Thermal and Economic Analysis of Thorium-Based Seed-Blanket Fuel Cycles for Nuclear Power Plants

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Report Date: August 2000
Appendices: No
 
Abstract

From the inception of nuclear power, thorium-based fuels have been of interest due to the abundance of thorium ore and to potential neutronic advantages n the efficiency of creating new fissile materials in the core.  Early reviews of nuclear fuuel cycles tended to conclude that the uranium cycle, currently in nuclear power plants, was more preferable than the thorium cycle, by they considered cycles that involved highly enriched uranium, relatively low fuel burnup and fuel processing and recycling.  The conditions of the nuclear industry have changed, focusing on high burnup once-through fuel cycels (no reporcessing) and U-235<20% of U.  This creates incetives for further analysis of the thoriu-based cycle to assess its economic performance and safety margins given the expected benefits of reduced waste production and enhanced proliferation resistance.  

This theisis analyzes alternative thorium-based fuel approaches from a thermal-hydraulics point of view. The proposed cycle's performance is optimized given constraint that will facilitate the implemenation of the concept in typical commercial power plants.  The new design are based on a seed and blanket configuration, where the seed region is rich in uranium fule (U-235), thus is the supplier of neutrons, and the blanket region is mostly thorium, thus a net neutron absorber to generate new fuel (U-233) from thorium.  

Two different designs are analyzed: the Seed and Blanket assembly as one Unit (SBU) and the Whole assembly as a Seed Blanket (WASB).  These designs are optimized from a thermal-hydraulic perpective and their economic performance is comparted to the current fuel cycle.  The optimization invovles extracting the maximum energy without violating the limits on heat flux from fuel rods to the coolant.  All calculaiton were performed using the subchannel analysis code VIPRE...

Program:     NFC Nuclear Fuel Cycle Program
Type:     TR 

RPT. No.: 25