Russia's Mashinostroitelny Zavod, a subsidiary of nuclear fuel company Tvel, has completed testing of fuel pellets produced using "dry" technology for the ageing Bilibino EGP-6 graphite-moderated boiling water reactors. Tvel said on 17 March that it had "begun to master" the technology in 2008 and had been using it to manufacture fuel for VVER reactors since 2010. "Dry" technology has several advantages over the "wet" variant, Tvel said. In addition to increasing productivity, the technology "eliminates the properties of powders produced in various configurations, lowers operating costs for equipment maintenance as well as processing costs", it said. The four EGP-6 reactors in eastern Siberia were constructed in the 1970s for cogeneration and are due to be decommissioned by 2022.
Meanwhile, Russia's AA Bochvar Research Institute of Inorganic Materials (VNIINM) has received an invention patent for a technique of making ceramic tubes for fuel rod cladding. "The invention relates to processes for development of high-temperature silicon carbide composite materials, which can be used in fabrication of ceramic tubes for fuel rod cladding and other units of the fuel assembly," a VNIINM statement said on 16 March. The new technique involves forming a tubular skeleton of fibre with a special structure and its impregnation with a ceramic precursor in inert gas shielding. This is followed by stage-by-stage heat treatment to obtain a ceramic matrix and ceramic composite during the final high-temperature treatment. VNIINM said this "helps avoid one of main problems with ceramic items, i.e. brittleness". Moreover, the use of components which do not contain chlorine makes the method environmentally safe. Research into replacement of zirconium in fuel rod cladding is being carried out as part of a wider effort to develop Advanced Tolerant Fuel (ATF).
