DE2448052A1 - DYNAMIC SECURITY CHANNEL - Google Patents

Description

2U8052

Hartmann & Braun 7/7/1974

Corporation.

Dynamic safety channel

The invention relates to a dynamic safety channel for nuclear reactors, the ionization chamber / a DC amplifier ,, has a limit monitor and a power stage.

There are a number of monitoring circuits in nuclear reactor plants provided that detect the neutron flux of the reactor and the y- ^ radiation at certain points. Inadmissible when occurring high values must be given shutdown commands and / or warning systems must be activated. The present circuit for Monitoring the neutron flux is used as a dynamic safety channel designated.

609816/0182

The safety channel basically consists of an ionization chamber, a highly sensitive DC amplifier, a dynamic limit indicator and a power switching stage. The ionization chamber detects the neutron flux in or on the reactor core. If this neutron flux exceeds one for one If there is a fault in the relevant limit value, the dynamic limit value indicator responds and the reactor is switched off.

The known security channel has the disadvantage that it cannot monitor itself. If z. B. the reactor with low power is driven, the ionization chamber of the safety channel does not yet deliver a measurable current, so that on Output of the safety channel no information is available on whether? the channel is ready or not. So could e.g. B. Defects in the high-voltage supply,

Measuring cable or on the DC voltage amplifier occur without these errors being noticed. Both the nuclear power plant operators as well as the supervisory authorities require constant monitoring of all safety devices.

The invention is therefore based on the object of providing the known safety channels with self-monitoring Mistake.

This object is achieved in that the High voltage source for the ionization chamber an alternating voltage generator of small amplitude is switched on that the

^! 60 98 1 6/0182

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periodic monitoring signal superimposed on the measurement signal is decoupled behind the DC amplifier and fed to the dynamic limit indicator and that the limit indicator Relay is connected downstream, which triggers an alarm in the absence of the monitoring signal.

An exemplary embodiment of the invention is based on the drawing explained.

1 designates an ionization chamber, the housing of which is connected via a shielded line 2 to a high voltage source 3 which has an alternating voltage generator 4 with a small amplitude. The signal electrode 1 a of the chamber 1 is connected to a direct current amplifier 6 via a further shielded line 5. The outcome of the. DC amplifier έ feeds both a low-pass filter 7 and a high-pass filter 8 with a pulse shaper. The output of the low-pass filter 7 feeds an isolation amplifier Io, which supplies a standardized display signal of 0-20 mA. In addition, the output voltage U. of the low-pass filter 7 is fed to a dynamic limit value indicator 11. A second input of this limit monitor is connected to the output of the pulse shaping stage 9. Furthermore, a reference voltage source U _{f is} connected to the limit indicator. At the output of the limit monitor there is a relay 12 which responds when the input signal is too high, and a power stage which gives an alarm and / or switches off the monitored object in the event of a fault in the monitoring circuit.

609816/0182

The circuit works as follows:

The alternating voltage transmitter 4, which comes from the high voltage converter is fed, a small square-wave voltage is superimposed on the high-voltage chamber. This is about the chamber capacity C " transferred to the signal electrode la and amplified by the DC amplifier 6. At the output of this amplifier the voltage U is available, which is available via low and

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High-pass filter 7 and 8 is divided into a measurement signal and a square-wave monitoring signal. The response value of the limit monitor ü is applied to the reference voltage source U r; set. The dynamic limit monitor is clocked by the square-wave signal. If this signal fails, the relay 12, which is operated in closed-circuit current, responds. This means that every fault in the high-voltage supply, the connecting cables and the DC amplifier is reported immediately.

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4 pages description

3 claims

1 sheet of drawing

609818/0182

Claims (3)

Claims ^ ι (1.) Dynamic safety channel for nuclear reactors, the one , Ionization chamber, a DC amplifier, a limit monitor and a power switching stage, characterized in that the high voltage source (2) for the ionization chamber (1) is an alternating voltage generator (4) small amplitude is applied that the measurement signal superimposed periodic monitoring signal behind the DC amplifier (6) coupled out and the dynamic Limit indicator (11) is supplied and that the limit indicator (11) is followed by a relay (12), which triggers an alarm if there is no monitoring signal. 2. Dynamic security channel according to: claim. J., thereby. characterized in that; the decoupling of the monitoring signals in a · high-pass filter (8), which is a pulse shaper (9) is connected downstream. 3. Dynamic safety channel according to claim 1, characterized in that the AC voltage generator (4) of the high voltage source (2) is fed. 609 8 ^ 6/0182 Le e rs e ite