Startup Instrumentation Control

System Overview

Continuous monitoring or neutron flux is required at all times during Approach to Critical (ATS), upon successful phase over of neutron power measurement by the plant permanently installed instrumentation used to measure neutron flux. During the initial fuel loading and for the first approach to critical the neutron source is from spontaneous fission only and in-core neutron counters are temporarily installed for monitoring at the initial, low flux levels.

After first approach to critical and a period of low power testing, the in-core start-up detectors are removed and a photoneutron source causes the shutdown flux to be 10-12 or greater. Neutron flux monitoring is achieved for this range using out-of-core start-up detectors (3He and BF3 neutron counters).

The in-core and out-of-core instrumentation is divided into three independent channels to provide redundancy. In addition to providing power measurements to the operator, the start-up instrumentation is connected into the three channels D, E, F of first shutdown system and can automatically trip the reactor if any two of the channels fail, or indicate neutron flux in excess of the trip set-point.

The SUIC system is broken down into 4 different sections: MCR Moveable instrumentation, In-core Moveable instrumentation, Ex-core moveable instrumentation and Utility panel. The MCR moveable cabinet is connected to the In-core detector cabinet or Ex-core detector cabinet (depending on which is in use) through a junction box (connectors JS/JP518/D-F and JS/JP448/D-F for In-core and Ex-core, respectively). The box is the connected to the MCR through connectors JS41 9/D-F ( for In-core), and JP449/D-F for Ex-core (see appendix C for MCR drawing, Appendix D for the In-core/Ex-core drawings and Appendix E for the simplified block drawing respectively.

Technical Specifications

The SUIC system is broken down into 4 different sections: MCR Moveable Instrumentation, In-core Moveable Instrumentation, Ex-core Moveable Instrumentation and Utility Panel. Each of these sections contains the equipment listed below.

MCR Moveable Instrumentation

  • Ortec 550A Single Chan11elAnalyzer
  • Ortec 996 Timer and Counter
  • Ortec 449-2 Log/Lin Ratemeter
  • Sartrex 997040 Alarm Control
  • Sartrex 997050 Interface Module
  • Isolator Module
  • Frequency Meter
  • ASPEC MCA (Spare D only)

In-core Moveable Instrumentation

  • LND Fission Chamber model 30773
  • Ortec 572AAmplifier
  • Ortec 556 High Voltage Power Supply
  • Ortec l42PC Preamplifier
  • Random Pulse Generator (“F” only)

Ex-Core Moveable Instrumentation

  • HE-3 Detector
  • BF-3 Detector
  • Ortec 572A Amplifier
  • Oitec 556 High Voltage Power Supply
  • Ortec 142PC Pre-amplifier
  • Random Pulse Generator (“F” only)

Utility Panel

  • Tektronix TDS 1001 Oscilloscope or equivalent
  • Pen Recorder
  • (4) Pen Recorder
  • Laptop PC
  • Panel (A Panel is supplied, for the above components to be attached to)


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