Cooperation of the MDP Department with Industrial Establishments
As one in five, the Department of Deformation and Dynamic Processes Modelling (henceforth referred to as MDP) was established as soon as in the act of foundation of the university institute New Technologies at the University of West Bohemia. Specifically, the personnel job description covers the applied research focused on the extreme loading of structure materials, complex structure elements, and sophisticated technical equipments.
Since our university institute came into being after having been prompted by the state’s intention to establish national research centres (however, the word national vanished soon) that should appreciably support the competitive strength of our industry and contribute to making its product’s added value higher, the representatives of some eminent companies were named to sit on the institute research board as guarantees of its professional level. By way of example, let us mention ČEZ, a.s., ŠKODA Auto, a.s., ŠKODA JS, a.s. and ZVVZ. We have therefore taken as our obligation that the research output must be presented not only in the form of technical publications (dominant in the academic milieu as yet) or contributions at the meetings of the scientific community (after all, we have given several contributions at world’s leading conferences) but that there is also a need to apply the achieved knowledge in concrete technical projects. Therefore I should like to take this opportunity for commenting the participation of the MDP department staff at the most significant jobs.
I should underline in the first place that we participated in preparing the technical documentation for rigorous and successful licensing procedure of the ŠKODA 440/84M-design basket for ŠKODA JS, a.s. To give a better insight into the subject let us throw in the explanation that the basket is an internal built-in device of the cask CASTOR 440/84M designed by the German concern GNS for transporting and storing the spent nuclear fuel in the power plant Dukovany. The basket is an internal supporting structure separating the fuel assemblies containing spent radioactive fuel from one another. Though the demand factor of the transportation and storage technology is generally taken in by the wide public, stringent requirements of the International Agency for Atom Energy in Vienna are less known. Primarily, the nuclear safety may not be endangered by any activity, not even in the hypothetical transport accidents when the stressing of the waste-full cask is equivalent to its drop from the height of 9 metres on a solid base. We have contributed, using the computer-aided modelling of such extreme stressing situations with a series of structure changes to be considered, to this range of problems. Finally we were engaged in design and preparation of the experiments by which the required strength of the most stressed basket substructures was verified and the reliability of the calculations was confirmed.
We have participated in assessing the strength of some other casks for ŠKODA JS including the design and verification of the shock absorber properties since the very origin of our department. The casks are intended for the transportation of highly radioactive materials used in several branches of energy industry, industry in itself, or health service in a number of European countries. We can for example point out the project of spent fuel transport from the research nuclear reactors of Russian origin which is financed by the USA, and is technically covered by the reputable institutions of the Russian Federation (let us mention R&D Company SOSNY, Russian Federal Nuclear Centre VNIIEF, Rosatom, Mayak). The project is supposed to prevent a potential misuse of the material for developing nuclear weapons. One of the department specialists even took part at the technical talks and successful opponency of the Skoda cask ŠKODA VPVR/M in Dimitrovgrad, Russia.
Appreciating our many years working experience on the expert issues of the above kind, the company ŠKODA JS called us in to cooperate in analyzing a hypothetical terroristic attack on a spent fuel storage area, at NPP Temelín site at first and later even at the store in NPP Dukovany that had been already operated by that time. So did also the Energoprojekt Division of the Nuclear Research Institute, Řež, having had appointed us as a head of the project. The subject was numerical simulation of what happens when a huge airliner crashes into the store. We were set the task of evaluating the dynamical effects on the spent fuel container system. It was necessary to analyze the effects caused partly by the impact of the airframe and aircraft engine as the most compact parts of an airplane, and partly by the collapsed buildings parts of the store, or it was required to analyze the cask drop on the store floor. A number of computational simulations were performed for evaluating the integrity and leaktightness of the casks. We also have taken advantage of the principles of terminal ballistics and the knowledge of deformational behaviour of materials at impact load condition. It remains, of course, to be noted that, for proving the credibility of our analyses, we have prospered from the results of wide-ranging experiments that were effected and published by the national laboratory Sandia, United States, as well as in Japan and which even such a big company as ČEZ were hardly able to finance.
