Основні напрямки підвищення ресурсу та ефективності ПЕЛ ПС СУЗ для ядерних реакторів України

• Дата: 2024
• Автори: Zuyok, V., Rud, R., Tretyakov, M., Chernov, I., Kushtym, Ya., Grudnitskii, V.
• Формат: Стаття
• Мова: Ukrainian
• Опубліковано: State Scientific and Technical Center for Nuclear and Radiation Safety 2024
• Онлайн доступ: https://nuclear-journal.com/index.php/journal/article/view/1132
• Назва журналу: Nuclear and Radiation Safety

The neutronic characteristics of known neutron absorbing materials (B4C, Hf, Ag-In-Cd, Dy2O3·TiO2, Eu2O3), which were used or are used in the design of the RCCAs for light water reactors, are systematized and generalized. The calculation results for neutron absorption physical efficiency, changes in isotopic composition, and radioactivity of neutron absorbing materials for VVER-1000 RCCAs (B4C, Hf, Dy2O3·TiO2) are presented. The ways to increase the efficiency of neutron absorption by RCCAs are proposed, the main ones being acceptable for all considered materials are an increase in the density and diameter of the neutron absorbing material for control rod. Among the materials considered, the most acceptable neutron absorption efficiency is achieved by metallic hafnium with an absorbing part diameter of 8.2 mm (the option of using hafnium rod without a cladding) and dysprosium hafnate Dy2O3·HfO2 in the pellet version of control rod filling. The initial relative neutron absorption efficiency of metallic hafnium is 88 %, and that of dysprosium hafnate is 84 %. The use of these materials in the lower part of the control rod will increase the efficiency of the entire control rod even if the lower part is increased from 300 mm to 500 mm. The possibility of using europium hafnate Eu2O3·HfO2 (stoichiometry Eu2HfO5) instead of boron carbide B4C in the upper part of the control rod (from 300 mm to 3500 mm) is considered. It is shown that europium hafnate in the form of pellets with a diameter of 6.85 mm and a density of 8.0 g/cm3 will have an initial neutron absorption efficiency of 95.6 % of that of boron carbide. The high neutron absorption efficiency will allow the use of less efficient (n,γ) absorbers in the lower part, such as Dy2O3·HfO2 or Hf with an absorbing stack length of more than 300 mm, probably without violating the neutronic criteria for control rod performance (requires additional calculations in a specific core configuration).