Use of Thorium for Transmutation of Plutonium and Minor Actinides in PWRs

Abstract

The objective of this work was to assess the potential of thorium based fuel to minimise Pu and MA production in Pressurised Water Reactors (PWRs). The assessment was carried out by examining destruction rates and residual amounts of Pu and MA in the fuel used for transmutation. In particular, sensitivity of these two parameters to the fuel lattice Hydrogen to Heavy Metal (H/HM) ratio and to the fuel composition was systematically investigated. All burn-up calculations were performed using CASMO4 -the fuel assembly burn-up code. The results indicate that up to 1 000 kg of reactor grade Pu can potentially be burned in thorium based fuel assemblies per GW e Year. Up to 75% of initial Pu can be destroyed per path. Addition of MA to the fuel mixture degrades the burning efficiency. The theoretically achievable limit for total TRU destruction per path is 50%. Efficient MA and Pu destruction in thorium based fuel generally requires a higher degree of neutron moderation and, therefore, higher fuel lattice H/HM ratio than typically used in the current generation of PWRs. Reactivity coefficients evaluation demonstrated the feasibility of designing a Th-Pu-MA fuel with negative Doppler and moderator temperature coefficients. 280

Diffuse reflectance spectra of U ions in ThO2

“…However increased sinterability of UO 2 -bearing fuel can be engendered by first sintering in air and then completing the cycle in hydrogen. UO 2 -ThO 2 fuels offer increased burnups via the breeding of fissile 233 U from the Th in addition to the fissile 235 U and there is recent renewed interest in such fuel [1][2][3][4]. These fuels can be produced by sintering in air.…”

Thorium-based mixed oxide fuel in a pressurized water reactor: A beginning of life feasibility analysis with MCNP

“…Since an initial fuel composition was needed to begin the core configuration analysis, a literature review was performed, and a Th-MOX fuel composition of 7 wt% PuO 2 and 93 wt% ThO 2 was selected from the work of Shwageraus et al (2004). The isotopic composition for plutonium used in this work and shown in Table 1 was also adopted from their work.…”

“…Shwageraus et al have investigated the use of Th-Pu fuel in PWRs for both the destruction of plutonium (Shwageraus et al, 2004) and improved economics (Shwageraus et al, 2002). Bjork et al studied the use of Th-Pu fuel for extending the operating cycle of a PWR .…”

Assembly-level analysis of heterogeneous Th–Pu PWR fuel

“…This increases the Pu incineration rate as additional Pu is not bred from 238 U, although fissile 233 U is bred instead (Galperin, 1995;Shwageraus et al, 2004a).…”