Power Range Analogue Module
The detector KNK-53M is a 10B lined, gamma compensated ionization chamber for detection of thermal neutrons in a flux range of 104 to 5*1010 nv. In a compensated ionization chamber a second ionization chamber detecting only gamma is placed as well. The signal from the gamma chamber (gamma sensitivity is 1,5*10-12 A/r/H) may be used to cancel the gamma contributions to the neutron chamber signal (neutron sensitivity 4*10-14 A/nv).
The Power Range Analog Module RNL-03.01 receives the signal of compensated ion chamber probe. The module is located in a double shielded box near to the detector (max. 8-m) but out of the reactor vessel. It is built in massive brass housing to protect from electro-magnetic interference waves and cross coupling. This unit is installed isolated into additional die-cast aluminum housing. This insulated installation provides an additional protective screen. Maximum 200-m long cable ensures the electrical connection between the analog module and NF computer.
Detector current flows into the virtual earth of the INPUT AMPLIFIER, which converts it to a proportional voltage at its output. Also range switching is accomplished here by RANGE SEL binary signal. Switch (DETECTOR CURRENT BYPASS SWITCH) is inserted between current input and earth. When it is switched on rejects all detector current flowing into the input amplifier and is therefore used for service purposes (e.g. calibration during maintenance). Output voltage of input amplifier enters the V/F converter input through an offset stage to cause the specified 200 Hz frequency offset. The output signal of the V/F converter drives the digital opto-isolator followed by the RS422A type line driver.
Another branch of output voltage of INPUT AMPLIFIER drives the input OF ISOLATION AMPLIFIER. The output of isolation amplifier drives four current loop inputs, connected in parallel to result output signals AUX1...AUX4. These output currents are proportional to the detector current.
There is an externally evoked testing function TG3 and controlled from TEST ON TG3 input. If this level is high, a well-defined extra current is adding to input (detector) one.
The positive and negative HV power supplies are built up of encapsulated circuits surrounded by current-loop driven isolated set-value controls and HV-monitoring isolation amplifiers. Set-value control signals from HV+CNTR and HV-CNTR are the current-loop inputs, monitoring signals from HV+MON and HV-MON leave the board in the form of current loop outputs.
The primary supply of power enters the board. Transient protection from the outside world is done by fuse diode. It saves the inputs of a four-member group of isolated DC-DC converters from damages. The unit also contains an isolation amplifier-current loop function to get the primary power monitoring signal (MON POWER S) output.
The output of the transient protector block appears also at pins +24VM and GND to serve as input monitoring signal for PCB1 under the same name.
Main Technical Data