Nuclear in-pile instrumentation

Our expertise

• Experimental comparative study of various sensors for thermal neutron flux measurements in the range 10 ¹⁰ -10 ¹⁵ n/(cm²s)
• Detailed modelling of all types of self-powered neutron detectors with a MCNP-based model and determination of absolute thermal neutron flux with uncertainty less than 10%
• Modelling and testing of (sub)miniature fission chambers (fabricated by CEA-Cadarache) for in-core thermal neutron flux detection
• Longstanding practical experience with all sensor types used in the framework of the SCK•CEN-CEA Joint Instrumentation Laboratory (Laboratoire Commun d'Instrumentation, LCI): development of innovative in-core instrumentation (gamma selective self-powered detectors, in-core fission chambers for fast neutron flux measurement, dimensional in-core measurements with fibre-optic methods, acoustic measurement of fission gas release)

Example of nuclear instrumentation:

• Top: gamma thermometer
• Mid position: 3 subminiature fission chambers
• Bottom: rhodium SPND

Test reference electrodes for irradiation in a PWR simulating environment: rhodium electrode (top) and YSZ mixed metal oxide reference electrode (bottom).

In-core detector types developed, tested, modelled and/or in use

Thermal neutron flux

• Self-powered neutron detectors (SPND) with rhodium emitter (Ø 0.5 mm, 0.7 mm, 1.0 mm, 1.5 mm), Ø 0.5 mm silver emitter, Ø 2.0 mm vanadium emitter and Ø 2.0 mm cobalt emitter;
  L. Vermeeren , M. Wéber, Ch. Blandin and S. Breaud, In-pile sub-miniature fission chamber testing in BR2, Proc. 11th Symp. on Reactor Dosimetry, Brussels, Belgium, Aug. 18-23, 2002, eds. J. Wagemans et al., World Scientific, 2003, pp. 364-371
• Subminiature 235U fission chambers (Ø 1.5 mm) and Ø 3 mm Photonis CFUR64 fission chambers with special cabling for acquisition in pulse, fluctuation and current modes (in collaboration with CEA);
  L. Oriol, Ch. Blandin, S. Breaud, L. Vermeeren, M. Wéber, In-pile CFUZ53 Sub-miniature fission chambers qualification in BR2 under PWR condition, Proc. Joint TRTR-IGORR Meeting, Gaithersburg, MD, USA, Sept. 12-16, 2005; http://www.ncnr.nist.gov/trtr2005/Proceedings/Oriol - CFUZ53 Fission Chamber.pdf

Fast neutron flux

• Ø 1.5 mm and Ø 3 mm fission chambers with ²⁴² Pu deposit to detect high fast neutron fluxes in the presence of a strong thermal neutron flux component and a significant gamma field (LCI);
  L. Oriol, P. Filliatre, L. Vermeeren, Détecteur pour la mesure en ligne des neutrons rapides dans un réacteur, Patent 07-60229 deposited at INPI, Paris, France (2007)

Gamma flux

• Modelling, development, testing and optimization of self-powered detectors with a lead emitter and with a bismuth emitter (outer diameter 3.2 mm) for the selective determination of the gamma flux in the presence of a high neutron flux (LCI);
  R. Van Nieuwenhove, L. Vermeeren, Online gamma dose-rate measurements by means of a self-powered gamma detector, IEEE Trans. Nucl. Sci. 49, 4, 1914-1918 (2002)

Nuclear heating

• Modelling, fabrication, calibration and testing of Halden type gamma thermometers (outer diameter 4.5 mm)

Temperature

• Standard thermocouples (e.g. K-type)
• W/Re thermocouples for central fuel temperature measurements
  R. Van Nieuwenhove and L. Vermeeren, Irradiation effects on temperature sensors for ITER application, Rev. Sci. Instr. 75, 75-83 (2004)

Displacement measurements

• Radiation-resistant LVDTs from Halden
• Acoustic methods under development (LCI)

Fission gas release

• Radiation-resistant pressure detectors using LVDTs supplied by Halden
• Fibre-optic methods under development (LCI)

Electro-chemical sensors

• Reference electrodes

Instrumentation cables

• Experimental and theoretical study of radiation-induced currents in mineral-isolated cables and of radiation-induced changes in thermoelectric sensitivities of conductors;
  L. Vermeeren and R. Van Nieuwenhove, Theoretical study of radiation induced electromotive force effects on mineral insulated cables, Rev. Sci. Instr. 74, 4667-4674 (2003)
  R. Van Nieuwenhove and L. Vermeeren, Experimental study of radiation induced electromotive force effects on mineral insulated cables, Rev. Sci. Instr. 74, 4675-4682 (2003)
  L. Vermeeren, Experimental study of radiation-induced currents in copper and stainless steel core mineral-insulated cables in the BR2 research reactor, Fusion Engineering and Design, 74, 885-889 (2005)
  L. Vermeeren, M. Wéber, Induced voltages and currents in copper and stainless steel core mineral insulated cables due to radiation and thermal gradients, Fusion Engineering and Design, 82:5-14, 1185-1191 (2007)

Contact: Dekeyser Jean