Radiation-induced amorphization of quartz under a high fast-neutron fluence

1989 ◽  
Vol 66 (3) ◽  
pp. 233-235 ◽  
Author(s):  
I. Kh. Abdukadyrova
Keyword(s):  
Fast Neutron ◽  
Neutron Fluence ◽  
Radiation Induced

scholarly journals Test of Fibre Bragg Gratings samples under High Fast Neutrons Fluence

2018 ◽  
Vol 170 ◽  
pp. 04004
Author(s):  
G. Cheymol ◽  
L. Remy ◽  
A. Gusarov ◽  
D. Kinet ◽  
P. Mégret ◽  
...  
Keyword(s):  
Refractive Index ◽  
Fast Neutron ◽  
Thermal Annealing ◽  
Bragg Peak ◽  
Neutron Fluence ◽  
Fibre Bragg Grating ◽  
Bragg Wavelength ◽  
Before And After ◽  
Radiation Induced ◽  
High Level

Optical fibre sensors (OFS) are worthy of interest for measurements in nuclear reactor thanks to their unique features, particularly compact size and remote multi-point sensing for some of them. But besides non negligible constraints associated with the high temperature environment of the experiments of interest, it is well known that the performances of OFS can be severely affected by high level of radiations. The Radiation Induced Attenuation (RIA) in the fibre is probably most known effect, which can be to some extent circumvented by using rad hard fibres to limit the dynamic loss. However, when the fast neutron fluence reaches 1018 to 1019 n/cm2, the density and index variations associated to structural changes may deteriorate drastically the performances of OFS even if they are based on rad hard fibres, by causing direct errors in the measurements of temperature and/or strain changes. The aim of the present study is to access the effect of nuclear radiations on the Fabry Perot (FP) and of Fibre Bragg Grating (FBG) sensors through the comparison of measurements made on these OFS - or part of them - before and after irradiation [1]. In the context of development of OFS for high irradiation environment and especially for Material Testing Reactors (MTRs), Sake 2 experiment consists in an irradiation campaign at high level of gamma and neutron fluxes conducted on samples of fibre optics – bare or functionalised with FBG. The irradiation was performed at two levels of fast neutron fluence: 1 and 3.1019 n/cm2 (E>1MeV), at 250°± 25°C, in the SCK•CEN BR2 reactor (Mol Belgium). An irradiation capsule was designed to allow irradiation at the specified temperature without active control. The neutron fluence was measured with activation dosimeters and the results were compared with MCPN computations. Investigation of bare samples gives information on the density changes, while for the FBGs both density and refractive index perturbation are involved. Some results for bare fibres were reported recently. In this paper, we will focus on the measurements made on FBGs that have been manufactured by different laboratories on SMF 28 fibers: CEA, University of St-Etienne and University of Mons. Tested gratings have been written using various conditions (type of fibre, of laser, writing wavelength, power density, post writing thermal annealing,…), leading to various behaviours after Sake 2 irradiation. Bragg wavelength and reflectivity have been measured before and after irradiation thanks to a special mounting at the same temperature. It appears that a change in the shape after irradiation of the Bragg peak disturb the retrieval of the Bragg wavelength. The measurements show that for nearly all gratings the Bragg peak remains visible after the irradiation, and that Radiation Induced Bragg Wavelength Shifts (RI-BWSs) vary from few pm (equivalent to an error of less than 1°C for a temperature sensor) to nearly 1 nm (equivalent to 100°C) depending of the FBG types. High RI-BWSs could indeed be expected when considering the huge refractive index variation and compaction of the bare fibre samples that have been measured by other techniques. Post writing thermal annealing is confirmed as a key parameter in order to obtain a more radiation tolerant FBG. Our results show that specific annealing regimes allow making FGBs suitable to perform temperature measurements in a MTR experiment.