Our further cooperation in nuclear machinery with ŠKODA JS was focused on judging the strength, life, and leaktightness of complex flange joints of WWER 440 and WWER1000 reactor upper blocks and on assessing their nozzles attachment to the reactor pressure vessel head. Though a fatal failure jeopardizing nuclear safety is excluded, emergency shutdowns of the nuclear units or shortening the lifetime of the flange joints are real and mean considerable financial losses for the power plant owner. That’s why, in the framework of the program "Lifetime Control” of the substructures under consideration, the company ŠKODA JS performs strenuous examinations of the representative loading modes that are encountered during the nuclear power plants operation. It is however necessary to determine some relevant information through the use of computationally numerical programs. If the NPP Temelín is the case, we can refer to hundreds of calculations for each flange joint. The Department of Deformation and Dynamic Processes Modelling of the university institute "New Technologies” participated in elaborating the methodology for setting up feasible calculation models and also performed a great number of calculations as such. Our reports are part of technical documentation of the WWER-type nuclear power plants not only in our country but also in Slovakia, Ukraine, Hungary, and Finland.
In the field of controlled ageing, the problems of the in-service inspections of thick-walled reinforced concrete structures belong to the first group of priorities that the Commission for Safety of Nuclear Equipments of the OECD Agency for Nuclear Energy in Paris announced. Our department collaborates on development of new diagnostic methods with our partners from the Nuclear Research Institute in Řež and Faculty of Civil Engineering of the Brno University of Technology. The development is supported by the Grant Agency of the Czech Republic, Ministry of Industry and Trade, and Czech Energy Agency. A method called Impact-Echo, which lies in exciting an acoustic wave applying a hit on the surface of the investigated wall and subsequent recording its reflection and dispersion, stays at the forefront of our attention. The original method, which is based on frequency analysis and is standardized by the American standard institution ASTM, is able to determine, regrettably, only the distance of the inner defect from the surface supposing the velocity of the wave propagation is known. Our department deals with the numerical simulations of the waves and, in the subsequent analysis, it takes into consideration their position in the entire time interval. This enables not only for the closed crack to be detected but also for its depth to be established supposing the crack comes from the adjacent or opposite surface of the examined wall. Moreover, we are facing an interesting half-finished problem of detecting the cracks that arise due to corrosion of the reinforcement. An actual commitment of the method under the working conditions calls for a large amount of both extra ingenuity and advanced electronics. On that account we also participate in the development and manufacturing of new sensing units prototypes and in designing an automatic exciting device based on the properties of piezoelectric materials.
Photo of construction of the testing laboratory in ÚJV Řež
We furthermore made use of our experience with the structural materials impact stressing and with computer-aided modelling of emergency situations in the calculations conducted for the drop simulation laboratory project at SÚRAO Litoměřice (where the vessels designed for transport of dangerous materials under 5 tons of total mass are tested) or in analyzing the impact of a tramway vehicle against an obstruction. On this ground the specialists of ŠKODA Výzkum, where the analysis of locomotive collision with a large obstruction is one of their development projects conducted for ŠKODA Transportation and aimed at its homologation, expressed their interest in our knowledge.
We have carried out several partial works for the companies ZVVZ Milevsko and ŠKODA Klatovy. A more extensive cooperation is still under way with Sokolov machinery works on a project assisted by the Ministry of Industry and Trade. The subject is about the development of a technology to be applied to the process of breaking down the worn-out tyres. Our contribution lies in computational optimization of breaking and shearing forces for the purposes of reducing the strain both of the cutting tools and other parts of the breaker and cutting machine, and for attaining the aim of the most efficient suppression of the noise.
Examples of output of tyre breaking numerical simulations and an example of a broken sample and of a test for determining material properties of a tyre