Fission chambers for ex-core use

Name: Fission chambers for ex-core use
Brand: Exosens

Photonis manufactures a broad range of fission chambers for out-of-core use in severe environmental conditions. They are used in thermal neutron detection detectors provide indication for up to 11 decades of neutron flux for wide-range reactor monitoring. They operate in extremely high gamma environments and at temperatures up to 600°C.

Detection of thermal neutrons in wide flux ranges

Very high safety of use

Customization according to the user’s needs

Fission chambers for ex-core use

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Technical information

Ex-core fission chambers without integral Cable

Basic type	External diameter (mm)	Length (mm)	Operating Range		Max. temp (°C)
			Pulse mode	Current mode
CFUM11	25.4	227	10 - 10⁷	10⁷ - 10¹¹	250
CFUL01	48	337	1 - 10⁶	10⁴ - 10¹⁰	250
CFUK09	60	395	0.3 - 3x10⁵	10⁵ - 10¹⁰	250

Ex-core fission chambers with integral Mineral Insulated Cable

Basic type	External diameter (mm)	Length (mm)	Operating Range		Max. temp (°C)
			Pulse mode	Current mode
CFUM18	25.4	263	10 - 10⁷	10⁷ - 10¹¹	250
CFUL08	48	384.5	1 - 10⁶	104 - 10¹⁰	250
CFUC06	48	412	1 – 10⁵	104 - 10¹⁰	600
CFUK08	60	362	0.3 – 3x10^{^5}	10^{^5} - 10^{^10}	250
CFUP08	76.5	389	1 - 10⁶	10⁴ - 10¹⁰	250
CFUG08	80	419	0.2 - 2x10⁵	10⁵ - 7x10¹⁰	250

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.

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.

LOCA rated versions of fission chamber standard models are available on demand. These fission chambers are typically designed with a maximum operating temperature of 250°C (although some versions can operate up to 600°C) and are equipped with an integrated mineral insulated cable and a HN connector.

Their outstanding gamma rejection capabilities allow them to be used in waste monitoring applications such as spent fuel monitoring.

Due to the extreme operating conditions of fission chambers, Photonis also recommends the use of mineral insulated cable extensions designed specifically for the detector.

Our fission chambers stand resilient in severe conditions, operating with precision in environments where others falter. Designed for thermal neutron detection, these detectors provide invaluable indications across a remarkable 11 decades of neutron flux in gamma fields of 10⁴ Gy/hr and temperatures as high as 600°C.

Why choose Photonis fission chambers?

Unmatched Precision: Accurate detection across a wide range for comprehensive reactor monitoring.
Resilient Performance: Operates seamlessly at temperatures up to 600°C, ensuring reliability even in advanced reactors.
Nuclear Quality: Our detectors are built to perform safety-related functions in the operating nuclear fleet. We manufacture to stringent quality standards, operating according to ISO9001, ISO19443, RCCE, NQA-1, and HAF604.

Essential to reactor neutron flux monitoring, our fission chambers play a pivotal role in detecting thermal neutrons, monitoring fuel burn-up, and controlling power across source, intermediate, and power ranges.

Custom coaxial cable extensions & connectors

By full control of the following processes, Photonis Nuclear Instrumentation can supply custom fission chambers for ex-core use with the highest quality and reliability levels:

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 expertise.
Export control, as an Authorized Economic Operator, Photonis acts in accordance with the EU international regulations.
Fissile material management & product storage

Examples of custom versions from basic types

Neutron sensitivity tailored to individual requirement.
Guard-ring (2 outputs) or coaxial (1 output) structure.
Stainless Steel or Nickel alloy for high temperature (>250°C).
Adapted mechanical interface with the equipment (Customized external dimensions, springs, threads, hooks).
LOCA (Losse Of Coolant Accident) and post-LOCA protection.
Ruggedized structure for harsh environment (radiation, temperature, humidity, mechanical stress).
Integral cable or integral connector.
Coaxial or triaxial mineral insulated cable.
Mineral insulated connector type (Coaxial HN, BNC, BNC HT, SMA or triaxial solutions). Reinforced types are available for high pressure, high temperature conditions.

Main features

Structure configuration: Coaxial or guard-ring.
Structure material: Aluminum for max. F32 operational temperature.
Integral cable: Coaxial Mineral insulated cable for pulse and current transmission, high immunity. Integral cables are recommended for the signal and for the high voltage when operating in severe -environments.
Connector: HN Mineral insulated connector for pulse and current transmission.
Insulators: Photonis only uses high-grade, radiation resistant alumina insulators from qualified suppliers to ensure the measurement of extremely low currents.

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 program took shape in the sixties.

Our references

PWR – wide range neutron flux monitoring – ex-core fission chambers CFUG – Switzerland.
VVER – wide range neutron flux monitoring – ex-core fission chambers CFUL – Hungary, Slovakia, Ukraine.
Fuel reprocessing plant – AREVA La Hague/ORANO – numerous fission chambers – France, Japan.
FBR – wide range neutron flux monitoring – high temperature 600 °C fission chambers CFUC – France.