MÖssbauer Study of Zircaloy After Neutron Irradiation at Power Reactor Temperatures

1994 ◽  
Vol 373 ◽  
Author(s):  
Jerzy A. Sawicki
Keyword(s):  
Electron Microscopy ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Power Reactor ◽  
Neutron Fluence ◽  
High Flux ◽  
Mössbauer Study ◽  
Fuel Channel ◽  
Partial Recrystallization ◽  
Radiation Induced

Abstract57Fe-Mössbauer spectroscopy was used to examine a specimen of Zircaloy-4 from a pressure tube extracted from a high-flux fuel channel of a CANDU* reactor. During 25 years of service the alloy was exposed to a fast-neutron fluence of 5.6×1021 n/cm2. The obtained spectra of unirradiated and neutron-irradiated specimens differ considerably. This is attributed to the radiation-induced dissolution and crystalline-to-amorphous transformation of Zr(Cr,Fe)2 precipitates, accompanied by reprecipitation and partial recrystallization of metastable Zr2Fe particles in the zirconium matrix. The correspondence between Mtssbauer and electron microscopy observations, as well as the similarity between neutron-irradiated and ion-implanted specimens, is discussed.

Neutron Irradiation-Induced Dimensional Changes in MEMS Glass Substrates

2001 ◽  
Vol 687 ◽  
Author(s):  
Clark L. Allred ◽  
Jeffrey T. Borenstein ◽  
Linn W. Hobbs
Keyword(s):  
Thermal Neutron ◽  
Fast Neutron ◽  
Neutron Fluence ◽  
Atomic Displacement ◽  
Mems Devices ◽  
Dimensional Changes ◽  
Glass Substrates ◽  
Radiation Induced ◽  
Flotation Technique ◽  
Transport Of Ions

AbstractA study is made of radiation-induced expansion/compaction in Pyrex and Hoya SD-2 glasses, which are used as substrates for MEMS devices. Glass samples were irradiated with a neutron fluence composed primarily of thermal neutrons, and a flotation technique was employed to measure the resulting density changes in the glass. Transport of Ions in Matter (TRIM) calculations were performed to relate fast (∼1 MeV) neutron atomic displacement damage to that of boron thermal neutron capture events, and measured density changes in the glass samples were thus proportionally attributed to thermal and fast neutron fluences. The trend for strain with thermal neutron fluence (n/cm2) was found to be a linear compaction of -2.8×10−20 for Pyrex and -1.0×10−21 for Hoya SD-2. For fast neutron fluence, the trend for strain was also linear: -6.1×10−21for Pyrex and -7.9×10−22 for Hoya SD-2. The measured radiation-induced compaction of Pyrex is found to agree with that of previous studies. To our knowledge, this work represents the first study of compaction in Hoya SD-2 with neutron fluence. Hoya SD-2 is of considerable importance to MEMS, owing to its close thermal expansivity match to silicon from 25-500 C.

scholarly journals To the issue of accuracy of determination of irradiation embrittlement coefficient

2020 ◽  
Vol 21 (3) ◽  
pp. 245-248
Author(s):  
L.I. Chyrko ◽  
◽  
V.M. Revka ◽  
Yu.V. Chaikovskyi ◽  
M.G. Goliak ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Statistical Analysis ◽  
Fast Neutron ◽  
Neutron Fluence ◽  
Reactor Vessel ◽  
Irradiation Embrittlement ◽  
Radiation Induced ◽  
The Impact ◽  
Surveillance Specimens

The paper presents the statistical analysis of experimental results of radiation-induced critical brittle temperature ΔTF shifts and reference temperatures ΔT0 obtained respectively from the impact bend and fracture toughness tests of the reactor vessel metal surveillance specimens to define the possibility of their mutual application for the irradiation embrittlement coefficient to be determined more accurately. The correlation between these parameters is shown to remain up to the accumulation of over-design fast neutron fluence.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

scholarly journals A Fast Neutron Fluence Reduction Strategy for Pressure Vessel Lifetime Extension

2000 ◽  
Vol 37 (sup1) ◽  
pp. 120-124 ◽  
Author(s):  
Jong Kyung Kim ◽  
Chang Ho Shin ◽  
Bo Kyun Seo ◽  
Myung Hyun Kim ◽  
Goung Jin Lee
Keyword(s):  
Fast Neutron ◽  
Pressure Vessel ◽  
Neutron Fluence ◽  
Reduction Strategy ◽  
Lifetime Extension

scholarly journals A Method to Estimate the Fast-Neutron Fluence for the Hiroshima Atomic Bomb

