Fabrication Development and Application of an Annular Al₂O₃-B₄C Burnable Absorber

The factors affecting MTC of thorium–plutonium-fuelled PWRs

“…We will first examine standard Wet Annular Burnable Absorbers (WABAs) and Integral Fuel Burnable Absorbers (IFBAs). WABAs are burnable absorber rods that comprise of thin-walled Al 2 O 3 -B 4 C annular pellets contained within two concentric and sealed Zircaloytubes, so as to allow the flow of coolant inside and outside of the tube (Radford et al, 1982), and are placed in guide tube positions. This means that they are usually removed from the assembly after the first cycle, so as to allow for the inevitable reshuffling of the assembly to control rod positions in the core.…”

Fabrication of oxide pellets containing lumped Gd2O3using Y2O3-stabilized ZrO2for burnable absorber fuel applications

“…3 Conversely, one possible way to overcome these problems is maximizing the use of BAs. 8,9 On the other hand, lanthanide oxides have a high neutron absorption cross section and a relatively lower sintering temperature; therefore, they can be mixed with uranium oxide fuel. 7 Burnable absorbers can be classified into 2 main categories, namely, boron compounds and lanthanide oxides.…”

“…Because of He gas productions, high sintering temperatures, a relatively low neutron absorption cross section, and a lower burn-out rate compared to that of Gd 2 O 3 , boron compounds are usually applied either as thin coatings on fuel pellets (as used in the integral fuel burnable absorber, in which a thin ZrB 2 coating is applied onto the UO 2 fuel pellet) or in a separate fuel rod (as used in the wet annular burnable absorber, where thin-walled Al 2 O 3 -B 4 C annular pellets are enclosed within 2 concentric and sealed Zircaloy tubes in a separate fuel rod). 8,9 On the other hand, lanthanide oxides have a high neutron absorption cross section and a relatively lower sintering temperature; therefore, they can be mixed with uranium oxide fuel. 10 The UO 2 -Gd 2 O 3 mixed oxide fuel is widely used as a BA for pressurized water-cooled reactors, because it offers a decreased water (moderator) displacement and also reduces the hazardous handling and personnel exposure in comparison with integral fuel burnable absorber.…”