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Low-pressure steam turbine retrofits; Nachruestung von Niederdruck-Dampfturbinen  

Energy Technology Data Exchange (ETDEWEB)

LP steam turbine retrofits are generally undertaken as a result of mechanical problems, for example due to stress corrosion cracking, torsional vibration or erosion. They present plant operators with an opportunity to introduce advanced aerodynamic technology, and at the same time improve efficiency and availability. Standard components, the majority proven in long-term service, can be used to obtain a permanent solution to the problems. In several European countries, retrofits have been carried out on intact LP steam turbines owned by utilities whose primary motivation is efficiency improvement. (orig.) [Deutsch] Niederdruck-Dampfturbinen werden in der Regel nur dann nachgeruestet, wenn waehrend des Betriebes Probleme durch Spannungsrisskorrosion, Torsionsschwingungen oder Erosion auftreten. In solchen Faellen bietet sich die Gelegenheit, eine moderne aerodynamische Loesung zu waehlen, die gleichzeitig Wirkungsgrad und Verfuegbarkeit verbessert. Es wird gezeigt, ...

1996-09-01

2

Experience with the austenite materials 1.4541 and 1.4550 in German boiling water reactors; Erfahrungen mit den austenitischen Werkstoffen 1.4541 und 1.4550 in deutschen Siedewasserreaktoren  

Energy Technology Data Exchange (ETDEWEB)

Stabilized austenitic steels can suffer intercrystalline stress corrosion cracking under BWR water conditions. This experience of the last three years, which is important for German nuclear power station technology, has resulted from the discovery of cracks, which were detected in pipework made from titanium-stabilized 1.4541 charged with hot reactor water in six boiling water reactors and in core components made from niobium-stabilized 1.4550 of one BWR plant. Remedies to the pipework have been found by applying optimized materials and fabrication procedures and also by improving water chemistry conditions. (orig.) [Deutsch] Stabilisierte austenitische Staehle koennen unter SWR-Reaktorwasser-Bedingungen interkristalline Spannungsrisskorrosion (IKSpRK) erleiden. Diese fuer die deutsche Kernkraftwerkstechnik bedeutsame Erfahrung der letzten drei Jahre ergab sich aus Rissbefunden, die in mit heissem Reaktorwasser beaufschlagten Rohrleitungen aus dem Ti-stabilisierten ...

1996-10-01

3

Investigation of the influence of nitrogen on the pitting corrosion of high alloyed austenitic Cr-Ni-Mo-steels (Part II); Untersuchungen zum Einfluss des Stickstoffs auf das Lochkorrosionsverhalten hochlegierter austenitischer Cr-Ni-Mo-Staehle (Teil II)  

Energy Technology Data Exchange (ETDEWEB)

Austenitic stainless steel (18% Cr, 12% Ni, Mo gradation between 0,06 to 3,6%) had been solution nitrided. By step-by-step removing, the samples could be prepared with various surface contents of nitrogen from 0.04 to 0.42%. In two test series the influence of nitrogen had been determined. The susceptibility against pitting corrosion of these samples had been tested by the chronopotentiostatical method. For the investigated steel composition and the used corrosion system there is no influence of molybdenum on the effectiveness of nitrogen. The effectiveness of nitrogen can be described by the factor 25 in the PRE. By the investigation of the surfaces with the XPS analysis, it could be shown that the passivation and the pit nucleation is influenced by nitrogen. In these ranges NO{sub x}, NH{sub x}, and NH{sub z}-spectra have been detected. Bound Mo was found in steels containing molybdenum. It is assumed that the repassivation mechanisms of N and Mo work independently of each other. ...

2004-11-01

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Modernizing steam turbines for nuclear power plants; Modernisierung von Dampfturbinen fuer Kernkraftwerke  

Energy Technology Data Exchange (ETDEWEB)

Economic and safe operation of nuclear power plants requires reliable steam turbines with high efficiencies. The progress in flow mechanics achieved over the past few years has allowed the use of powerful methods of flow calculation in developments of new blading with greatly enhanced efficiencies. Thanks to the latest manufacturing techniques, the newly developed blading systems can be produced at low cost. Next to progress in flow mechanics, also the broadbased use of advanced finite-element calculations resulted in a more thorough grasp of the many problems associated with structural mechanics assessment of steam turbine components. The theoretical methods have been supplemented by comprehensive efforts in fracture mechanics and experimental materials studies, thus helping to create a reliable knowledge base which will help to avoid the dreaded stress corrosion cracking phenomenon, in components of steam turbines. The measures introduced to improve operational reliability already in ...

1996-01-01