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The RBMK design-stage service life was assumed to be 30 years. Ten power-generating units have now exceeded this limit. Service life extension of nuclear power plants is a common practice in countries using nuclear energy. This approach was also applied to power-generating units with RBMK-1000 with servicelife extension to 45 years or more. To maintain electricity production in NPPs with RBMK, a technology for restoring the service-life characteristics was developed and implemented in the No. 1 unit of the Leningradskaya NPP. The results of the adoption of this technology in combination with experimental and computational validation of safety made it possible to extend the operation of the No. 1 unit of the Leningradskaya NPP in the power-generation mode since December 2013. Similar work was subsequently successfully completed in other power-generating units with RBMK.

The basic results of the measures taken to increase the fuel utilization efficiency of RBMK reactors and the promising directions for developing them are examined. The results of a staged increase of fuel enrichment and the introduction of a consumable absorber (erbium) into the fuel are presented. It is shown that the work performed not only greatly improved the cost-effectiveness of RBMK-1000 but should also increase the reliability of fuel operation, which was reflected in a substantial decrease of fuel assembly failures.

The main reasons for and the results of switching to uranium-erbium fuel in the units of the Lengingrad, Kursk, and Smolensk nuclear power plants are presented. It is shown that uranium-erbium fuel made it possible to regulate the steam coefficient of reactivity, upgrade the control rods, lower the power density in the core, increase the reliability of the fuel assemblies, increase burnup, decrease the volume of spent fuel, and improve the commercial indicators. The prospects for improving the characteristics of uranium-erbium fuel for RBMK-1000 reactors are also presented.

It is shown that radiation doping of silicon and the production of medical and industrial radioisotopes in the reactors at the Leningrad nuclear power plant are possible and safe. The production of cobalt with specific activity ~100 Ci/g in an RBMK-1000 reactor is studied. Some promising developments for improving the quality of the radioisotopes produced are described. It is shown that the production volumes can be increased by linking up other nuclear power plants with RBMK reactors into the production chain.

The total amount of stored energy (Wigner energy) and the physical-mechanical properties of the graphite plunger, which exhausted its total service life (6 yr), in the No. 2 unit of the Kursk nuclear power plant were estimated experimentally. The results showed that the total accumulated energy was 180–220 cal/g ((8–10)·105 J/ kg). The real tempearture of the graphite plunger was found to be much lower – 70–80°C compared with the computed value 180–200°C. The energy was nonuniformly distributed over the cross section and azimuth of the plunger.

The changes produced in the physical characteristics by switching to uranium–erbium fuel change the parameters determining the passage of a reactor through the iodine well, and they make it possible to decrease the stand time after a planned shutdown of the unit, thereby increasing the coefficient of utilization of the installed power. It is shown for the reactor in the No. 3 unit of the Smolensk nuclear power plant, using a computer simulation of different core-loading variants, that the stand time can be decreased from 2 to 1 day, since in so doing the reactivity coefficients and effects remain acceptable.

The possibility of using fuel based on weapons-plutonium in RBMK reactors is examined. It is shown that the neutron-physical properties of the RBMK core can be imporved by using such fuel with europium or erbium added as a burnable absorber. 2 figures, 1 table, 4 references.

Experience with uranium-erbium fuel assemblies at the Ignalinsk Atomic Power Plant confirms the possibility of removing additional absorbers and considerably increasing the depth of fuel burnup, while maintaining permissible values of the steam reactivity and other characteristics important for reactor safety. Conversion of the reactor to uranium-erbium fuel permits not only the maintenance of αϕ within specified limits but also compensation for its growth on account of replacement of the control rods. The effectiveness of uranium-erbium fuel up to degrees of burnup close to the design value (∼20 MW·day/kg) has been demonstrated. The good agreement of the theoretical predictions and the actual characteristics offers hope that the complete conversion of reactors to uranium-erbium fuel and appropriate removal of additional absorbers will yield high fuel burnup and considerable improvement in the economic performance of atomic power plants. Other means of increasing the fuel burnup in RBMK-1500 reactors might be to increase the fuel enrichment and erbium content, to use zirconium spacers, and to reduce the operational reserve of reactivity.