MODULAR NUCLEAR INSTRUMENTATION CHANNELS FOR RESEARCH REACTORS

The NLW-1000 wide-range logarithmic channel combines the functions of logarithmic counting and logarithmic current conversion to provide a continuous indication of reactor power from source level to full power. A remotely located pre-amplifier minimizes EMI and other sources of interference and adjustable discriminator and gain controls allow flexibility in channel calibration with existing detectors. A differentiator circuit provides continuous indication of rate of change of power, and self test functions can sequentially check count rate, current, period and high voltage. Provision is made for permissive operation by computer of all test functions.

The NMP-1000 is an analog, wide range, linear current mode module with range switching. Ranges maybe selected either manually or automatically, locally or remotely. Full scale sensitivities from 1 x 10^-11 to 1 x 10^-3 A are provided with indication of percent power on a front panel meter, as well as a front panel LED indication of each decade range. For remote operation, a separate panel assembly can be provided with identical range indicating LEDs, display of current and voltage, as well as channel self test functions. Compensation voltage as well as adjustable high voltage power supplies are provided in the module to allow operation with most existing current mode detectors.

The NLS-1000 is a channel module for use with existing fission chamber assemblies or neutron sensitive proportional counters to indicate reactor power in the startup or source region. Signals from the neutron counter are fed through a remotely located preamplifier into the startup channel electronics module. This channel uses the function of logarithmic counting to provide a continuous indication of reactor power covering seven decades. A differential circuit provides continuous indication of rate of change of power and self test functions can sequentially check count rate, period and high voltage.

The NP-1000 and NPP-1000 analog safety channels are versatile, modular current mode instruments with user selectable input and output parameters. The NP-1000 percent power module provides linear current ranges from 1 x 10^-9 A full scale sensitivity. Isolated voltage and current outputs are provided, as are bistable trip contacts in flame-proof conduit connectors. Self test features may be applied either locally or remotely. The NPP-1000 has all the features of the NP-1000, plus isolated peak power and total energy outputs for use in pulsing reactor applications. Low drift peak and integral circuitry allows ample time for both manual as well as automatic data acquisition of pulse data.

The NLI-1000 is an intermediate range power channel for accurate logarithmic display of reactor power, detector high voltage and reactor period. Bistable trip circuits provide alarm and scram signals for power, detector high voltage and reactor period. Test and calibration circuits are provided which feed appropriate signals to check the log N amplifier, the bistable trips and the period circuit. Compensation voltage as well as adjustable high voltage power supplies are provided in the module to allow operation with most existing current mode detectors.

The NMS-1000 Magnet Power Supply contains three identical magnet power supplies mounted symmetrically on a printed circuit board, capable of regulating 150 mA of current to a magnet of 200 ohms. The power supplies are monitored in a closed loop system which adjusts the output to compensate for any variation in magnet resistance.