–    reliability of power plant facilities and aging management;

–    development and research of multifunctional materials and composites;

–    testing of materials, assessment and analysis of their qualitative indicators.

 

RELIABILITY OF POWER PLANT FACILITIES: RESEARCH OF METAL AGEING PROCESSES AND PROPERTIES DEGRADATION DUE TO THE IMPACT OF OPERATIONAL FACTORS

 

The Laboratory carries out research related to the investigation of the processes of ageing of metal alloys that are used as the constructional elements of power plants and to solve issues of their service life and aging control. Applying mechanical tests, X-ray Diffraction (XRD) and elemental composition analysis, as well as optic and scanning electron microscopy, structural and property changes of steel and non-ferrous metal alloys were studied. Experimental and numerical methods are used to predict operational reliability taking into account material ageing processes and other operational factors. The implementation of this work is focussed on the investigation of the fundamental physical and chemical phenomena affecting structure and properties of metals.

 

The work, initiated in 2010, under the agreement with JSC GEOTERMA on Preparation and Application of Complex Measures for Work Optimisation and Life-Time Expansion of Absorption Heat Pumps (AHP) was continued. The main tasks of the project are to analyse and identify the factors which influence corrosion process and material costs in the geothermal power plant; to give recommendations for the minimisation of corrosion process and material consumption costs as well for ensuring of stable parameters of lithium bromide solution used in heat pumps. The work includes the analysis of AHP monitoring data, control and maintaining of LiBr solution parameters. In addition, preventive means for reducing the probability of LiBr solution contamination with thermal and/ or geothermal water are foreseen.

Apart from the mentioned research aimed to optimize performance and increase AHP lifetime, the investigation of the influence of the operational factors on long-term structural integrity of materials was performed. Corrosion research and mechanical testing were used for the assessment of operating condition and justification of further service possibility of cooper-nickel tubes, used in the thermal assembly. In addition, other research on the optimisation and maintenance of operational parameters of equipment was also performed.

 

The researchers of the Laboratory are continuing the research on degrading effect of hydrogen and hydrides on zirconium alloys, initiated in 1998. Since 2011, the Laboratory is participating in a new International Atomic Energy Agency (IAEA) project Analysis of Nuclear Fuel Cladding Resistance to Hydride Cracking During Long-Term Storage. The aim of this project is to develop experimental procedures in order to assess the conditions of hydride cracking in zirconium alloy fuel cladding and to determine the values of stress intensity and temperature limits at which the failure of fuel claddings can occur. The research is important for solving the issues of ensuring safe operation of nuclear power plants and assessing the resistance of fuel cladding to the hydride cracking during long-term storage of spent nuclear fuel.

 

Achievements of the project the project MATTER (MATerials TEsting and Rules). On 13 December 2010 a new European Union 7th Framework Programme project MATTERwas signed and its implementation was initiated on 1 January 2011. Joint team including researchers from Laboratory of Nuclear Installation Safety takes part in the project. 15 work packages were established according to the project tasks, and the Laboratories participate in two working groups: “Manufacturing and welding” and “Testing activities in support of design”. In the scope of the project, a new research on materials behaviour in the operational conditions of IV generation reactors was initiated. It is aimed at the determination of the highest reliability criteria of application of new materials taking into consideration material ageing mechanisms. One of the main objectives of this experimental research is to identify the allowable fatigue resistance limits and coefficient values of steel welds in nuclear components, operating under high temperature and manufactured by applying up-to-date welding technologies. Taking into account the requirements for modern experimental procedures, a research methodology was developed for carrying out the experiments. The fatigue resistance tests are performed under strain controlled conditions at 550 °C using dynamic testing machine Instron (Model 8801, 100kN). During the implementation of this work, new data describing the high temperature creep and fatigue behaviour where obtained which are relevant for predicting the lifetime of welds in the reactor components and assessing the suitability of welding technologies in continuation of further research on the welding materials and assessment of influence of operational factors on the welded components in the nuclear industry.

