Extension of Operational Life-Time of WWER-440/213 Type Units at Paks Nuclear Power Plant

Operational license of WWER-440/213 units at Paks NPP, Hungary is limited to the design lifetime of 30 years. Prolongation by additional 20 years of the operational lifetime is feasible. Moreover, enhancement of the reactor thermal power by 8% will increase both the net power output and the competitiveness of the plant. Paks NPP is a pioneer considering the power up-rate and preparation of long-term operation of WWER-440/213 design. Systematic preparatory work for longterm operation of Paks NPP has been started in 2000. A regulatory framework and a comprehensive engineering practice have been developed. According to the authors view, creation of a gapless engineering system via consequent application of best practices, and feed-back of experiences together with proper consideration of WWER-440/V213 features are the decisive elements of ensuring the safety of long-term operation. That systematic engineering approach is in the focus of recent paper. Key elements of justification and measures for ensuring the safety of long-term operation of Paks NPP WWER-440/213 units are identified and discussed. These are the assessment of plant condition and review of adequacy of ageing management programmes, also the review, validation and reconstitution of time limited ageing analyses as core tasks of licence renewal

A Paksi Atomerőmű jövője

A Paksi Atomerımő az egyetlen atomerımőve hazánknak, amelynek - eltérıen a többi villamosenergia-termelı egységtıl - sajátos energiapolitikai szerepe van: az atomerımő által megvalósul és fenntartható a primer energiahordozók diverzitása. Az atomerımő ma a hazai termelés 38-40%-át adó, nemzeti tulajdonban lévı kapacitásként a piacszabályozás, a gazdaságpolitikai intervenciók lehetséges eszköze. A nukleáris energia alkalmazásához, a magas színvonalú, biztonságos üzemeltetéshez szükséges hozzáértés és szakmai kultúra megtartása egyben az ország szellemi potenciáljának megtartását szolgálja. Mindezek meghatározzák a nukleáris energia szerepét a jövı energetikájában, s kijelölik azt a stratégiát, amit a nukleáris energetika alkalmazása terén követni célszerő, hogy hosszú távon biztosítsuk a nemzet gazdasági fejlıdésének feltételeit. Az elkövetkezı két évtizedben a nukleáris energetika meghatározó, s távlatilag állandó eleme lesz a hazai villamosenergia-termelésnek, amelyet a Paksi Atomerımő biztonságos üzemeltetésével, a blokkok élettartamának meghosszabbításával, az erımő teljesítményének maximális kihasználásával és az atomerımő bıvítésével kell biztosítani

Key Elements of the Ageing Management of the WWER-440/213 type Nuclear Power Plants

The owner’s intention of WWER-440/213 units in Central Europe is to keep the plants in operation as long as technically feasible and reasonable from business point of view. The preconditions of the long term operation and license renewal are the safety and good plant condition. The past and recent ageing management practices have to ensure the required condition and performance of the essential structures, systems and components. In the paper an overall picture of the long term operation of WWER-440/213 units is given. The review covers ageing of mechanical equipment, building structures and electrical equipment to. Key elements of the ageing management are identified and described. Basic issues of assessment of ageing of essential structures, systems and components, also the issues related to availability of design basis information and lacking environmental qualification are discussed. Reference examples typical for WWER-440/213 plants long term operation are given from Paks Nuclear Power Plant practice

Lifetime-Management and Operational Lifetime Extension at Paks Nuclear Power Plant

The design life of the NPP PAKS WWER-440/213 units is 30 years. Formally the design life limits the operational licence. The condition of the equipment after almost 20 years of operation is excellent. The lifetime management activity of the Paks NPP provides a proper basis for the continuation of safe operation. The current Hungarian Nuclear Regulations allow the extension of the operation licence of the NPP Units beyond the design life. To prove the acceptability of continuation of operation the Licensee have to prepare a Licence Renewal Application not later than 5 years before the expiration of the design lifetime. The Licence Renewal process based mainly on USNRC approach taking into account the special features of the WWER-440/213 Units. Summary of the preconditions of the Licence Renewal and the activity for the preparation of the operational lifetime extension are reported in the paper

A Paksi Atomerőmű jövője, élettartam-gazdálkodás, élettartam-növelés

A Paksi Atomerımő eredetileg tervezett élettartamán túlnyúló, biztonságos üzemeletetése olyan mőszaki-gazdasági feladat, amely két okból is kiérdemelheti a magyar tudós társadalom érdeklıdését: A nukleáris energia alkalmazásához, az atomerımő biztonságos üzemeltetéshez olyan hozzáértés és szakmai kultúra szükséges, amelynek megtartása, illetve továbbfejlesztése az ország szellemi potenciáljának megtartását-erısítését is szolgálja. Az atomerımő élettartamának meghosszabbítása olyan gyakorlati problémák megoldását követeli meg, amely a fizika, kémia, anyagtudomány eredményeinek újszerő alkalmazását igényli, sıt bizonyos területeken a továbbfejlıdést inspirálja

Phase-field modeling of eutectic structures on the nanoscale: the effect of anisotropy

This is a post-peer-review, pre-copyedit version of an article published in Journal of Materials Science. The final authenticated version is available online at: https://doi.org/10.1007/s10853-017-0853-8A simple phase-field model is used to address anisotropic eutectic freezing on the nanoscale in two (2D) and three dimensions (3D). Comparing parameter-free simulations with experiments, it is demonstrated that the employed model can be made quantitative for Ag-Cu. Next, we explore the effect of material properties, and the conditions of freezing on the eutectic pattern. We find that the anisotropies of kinetic coefficient and the interfacial free energies (solid-liquid and solid-solid), the crystal misorientation relative to pulling, the lateral temperature gradient, play essential roles in determining the eutectic pattern. Finally, we explore eutectic morphologies, which form when one of the solid phases are faceted, and investigate cases, in which the kinetic anisotropy for the two solid phases are drastically different

Silver environment and covalent network rearrangement in GeS3–AgGeS_{3}–Ag glasses

The structure of Ag-doped GeS3 glasses (0, 15, 20, 25 at.% Ag) was investigated by diffraction techniques and extended x-ray absorption fine structure measurements. Structural models were obtained by fitting the experimental datasets simultaneously by the reverse Monte Carlo simulation technique. It is observed that Ge has mostly S neighbours in GeS3, but Ge–Ge bonds appear already at 15% Ag content. Sulfur has ~2 S/Ge neighbours over the whole concentration range, while the S–Ag coordination number increases with increasing Ag content. Ag–Ag pairs can already be found at 15% Ag. The Ag–S mean coordination number changes from 2.17 ± 0.2 to 2.86 ± 0.2 between 15% and 25% Ag content. Unlike the As–S network in AsS2–25Ag glass, the Ge–S network is not fragmented upon Ag-doping of GeS3 glass