[en] For the last 15 years at the Research Institute of Atomic Reactors, a wide variety of work has been carried out on the development of the reactor fuel cycle using the electrochemical method for granulated oxide fuel production and technology for manufacture of fuel elements and assemblies with vibropac cores. These studies are discussed

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[en] There are presented main principles of creation and operation of Quality Management Program in fabricating vibropack oxide fuel pins for BOR-60 and BN-600 being in force in SSC RF RIAR. There is given structure of documentation for QS principal elements. Under Quality System there are defined all the procedures, assuring that fuel pin meets the normative requirements. The system model is complied with the standard model IS 9001. There are shown technologic flowchart and check operation, statistic results of pin critical parameter check as well as main results of in-pile tests. (author)

[en] The main aspects of radiation behavior of fuel elements on the basis of UPuO₂ vibropac fuel are studied in particular, fuel swelling, thermal-mechanical and physical-chemical interaction of fuel with the cladding in stationary and transient operating conditions and fission products behavior. It was shown that fuel elements with a composition based on vibropac, have no corrosion damage of the internal surface of the cladding and that the availability of peripheral area with initial granulate provides a decrease in thermal-mechanical stresses. (R.P.)

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[en] The main results on investigations of fast reactor fuel pins with (UPu)O₂ vibropac fuel to substantiate their serviceability up to the super-high burnups are presented. The BOR-60 reactor fuel pins radiation behaviour in stationary, transient and designed emergency conditions has been determined from the fuel pins dimensional stability analysis having regard to the results of investigation fuel and cladding swelling as well as estimations of fuel and cladding thermal-mechanical and physico-chemical interactions. It is shown that the change of the outer diameter is minimum in fuel pins with VMOX fuel with a getter-metallic uranium powder and ferrito-martensite steel cladding, and the corrosion damage of the cladding inner surface is absent up to 26% h.a. The experiments with over-heating of the irradiated fuel pins cladding up to 850 deg. C did not lead to any changes in pins integrity. The availability of the periphery area of the vibropac fuel cure initial structure provides the minimum level of the thermal-mechanical stress at transient conditions of reactor operation. (author)

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[en] The objective of the work is to obtain experimental data on time history of thermal-physical behaviour of standard FA fuel pin under BOR-60 operation. The contact-free technique is used which is based on processing of the results of special dynamic experiments ''power variation - temperature response'' with fast registration of sodium temperature by means of a thermal probe mounted over cell D-23 of the BOR-60 reactor. The method in use makes it possible to evaluate integral thermal physical characteristics of fuel rods in any power changes, for example, under planned bringing to power and also from results of passive registration of natural noise of power and temperature. Subsequent reprocessing of registration results by using specialized technique provides information about integral thermal-physical characteristics of the fuel rod on different operation stages. Tracing of standard vibropac MOX FA characteristics according to this method during 6000 hours shows that the integral thermal resistance of the fuel rods decreases by a factor of 1.5-2. It is explained by fuel densification when sintering, which causes fuel restructuration and thermal conductivity increase. (author)

No abstract available

[en] Since the end of 1981 RIAR has been carrying out integrated investigations and developments to validate fuel cycle of fast reactors BOR-60, BN-350 and BN-600. These investigations and developments involve fabrication, in-pile tests and postirradiation examinations of fuel pins and FA containing granulated vibropac MOX fuel. Plutonium of various grades and levels of FP purification has been used for this fuel production (WG - weapon-grade; PG - power-generating plutonium including the one with low level of FP purification and MA additives). In present-day design of vibropac MOX fuel pin the most significant parameters, determining reliability of the fuel pin, are getter additive in the form of 5-10%wt of metal uranium particles and cladding material of the fuel pin. Experience in vibropac fuel tests in the BOR-60 reactor showed that vibropac MOX fuel had satisfactory life-time characteristics even at a superhigh burnup, up to 30%h.a. All EFAs operated in the BN-600 reactor for the specified life in accordance with the test program. The maximum thermal loadings of fuel pins in the FA were in the range of 39.5-46.8 kW/m, the maximum cladding temperature was within 627-703 deg. C taking into consideration uncertainty of parameters. The maximum dwell-time of EFA in the core was 569 eff. days. The peak achieved burnup was 10.6 % h.a., damage dose - 80.9 dpa. No violations of safe operation limits were observed during experimental FAs irradiation in the BN-600 reactor. Information about the quantity of manufactured fuel pins and FAs, their purposes and types of granulated fuel used in these FAs is presented. In most fuel pins fuel contained a 'dedicated' additive - getter in the form of metal uranium particles (3 -10 %wt). Along with mass fabrication of the fuel pins and FAs, RIAR has developed procedures of producing granulated oxide fuels and fuel pins for fast reactors of the next generation. These are fuel pins containing recycled PuO₂, residual fission products (up to 8%wt), recycled MOX fuel, MA additives NpO₂, Am_xO_y (2 - 5 %wt), high in PuO₂ (up to 45%wt), etc. The fuel pins with these types of fuel are irradiated in the BOR-60 reactor, and in most cases they are incorporated in dismountable FAs, which makes it possible to perform interim nondestructive inspection of the tested fuel pins. From results of RIAR research and developments a decision was taken about creation of facility for granulated MOX fuel production and BN-800 vibropac FA fabrication