RESTORATION OF THE PROPERTIES OF CICULATION PUMPS BLADES METALS BY SURFACE ULTRASONIC IMPACT TREATMENT

Abstract

During the transition period to a market economy, factoryies- manufacturers of equipment for the nuclear industry became lame duck companies. The Mmarket of for heavy industry equipment reduced dramatically, quality control requirements imposed to on the goods became lowered. Deviations from regulations requirements, technical specifications for equipment manufacture, resulted in an inevitable decrease of reliability not only during operations stage but also during check teststests. It is not always possible to promptly replace non-conforming equipment, in such cases it is required to apply compensatory measures to restore properties up to an acceptable level in order to ensure operational reliability due to the strength improvement of equipment parts and structures during the whole service life or up to the scheduled date of equipment replacement.

This paper is dedicated to the development and practical implementation of surface ultrasonic treatment restoration technology used for working with the metal wheels blades metal of  circulation pumps of type 16DPA10-28 located at Novovoronezh NPP-2 unit pump station 10URS. Dynamic surface treatment was implemented to compensate for the process flaws of the metal blades metal. It was demonstrated that impact elastic-plastic deformation has a comprehensive compensation impact on the metal blades metal of the equipment’s initial state and creates a surface hardening layer of 1,.5 mm with higher strength properties. Surface strain hardening increases the cyclic strength, re-distributes the beneficially residual process and maintenance stress, as well as heals repairing minor surface cracks improving the surface quality. The developed technology was used for the treatment of 32 blades of circulation pumps 10PAC01AP001, 10PAC02AP001, 10PAC03AP001, 10PAC04AP001 working wheels.  100-hours tests in situ proved the high efficiency of the developed technology and allow us to recommend its application at during the stage of blades manufacture of the blades as well as during the operational lifetime of the pumps operation with the a view to extending their service life.