Evaluation of the optical changes for a soda-lime-silicate glass exposed to radiation

A soda-lime-silicate glass is exposed to beta radiation from an ⁹⁰Sr source and gamma radiation from a ⁶⁰Co source. Under exposure to radiation of the ⁹⁰Sr and ⁶⁰Co radioisotopes, the glass changes its color depending on the irradiation doses. The effect of beta irradiation on the optical properties of the glass is compared with that of gamma irradiation. The optical properties of the irradiated glasses differ significantly from those of the unirradiated glasses. Under exposure to beta and gamma radiation, the three main optical absorption bands appear at ～380–460, ～620, and ～1050 nm. It is established that the absorption band at ～420 nm, which is attributed to Fe³⁺ ions, is very sensitive to beta and gamma irradiation.     

Effect of CdO addition on photon,electron, and neutron attenuation properties of boro-tellurite glasses

This research article aims to study the effect of CdO addition on the radiation shielding characteristics of boro-tellurite glasses in the composition of 50B₂O₃ - (50-x) TeO2- xCdO, where x = 0, 10, 20, 30, 40 and 50 mol%. These glasses were exposed to gamma radiation and the transmitted gamma photons were evaluated for energies varying from 15 keV to 15 MeV using Geant4 simulation toolkit. The number of transmitted photons was then used to characterize the gamma shielding for the studied glasses in terms of linear/mass attenuation coefficients, MFP, Z_eff, and HVL. The simulation outcomes were theoretically confirmed by using Phy-X software. The beta (electron) shielding characterization of the involved glasses was also investigated by determining the projectile range and stopping power using ESTAR software. Additionally, the fast neutron shielding characterization of the glasses was achieved by evaluating removal cross-section (Σ_R). The results reveal that the CdO has a small influence on the shielding performance of the boro-tellurite glasses against gamma, beta, and neutron radiations. The shielding performance of the boro-tellurite glasses was compared with that of common shielding materials in terms of MFP. It can be concluded that the boro-tellurite glasses regardless of the concentration of CdO content have promising shielding performance to be used for radiation applications.     

Fluorine Gettering by Activated Charcoal in a Radiation Environment

Abstract

Activated charcoal has been shown to be an effective gettering agent for the fluorine gas that is liberated in a radiation environment. Even though activated charcoal is a commonly used getter, little is known about the radiation stability of the fluorine-charcoal product. This work has shown that not only is the product stable in high gamma radiation fields, but also that radiation enhances the capacity of the charcoal for the fluorine. The most useful application of this work is with the Molten Salt Reactor Experiment (MSRE) fuel salt because the radioactive components (fission products and actinides) cause radiolytic damage to the solid LiF-BeF²-ZrF⁴-UF⁴ (64.5, 30.3, 5.0, 0.13 mol %, respectively) resulting in the liberation of fluorine gas. This work has also demonstrated that the maximum damage to the fuel salt by ～3 × 10⁷ R/h gamma radiation is approximately 2%, at which point the the rate of recombination of fluorine with active metal sites within the salt lattice equals the rate of fluorine generation. The enhanced reactivity of the activated charcoal and radiation stability of the product ensures that the gettered fluorine will stay sequestered in the charcoal.     

Finite element analysis of composite T-joints used in wind turbine blades

Abstract

This paper presents a finite element (FE) analysis of the fracture behaviour of composite T-joints with various fibre reinforcement architectures subjected to pull-out loading. The FE model accounts for the effect of interface strength and interlaminar fracture energy on the ultimate load to failure; a linear softening fracture based law is adopted to describe crack growth in the form of delamination. The numerical simulation shows that the failure load increases with increasing interlaminar strength, which controls delamination initiation. The FE also demonstrates that the failure load increases with increasing interface fracture energy and the delamination propagation depends largely upon the fracture energy, which is enhanced by introducing interlaminar veils or through-thickness tuft yarns (stitching). Predictions were validated using experimental data for E-glass fibre/epoxy T-joints subjected to a tensile pull-out loading. The load–displacement response from the FE analysis is in a good agreement with measurements, illustrating the effectiveness of through thickness tufting that results to progressive, a more ‘ductile’, rather than abrupt catastrophic failure.     

