Fission chambers for in-core use

Photonis fission chambers for in-core use can be made to operate at temperatures up to 600°C depending on the reactor types and the detection requirements.

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In-core measurements of neutron flux ranges
Watertight stainless steel structure
Customization according to the user’s needs

Fission chambers for in-core use

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Technical information

In-core fission chambers optimized for pulse mode operation
Basic typeExt
diam
(mm)
Length
(mm)
Operating RangeMax.
temp
(°C)
   Pulse mode (nv)Current mode (nv) 
CFUR44346104 - 109-300
CFUF344.785103 - 108-400

 

In core fission chambers for current mode operation
Basic typeExt
diam
(mm)
Length
(mm)
Operating RangeMax.
temp
(°C)
   Pulse mode (nv)Current mode (nv) 
CFUZ531.549-2 x 1011 - 1014350
CFUR43348.5-1011 – 1.5 x 1014350
CFUF434.786-1010 - 1014350

 

In core fission chambers for wide range operation
Basic typeExt
diam
(mm)
Length
(mm)
Operating RangeMax.
temp
(°C)
   Pulse mode (nv)Current mode (nv) 
CFUR64342106 - 10111012 - 1015300
CFUE247150102 - 108108 - 1012400
CFUE327150103 - 108109 - 1013600

 

 

Description

Fission chambers are critical components for reactor neutron flux monitoring and can be used to detect thermal neutrons in high flux, to monitor the reactor fuel burn-up, and to control power in the source, intermediate, and power ranges.

Gas filled neutron detectors are designed to operate in three modes: 

  • Pulse mode analyzes and counts individual detector pulses.
  • Fluctuation, or Campbell mode, is used to analyze the fluctuation of the direct current from the detector.
  • Current mode is used to measure the mean of the direct current from the detector.

Fission chambers are filled with the appropriate gas for both high-temperature operation and fast response and are extremely radiation resistant.

Depending on the type of fission chamber required, a BNC or HN connector can be mounted on the integrated mineral insulated cable designed specifically for the detector. 

Fission chambers for in-core use may be designed to be movable inside the reactor core during operation. In research environments, our 1.5 mm external diameter subminiature chambers allow measurements close to the physical phenomenon.

Custom fission chambers for in-core use

  • Adaptation of industrialized fission chambers to customer specific requirements.
  • Development of new fission chambers with our experienced R&D team.
  • Long term collaboration with the French Alternative Energies and Atomic Energy Commission / CEA (theoretical approach, modeling, qualification tests in research reactors).
  • Complete manufacturing process on site.
  • Support from all the Photonis Group activities, experience and knowledge.
  • Certifications & Quality Assurance programs adapted to the customer environment.
  • Technical support, applying our expertise in the design and manufacture of nuclear instruments to solve customer challenges.
  • Export control, as an Authorized Economic Operator, Photonis acts in accordance with the EU international regulations.
  • Fissile material management & product storage.
  • Calibration in reactor for measurements in high flux.

Examples of customization of standard parts

  • Neutron sensitivity tailored to individual application requirements.
  • Isotopic composition (enriched U-235, natural, or depleted Uranium).
  • Mechanical interface with the equipment (Customized external dimensions).
  • Ruggedized structure for harsh environment (radiation, temperature, humidity, mechanical stress).
  • Adapted and ruggedized cable to allow propulsion in the core.
  • Mineral insulated connector type (Coaxial HN, BNC, BNC HT, SMA or others). Reinforced connectors are available.

fission chambers for in-core use

References

The French Alternative Energies and Atomic Energy Commission (CEA) selected Photonis as its technological partner for a cooperative development of neutron and gamma detectors when the French nuclear power programme took shape in the sixties.

  • PWR – neutron flux mapping – in-core fission chambers CFUF – Belgium, China, France, South Africa, South Korea, Slovenia.
  • ADS – wide range neutron flux monitoring – CFUF – Ukraine
  • BWR – start-up and intermediate range – In-core movable fission chamber CFUE – Finland, Sweden
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PHOTONIS Wide Range Fission Chamber

Documentation

Brochure/Leaflet