Available systems

Explore GE Hitachi’s NUMAC monitoring systems

Neutron Monitoring

Power Range Neutron Monitoring (PRNM) System

Observes operation reactor power levels from 20% to 125% capacity during normal operation and transmits reactor trip signals to the plant safety systems.

  • More than 30 systems installed since 1994
  • Connects to fixed in-core Local Power Range Monitoring (LPRM) sensors
  • 4-channel trip voting logic reduces spurious SCRAM occurrences by 50%
  • Enables core stability monitor options

Wide Range Neutron Monitoring (WRNM)

Intended to replace the entire source range monitor (SRM) and intermediate range monitor (IRM) system, the WRNM tracks reactor power from 0% to 20% capacity and transmits trip logic at startup power levels.

  • More than 15 systems installed since 1989
  • 8 fixed, in-core sensors versus 12 retractable SRM/IRM sensors
  • Auto-range switching and rate-based logic removes spurious trips
  • Reduced maintenance and dose
  • Transmits reactor trip signals to the plant safety systems

Automatic Traversing Incore Probe (ATIP)

Compares readings to values from the PRNM system to calibrate the in-core power sensors. It controls a drive mechanism and indexer that governs a sensor next to each LPRM sensor.

  • More than 15 systems installed since 1986
  • Automatic sequencing of all channels simultaneously
  • Digital torque data available
  • Calibrates the LPRM sensors
  • Redundant internal power supplies
  • Improved position indication for:
    • Less maintenance
    • Improved reliability
  • Expanded memory for greater data collection/analysis/trending

Reactivity Control

Rod Control System – Reactor operators can insert or withdraw control rods via the rod control system for power generation purposes and to monitor rod status.

  • 6 systems installed since 2009
  • Reduced:
    • Operator fatigue and error
    • Maintenance costs
    • Single points of vulnerability (SPVs)
  • Self-monitoring system diagnostics and information functional features and automation (rod prompt; collet unlatch)
  • Real-time systems’ status and notifications
  • Automated test routines and diagnostics

Rad Monitoring/Other

  • Log Rad Monitor (LRM), Process Rad Monitor (PRM), Area Rad Monitor (ARM), and Linear Rad Monitors (LiRM) (all since 1987)
  • Leak Detection, Pool Temperature, and others (all since 1985)
  • LINK –NUMAC optical to ethernet data (since 2017)


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