Nuclear applications, membrane

In nuclear applications, membrane fouling is a particular problem. Frequent cleaning of the membranes creates secondary wastes that are radioactive and require additional treatment. Thus, the elimination of the phenomena that lead to membrane fouling is a key issue in the design of membrane installations. 

All major industrial participants in the developments that took place in the period 1980-1985, were companies which actively participated in the development and manufacture of inorganic membranes for nuclear applications. 

Since membranes no longer had important nuclear applications in future, SPEC was sold in 1987 by the CEA to the French company Rhone-Poulenc which merged them with their polymeric membrane division to form the new subsidiary, currently known as Tech Sep. Zr02 based ultrafiltration membranes on 6 mm inner-diameter carbon tubes continues to be the main product line of Tech Sep in terms of inorganic membranes. 

In addition to the U.S. and France, other countries such as the Soviet Union, China and England were also involved in using presumably inorganic membranes for its gaseous diffusion opierations although little has been documented. Ceramic membranes were also made by the anodic oxide process (to be discussed later in Chapter 3) in Sweden for military and nuclear applications. 

It has been demonstrated that membrane separation processes can be successfully used in the removal of radioactive substances, with some distinct advantages over conventional processes. Following the development of suitable membrane materials and their long-term verification in conventional water purification, membrane processes have been adopted by the nuclear industry as a viable alternative for the treatment of radioactive liquid wastes [1]. In most applications, membrane processes are used as one or more of the treatment steps in complex waste treatment systems, which combine both conventional and membrane treatment technologies. These combined systems have proved more efficient and effective for similar tasks than conventional methods alone. 

More radical chemical cleaning resulted in a decline in the membrane-bound activity however, it remained significant. The lowest adsorption observed at the SMM3 and SMM41 membranes predestines these materials to nuclear applications, namely, radioactive waste treatment. 

Andalaft, E., Vega, R., Correa, M., Araya, R. and Loyola, R 1997. Zeta potential control in decontamination with inorganic membranes and inorganic adsorbents. In Treatment Technologies for Low and Intermediate Level Waste from Nuclear Applications. Final Report of a Coordinated Research Programme 1991-1996. IAEA-TECDOC-929, pp. 15-32. IAEA Vienna. 

A question of practical interest is the amount of electrolyte adsorbed into nanostructures and how this depends on various surface and solution parameters. The equilibrium concentration of ions inside porous structures will affect the applications, such as ion exchange resins and membranes, containment of nuclear wastes [67], and battery materials [68]. Experimental studies of electrosorption studies on a single planar electrode were reported [69]. Studies on porous structures are difficult, since most structures are ill defined with a wide distribution of pore sizes and surface charges. Only rough estimates of the average number of fixed charges and pore sizes were reported [70-73]. Molecular simulations of nonelectrolyte adsorption into nanopores were widely reported [58]. The confinement effect can lead to abnormalities of lowered critical points and compressed two-phase envelope [74]. 

Lipari G. and Szabo A. (1980) Effect of Vibrational Motion on Fluorescence Depolarization and Nuclear Magnetic Resonance Relaxation in Macromolecules and Membranes, Biophys. J. 30, 489—506. Steiner R. F. (1991) Fluorescence Anisotropy Theory and Applications, in Lakowicz J. R. (Ed.), Topics in Fluorescence Spectroscopy, Vol. 2, Principles, Plenum Press, New York, pp. 127-176. 

In summary, the development of inorganic membranes was initially oriented towards uranium enrichment which is still by very far their most significant application. Some of the key participants involved in the nuclear programs further developed them into cross-flow filtration membranes. The recent years have seen the start of a much broader exploration of the manyfold potentialities of inorganic membranes, both in terms of materials and applications. Thus, a multifaceted new field of technology is emerging. 

The stain/fixation method is usually used for surface markers that can withstand fixation and is followed by the application of a DNA-binding fluoro-chrome. The fixation/stain method is used not only for surface markers that can withstand fixation, but also for intracellular constituents, such as cytoplasmic proteins, nuclear membrane, and nuclear proteins. This is accomplished by using a crosslinking fixative (e.g., paraformaldehyde [PFA] or formalin) followed by a permeabilizing agent (e.g., Triton X-100, Tween-20, saponin, or lysolecithin). Some of the precipitating agents (e.g., ethanol, methanol, or acetone) can also be used for permeabilization after the initial fixation with PFA or formalin, or they can be used alone for both fixation and permeabilization (see Chapter 8). 

CSM is extensively used in construction and electrical applications. This includes roofing membranes, automotive ignition boots and wire, roll compounds, and in some automotive hoses requiring good heat and oil resistance, eg, air conditioning and power steering. It is also used in nuclear power plants because of its excellent resistance to radiation degradation. 

The successful application of the sol-gel route has been realized in the International technological practice of many branches of the industries—electronics, optics, construction of engines, nuclear energetics, chemical, and food industry equipment. Among these materials are ferro-, piezo-, and dielectrics, solid electrolytes, refractory materials, membranes, protective and decorative coatings, and also films with special optical and electrophysical properties, like hightemperature superconductors. 

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