scholarly journals Report of High Temperature Measurements with a Fabry-Perot Extensometer

2020 ◽  
Vol 225 ◽  
pp. 01011
Author(s):  
G. Cheymol ◽  
A. Verneuil ◽  
P. Grange ◽  
H. Maskrot ◽  
C. Destouches
Keyword(s):  
High Temperature ◽  
Reactor Core ◽  
Young Modulus ◽  
Neutron Radiation ◽  
Physical Parameters ◽  
Useful Signal ◽  
Compact Size ◽  
Fabry Perot ◽  
Radiation Induced ◽  
The Impact

Fabry-Perot (FP) sensors like other Fiber Optic (FO) sensors may be of particular interest for in pile experiments in MTR with little room available thanks to their compact size. Light weight also reduces gamma heating hence limiting the thermal effect. Different physical parameters such as temperature, strain, displacement, vibration, pressure, or refractive index may be sensed through the measurement of the optical path length difference in the cavity. We have developed a Fabry-Perot extensometer able to operate at high temperature (up to 400°C), under a high level of radiation (neutron and gamma flux). The measurement based on interferometry is largely insensitive to radiation induced attenuation (RIA) thanks to the wavelength encoding of the useful signal, but for such high fluence as encountered in a reactor core, a special rad-hard fiber is needed. Operating in the wavelength domain around 1ím remains preferable to minimize the impact of irradiation. Moreover, fast neutron radiation is expected to change the structure of the fiber and possibly others materials in the transducer. Then, we revised the basic scheme of Extrinsic Fabry-Perot Interferometer (EFPI) so that the effects of compaction remain limited. Tests under mixed neutron and gamma irradiation permitted to verify the general behavior and particularly the low drift with radiation induced compaction (RIC). Also, two types of tests have been conducted to verify the accuracy at high temperature. The first ones are “measurements” of thermal dilatation of materials: the sensor is fixed on a sample and knowing its thermal expansion, it is possible to predict the measurement expected from the optical sensor when the temperature is increased from low to high temperature. The comparison between the predicted and experimental outputs informs on how the sensor is accurate. The second types are tests on a tensile test bench operating at high temperature. The Fabry-Perot measurements are compared, in the elastic domain, with the expected strain given by the Young modulus of the material, and also on a larger strain domain, with the measurements of a high temperature axial extensometer. Both types of tests are presented and commented.

scholarly journals Active Compensation of Radiation Effects on Optical Fibers for Sensing Applications

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8193
Author(s):  
Sohel Rana ◽  
Austin Fleming ◽  
Nirmala Kandadai ◽  
Harish Subbaraman
Keyword(s):  
Optical Fibers ◽  
Radiation Effects ◽  
Accurate Determination ◽  
Radiation Environment ◽  
Physical Parameters ◽  
Air Cavity ◽  
Sensing Applications ◽  
Fabry Perot ◽  
Radiation Induced

Neutron and gamma irradiation is known to compact silica, resulting in macroscopic changes in refractive index (RI) and geometric structure. The change in RI and linear compaction in a radiation environment is caused by three well-known mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced compaction (RIC), and (iii) radiation-induced emission (RIE). These macroscopic changes induce errors in monitoring physical parameters such as temperature, pressure, and strain in optical fiber-based sensors, which limit their application in radiation environments. We present a cascaded Fabry–Perot interferometer (FPI) technique to measure macroscopic properties, such as radiation-induced change in RI and length compaction in real time to actively account for sensor drift. The proposed cascaded FPI consists of two cavities: the first cavity is an air cavity, and the second is a silica cavity. The length compaction from the air cavity is used to deduce the RI change within the silica cavity. We utilize fast Fourier transform (FFT) algorithm and two bandpass filters for the signal extraction of each cavity. Inclusion of such a simple cascaded FPI structure will enable accurate determination of physical parameters under the test.

