PRODUCTION OF NUCLEAR CERAMIC FUEL FOR NPP AT "ULBA METALLURGICAL PLANT" OSC

V.G. Khadeyev "Ulba Metallurgical Plant" OSC

Uranium production exists at "Ulba Metallurgical Plant" Open Stock Company for more than 40 years. During the years an up-to-date production of nuclear ceramic fuel of uranium dioxide has been formed making possible to solve problems of products development, timely meeting of requirements of active area designers for pellets to provide reactor safety".

The paper describes the flow-sheet of production of uranium dioxide powders and nuclear ceramic fuel pellets of them existing at the facility. "UMP" OSC applies ADU extraction process of U02 powders production. An indisputable success of the process is the possibility of use of the wide range of raw materials. Uranium hexafluoride, uranium oxides, uranium metal, uranium tetrafluoride, uranyl salts, uranium ore concentrates, all possible types of uranium-containing materials the processing of which by routine methods is difficult (ashes, scraps, etc.) are used as the raw materials. In addition, a reprocessed nuclear fuel can be used for fuel production. The quality of uranium dioxide powder produced does not depend on the type of uranium raw material used. High selectivity of extraction refining makes possible to obtain material with rather low impurities content that meets practically all specifications for uranium dioxide known to us. Ceramic and process features of uranium dioxide powders, namely, specific surface, bulk density, grain size and sinter ability make possible to produce nuclear ceramic fuel with specified features. Quality of uranium dioxide powders produced by "UMP"OSC was highly rated by General Electric company that is one of the leading companies from fuel manufactures in the USA market. It has certified "UMP"OSC as its supplier. Currently, our company makes great efforts on establishing production of uranium dioxide powders with natural isotopes content for production of fuel for CANDU reactors. Trial lots of such powders are under tests at some companies manufacturing fuel for this type reactors in Canada, USA and Korea.

Fuel pellets are manufactured at "UMP"OSC by powder metallurgy methods. The company has successfully introduced the process of dry uranium dioxide powders pressing without their preliminary compacting. It was due to high quality of uranium dioxide powders. A process of fuel pellets production with controlled parameters of micro structure of nuclear ceramic fuel has been developed. The use of uranium dioxide powders with high sinter ability make possible to produce fuel with the grain size 15-25 mm that is the best to provide safety and high effectiveness of reactor operation. The use of special foaming agents make possible to achieve the needed distribution of pores in a fuel pellet allowing to avoid the fuel swelling during the long high temperature treatment. The methods of manufacture of uranium/gadolinium and uranium/erbium fuels the use of which also increases reactor safety level have been introduced and are widely used at the facility.

In 1999 "UMP"OSC developed and introduced the method of uranium ore concentrates processing making possible to obtain nuclear grade material in one cycle of processing without the use of additional refining operation in further conversion in the nuclear fuel cycle. At present, the most pan of uranium mined in Kazakhstan is processed by the method at "UMP"OSC.

The facility is active in offering its services and has its own niche in the market of conversion of uranium-containing materials, such as scrap, clean-outs, non-conforming products of ceramic nuclear fuel production. The use of special conditions of these materials digestion and high technology refining operations make possible to involve considerable quantity of uranium into production.

Production of ceramic nuclear fuel at "UMP" OSC was certified by RV TUW for its compliance with ISP 9000 specification. All products of the facility exhibit fine quality and the company has never had any claims from its customers.

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