Analysis for the use of thorium based fuel in LWRs

• Published in: Annals of nuclear energy Vol. 174; p. 109162
• Main Authors: Raj, Devesh, Kannan, Umasankari
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2022
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/j.anucene.2022.109162

•Performance potential of thorium based fuels in representative LWR has been studied.•Comparison of square and hexagonal lattices is presented.•Reactivity effect due to decay of Pa233 and Np239 in thorium and uranium based fuel quantified.•Reactivity coefficients and kinetic parameters do not preclude use of thorium based fuel in LWRs•Potential of thorium based fuel for Pu disposition and effect on Pu and MA production presented. A detailed study has been taken up to assess the use of different fuel cycles based on thorium in current LWRs. Implications of use of thorium based oxide fuel in the existing LWRs, without requiring any structural and geometrical change, has been explored and compared with the prevailing uranium oxide fuel cycle. Owing to lack of intrinsic fissile component in thorium several possible fuel types have been considered which are mixture of thorium with a fissile component. The study has only been made with respect to the operational reactor physics aspects of use of such thorium based fuel. The fuel cycles considered are based on U235, Pu and U233 with thorium. The salient operational reactor physics characteristics, such as burnup of the fuel, reactivity coefficients, worth of the dissolved boron together with the kinetic parameters which has effect on the reactor operation and transients have been highlighted. The study shows that it is possible to use thorium fuel cycles in LWRs without any compromise on reactivity coefficients, except for the U233 + Th fuel where the moderator temperature coefficient of reactivity becomes positive even at modest concentration of dissolved boron.