Abstract. This paper presents the results of a round robin exercise carried out to compare specific activity measurements performed by eight European organisations on a set of ten neutron activation detectors containing the radio-nuclides 110m Ag, 60 Co, 54 Mn, 46 Sc and 94 Nb. The purpose of the exercise was to demonstrate the level of consistency between the participating organisations in blind tests of measurements relevant to reactor metrology. The samples used were selected from a stock of pre-existing irradiated material held at SCK•CEN. Taking turns over a period of approximately 9 months, the participating organisations received the samples, measured them and provided their results to an independent referee who collated and compared the data. The inter-comparison has demonstrated good agreement between the participants with standard deviations for each dosimeter varying between 1.6% and 3.1%. The paper provides results of the EWGRD Round Robin in an anonymised form together with discussion and conclusions which may be drawn from the exercise.
International benchmarks for cross-sections qualification are very poor in experimental means able to provide information on the neutron spectrum around 1 MeV. To fill this vacancy, one possible solution is to use the activation of rhodium. The reaction of inelastic neutron scattering on this element, in the energy range of 0.5 MeV to 5 MeV, leads to the formation of 103 Rh m . The return to the ground level of this radionuclide emits X-rays of low energy. This paper describes a method for determining the activity of 103 Rh m taking into account the constraining characteristics of this radionuclide and proposes a computed to measured results comparison for an experiment irradiated in the French CEA critical facility EOLE. Index Terms-efficiency calibration, 103 Rh m , X-ray measurement, scattered rays, escape rays. K α Bump scattered Raie K α = 20,17 keV Raie K α1 = 20,22 keV Raie K α2 = 20,07 keV K β bump scattered Raie K β2 23,20 keV Raie K β1 22,81 keV Raie K β = 22,87 keV K α Bump scattered Raie K α = 20,17 keV Raie K α1 = 20,22 keV Raie K α2 = 20,07 keV K β bump scattered Raie K β2 23,20 keV Raie K β1 22,81 keV Raie K β = 22,87 keV
The main goal of the Reactor Dosimetry is to provide information (reaction rates, fluence, fluence rate...) for the interpretation of experiments irradiated in critical mock-up, test reactors or power nuclear reactors. Various techniques are used, including analysis of irradiated activation or fission dosimeters whose radioactivity is measured afterwards.The MADERE platform (Measurement Applied to DosimEtry for REactors) is a CEA facility which is dedicated to the activation dosimeters manufacturing and their activity measurement after irradiation in a nuclear reactor. The laboratory is accredited by the French Accreditation Committee for specific activity measurements of solid samples using gamma and X-rays spectrometry.The choice of dosimeters takes into account limitations coming from the characteristics of the measurement devices. To meet experimenter's new demands, the MADERE platform set out to improve its offer by lowering the energy of measured radiations down to 10 keV, and the activity level down to the tenth of Becquerel (Bq). Doing so, the range of usable dosimeters and by the way, the energy range of the neutron spectrum is expanded.Dosimeter, wires or foils, few millimeters large, are manufactured using ultra-pure material (Gold, Iron, Nickel,...). Some of them are encapsulated in quartz containers for integration into experimental devices.
FLUOLE-2 is a benchmark-type experiment dedicated to 900 and 1450 MWe PWR vessels surveillance dosimetry. This two-year program started in 2014 and will end in 2015. It will provide precise experimental data for the validation of the neutron spectrum propagation calculation from core to vessel. It is composed of a square core surrounded by a stainless steel baffle and internals: PWR barrel is simulated by steel structures leading to different steel-water slides; two steel components stand for a surveillance capsule holder and for a part of the pressure vessel. Measurement locations are available on the whole experimental structure. The experimental knowledge of core sources will be obtained by integral gamma scanning measurements directly on fuel pins. Reaction rates measured by calibrated fission chambers and a large set of dosimeters will give information on the neutron energy and spatial distributions. Due to the low level neutron flux of EOLE ZPR a special, high efficiency, calibrated gamma spectrometry device will be used for some dosimeters, allowing to measure an activity as low as 7. 10 −2 Bq per sample. 103m Rh activities will be measured on an absolute calibrated X spectrometry device. FLUOLE-2 experiment goal is to usefully complete the current experimental benchmarks database used for the validation of neutron calculation codes. This two-year program completes the initial FLUOLE program held in 2006-2007 in a geometry representative of 1300 MWe PWR.
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