Coupled processes of deformation and long-term damage of fibrous materials with the microdurability of the matrix described by an exponential power function

AbstractThe magnetism and microstructure of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes after 5 years of service were investigated in this paper. The saturation magnetization of the Cr25Ni35Nb alloy tube in the thickness direction is more than 20 emu/g, and the tube becomes ferromagnetic. The inner and outer walls of Cr35Ni45Nb alloy tubes also become ferromagnetic. But the saturation magnetization of the Cr35Ni45Nb alloy tubes approaches to zero in the center zone. The primary carbides M7C3 and NbC are changed into M23C6 and G phase at the outer region of the furnace tube. However, the M23C6-type carbides were replaced by carbon-rich carbides M7C3 at the carburization zone. Cr-depleted zones are formed at the inner and outer walls of the furnace tubes owing to oxidation. Carburization and oxidation reduce the Cr content of the matrix. Accordingly, the saturation magnetization is very high at the carburization zone and Cr-depleted zone. The magnetism of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes has a high correlation with the Cr content of the matrix. Carburization and oxidation are the main reasons that make the paramagnetic ethylene pyrolysis furnace tube change to ferromagnetic.

Download Full-text

Dissolution of spent nuclear fuel fragments at high alkaline conditions under H2 overpressure

MRS Advances ◽

10.1557/adv.2017.204 ◽

2016 ◽

Vol 1 (62) ◽

pp. 4163-4168

Author(s):

E. González-Robles ◽

M. Herm ◽

V. Montoya ◽

N. Müller ◽

B. Kienzler ◽

...

Keyword(s):

Aqueous Solution ◽

Partial Pressure ◽

Nuclear Fuel ◽

Alkaline Solution ◽

Spent Nuclear Fuel ◽

Dissolution Tests ◽

The Matrix ◽

Alkaline Conditions ◽

Long Term Behavior

ABSTRACTThe long-term behavior of the UO2 fuel matrix under conditions of the Belgian “Supercontainer design” was investigated by dissolution tests of high burn-up spent nuclear fuel (SNF) in high alkaline solution under 40 bar of (Ar + 8%H2) atmosphere. Four fragments of SNF, obtained from a pellet previously leached during two years, were exposed to young cement water with Ca (YCWCa) under 3.2 bar H2 partial pressure in four single/independent autoclave experiments for a period of 59, 182, 252 and 341 days, respectively. After a decrease of the concentration of dissolved 238U, which is associated with a reduction of U(VI) to U(IV), the concentration of 238U in solution is constant in the experiments running for 252 and 341 days. These observations indicate an inhibition of the matrix dissolution due to the presence of H2. A slight increase in the concentration of 90Sr and 137Cs in the aqueous solution indicates that there is still dissolution of the grain boundaries. These findings are similar to those reported for spent nuclear fuel corrosion in synthetic near neutral pH solutions.

Download Full-text

Self-healing organic coatings based on microcapsules – A patent-based review

Current Applied Polymer Science ◽

10.2174/2452271604666210913103301 ◽

2021 ◽

Vol 04 ◽

Author(s):

Diego Moreira Schlemper ◽

Sérgio Henrique Pezzin

Keyword(s):

Corrosion Protection ◽

State Of The Art ◽

Review Article ◽

The State ◽

Organic Coatings ◽

Self Healing ◽

Future Challenges ◽

The Matrix ◽

Healing Agent

: Self-healing coatings are intended to increase long-term durability and reliability and can be enabled by the presence of microcapsules containing a self-healing agent capable of interacting with the matrix and regenerating the system. This review article provides an overview of the state-of-the-art, focusing on the patents published in the field of microcapsule-based self-healing organic coatings, since the early 2000’s. A discussion about coatings for corrosion protection and the different self-healing approaches and mechanisms are also addressed, as well as future challenges and expectations for this kind of coatings.

Download Full-text

Introducing the Dynamic Destination Satisfaction Method: An Analytical Tool to Track Tourism Destination Satisfaction Trends with Repeated Cross-sectional Data

Journal of Travel Research ◽

10.1177/0047287520958205 ◽

2020 ◽

pp. 004728752095820

Author(s):

Andrea Guizzardi ◽

Marcello M. Mariani

Keyword(s):

Large Data ◽

System Level ◽

Set Covering ◽

Tourism Destination ◽

Cross Sectional ◽

Data Set ◽

Individual Level ◽

Specific Attribute ◽

The Matrix

This study introduces a new method, named Dynamic Destination Satisfaction Method (DDSME), to model tourists’ satisfaction with a destination (and its attributes), breaking it down into an individual-level component (linked to the specific individual tourists’ perceptions) and a system-level (time-related) component (common to all the tourists). Moreover, this work develops a matrix “entropy/trend accuracy” that destination managers can use to understand to what extent managing a specific attribute has increased tourists’ satisfaction with the destination over multiyear time spans. We test the innovative method on a large data set, covering the period 1997-2015 and including almost 0.8 million observations. By doing so, we analyze tourists’ satisfaction with tourism-related sectors and attributes of Italy as an inbound tourism destination and we use the matrix to map out destination attributes over time. The findings indicate that courtesy, art, and food are strategic attributes to enhance satisfaction in the long term.

