Metal irradiation effects

Particle irradiation effects in halides and especially in alkali halides have been intensively studied. One reason is that salt mines can be used to store radioactive waste. Alkali halides in thermal equilibrium are Schottky-type disordered materials. Defects in NaCl which form under electron bombardment at low temperature are neutral anion vacancies (Vx) and a corresponding number of anion interstitials (Xf). Even at liquid nitrogen temperature, these primary radiation defects are still somewhat mobile. Thus, they can either recombine (Xf+Vx = Xx) or form clusters. First, clusters will form according to /i-Xf = X j. Also, Xf and Xf j may be trapped at impurities. Later, vacancies will cluster as well. If X is trapped by a vacancy pair [VA Vx] (which is, in other words, an empty site of a lattice molecule, i.e., the smallest possible pore ) we have the smallest possible halogen molecule bubble . Further clustering of these defects may lead to dislocation loops. In contrast, aggregates of only anion vacancies are equivalent to small metal colloid particles. 

V.T. Gritsyna, et al., Neutron irradiation effects in magnesium-aluminate spinel doped with transition metals../. Nucl. Mater. 283(Part B), 927-931 (2000). 

Fe(N03)3.9H20 or Ni(N03)2.6H20 with a molar ratio of 10% nitrate per alkoxide was added to the gelling solution. Some films, with a thickness of 500 nm, were irradiated with lO Au ions/cm of energy 3 MeV stopping into the substrate. This fluence was chosen because the irradiation effects on the gel densification and on the growth of other metallic clusters (Ag, Cu) in both matrices [4], Other films and monoliths were annealed for Ih at 600 or 1000°C in a vacuum of 10 Torr. 

Qualitative Representation of Neutron Irradiation Effect on Many Metals. 40... 

Belcher W, Priest R and Boothby R (2002), In-service irradiation effects in PWR RPV SA508 Class 3 forging and weld metal , Proceedings of the Tenth International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors, NACE International, Houston, TX, USA. 

The XPS study of ion-beam irradiation effects in polyamide layers have been studied by Karpuzov et al. (1989). Thin polyamide films deposited on silicon or metal covered glass-ceramic substrates were exposed to ion bombardment at different fluences ranging from 1 x 10 to 1.5x 10 cm. The XPS technique was used to study the polymer stoichiometry of the near surface layers ( 75 A) before and after the bombardment. The results show that the stoichiometric ratio of O, N, and C-groups remains approximately constant with depth for unirradiated samples. 

Taking into account that dissolved cobalt species are assumed to be primarily responsible for contamination buildup (see below), it still seems questionable whether the irradiation effect, which results in an enhanced release of metal atoms from the materials, will significantly affect the rate and the magnitude of deposition of radioactive cobalt on the out-of-core surfaces. 

Electron paramagnetic resonance (EPR) spectroscopy (also called electron spin resonance (ESR) spectroscopy), is used to study paramagnetic species with one or more unpaired electrons, e.g. free radicals, diradicals, metal complexes containing paramagnetic metal centres, defects in semiconductors and irradiation effects in solids. While diamagnetic materials are EPR silent, paramagnetic species always exhibit an EPR spectrum. This consists of one or more lines, depending on the interactions between the unpaired electron (which acts as a probe ) and the molecular framework in which it is located. Analysis of the shape of the EPR spectrum (the number and positions of EPR lines, their intensities and line widths) provides information... 

S. Moradi, S. Kamal, P. Englezos, and S. G. Hatzikiriakos, Femtosecond laser irradiation of metallic surfaces Effects of laser parameters on superhydropho-bicity Nanotechnology 24, 415302-415313 (2013). 

Future projects are considering the use of ceramic composites where radiation doses, environmental challenges, or temperatures (up to or beyond 1000°C) will exceed the capabilities of the metallic materials (Corwin et al., 2008). However, widespread property data, standardization of the characterization methods and the development of design codes of ceramic composites are required for in-core structural components. The baseline thermal and mechanical properties of some nuclear-grade C/C composites were measured. The oxidation behaviors of composites in air and He with controlled minor impurities and irradiation effects using Si ions were also evaluated (Kim et al., 2009b Hong et al., 2012 Corwin et al., 2008 Carre et al., 2010). 

In general, it has been observed that neutron irradiation does not impact the corrosion mechanism and the rate of reference structural materials exposed to liquid Na, Pb and Pb-Bi. On the contrary, neutron irradiation and liquid metal synergetic effects on the degradation of the mechanical properties of structural materials have been observed. As an example, ferritic/martensitic steels when neutron-irradiated and in contact with liquid Pb-Bi show degraded mechanical properties attributable to both the irradiation defects and the Uquid metal impact. As already reported before, from the reactor operation point of view, the design criteria of reactor components have to include these phenomena. 

There is considerable interest in irradiation effects in intermetallic compounds from both the applied and fundamental aspects. Initially, this interest was associated mainly with nuclear reactor programs but it now extends to the fields of ion-beam modification of metals, behavior of amorphous materials, ion-beam processing of electronic materials, and ion-beam simulations of various kinds. 

Heat stabilizers protect polymers from the chemical degrading effects of heat or uv irradiation. These additives include a wide variety of chemical substances, ranging from purely organic chemicals to metallic soaps to complex organometaUic compounds. By far the most common polymer requiring the use of heat stabilizers is poly(vinyl chloride) (PVC). However, copolymers of PVC, chlorinated poly(vinyl chloride) (CPVC), poly(vinyhdene chloride) (PVDC), and chlorinated polyethylene (CPE), also benefit from this technology. Without the use of heat stabilizers, PVC could not be the widely used polymer that it is, with worldwide production of nearly 16 million metric tons in 1991 alone (see Vinyl polymers). 

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