GLSEQ introduces the

Intrinsically Smart – Severe Accident Instrumentation Line (IS-SAIL)

Designed To Make Nuclear Power Plants Even Safer!

Adding a whole new level of protection for nuclear plants


IEEE Std 497™-2016 Type F Instrumentation

GLSEQ’s SAIL Instrumentation meets “IEEE Standard Criteria for Accident Monitoring Instrumentation for Nuclear Power Generating Stations” IEEE Std 497™-2016.



Identify Fuel Damage

Type F variables provide primary information to accident management personnel to indicate fuel damage and the effects of fuel damage.  

Severe Accident Mitigation

Type F variables provide the most direct indication of the parameters needed to execute the severe accident mitigation guidelines (SAMGs) and/or variables needed to mitigate those accidents postulated in nuclear plants severe accident analysis.

Located where you need it most

Hydrogen Locations

The GLSEQ Severe Accident Information System (SAIS) is able to locate the source of the hydrogen leak.

Inside Containment

The GLSEQ SAIS is able to measure hydrogen concentration inside containment within the reactor top head flange and
suppression pool hatches.

Outside Containment

The GLSEQ SAIS is able to measure hydrogen concentration outside containment monitoring leakage from piping and electrical penetrations, machine hatches, airlocks, spent fuel pool, and standby battery rooms.

Hydrogen & Oxygen Monitoring System

GLSEQ’s first monitoring system in our new Intrinsically Smart – Severe Accident Instrumentation Line is our Hydrogen Oxygen Monitoring System (HOMS).

Significance to Plant SAMGs

During an accident, information is needed to diagnose a nuclear plants status and confirm its response to mitigative actions. It is important to determine the information necessary for severe accident management and to ensure that this information could be derived from plant instrumentation.  

Severe Accident (SA) Scenarios are greatly simplified with GLSEQ’s SAIL Instrumentation Hydrogen and Oxygen Measuring System (HOMS). HOMS is diverse instrumentation designed and tested for the world’s worst SAs. HOMS is always on, direct measurement monitoring of: 

  • Hydrogen gas concentration 
  • Oxygen gas concentration 
  • Temperature 
  • Pressure 

HOMS provides unambiguous information to the plant operators of: 

  • The occurrence of fuel damage. 
  • Molten Core Concrete Interaction (MCCI) 
  • Risk of Hydrogen Explosion inside and outside of containment 
  • Independent and diverse direct measurement of SA conditions 
  • Simplifies Severe Accident Management Guidelines (SAMG) and Scenarios 

Fukushima Lessons Learned: Hydrogen Monitoring

One of the lessons learned from the Severe Accidents at Fukushima Daiichi in 2011 was to develop advanced hydrogen monitoring. 

Instrumentation systems in the nuclear power plant are very important systems to monitor plant conditions for safe operation and shutdown. TEPCO’s Fukushima Daiichi Nuclear Power Station accident caused severe accidents such as severe core damage and loss of function of instrumentation systems. 

A research and development (R&D) program for an Advanced Instrumentation System for Severe Accidents was carried out as a result of a public offering by the Japan Agency for Natural Resources and Energy. In the R&D, the aim was to contribute to limiting accidents from turning to severe accidents such as TEPCO’s Fukushima Daiichi Accident.  

Specifications for instrumentation systems during the severe accident that took into account TEPCO’s Fukushima Daiichi Accident were developed. Investigations and development were performed on new advanced instrumentation systems that are able to measure important parameters (e.g., pressure, hydrogen concentration, etc.) in nuclear power plants during a severe accident. 

GLSEQ’s hydrogen monitoring system won the international R&D competition and the multi-phase, multi-year (2012 to 2015) verification process, which was a part of the results of the collaborative project by Japanese electric power companies and plant manufacturers that is carried out as the Safety Enhancement for LWRs program by Agency for Natural Resources and Energy. 


GLSEQ's HOMS doesn't miss important hydrogen measurements!

Replaces combustible gas systems that are difficult to maintain.

Replaces combustible gas systems that have failed during severe accidents.

Interested in Severe Accident Instrumentation?