A. M. Fedosov

Experience with uranium-erbium fuel at the Ignalinsk Atimic Power Plant

ConclusionsExperience 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.

Use of Uranium-Erbium and Plutonium-Erbium Fuel in Rbmk Reactors

The history of RBMK reactors is characterized by continuous transition from one type of fuel to another. The first RBMK units used 1.8% enriched fuel. After that, a decision was made to increase the enrichment to 2.0%. In 1986, it was decided to increase the enrichment further to 2.4%. Currently, transition to fuel with erbium poison and an enrichment of 2.6% is being implemented. These transitions were accomplished with relative ease due to on-line refuelling which is a special feature of RBMKs.

Depth of the Iodine Well in RBMK Burning Uranium–Erbium Fuel

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.

Use of mixed uranium-plutonium fuel with different burnable absorbers in RBMK reactors

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.