Monitoring concept for structural integration of PZT-fiber arrays in metal sheets: a numerical and experimental study

ABSTRACT

The technique joining by forming allows the structural integration of piezoceramic fibers into locally microstructured metal sheets without any elastic interlayers. A high-volume production of the joining partners causes in statistical deviations from the nominal dimensions. A numerical simulation on geometric process sensitivity shows that the deviations have a high significant influence on the resulting fiber stresses after the joining by forming operation and demonstrate the necessity of a monitoring concept. On this basis, the electromechanical behavior of piezoceramic array transducers is investigated experimentally before, during and after the joining process. The piezoceramic array transducer consists of an arrangement of five electrical interconnected piezoceramic fibers. The findings show that the impedance spectrum depends on the fiber stresses and can be used for in-process monitoring during the joining process. Based on the impedance values the preload state of the interconnected piezoceramic fibers can be specifically controlled and a fiber overload.     

Gas formation regularities at the consecutive and simultaneous impact of ionizing radiations and heat on Turkish lignites

The regularities of formation of gases H₂, CO and hydrocarbons C₁-C₄ at the consecutive and simultaneous influence of ionizing radiations and heat on Turkish lignites of Karaman-Ermenek deposit was researched. It is shown that at the consecutive influence of radiation and heat the gas yield depends extremely on the preliminary irradiation dose. The simultaneous influence of these factors on lignite leads to the gas yield increase which is connected with acceleration of the active radiolytic particles’ diffusion and breaking off reactions with their participation. Under the influence of the accelerated electron beam lignite decomposes with the relatively high radiation-chemical yields than under the influence of gamma radiation which is connected with acceleration of the diffusion processes due to the irradiated sample’s heating.     

Effect of Laser Radiation on Dyed Polymeric Films

Abstract

Destruction of the thin dyed polymeric films under the action of resonant and non-resonant laser radiation has been investigated. It is shown thai laser stability of dyed polymers depends on the type of incorporated dye and it is independent of film thickness and dye concentration at the same powers of absorbed laser radiation. Moreover, laser stability of polymeric films with chemically bonded dye is higher than the polymer stability with dissolved dye. Comparative analysis showed that the polymer laser stability is determined by the kinetics of the polymer thermodegradation. which results in the appearance and accumulation of the products absorbing laser radiation. It is established that resonant irradiation of dyed polymers is considerably more efficient for polymer destruction than the nonresonant one.     

Gamma‐irradiated metallocenic polyethylene and ethylene‐1‐hexene copolymers

The aim of this work is to present a detailed study of the changes introduced by gamma radiation on several metallocenic polyethylene copolymers. Therefore, metallocenic polyethylene and copolymers with 3.3, 9.2, and 16.1 mol % of hexene comonomer content were synthesized and irradiated with ⁶⁰Co gamma radiation under vacuum at room temperature with radiation doses ranging from 0 to 100 kGy. Size Exclusion Chromatography data show that crosslinking reactions predominate over scission, even for the copolymer with the highest tertiary carbon content. Over a certain critical dose, which depends on the molecular weight and molecular structure of the initial polymer, an insoluble gel forms. The irradiated polymers also exhibit complex rheological behavior with increasing melt viscosity and elasticity, consistent with long chain branching and/or crosslinking. FTIR confirms depletion of terminal vinyl groups and increase of trans unsaturations with dose. The rate at which these two reactions evolve seems to depend on the comonomer content of the irradiated copolymers. Differential scanning calorimetry and Raman spectroscopy analyzes indicate less crystallinity and thicker interphases in irradiated materials. A mathematical model, which accounts for scission and crosslinking reactions, fitted well the evolution with radiation dose of the measured molecular weight data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A Techno‐Economic Analysis of Chemical Processing with Ionizing Radiation

Photons and electrons with energies above the ionization potential of most atoms can be used to facilitate chemical reactions not otherwise possible thermochemically or under more preferable process conditions. An analysis and comparison of the economics of using sources of ultraviolet photons, high‐energy electrons, γ‐rays, and X‐rays in a chemical conversion process is presented. In many processes where the penetration depth is sufficient, the overall production costs for equivalent products are lowest for electron‐beam based systems followed, in order, by ultraviolet, gamma rays from ⁶⁰Co, and X‐ray sources. In process applications where large volume, high pressure, chemical reactors are required, gamma radiation has potential design advantages provided commercial gamma sources of lower cost than ⁶⁰Co become available.     