Effect of Irradiation Deformation and Graphite Varieties on the Irradiation Equivalent Stress and Life of Nuclear Graphite

2010 ◽  
Author(s):  
Xiang Fang ◽  
Haitao Wang ◽  
Suyuan Yu
Keyword(s):  
High Temperature ◽  
Creep Property ◽  
Dimensional Change ◽  
Creep Process ◽  
Physical Parameters ◽  
Elastic Model ◽  
Secondary Creep ◽  
Nuclear Graphite ◽  
The Impact ◽  
Irradiation Behavior

Graphite is selected as moderator, reflector and major internal structural material in high temperature gas-cooled reactors (HTRs) because of its unique characteristics. Inside the core, both high temperature and fast neutron irradiation can influence the mechanical property, thermal property, dimensional change and some other characteristics of graphite in evidence, while the creep of graphite plays an important role in the whole process. There have been several kinds of creep models, and the creep process is divided into two parts in most of models: primary creep and secondary creep. The primary is always treated as exponential function while the secondary is linear. A code based on user subroutines of MSC.MARC is developed in INET in order to perform three-dimensional finite element analysis of irradiation behavior of the graphite components for the HTRs. In this paper, the irradiation behavior of nuclear graphite was simulated, and the impact of irradiation-induced deformation of various kinds of graphite on the irradiation-induced stresses and lives is discussed. In order to describe the creep behavior, the linear elastic model is chosen while the influence of high temperature and irradiation to the dimensional change, physical parameters and creep property of nuclear graphite is used as original data.

The Reliability Prediction of HTR’s Graphite Component in Various Temperature and Neutron Dose Levels

2013 ◽  
Author(s):  
Xiang Fang ◽  
Haitao Wang ◽  
Xingtuan Yang ◽  
Suyuan Yu
Keyword(s):  
High Temperature ◽  
Neutron Irradiation ◽  
Three Dimensional ◽  
Reactor Core ◽  
Neutron Dose ◽  
Element Analysis ◽  
The Core ◽  
Three Dimensional Finite Element ◽  
Dose Levels ◽  
The Impact

In high temperature gas-cooled reactors (HTRs), graphite is used as the main structure material. The side reflecter of the reactor core is composed by a pile of graphite bricks. In real operational condition of the reactor, both high temperature and fast neutron irradiation have great effect on the behavior of graphite components. The non-uniform distribution of temperature and neutron dose cause obvious stress accumulation, which greatly affects the security and reliability of the graphite components. In addition, high temperature and neutron irradiation make the properties of graphite change in evidence, and the changes are not linear. Such changes must be considered and simulated in the calculation, in order to predict the stress concentration condition and the reliability of the graphite brick correctly. A FORTRAN code based on user subroutines of MSC.MARC is developed in INET in order to perform three-dimensional finite element analysis of irradiated behavior of the graphite components for the HTRs. In this paper, the stress level and failure probability of graphite components are calculated and obtained under different in-core temperatures and neutron dose levels of the core side of brick. 400°C, 500°C, 600°C and 700°C are selected as the core side temperature, while the range of neutron dose is 0 to 1022n cm-2 (EDN). Different constitutive laws are used in stress analysis procedure. The impact of different temperature and neutron dose levels are discussed.

scholarly journals Numerical Analysis of Radiation Effects on Fiber Optic Sensors

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4111
Author(s):  
Sohel Rana ◽  
Harish Subbaraman ◽  
Austin Fleming ◽  
Nirmala Kandadai
Keyword(s):  
Radiation Effects ◽  
Physical Parameters ◽  
Potential Candidate ◽  
Low Dose Radiation ◽  
Long Period Grating ◽  
Fiber Sensors ◽  
Fabry Perot ◽  
Radiation Induced ◽  
High Doses ◽  
Dose Radiation

Optical fiber sensors (OFS) are a potential candidate for monitoring physical parameters in nuclear environments. However, under an irradiation field the optical response of the OFS is modified via three primary mechanisms: (i) radiation-induced attenuation (RIA), (ii) radiation-induced emission (RIE), and (iii) radiation-induced compaction (RIC). For resonance-based sensors, RIC plays a significant role in modifying their performance characteristics. In this paper, we numerically investigate independently the effects of RIC and RIA on three types of OFS widely considered for radiation environments: fiber Bragg grating (FBG), long-period grating (LPG), and Fabry-Perot (F-P) sensors. In our RIC modeling, experimentally calculated refractive index (RI) changes due to low-dose radiation are extrapolated using a power law to calculate density changes at high doses. The changes in RI and length are subsequently calculated using the Lorentz–Lorenz relation and an established empirical equation, respectively. The effects of both the change in the RI and length contraction on OFS are modeled for both low and high doses using FIMMWAVE, a commercially available vectorial mode solver. An in-depth understanding of how radiation affects OFS may reveal various potential OFS applications in several types of radiation environments, such as nuclear reactors or in space.

