2020, Savander, V. I., Alassaf, S. H., Савандер, Владимир Игоревич

The efficiency of applying extended operating periods on foreign NPPs under construction with VVER-type reactors designed in Russia has been analyzed in the cases of the temporary storage of spent fuel assemblies on site of the NPP and their transportation to Russia for long-term storage. In order to reduce the flow of spent fuel assemblies for temporary storage, increasing the enrichment of the makeup fuel has been considered, which leads to increases in the fuel burnup and operating period.

2020, Demin, V. M., Savander, V. I., Ternovykh, M. Y., Abu, Sondos, M. A., Демин, Виктор Максимович, Савандер, Владимир Игоревич, Терновых, Михаил Юрьевич

© 2020, Pleiades Publishing, Ltd.Abstract: As the burnup increases, the requirements of nuclear and radiation safety for spent nuclear fuel (SNF) at the subsequent stages of operation grow. The analysis and estimation of the required cooling time of the spent fuel assemblies (SFAs) of the VVER-1200 reactor for transportation in various types of transport containers (TUK-13 and TUK-141O) are performed. The estimates are based on the analysis of residual energy release and gamma-radiation intensity of SNF depending on the cooling time for different burnups. The data on the absorbed dose rate of neutron and gamma radiation from SNF after 4 and 5 yr of cooling are presented.

2020, Alassaf, S. H., Savander, V. I., Hassan, A. A., Савандер, Владимир Игоревич

© 2020 Obninsk Institute for Nuclear Power Engineering, National Research Nuclear University 'MEPhI'. All rights reserved.The paper presents the results of a computational and theoretical analysis dealing with the use of erbium as a burnable absorber in VVER$type reactors. Partial refueling options for the reactor life extension (to a year and a half to two years) are considered, the refueling ratio being equal to three for the former and to two for the latter. Erbium is expected to be present in all fuel elements in the FA with the same weight content. The influence of the erbium weight content on such reactor and fuel neutronic characteristics as burn$up, reactivity coefficients, residual volume of «liquid control», and volumes of the liquid radioactive waste formed has been estimated. Calculations were performed based on a simplified refueling model without FA reshuffling. An infinite mesh of polycells, consisting of FAs with different in$core times, was considered. The neutron escape from the core was taken into account through the selection of the critical value KҐ at the end of life. Erbium does not burn up altogether for the core life which affects the fuel burn$ up reduction as compared with the liquid system for excessive reactivity compensation. The reduction is 0.7% per 0.1% of the erbium weight load in the fuel element. This, however, also reduces the maximum content of the boron absorber in the coolant and the accumulation of LRW in the ratio of 5% per 0.1% of the erbium weight load. Erbium influences the spectral component of the coolant temperature reactivity coefficient which turns out to be negative even with a minor weight fraction in fuel and the decrease in the boron absorber fraction leads to a positive value of the density reactivity coefficient. As the result, the total coolant temperature reactivity coefficient has a negative value throughout the life.