Intercomparison of neutron noise measurement systems in the CROCUS reactor

Research output: Contribution to report/book/conference proceedingsIn-proceedings paper


  • Vincent Lamirand
  • Grégoire De Izarra
  • Antonin Krása
  • Grégory Perret
  • Oskari Pakari
  • Pavel Frajtag
  • Mathieu Hursin
  • Patrick Blaise
  • Jan Wagemans
  • Andreas Pautz

Institutes & Expert groups

  • EPFL - École polytechnique fédérale de Lausanne
  • CEA Cadarache - Commissariat à l'Énergie Atomique
  • PSI - Paul Scherrer Institute


In the framework of an international collaboration, the critical decay constant (α0 = β/Λ), and delayed neutron fraction (β) of the CROCUS reactor were measured by teams of EPFL/PSI, CEA and SCK•CEN research institutes using the Rossi-α and Power Spectral Density neutron noise measurement techniques. These measurements contribute to the experimental database of kinetic parameters used to improve nuclear data files and validate modern methods in Monte Carlo codes. CROCUS is a light-water zero-power reactor composed of two interlocked fuel zones with square lattices of different pitches, and different enrichments. An extensive experimental campaign was carried out at various critical levels and in four different subcritical configurations, with numerous detectors setups. This article is focusing on the first results in critical state for two powers (40 mW and 200mW) with the most sensitive detectors, namely 1 g 235U fission chambers set at the core-reflector interface. Values of α0 and β determined by the three institutes and with the different techniques are consistent for the configurations envisaged. Results for α0 are in agreement within one standard deviation with MCNPv5-1.6 calculation results, whereas discrepancies are observed for β, up to 10% depending on the used nuclear data library.


Original languageEnglish
Title of host publicationProceedings of the PHYSOR 2018, Cancun, Mexico
PublisherANS - American Nuclear Society
Number of pages11
Publication statusPublished - 9 Jan 2019
Event2018 - PHYSOR: Reactor Physics Paving The Way Towards More Efficient Systems - Marriot Casa Magna, Cancun, Mexico
Duration: 22 Apr 201826 Apr 2018


Conference2018 - PHYSOR
OtherPHYSOR is one of the biggest conferences in reactor physics and is held every second year. Organized and mainly sponsored by the American Nuclear Society, it cover topics of both computational and experimental topics in reactor physics such as in and ex core fuel management, safety analysis and uncertainty quantification applied to licensing procedures
Internet address


  • CROCUS, Rossi-alpha, kinetic parameters, delayed neutron fraction, decay constant, neutron noise

ID: 4740216