Influence of Initial Grain Boundary Composition on the Evolution of Radiation-Induced Segregation Profiles

1998 ◽  
Vol 540 ◽  
Author(s):  
J.T. Busby ◽  
G.S. Was ◽  
S.M. Bruemmer ◽  
D. J. Edwards ◽  
E.A. Kenik
Keyword(s):  
Grain Boundary ◽  
Stainless Steels ◽  
Boundary Segregation ◽  
Reactor Core ◽  
Austenitic Stainless Steels ◽  
Central Peak ◽  
Boundary Composition ◽  
Radiation Induced ◽  
The Impact ◽  
Profile Development

AbstractRadiation-induced segregation (RIS) has been identified as a potential contributor to irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels in reactor core components. The occurrence of grain boundary segregation prior to irradiation influences both the shape and magnitude of RIS profile development during subsequent irradiation. In an effort to better understand the impact of this pre-irradiation enrichment on RIS profile development, the evolution of grain boundary Cr segregation profiles with irradiation dose has been characterized. Commercial purity and high-purity austenitic stainless steels with different initial levels of grain boundary Cr have been irradiated with neutrons (at 275°C) or protons (at 360-400°C) to doses up to ∼5 dpa. Grain boundary composition profiles were measured before and after irradiation using scanning transmission electron microscopy with energy dispersive xray spectroscopy (STEM-EDS). The initial enrichment of Cr is shown to delay radiation-induced Cr depletion and produce a “W-shaped” profile at low irradiation doses. Further irradiation causes the central peak of the W to decrease, eventually resulting in the classical “V-shaped” depletion profile. Possible mechanisms for the pre-irradiation enrichment and its evolution into a “W-shaped” profile will be discussed.

A NEW WELDING MATERIAL FOR REGENERATION IN THE WELDING TECHNOLOGY BASED ON NICKEL. ANALYSIS OF THE COMPOSITION AND PROPERTIES OF DEFORMABLE HEAT-RESISTANT HIGH-CHROMIUM NICKEL-BASED ALLOYS FOR WELDED PARTS. ANALYSIS OF EXISTING FUELLING STATIONS TYPES AND VEHICLES USING HYDROGEN, HYDROGEN PRODUCTION AND STORING METHODS

2019 ◽  
pp. 43-48
Author(s):  
Ben Nengjun ◽  
Zhou Pengfei ◽  
Oleksandr Labartkava ◽  
Mykhailo Samokhin
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Nickel Alloys ◽  
Total Content ◽  
Operating Conditions ◽  
High Temperature Strength ◽  
High Chromium ◽  
Salt Corrosion ◽  
Tcp Phases ◽  
The Impact

