PWR Cutaway


Reuter-Stokes is a world leader in fission chamber design and manufacture including miniaturized fission chambers in our movable in-core (MIC) sensors, used in Pressurized water reactors (PWR). With over 50 years of design experience, and thousands of fission chambers installed, we have a unique track record of excellent operational performance in some of the harshest environments.

Our fission chambers measure neutron flux in various flux ranges to help manage, control, and protect the nuclear reactor. We offer fission chambers in both guarded and un-guarded styles. The guarded fission chambers are particularly well suited to applications where low signal and anticipated operational environments demand the highest level of immunity against electromagnetic interference.

To enable the critical signal of the fission chamber to arrive to the control room, we can utilize safety-related mineral-insulated signal transmission cables (coaxial and tri-axial), as well as safety-related electrical connectors. Both cables and connectors are designed and manufactured to provide high levels of electrical isolation under the demanding environmental conditions present in containment. Fission chambers designed for critical applications must have the highest level of reliability. 

With hundreds of instruments installed in the field, reliability for us is more than just a claim, it is a proven capability.

Please contact us with your nuclear instrumentation and control needs to discover what other solutions we can provide.

MIC Neutron Detectors for Pressurized Water Reactors
Designed for Peak Performance and Reliability

Reuter-Stokes, with more than 50 years of experience, is one of the world’s leaders in miniaturized fission chambers. The Reuter-Stokes MIC (movable in-core) sensor, used in pressurized water reactors (PWR), maps the thermal neutron flux in the water gap between adjacent fuel bundles and is compatible with existing installed systems.

The precisely matched, machined, and bonded components of the Reuter-Stokes MIC increases reliability by minimizing the possibility of detector failure resulting from insertion and removal. This means exact radiation readings when you need them, every time. Reuter-Stokes MIC detectors are compatible with all equipment vendors and can perform as direct replacements for current movable in-core probes.

Accurate Output Signal

The unique uranium coated miniature fission chamber and mineral insulated cable technology of the MIC enables detection of the core thermal neutron radiation levels by traversing the active fuel region and producing a direct current that is proportional to the neutron flux in the water gap.

The accurate signal of the MIC, enabled by the ceramic to metal seal that isolates the detector and cable assembly, eliminates variation at temperature from gas expansion and provides a signal that is precise and repeatable over hundreds of flux scans. This allows greater confidence in the neutron monitoring system operation.

Functional Flexibility Over a Long Detector Lifetime

Superior insulation resistance at temperature in the Reuter-Stokes MIC probes aids in exact flux measurement by minimizing leakage currents. This proven design permits usage of the detector over a wide range of temperatures, decreasing the need for frequent replacements. The long detector lifetime contributes to increased operation efficiency and decreased maintenance costs.

Customer-Focused Solutions

Reuter-Stokes is dedicated to continuous improvement in the performance of our products. By utilizing Six Sigma quality development and efficient, short-cycle production, we are able to meet customer needs quickly and to provide MIC probes in an industry-leading order-to-delivery time. 

Reuter-Stokes has also invested in plant and equipment to remain at the forefront of technology. Enhanced uranium plating, state of the art cleanroom assembly, and testing processes employed in the manufacture of the Reuter-Stokes MIC probes ensures the high level of quality our customers have come to expect.

Vast Global Install Base

Reuter-Stokes is committed to our customers around the globe, with experts available to meet deadlines when you need them and on your schedule. Reuter-Stokes MIC probes are installed in more than 25 PWR plants worldwide.

Performance Benefits
  • Reliable, trouble-free detector operation
  • MIC probes are available in right-handed or left-handed models and in custom lengths.
  • Responsive technical support
  • Extensive miniaturized fission chamber manufacturing experience for over 50 years

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