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.
Abstract. Reactor dosimetry is based on the analysis of the activity of irradiated dosimeters, such as 93m Nb and 103m Rh. The activity measurement of these dosimeters is conventionally performed by X-ray spectrometry, but the low-energy of emitted photons makes it difficult to derive reliable results with low uncertainties. Approaches to improve these characterisations are presented: they include high accuracy efficiency calibration of a HPGe detector using both experiments and Monte Carlo simulation, calculation of corrective factors for the geometry (selfabsorption) and self-fluorescence effects. Improvement of the knowledge of the 103m Rh decay scheme is also required and a specific experiment is proposed, including activity measurement of a 103m Rh solution by liquid scintillation, and measurement of the photon emission intensities by X-ray spectrometry. A method for calculating coefficients to take into account the self-fluorescence effects in dosimeters is also suggested to improve the uncertainties on activity measurements.
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