STUDY OF HEAT AND MASS TRANSFER DURING IR DRYING OF PAPER

ABSTRACT

A mathematical model has been developed to study the drying of paper using a gas-fired IR dryer. The model accounts for various phenomena : water and vapour mass transfer, conduction, convection and radiation heat transfer. The phenomenological equations are solved with a finite difference scheme, including a modified upwind differencing scheme to account for water migration within the paper sheet. The simulation results illustrate the basic underlying phenomena involved in IR paper drying and can be instrumental to the engineer to make the detailed analyses of such a drying process. A sensitivity analysis has shown that the drying rate is most sensitive to parameters governing the IR beat transfer process whereas the paper sheet temperature is most sensitive to parameters governing the mass transfer process with the surroundings.     

Effect of melting atmospheres on the optical property of radiation-hard fluorophosphate glass

High-energy radiation in space and nuclear irradiation environment induces colour centres in optical glass, causing solarisation, and a serious condition can render optical systems and optical loads unusable. To develop space radiation-resistant optical glass, CeO₂-stabilised radiation-hard fluorophosphate glass was prepared under three different atmospheres (nitrogen, oxygen, and ambient air). The glass-melting atmospheres' effects on the glass's transmission, defect formation, and structural changes before and after exposure to gamma radiation were investigated by a comprehensive study on their transmittance, absorption, and electron paramagnetic resonance spectra. Introducing a small amount of CeO₂ (～0.34 wt%) into the fluorophosphate base glass converted NBO and BO into ABO in the glass network, red-shifted the UV absorption edge, and decreased the optical density increment by almost half after radiation. As the total dose of gamma radiation increased, the transmittance of the irradiated glass at a wavelength of 385 nm significantly increased due to absorption of POHC2 defects. After exposure to 250 k of rad gamma irradiation, the corresponding optical density increment per centimeter thickness at 385 nm of the radiation-hard fluorophosphate glass that melted in the nitrogen, oxygen, and air atmospheres decreased from 1.839 to 1.388 and 1.215. As it melted in air, the NBO ratio of the fluorophosphate glass reached the lowest level and the Ce⁴⁺ ratio in the glass was 92.49%, which helped suppress the generation of POHC, Fe³⁺, PO₄-EC, and PO₃-EC defects during the gamma irradiation process, improving the glass's radiation resistance.     

Salt Splitting Using Ceramic Membranes

Abstract

Inorganic ceramic membranes for salt splitting of radioactively contaminated sodium salt solutions are being developed for treating U.S. Department of Energy tank wastes. The process consists of electrochemical separation of sodium ions from the salt solution using sodium (Na) Super Ion Conductors (NASICON) membranes. In contrast to conventional organic-based bipolar or ion exchange membranes used in salt splitting, NaSICON membranes are resistant to gamma/beta radiation and are highly selective for sodium ions. Potential applications include 1) caustic recycle for sludge leaching, regeneration of ion exchange resins, inhibition of corrosion in carbon steel tanks, or retrieval of tank wastes; 2) pH adjustmet and reduction of competing cations to enhance cesium ion exchange processes; 3) sodium reduction in high-level waste sludges; and 4) sodium removal from acidic wastes to facilitate calcining. Initial experiments with dysprosium-based NaSICON membranes have demonstrated the feasibility of the process.     

A versatile radiochromic dosimeter for low‐medium gamma radiation and its application to food irradiation

This article presents a novel radiochromic film for selective detection of low‐medium (0–10 kGy) gamma radiation (⁶⁰Co) doses. This dosimeter is based on a printed fluorescent multilayer structure comprising a paper substrate having layers of copper phthalocyanine (DY220) (a green emitter material) on the bottom, and layers of poly[2‐methoxy‐5(2′‐ethylhexyloxy)‐p‐phenylenevinylene] (MEH‐PPV) (a green‐light absorber, red emitter, and radiation sensitive polymer) on the top. The effect of gamma radiation on the optical properties of DY220/MEH‐PPV was described: it was observed as a strong correlation between radiation dose and fluorescent, color coordinates for CIE (1931) chromatic diagram, and Pantone color reference of the dosimeter. The rate of these changes can be altered by manipulation of top–bottom layers to represent easily the radiation dose to be determined in a wide range. This versatile dosimeter has many uses in the field of food radiation for monitoring, quality assurance, and control of the gamma radiation process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45729.     