             

A state subsidy-funded scientific research Impact of modifying additives and nano-fillers on structure and properties of constructional composite materials was initiated in 2011. It analyses the impact of nanosized fillers and other modifying additives on the structure and properties of innovative composites, and compatibility of nano-fillers with the binders. In the first stage of project implementation, the parameters of pure gyrolite and sodium substituted gyrolite crystal lattices, exact positions and the fractional occupancy of their atom sites were determined by applying Rietveld crystal structure refinement method. X-ray diffraction analysis, Rietveld structure refinement and crystal structure modelling methods were combined to prepare a methodology for the determination of the exact atomic positions and the amount of inserted Na+ ions in the crystal lattice of low crystallographic symmetry minerals – synthetic gyrolite and sodium substituted gyrolite.

 

Physical and mechanical properties of both inorganic binder and constructional material may be significantly improved by changing the amount of any of the modifying additive. Therefore, one of the purposes of this project is to analyse the impact of modifying additives on the structure and properties of a composite constructional material with inorganic binder. Research was focussed on the inorganic binder which is one of the main components of refractory composites used for repair of heat linings.

 In order to prolong the lifetime of the composites, several modifying additives were selected, namely silicon dioxide micro-dust, microfiber and layered silicate, each of which has a specific function, i.e. to prevent the formation of macrocracks in the material, to increase material volume or reduce the content of the binder. Whereas the material is to be used under high temperature, the impact of temperature on the physical-mechanical properties of the modified adhesive was evaluated experimentally. Furthermore, X-ray diffraction analysis was carried out, microstructural changes of the binder were investigated according to the selected modifying additive, and the optimal amount of additives in the material was determined.

 

Researchers of the Laboratory are taking part in activity COST MP0701 Composites with Novel Functional and Structural Properties by Nanoscale Materials of the first working group WG1 Nanoparticles/Interfaces (selection of matrix and nanoparticles, production of nanoparticles, surface modification/chemical treatments of nanoparticles). The objective of participating in the COST MPO701 activity is to develop the preparation methodology of polymer nanocomposite with epoxy matrix and nanosized filler, to investigate the impact of different factors (filler dispersion method, its chemical modification, selection of polymer composition and compatibility with filler) on intercalation/exfoliation of mineral filler in polymer matrix. Pure synthetic nanosized filler gyrolite, as well as sodium substituted gyrolite was used in this research. Surface characteristics of the filler were changed by organic compounds and ultrasound mixing to achieve effective compatibility with polymer matrix. A nanocomposite was prepared from the modified nanosized filler and polymer composition and its mechanical properties were determined.

Participating in COST MP0701 activity, Laboratory researchers cooperate with researchers from Department of Silicate Technology, Faculty of Chemical Technology of Kaunas University of Technology, who synthesize the nanosized gyrolite filler.

 

Project Nanotechnology Enhanced Extruded Fibre Reinforced Foam Cement Based Environmentally Friendly Sandwich Material for Building Applications (FIBCEM) of the Project Nanotechnology Enhanced Extruded Fibre Reinforced Foam Cement Based Environmentally Friendly Sandwich Material for Building Applications (FIBCEM) of the European Union 7th Framework Programme. The three-year FIBCEM project was initiated in December 2011 with participation of 10 partners from 5 countries: Italy, Spain, the United Kingdom, Denmark and Lithuania. Following the work schedule, the researchers of the Laboratory participate in the activity of the 4th working group, which main objective is to modify nanoclay. The aim of the FIBCEM project is to develop a promising, low-energy consuming technology for the production of foam-cement boards enabling the reduction of carbon dioxide emission.

 

 

Researchers of the Laboratory provide accredited services; perform material testing and assessment of their quality in accordance with the LST EN ISO/IEC 17025 standard. As a result of successful collaboration with commercial enterprises, the Laboratory carries out research and gives advises on guarantee for quality of products.

Laboratory is accredited to carry out tests of:

 

*     plastic pipes,

*     pre-insulated pipes,

*     building mortars,

*     adhesives for tiles,

*     building putties,

*     refractory materials and products.

 

The achievements of Laboratory in 2011 are the following: 7 scientific articles: 4 of them in the publications on the ISI list and 3 in reviewed conference materials were published. The researchers also participated and presented reports in 3 international conferences.