The Electric Power Research Institute (EPRI) is sponsoring the development of tools to support long-term strategic planning for research, development, and demonstration and for evaluation of advanced nuclear fuel cycles (NFCs). The EPRI-sponsored work under way at Vanderbilt University (VU) is developing a new, comparative risk assessment tool for NFCs. In the course of conducting a demonstration application of the assessment tool, it was observed that the relative contribution of NFC operations to radiological worker impacts estimated by the assessment tool was substantially different from widely used historical data and conventional wisdom. This paper analyzes these differences by first describing the NFC and the nature of radiological worker impacts. Then, the assessment tool developed by VU is described, along with assessment results; historical data relevant to radiological worker impacts are then summarized, and key differences between assessment results and previously reported impacts are identified. This comparison is followed by an analysis of the major factors causing the differences and an assessment of their validity. Finally, several implications of the differences are discussed.