Radiolysis of Tributyl Phosphate by Particles of High Linear Energy Transfer

Tributyl Phosphate (TBP), used in chemical separation processes for used nuclear fuel, is susceptible to radiolysis causing losses in process performance. We have studied its degradation by exposing dry 1M TBP/n-dodecane solutions to gamma radiation from a cesium-137 source and in a mix of low and high linear energy transfer (LET) radiation by irradiating samples in the UC Irvine TRIGA^® reactor and utilizing the ¹⁰B(n,α)⁷Li reaction. In a 1 M solution of TBP in n-dodecane the degradation of TBP (G^?_TBP) was found to be 0.36 and 0.14 μmol/J for low and high LET radiation, respectively. The formation of dibutyl phosphoric acid, DBP, (G⁺_DBP) in this solution was found to be 0.18 and 0.047 μmol/J for low and high LET radiation, respectively. In samples exposed to low LET as well as a mix of low and high LET a variety of TBP degradation products containing phosphorus were observed indicating that other degradation products than DBP and the monobutyl diacid (MBP) were formed. Our results for both low and high LET radiation compare well with previous studies on these systems indicating that high LET degrades TBP to a lesser extent than gamma radiation. Available data for high LET is not as abundant as for low LET making such comparisons challenging. Nevertheless, our method yields a value for G⁺_DBP that agrees well with previous alpha radiolysis studies indicating that our method shows promise for studying high LET radiolysis in liquid-liquid extraction systems.     

Tunable broadband emission from red to blue by gamma radiation in multicomponent phosphate glasses

We demonstrate for the first time that the tunable broadband emission from red to blue can be obtained by gamma radiation in multicomponent phosphate glasses. Gamma radiation causes the increased phosphate-related non-bridging oxygen hole center and oxygen hole center defects, which lead to the enhanced emission peaking at 452 nm. Meanwhile, the vibration amplitude of O-P-O chain's internal decrease, resulting in the decreased emission at 660 nm. Besides, the increased isolated phosphate units (Q⁰ and Q¹), as well as the gradual decrease in P atoms that make up the main phosphate chain contribute to the blue-shift of the main emission peak at 616 nm, which directly results in the tunable broadband emission from 616 to 460 nm. The gamma radiation process endows this type of multicomponent phosphate glasses with promising applications in solid-state lighting devices.     

Actinide Separation of High-Level Waste Using Solvent Extractants on Magnetic Microparticles

Abstract

Polymeric-coated ferromagnetic particles with an absorbed layer of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide diluted by tributyl phosphate are being evaluated for application in the separation and the recovery of low concentrations of americium and plutonium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles, which can be recovered from the waste solution using a magnet. The effectiveness of the extractant-absorbed particles at removing transuranics (TRU) from simulated solutions and various nitric acid solutions was measured by gamma and liquid scintillation counting of plutonium and americium. The HNO₃ concentration range was 0.01 to 6 M. The partition coefficients (K _d) for various actinides at 2 M HNO₃ were determined to be between 3000 and 30,000. These values are larger than those projected for TRU recovery by traditional liquid/liquid extraction. Results from transmission electron microscopy indicated a large dependence of K _d on relative magnetite location within the polymer and the polymer surface area. Energy disperse spectroscopy demonstrated homogeneous metal complexation on the polymer surface with no metal clustering. The radiolytic stability of the particles was determined by using ⁶⁰Co gamma irradiation under various conditions. The results showed that K _dmore strongly depends on the nitric acid dissolution rate of the magnetite than the gamma irradiation dose. Results of actinide separation from simulated high-level waste representatives of that at various DOE sites are also discussed.     

