High conversion Th-U233 fuel for current generation of PWRs: Part I – Assembly level analysis

High conversion pressurized water reactor with boiling channels

“…Optimal configurations and compositions of the fissile and fertile fuel zones with high breeding ratio were studied by Shwageraus et al (2009) and Baldova et al (2014). These studies considered a square fuel lattice with radial heterogeneity, where the fissile seed is located in the center and fertile blanket in the periphery of the fuel assembly.…”

“…As a result, the safety constraints will inevitably limit the practically achievable core power density. In previous studies, Volaski et al (2009), Kotlyar and Shwageraus (2012a,b) and Baldova et al (2014), it was estimated that the high power peaking imposed a reduction in the core power density by at least 30%. Although these studies presented designs with conversion ratio of unity or higher, the required power reduction of the core would diminish the economic advantage of the concept.…”

“…Although in conventional PWRs limited sub-cooled boiling is allowed, it is an undesired phenomenon because it leads to preferential deposition of crud, precipitation of soluble boron and resulting axial power shape distortion. In high conversion PWRs Kotlyar and Shwageraus, 2012a,b;Baldova et al, 2014) however, the excess core reactivity is very small and may allow operation without soluble boron using only mechanical (control rods) shim. In such case, boiling may no longer be an issue as long as the operating and safety envelope of the core is preserved.…”

Review of the microheterogeneous thoria‐urania fuel for micro‐sized high temperature reactors

“…Examples of seed elements other than the 235 U is 233 U, which has a higher reproduction factor value, η (the average number of neutrons from fission per neutron absorbed by fuel) than other fissile materials. This possibly ensures extended fuel burnup and increased breeding rate of 233 U from 232 Th 53,54 . Alternatively, innovative fuel design such as duplex fuel pellet could be used to extend ThO 2 burnup 11,14,17,23,47,54‐56 …”

Comparison of neutronic behavior of UO 2 , (Th- 233 U)O 2 and (Th- 235 U)O 2 fuels in a typical heavy water reactor

“…Proliferation resistance of thorium-based fuel matrixes is another advantage of these fuels regarding noticeable reduction of the high radiotoxic waste production views [3]. Thorium fuel can be used in all types of reactors, such as the Boiling Water Reactor (BWR) [4], Pressurized Water Reactor (PWR) [5], Fast Reactor [6], Accelerator Driven Subcritical Reactor (ADSR), and Pressurized Heavy Water Reactor (PHWR) [7].…”