This work involves an analysis of high-chromium high-temperature deformable wieldable nickel alloys for use in GTE repair assemblies. It is shown that the alloys EP868 (VZh98) and Haynes 230 can be used in welded assemblies with an operating temperature of 800-1100 °C. The alloys Nimonic 81, Nimonic 91, IN 935, IN 939, and Nicrotan 2100 GT also have a high potential for use in welded assemblies. They are characterized by a combination of good weldability, high-temperature strength, and resistance to scaling. There have been conducted studies on high-temperature salt corrosion of model nickel alloys. They allowed establishing the patterns of the impact of base metal alloying with chromium, aluminum, titanium, cobalt, tungsten, molybdenum, niobium, tantalum and rare earth metals on the critical temperature of the start of salt corrosion Tcor and the alloy mass loss. It has been established that alloys with a moderate concentration (13-16%) of chromium can possess satisfactory hightemperature corrosion resistance (HTC resistance) under the operating conditions of ship GTE. The HTC resistance of CrAl-Ti alloys improves upon reaching the ratio Ti/Al ˃ 1. Meanwhile, the ratio Ti/Al ˂ 1 promotes the formation of corrosion products with low protective properties. The positive effect of tantalum on the HTC resistance of alloys is manifested at higher test temperatures than that of titanium, and the total content of molybdenum and tungsten in alloys is limited by the condition 8Mo2 – 2W2 = 89. The presence of refractory elements stabilizes the strengthening phase and prevents formation of the ɳ-phase. However, their excess promotes formation of the embrittling topologically close packed (TCP) phases and boundary carbides of an unfavorable morphology. Based on the studies of the HTC resistance, there has been identified a class of model high-temperature corrosionresistant nickel alloys with a moderate or high chromium content (30%), Ti/Al ˃ 1, and a balanced content of refractory and rare-earth elements.

scholarly journals Temperature, Disease, and Death in London: Analyzing Weekly Data for the Century from 1866 to 1965

2021 ◽  
pp. 1-41
Author(s):  
W. Walker Hanlon ◽  
Casper Worm Hansen ◽  
Jake Kantor
Keyword(s):  
Nineteenth Century ◽  
High Temperature ◽  
Mortality Data ◽  
Late Nineteenth Century ◽  
Infant Deaths ◽  
Digestive Diseases ◽  
Late Nineteenth ◽  
The Impact ◽  
The City

Using novel weekly mortality data for London spanning 1866-1965, we analyze the changing relationship between temperature and mortality as the city developed. Our main results show that warm weeks led to elevated mortality in the late nineteenth century, mainly due to infant deaths from digestive diseases. However, this pattern largely disappeared after WWI as infant digestive diseases became less prevalent. The resulting change in the temperature-mortality relationship meant that thousands of heat-related deaths—equal to 0.9-1.4 percent of all deaths— were averted. These findings show that improving the disease environment can dramatically alter the impact of high temperature on mortality.

scholarly journals Damage Evolution of Granodiorite after Heating and Cooling Treatments

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 779
Author(s):  
Mohamed Gomah ◽  
Guichen Li ◽  
Salah Bader ◽  
Mohamed Elkarmoty ◽  
Mohamed Ismael
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Failure Mode ◽  
Physical And Mechanical Properties ◽  
P Wave ◽  
Physical Parameters ◽  
Slow Cooling ◽  
Heating And Cooling ◽  
Natural Rock ◽  
The Impact

The awareness of the impact of high temperatures on rock properties is essential to the design of deep geotechnical applications. The purpose of this research is to assess the influence of heating and cooling treatments on the physical and mechanical properties of Egyptian granodiorite as a degrading factor. The samples were heated to various temperatures (200, 400, 600, and 800 °C) and then cooled at different rates, either slowly cooled in the oven and air or quickly cooled in water. The porosity, water absorption, P-wave velocity, tensile strength, failure mode, and associated microstructural alterations due to thermal effect have been studied. The study revealed that the granodiorite has a slight drop in tensile strength, up to 400 °C, for slow cooling routes and that most of the physical attributes are comparable to natural rock. Despite this, granodiorite thermal deterioration is substantially higher for quick cooling than for slow cooling. Between 400:600 °C is ‘the transitional stage’, where the physical and mechanical characteristics degraded exponentially for all cooling pathways. Independent of the cooling method, the granodiorite showed a ductile failure mode associated with reduced peak tensile strengths. Additionally, the microstructure altered from predominantly intergranular cracking to more trans-granular cracking at 600 °C. The integrity of the granodiorite structure was compromised at 800 °C, the physical parameters deteriorated, and the rock tensile strength was negligible. In this research, the temperatures of 400, 600, and 800 °C were remarked to be typical of three divergent phases of granodiorite mechanical and physical properties evolution. Furthermore, 400 °C could be considered as the threshold limit for Egyptian granodiorite physical and mechanical properties for typical thermal underground applications.

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