Absorption Spectra and Bioactivity Behavior of Gamma Irradiated CeO2-Doped Bioglasses

The synthesis and characterization of some bioglasses based on Hench’s Bioglass® 45S5 with additions of CeO₂ (1.0, 2.0, or 3.0%) have been carried out. Two objectives have been focused upon; first, the effect of successive ionizing gamma irradiation on the undoped and CeO₂-doped bioglass samples has been evaluated with the aim of justifying the role of the rare earth oxide CeO₂ on gamma irradiation. The second objective was directed to test the bioactivity of such prepared CeO₂-doped samples after soaking for 1 month in a simulated body fluid at 37 °C. The results indicate that the additions of CeO₂ suppress, to a marked extent, the generation of radiation induced defects especially in the visible region. The bioactivity results show that the studied CeO₂-doped bioglass samples gave rise to a calcium phosphate surface layer upon immersion in a simulated body fluid for 1 month at 37 °C and the bioactivity extent was almost identical in the CeO₂ doping interval limit (1?→?3% CeO₂) to that of the undoped base Hench’s Bioglass. The presence of both Ce³⁺ and Ce⁴⁺ ions were confirmed by optical absorption spectra. Electron spin resonance (ESR) studies of gamma irradiated CeO₂-doped glasses indicate and confirm the dominance of Ce⁴⁺ in the bioglass compositions and its transformation to Ce³⁺ by high gamma irradiation.     

Study of elementary reactions of free radicals formed on oxide and platinum containing catalysts

The formation of alkylperoxy radicals on catalysts CuCr₂O₄/ -Al₂O₃, Pt /--Al₂O₃ and on alumina upon the interaction of amines and alcohols with oxygen has been observed applying the matrix isolation ESR technique. Surface-generated gas phase radicals are shown to initiate a radical chain reaction. The efficiency of the yield of radicals depends on the catalyst mass and its arrangement in a reactor: the desorption of radicals into the gas phase occurs primarily from the outer geometrical surface of catalyst granules.     

Lead—Natural rubber composites as gamma radiation shields. II: High concentration

Natural rubber composites were prepared by the incorporation of different lead concentration, namely: 100, 300, 500, 1000, 1500 and 2000 phr to be used as gamma radiation shields. A non‐linear dependence of the attenuation coefficient upon the lead concentration was observed for both ⁶⁰Co and ¹³⁷Cs as gamma radiation sources. Sample containing the ultimate lead concentration (2000 phr) and thickness 1 mm was found to have 0.336 mm and 0.383 mm lead equivalent for ⁶⁰Co and ¹³⁷Cs respectively. Electrical and mechanical properties of the investigated composites were also measured.     

Titanium Dioxide and Gamma Irradiation Induced Changes in the Structural,Morphology, and Mechanical Behavior of Ethylene Vinyl Acetate Copolymer

Some composites were prepared depending on ethylene vinyl acetate (EVA) copolymer with 18% VA content and titanium dioxide (TiO₂). These composites were prepared in the ratios of 100/0, 90/10, 80/20, 70/30, and 60/40 by melt mixing method. Gamma radiation at differing doses was applied on pure EVA and composites to investigate the impact on modification of composites. Gel percentage and the Charlesby‐Pinner equation were used to confirm crosslinking increases. X‐Ray diffraction measurement (XRD), scanning electron microscope (SEM), and mechanical testing were all used to investigate the varying effects of the different processes on the structure, morphology, and mechanical behavior of EVA. It was observed that the addition of TiO₂ and gamma irradiation both have a significant effect on the structure and, therefore, the composites' surface morphology. Notable changes of the lattice structure were revealed by the XRD results for both unirradiated and irradiated composites, which were also confirmed by examination of the samples' surface morphology. It was found that the presence and amount of TiO₂ along with the irradiation process has a significant influence upon the EVA's mechanical behavior. When compared with the pure EVA, the results demonstrated a significant enhancement in the mechanical parameters of both unirradiated and irradiated composites, except elongation at break. The mechanical results were in line with gel content analysis. The reliability of gamma radiation as an applied method for controlling long‐term properties is clearly demonstrated. J. VINYL ADDIT. TECHNOL., 26:224–235, 2020. © 2019 Society of Plastics Engineers