Globally, it is extremely relevant to complement and expand fundamental research on the extension of service life, safety, and reliability of Gen II and III nuclear reactors, with particular attention to the new requirements of the amended European Commission Nuclear Safety Directive.  The main objective of the research underlying this project is to develop deterministic predictive models of general and localized corrosion and corrosion-mechanical degradation of reactor internals and materials of steam generators, to parameterize, validate and verify them using dedicated experimental data produced in-house, as well as laboratory and plant data available in the open literature.  In the field of flow-assisted corrosion and sludge deposition, development of an improved deterministic model of monophasic flow-assisted corrosion - quantitative assessment of the input flow of particles and soluble iron in PWR nuclear plants depending on temperature and water-chemical regime, and development of a deterministic model of slurry formation and consolidation in steam generators are envisaged.

Current project

University of Chemical Technology and Metallurgy - host organization, research group №: 3.1.4 "Clean Technologies to extend the life cycle of energy systems"

Due to its exceptional fuel characteristics, butanol is rightly considered the fuel of the future. The possibility of obtaining it as a bioproduct, through fermentation, has been the subject of unceasing interest for more than a century. The production of 1-butanol by fermentation of sugars from species of the genus Clostridium (so-called ABE-fermentation) is one of the first fermentations carried out on an industrial scale - as early as the beginning of the twentieth century. Until now, however, due to its low concentration and yield, the resulting product has a high cost and cannot be used as a fuel. The reason is the extreme toxicity of 1-butanol to the cells that produce it. Therefore, over the past few decades, the tolerance of microorganisms to 1-butanol has been the subject of continuous research - use of modified producers, new methods of process control and product recovery, modifications to increase the resistance of organisms, study of genetic factors for tolerance etc. Unfortunately, to this day, despite the accumulated knowledge, these attempts have little success - the maximum concentration of 1-butanol obtained by fermentation remains within the limits of 20-22 g/l., as it was a century ago.

On the other hand, interest in the microbial production of 2-butanol dates back only 5–6 years. A definite and perhaps decisive advantage of 2-butanol as a fermentation product is its significantly lower toxicity. However, the production of 2-butanol has been poorly studied due to the extreme specificity of the required substrate and organism. As a metabolite, 2-butanol is obtained only from the meso form of another metabolic product – 2,3-butanediol, through the metabolism of only a few species of the genus Lactobacillus, by means of the enzymes diol dehydratase (pduCDE) and diol dehydrogenase (pduQ). It is important to note that lactobacilli themselves do not produce 2,3-butanediol, although they are capable of digesting it. Through pduCDE and pduQ enzymes, they metabolize glycerol to 1,3-propanediol and cannot serve as 2-butanol producers in an economically viable process.

In the present project, we propose a new strategy for the production of 2-butanol - through genetic modifications of overproducers of meso-2,3-butanediol. By introducing genes for diol dehydratase and diol dehydrogenase into these organisms, the metabolic pathways to produce 2,3-butanediol and 2-butanol will be combined. In this way, 2-butanol will be obtained directly from sugars, in a one-step process through the metabolism of a single, genetically modified organism.

Current project

 Institute of Chemical Engeneering - host organization

 Institute of Microbiology, Bulgarian Academy of Sciences