The HTGR offers significant improvements in the utilization of uranium and thorium by increases in the conversion ratio of fissile nuclides. The possible tradeoffs in core design features which result in higher conversion ratios are discussed. The cost effects of fuel cycle tradeoffs affecting resource utilization are presented in graphical form. The standard commercial HTGR design shows a clear capability for achieving a conversion ratio approaching 0.8 without significant changes in core structure. A conversion ratio above 0.8 can be achieved with changes in power density. (auth)