Authors & Affiliations
Beznosov A.V., Zudin A.D., Korotin A.S., Talin V.A.
A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
Zudin A.D. – graduate student, Nizhny Novgorod State Technical Un iversity n.a. P.E. Alekseeva. Contacts: 24, Minin st., Nizhny Novgorod, Russia, 603950. Tel.: 8(902)305-60-99; e-mail:
Beznosov A.V. – Dr. Sci. (Tech.), Professor, Nizhny Novgorod State Technical Un iversity n.a. P.E. Alekseeva.
Korotin A.S. – postgraduate student, Nizhny Novgorod State Technical Un iversity n.a. P.E. Alekseeva.
Talin V.A. – postgraduate student, Atomic and thermal power station of Institute of Nuclear energy and technical physics, Nizhny Novgorod State Technical Un iversity n.a. P.E. Alekseeva.
Abstract
At the present time, specialists in Russia are engaged in designing the BREST-OD-300 fast neutron lead-coolant reactor plant. There is currently no experience in designing and operating axial pumps of lead-coolant reactor plants, including one of their major units – bearing unit. Using a hydrodynamic bearing in systems running on liquid-metal coolants (Pb, Na, Pb-Bi, etc.) is impossible due to the following reasons. The conventional working process of such bearings, which is based on creating a hydrodynamic lift force, implies two necessary conditions: complete wetting of the shaft surfaces with a liquid lubricant and of the sleeve with a lubricating fluid, and high viscosity of such fluid. In bearing units of loops running on lead and lead-bismuth coolants, either of these conditions is missing. Due to low viscosity at operating temperatures, any calculation according to the conventional methods (for conditions of wetting with oils) provides small levels of relative and absolute values of gaps between the shaft and the sleeve, which makes it impossible to create such structures. On benches using lead and lead-bismuth coolants, boundary or contact friction bearings made of steel and cast iron are widely used. For friction-type bearings of test bench pumps, an operational life of several years and less is sufficient. Subject to mandatory stops of the benches and as consisted with their operational programs, a simple and rapid replacement (once in one-two years) of bearing pairs is satisfactory unlike the operational conditions of bearings used in reactor loop pumps.
The particular features of contact friction bearings operation in a lead and lead-bismuth coolant medium may include as follows: - mandatory presence of oxide coatings (films) on the surfaces of structural components; - intensive removal by liquid metals of heat generated in the friction zone.
The conventional contact friction conditions mean conditions, under which between friction surfa ces, there is no liquid or non-fluid oil wetting such friction surfaces. A dry wetting substance in a solid phase may be present, such as oxide films on metal surfaces, as well as a periodic or constant flush of contact surfaces with a low-viscous fluid not wetting the surfaces and being no lubricant.
The purpose of these experimental investigative tests is to define tribotechnical characteristics of a contact friction bearing model and geometrical relationship of the bearing components on the NNSTU FT-6 bench in a high-temperature lead coolant medium taking into account specific features of such coolant.The operating results of the liquid-metal pumps developed and tested at the NNSTU prove the possibility of using contact friction bearings in pumps intended to pump lead, lead-bismuth and lead-lithium coolants having a temperature up to 510°C (maybe higher) on test benches with a time to removal of bearing units at least 1,500-2,000 hours.
Keywords
fast neutron lead-coolant reactor, heavy liquidmetal coolant, slide bearings, contact friction bearings, tribotechnical characteristics, oxide coatings, friction, wear, contact surfaces, oxygen activity in the lead, resource
Article Text (PDF, in Russian)
UDC 621.039
Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2016, issue 4, 4:8