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Criticality Accident Alarm System

The CAAS-3S is a next generation system based on operational excellence established over forty years.

Tag Features

  • Neutron-only, gamma-only or combined detection capability
  • Completely redundant architecture at all system levels
  • Response time less than 300 ms per criticality standards
  • Multiple zone coverage - 10 zones with 2 out of 3, or 8 zones with 2 out of 4 voting logic
  • Continuous state-of-health monitoring on each detector
  • Remote supervision
  • Qualified under real criticality situations at CALIBAN and PROSPERO reactors of the French Atomic Energy Commission (CEA)
  • Complies with the IEC 60860 (2014), ISO 7753 (1987) and ANSI/ANS-8.3 (1997)
  • Designed to comply with SIL2 IEC 61511-1



The CAAS-3S is a next generation system based on operational excellence established over forty years. The new design is based on the highly reliable analog signal chain used in the probe design for the previous EDAC-2 and later EDAC-21 products which have had successful safety records and very low false alarm rates. This new system addresses the next several decades of facility operation.


Detection capabilities include gamma-only, neutron-only, and combined neutron + gamma probes to cover all types of installations and criticality excursions

Use of scintillation technology and ruggedized electronic components provides very high-reliability and allows accident and post-accident monitoring of dose rate


The system is designed to meet SIL2 IEC61511, with full redundancy of the safety channel from probe to alarm output

Tested and proven to detect a criticality event and trigger alarms under seismic conditions

Key Benefits

  • Low false alarm rates
  • Negligible operational interruption
  • Low maintenance requirements and minimal facility downtime
  • Adaptability to various accidents, shielding, legacy installations and regulations through both gamma and neutron detection
  • Post-accident monitoring capabilities


  •  Fuel Cycle Facilities including enrichment, fabrication, and reprocessing
  •  Research & Military applications
  •  Waste & Storage applications

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