[en] This publication describes the investigation of mecanorootlet constituted by using mechanical means on PMMA with ESR techniques

[en] With the use of finite element simulations the effect of austenitic corrosion resistant weld deposited cladding on WWER pressure vessel integrity under pressurized thermal shock on emergency is investigated. The calculation of thermal and stress fields is made with accounting for distinctions between properties of vessel base metal and those of cladding material as well as taking into consideration a substantial loss of plasticity in austenitic steel under irradiation. The results of integrity assessment within the framework of elastic-plastic fracture theory show that the role of the cladding in reactor vessel failure is greatly dependent of reactor lifetime. It is concluded that the presently accepted standard calculations of stresses without accounting for embrittlement of the austenitic layer during the whole reactor service life result in underestimated values of stresses in weld deposited cladding

[en] An explicit construction of the BRST symmetry is presented in the Hamiltonian approach. The construction is based on the splitting homotopy and the transference problem. (author). 16 refs

[en] The gauging of the Virasoro and w-infinity algebras are discussed from the point of view of BRST symmetry. Both algebras are realised as ''Russian formulas'' for the curvatures built from the generators of the Lie algebras and the corresponding gauge fields. The generalized curvatures are used to determine the gauge invariant Lagrangians as well as the anomaly structures of the conformal two dimensional theory and the w-gravity. (author). 21 refs

[en] Anti-symmetric tensor gauge theories are quantized via Batalin-Vilkovsky and the Faddeev-Popov procedures and a relation between these two procedures is established. (Author)

[en] Full text: The first part of the paper summarise the already existing research results obtained in the frame of PLIM related research in Hungary. The second part of the paper introduces the ongoing research providing a strong background for the PLIM of NPP Paks. Several actions are available to extend the operational time of the WWER-440 V213 RPVs. The lifetime of structural materials influences the safe service time of equipment to a great extent. Longer lifetime is generally more advantageous both from the economic and environmental aspect, as waste volume decreases if decommissioning occurs less frequently. Enhancement of lifetime calculation is an important economic aspect in case of valuable equipment. WWER-440 V213 units provide about 40% of the electricity of Hungary, and play a similarly important role in several countries in the area. In lifetime management of nuclear power plants reactor pressure vessels play a crucial role in safety. Their safe lifetime can be prolonged by mitigation actions, thus plant lifetime is not limited technically by the RPV. Generally the life limiting consideration of the WWER-440 vessels are the PTS calculations results. To extend the safe operational lifetime of the WWER-440 V213 vessels - among other options using hardware solutions - the following actions -or at least one of them -are suggested: consideration of the clad in elastic-plastic PTS analysis; application of less over-conservative trend curves, especially the Master Curve; extension of the analysis with crack arrest considerations; increasing the understanding of vessel annealing, and elaborate the optimal annealing strategy; development nondestructive measurement methods of material degradation These actions require further study of the material ageing mechanism. The purpose of the present paper is to show some of the realistic solutions for WWER-440 V-213 RPV PLIM and to propose the direction of further studies. Although this paper specifically considers the life management of WWER-440 V213 type vessels, other type RPVs need similar R and D activity. (author)

[en] Full text: The RPV cladding generally not involved into the stress and strain analysis, even it is considered in structural integrity assessment only as a layer in the heat transfer models. The IAEA PTS guide of WWER-440 RPV-s allows to consider only underclad hypothetic cracks if the RPV cladding is free of defects and ductile. The cladding is a welded structure. According to the chemical composition it is austenitic, but due to the welding it has 5-10% delta ferrite. The delta ferrite changes the material behavior, it shown transition properties of ferrite and austenitic material. Irradiation increases the strength of it, and decreases the toughness. To evaluate the ductility and mechanical properties of the WWER reactor's cladding test blocks have been cut from the Zarnowiec and Greifswald 8 units. Both reactors were manufactured at Skoda Works (Czech Republic) but they never operated. Cladding specimens have been irradiated, annealed and re-irradiated in the Budapest Research Reactor and tested. Several mechanical tests (tensile and fracture properties) and metallographic samples have been studied to evaluate the properties of the irradiated cladding. Database of irradiated cladding properties have been collected to allow elastic plastic analysis of the reactor pressure vessels during transient thermal stresses. The data have been used for PTS evaluation of WWER-440 V-231 type blocks. Calculation have been performed by traditional elastic stress analyses using surface and sub-cladding hypothetical cracks, and by elastic-plastic finite element code using sub-clad hypothetical defects according to the IAEA PTS guide and the VERLIFE guide. The calculated safe lifetime is doubled in the case of the critical transients. (author)

[en] The RPV cladding generally not involved into the stress and strain analysis, even it is considered in structural integrity assessment only as a layer in the heat transfer models. The IAEA PTS guide of WWER-440 RPV-s allows to consider only underclad hypothetic cracks if the RPV cladding is free of defects and ductile.The cladding is a welded structure. According to the chemical composition it is austenitic, but due to the welding it has 5-10% delta ferrite. The delta ferrite changes the material behavior, it shown transition properties of ferrite and austenitic material. Irradiation increases the strength of it, and decreases the toughness.To evaluate the ductility and mechanical properties of the WWER reactor's cladding test blocks have been cut from the Zarnowiec and Greifswald 8 units. Both reactors were manufactured at Skoda Works (Czech Republic) but they never operated. Cladding specimens have been irradiated, annealed and re-irradiated in the Budapest Research Reactor and tested. Several mechanical tests (tensile and fracture properties) and metallographic samples have been studied to evaluate the properties of the irradiated cladding. Database of irradiated cladding properties have been collected to allow elastic plastic analysis of the reactor pressure vessels during transient thermal stresses. The data have been used for PTS evaluation of WWER-440 V-213 type units. Calculation have been performed by traditional elastic stress analyses using surface and sub-cladding hypothetical cracks, and by elasticplastic finite element code using sub-clad hypothetical defects according to the IAEA PTS guide and the VERLIFE guide. The calculated safe lifetime is doubled in the case of the critical transients. (author)

[en] Plant Life Management is the most important task for the TSO organizations in Hungary for the following years. NPP Paks has decided to extend the lifetime to 50 years operation. Four VVER-440/V213 units are in operation a Paks, and they produce 40% of nation electricity. The nuclear electricity is not only contributing the country to keep the release of the polluting gases low, but one of the cheapest too. Several institutes and universities are working on the life extension program. The life barriers of the Paks units are: the embrittlement of the RPV-s and the corrosion of the steam generator pipes. Both barriers allow the planned 50 years operation without the reduction of safety in case of using correct mitigation actions. This paper introduces the R and D efforts for Life Management of the RPV-s. (author)

[en] The two-dimensional conformal field theory has Virasoro algebra as the underlying symmetry. This algebra can be used to describe the coupling of two-dimensional gravity to matter and can be generalized at w-infinity algebra to describe w-gravity. In this paper the gauging of the Virasoro and w-infinity algebras is discussed from the point of view of BRST symmetry. Both algebras are realized as 'Russian formulas' for the curvatures built from the generators of the Lie algebra and the corresponding gauge fields and ghosts. The generalized curvatures are used to determine the gauge invariant Lagrangians as well as the anomaly structures of the conformal two-dimensional theory and the w-gravity. (Author)