresponds to the falling distance of the control elements, is terminated. For this 1 page drawings Field of application of the invention The invention relates to a method for evaluating the operation of control elements of nuclear reactors by measuring their fall time and speed. Characteristic of the known technical solutions It is known from the prior art that the entire driving range of control cassettes is provided with a plurality of transformers and a core coupled to the cassette to be moved changes the inductance of the next coil or coils and the transformer indicates the position of the cassette with a changed inductance (DD-PS 118327). This type of position determination is relatively coarse, so that cartridge case times can only be determined with high errors. In addition, it is known from DD-WP 131 201, to determine the height position of the control elements via a magneto-inductive encoder arrangement and the movement times or. Fall times of these control elements between different height positions to measure. This procedure is also subject to large errors due to the coarse and relatively sluggish determination of the height position. More precise methods for determining the falling times of control cassettes, which exploit the structure-borne noise caused by the case for starting and stopping Zeitmeßeinrichtungen are known from DD-PS 214020 and DD-WP G 21 C / 2767045. A disadvantage of this method is that they allow only the determination of the total case time of the cassettes, but on the nature of falling-z. B. in the form of speed gradients-no statements allow. Moreover, it is known from DE-OS 2102 565 to move the control rod within a Gesamtinduktivität. The then caused by the change in position of the rod impedance change of the superimposed with alternating inductance then serves to display the control rod position. In continuation of this technical solution, a two-coil arrangement is used in DE-OS 2242951. In this case, a secondary coil is inductively excited by the AC-carrying primary coil. The inductive coupling of the two concentrically arranged coils is determined and influenced by the tax deduction in the direction of axial expansion of the inner coil. The alternating voltage generated inductively on the second coil is rectified and then serves to position the control rod. Object of the invention The aim of the invention is to increase the safety of the reactor by monitoring the proper functioning of the control elements of nuclear reactors. Explanation of the essence of the invention The invention has for its object to provide a method for evaluating the operation of control elements of nuclear reactors by measuring their fall time and falling speed to increase by timely detection of any irregularities occurring reactor safety. According to the invention the object is achieved in that the motor voltage of the control element is tapped. For reactor shutdown, the control cassettes drive in free fall in the gap zone of the reactor by the holding voltage is switched off by the motor of the control element, so that the existing of a permanent magnet rotor of the motor no holding magnetic field of the stator finds more and - due to its rigid coupling with the Cassette according to their downward movement - can rotate freely. This switching off the holding voltage is