Retrospective Dosimetry of Fast Neutrons Focused on the Reactions

Voorbraak, W. P.; Kekki, Tommi; Serén, Tom; Bockxstaele, M. Van; Wagemans, J.; Woittiez, J. R. W.

doi:10.1520/stp45470s

Cited by 3 publications

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“…Here, the target is placed at the angle of 45°relative to the incident beam; thus, α = β, what simplifies Eqn (2). By integrating this equation on the target thickness and the solid angle, we can deduce the partial K fluorescence yield:…”

Section: Fluorescence Yieldsmentioning

confidence: 99%

“…Inelastic scattering reactions (n,n 0 ) are useful to characterize the neutron beams with energy around 1 MeV. [1][2][3][4] Rh are of particular importance, and the activities of niobium and rhodium dosimeters are the basic data that can allow tracing back the reactor operating information. The activity of these dosimeters is measured by X-ray spectrometry [3,4] , using spectrometers equipped with high purity germanium detectors, because 93m Nb [5] and 103m Rh [6] are radionuclides which emit only X-rays (Figs 1 and 2).…”

Section: Introductionmentioning

confidence: 99%

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Measurement of K fluorescence yields of niobium and rhodium using monochromatic radiation

et al. 2017

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Both reactions Nb-93(n,n 0 )Nb-93 m and Rh-103(n,n 0 )Rh-103 m are of particular importance for dosimetry in reactor, and the measurement of the activity of Nb and Rh dosimeters provides the basic data that can be traced back to the reactor operating information. These radionuclides emit only X-rays of which emission intensities in recommended data are determined thanks to the γ-ray transition probabilities and fluorescence yield values. In general, the knowledge of fluorescence yields is rather poor and based on old measurements. Nowadays, the use of tunable monochromatic X-ray sources allows performing optimized measurements. In a first step, accurate values of the attenuation coefficients are measured at the metrology beam line of the SOLEIL synchrotron, using procedures such as optimized for similar measurements. In a second step, the fluorescence yields are determined using experimental approaches in a traditional experimental configuration. For both materials, several incident energies are used to get experimental spectra with energy-dispersive spectrometer. The peaks of interest are processed using the COLEGRAM software, which allows detailed fitting of the peak shape. The K fluorescence yields are derived with about 2% relative uncertainty.

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Section: Fluorescence Yieldsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of K fluorescence yields of niobium and rhodium using monochromatic radiation

et al. 2017

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“…Where "CN, X" is self-fluorescence coefficient for the radionuclide "N" (N = 182 Ta, 95 Nb…) and the specific characteristic X-ray "X" (X = Kα or Kβ), "NXi" is the number of counts under the full-energy peak for the line "Xi" (i = [1,2] for Kα or i = [1,5] for Kβ), "ND" is the number of simulated decay and "εX" is the efficiency for the mean energy of the line "X". The total coefficient "CN" for a radionuclide is simply the addition of the "CN, Kα" and "CN, Kβ" coefficient values.…”

Section: Geant4 Simulationmentioning

confidence: 99%

“…This technique is based on the analysis of the activity of irradiated dosimeters including isotopes which are subject to activation or fission reactions under the neutron flux. For example, inelastic scattering reactions (n, n') are useful to characterise neutron beams with energies around 1 MeV [1][2][3][4]. Both reactions 93 Nb(n,n') 93m…”

Section: Introductionmentioning

confidence: 99%

Improvement of ^93mNb and ^103mRh activity measurement methodology for reactor dosimetry

et al. 2017

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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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Testing of the Retrospective Dosimetry Procedure Based on Niobium Extraction from VVER-1000 Cladding Material Samples after Their Irradiation in Research Reactor

Kochkin

Дмитриева

Reshetnikov

et al. 2018

Reactor Dosimetry: 16th International Symposium

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At present, many VVER-1000 reactors in Russia are approaching the end of their design lifetime. Therefore, the problem of their lifetime extension is of immediate interest. Precise evaluation of neutron fluence with E greater than 0.5 MeV at the reactor pressure vessel (RPV) wall is one of the main issues in the lifetime extension process. One of the most reliable experimental techniques that could be used for the refinement of fast neutron fluence value on RPV is the investigation of samples from RPV cladding with approximately 1 % niobium (Nb) content. It is necessary to validate this technique before taking samples from the RPV cladding of reactors currently in operation. Toward this goal, a dosimetry experiment has been carried out at Russia’s Kurchatov Institute. The main idea of the experiment was to compare 93mNb activity in niobium dosimeters and in cladding samples irradiated together to a certain fluence in the research reactor. Another goal was to measure and compare 54Mn activity formed as a result of 54Fe(n,p) reaction in an irradiated RPV material and in iron dosimeters. This task is important due to the widespread use of this technique for the study of the surveillance sets of Russian VVER-440 and VVER-1000 reactors, which are not equipped with a sufficient number of neutron dosimeters.

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Retrospective Dosimetry of Fast Neutrons Focused on the Reactions

Cited by 3 publications

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Measurement of K fluorescence yields of niobium and rhodium using monochromatic radiation

Measurement of K fluorescence yields of niobium and rhodium using monochromatic radiation

Improvement of ^93mNb and ^103mRh activity measurement methodology for reactor dosimetry

Testing of the Retrospective Dosimetry Procedure Based on Niobium Extraction from VVER-1000 Cladding Material Samples after Their Irradiation in Research Reactor

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Retrospective Dosimetry of Fast Neutrons Focused on the Reactions

Cited by 3 publications

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Measurement of K fluorescence yields of niobium and rhodium using monochromatic radiation

Measurement of K fluorescence yields of niobium and rhodium using monochromatic radiation

Improvement of 93mNb and 103mRh activity measurement methodology for reactor dosimetry

Testing of the Retrospective Dosimetry Procedure Based on Niobium Extraction from VVER-1000 Cladding Material Samples after Their Irradiation in Research Reactor

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Improvement of ^93mNb and ^103mRh activity measurement methodology for reactor dosimetry