Products & Services

Instrumentation & hardware

Ex-core neutron detectors

Rolls-Royce is a world leader in Neutron instrumentation, from sensors to electronic conditioning and processing.

For 40 years now, we have been designing, manufacturing, installing and maintaining ex-core neutron detectors that provide measurement of the reactor neutron flux for the Neutron Instrumentation System (NIS) to continuously monitor instantaneous nuclear power, power fluctuations, and radial/axial power distribution in the reactor.

We provide three different types of neutron detectors:

  • Boron-lined proportional counter for the low level range (CPNB type)
  • Compensated boron-lined ionisations chamber for the intermediate level range (CC type)
  • Non-compensated boron-lined ionisations chamber for the power level range (CNC or CBL type)

Our designs amalgamate different detector types, such as proportional counters, ionisation chambers and fission chambers. All comply with international standards (IEC 780, IEEE 323, IEEE 344).

We have the experience and expertise is to design custom neutron detectors to meet customer specific reactor designs.


  • Enhanced performance through the detectors extended lifetime
  • Extensive feedback experience due to our installed base in more than 120 nuclear reactors