1994 ◽  
Vol 63 (10) ◽  
pp. 3546-3547 ◽  
Author(s):  
Tokushi Shibata ◽  
Mineo Imamura ◽  
Seiichi Shibata ◽  
Yoshitomo Uwamino ◽  
Tohru Ohkubo ◽  
...  
Keyword(s):  
Fast Neutron ◽  
Atomic Bomb ◽  
Neutron Fluence

3D Calculations of PWR Vessels Neutron Fluence With EFLUVE 3D Code

2013 ◽  
Author(s):  
Cécile-Aline Gosmain ◽  
Sylvain Rollet ◽  
Damien Schmitt
Keyword(s):  
Monte Carlo ◽  
Fast Neutron ◽  
Pressure Vessel ◽  
Reaction Rate ◽  
Neutron Fluence ◽  
Neutron Transport ◽  
Reaction Rates ◽  
Surveillance Program ◽  
Monte Carlo Code ◽  
Neutron Sources

In the framework of surveillance program dosimetry, the main parameter in the determination of the fracture toughness and the integrity of the reactor pressure vessel (RPV) is the fast neutron fluence on pressure vessel. Its calculated value is extrapolated using neutron transport codes from measured reaction rate value on dosimeters located on the core barrel. EDF R&D has developed a new 3D tool called EFLUVE3D based on the adjoint flux theory. This tool is able to reproduce on a given configuration the neutron flux, fast neutron fluence and reaction rate or dpa results of an exact Monte Carlo calculation with nearly the same accuracy. These EFLUVE3D calculations does the Source*Importance product which allows the calculation of the flux, the neutronic fluence (flux over 1MeV integrated on time) received at any point of the interface between the skin and the pressure vessel but also at the capsules of the pressurized water reactor vessels surveillance program and the dpa and reaction rates at different axial positions and different azimuthal positions of the vessel as well as at the surveillance capsules. Moreover, these calculations can be carried out monthly for each of the 58 reactors of the French current fleet in challenging time (less than 10mn for the total fluence and reaction rates calculations considering 14 different neutron sources of a classical power plant unit compared to more than 2 days for a classic Monte Carlo flux calculation at a given neutron source). The code needs as input: - for each reaction rate, the geometric importance matrix produced for a 3D pin by pin mesh on the basis of Green’s functions calculated by the Monte Carlo code TRIPOLI; - the neutron sources calculated on assemblies data (enrichment, position, fission fraction as a function of evolution), pin by pin power and irradiation. These last terms are based on local in-core activities measurements extrapolated to the whole core by use of the EDF core calculation scheme and a pin by pin power reconstruction methodology. This paper presents the fundamental principles of the code and its validation comparing its results to the direct Monte Carlo TRIPOLI results. Theses comparisons show a discrepancy of less than 0,5% between the two codes equivalent to the order of magnitude of the stochastic convergence of Monte Carlo results.

scholarly journals Глубокие центры радиационных дефектов в монокристаллах CdZnTe, созданные потоком быстрых нейтронов

2018 ◽  
Vol 52 (3) ◽  
pp. 322 ◽  
Author(s):  
С.В. Пляцко ◽  
Л.В. Рашковецкий
Keyword(s):  
Activation Energy ◽  
Neutron Flux ◽  
Fast Neutron ◽  
Single Crystals ◽  
Isothermal Annealing ◽  
Fast Neutron Flux ◽  
Photoluminescence Properties ◽  
Radiation Induced ◽  
Induced Defects

AbstractThe effect of a fast neutron flux (Φ = 10^14–10^15 cm^–2) on the electrical and photoluminescence properties of p -CdZnTe single crystals is studied. Isothermal annealing is performed ( T = 400–500 K), and the activation energy of the dissociation of radiation-induced defects is determined at E _D ≈ 0.75 eV.

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