Download Full-text

Constraints by Experimental Data for Modeling of Radionuclide Release from Spent Fuel

MRS Proceedings ◽

10.1557/proc-176-465 ◽

1989 ◽

Vol 176 ◽

Cited By ~ 11

Author(s):

Bernd Grambow ◽

L.O. Werme ◽

R.S. Forsyth ◽

J. Bruno

Keyword(s):

Experimental Data ◽

Product Layer ◽

Spent Fuel ◽

Upper Limits ◽

The Matrix ◽

The Usa ◽

Oxidant Production ◽

Release Data ◽

Radionuclide Release

ABSTRACTComparison of spent fuel corrosion data from nuclear waste management projects in Canada, Sweden and the USA strongly suggests that the release of 90Sr to the leachant can be used as a measure of the degradation (oxidation/dissolution) of the fuel matrix. A surprisingly quantitative similarity in the 90 Sr release data for fuel of various types (BWR, PWR, Candu), linear power ratings and burnups leached under oxic conditions was observed in the comparison. After 1000 days of leachant contact, static or sequential, the fractional release rates for 90Sr (and for cesium nuclides) were of the order of 10−7/d.The rate of spent fuel degradation (alteration) under oxic conditions can be considered to be controlled either by the growth rates of secondary alteration products, by oxygen diffusion through a product layer, by the rate of formation of radiolytic oxidants or by solubility-controlled dissolution of the matrix. These processes are discussed. Methods for determining upper limits for long-term 90Sr release, and hence fuel degradation, have been derived from the experimental data and consideration of radiolytic oxidant production.

Download Full-text

Spent Fuel Corrosion Behavior in Salt Solution in the Presence of Hydrogen Overpressure

Volume 2: Mgmt. Low/Interm. Level Waste; Spent Fuel; Economics/Analyses for Waste Mgmt.; Radiological Characterization/Application Release Criteria; Panel Sessions; Solid Waste Reduction/Treatment; Current Activities in Central/Eastern Europe; Environmental Remediation Technology; LL/ILW; HLW/Spent Fuel; Chernobyl; D&D Waste; Performance Assessment; MOX and Spent UOX; D&D Nuclear Reactors; Decommissioning of Other Nuclear Facilities ◽

10.1115/icem2001-1127 ◽

2001 ◽

Author(s):

Andreas Loida ◽

Bernd Grambow ◽

Horst Geckeis

Keyword(s):

Gas Phase ◽

Spent Fuel ◽

Nacl Solution ◽

Release Rates ◽

Corrosion Rates ◽

The Matrix ◽

Matrix Bound ◽

Safety Assessments ◽

Container Material

Abstract The simultaneous corrosion of spent fuel and Fe-based container material is characterized by the formation of large amounts of hydrogen, which control the composition of the gas phase. Various experimental data indicate that the matrix dissolution rate and the release rates of important radionuclides decrease, if the H2 overpressure increases. To quantify to what extent the hydrogen overpressure may counteract radiolysis enhanced matrix dissolution rates, and to take credit from the effect of hydrogen overpressure in long-term safety assessments of the repository, a detailed experimental investigation has been initiated. High burnup spent fuel is being corroded under anoxic conditions in the absence of carbonate in 5m NaCl solution under an external H2 overpressure of 3.3 bar. This pressure is in the same range as observed in a long-term test using spent fuel and Fe-powder. Results obtained after 117 days of testing show that due to constant or decreasing concentrations of Sr and other matrix bound radionuclides, corrosion rates were not measurable indicating a stop of matrix dissolution or very low long-term rates. Grain boundary release of Cs and fission gases was found to continue under hydrogen overpressure. Compared to tests in the absence of hydrogen solution concentrations decreased by about ca. 1.5 orders of magnitude for U (10−8 M), Am, Eu (10−10 M), whereas the decrease of Np (3×10−10 M), Tc (5×10−9 M) and Pu (4×10−9 M) concentrations was found to be less significant.

Download Full-text