Special Nuclear Material Inventory Processes at US Domestic Nuclear Power Plants

摘要

A general examination of the processes used to generate and analyze the calculated plutonium inventory of irradiated and spent fuel at US domestic commercial nuclear power plants is presented. Our considerations are motivated, in part, by the desire to identify and understand the source of potential shipper-receiver differences for nuclear safeguards. When differences between the shipper-declared values and the receiver's measured values exist, approximations in the codes, methods, and procedures used to generate the calculated spent fuel burnup and isotopic inventory could be responsible, in whole or part. We examine the US reporting requirements of commercial reactor operators required by the Nuclear Regulatory Commission (NRC), the computational predictions made by reactor designers to support these reporting requirements, and the implementation of these computational predictions at the nuclear power plant. The reactor design calculations and plant implementations vary widely among the reactor types, vendors, and utilities involved, but this high-level review provides an indication of the potential and type of uncertainties involved. The discussion is based on the current US domestic commercial nuclear power industry, although international approaches and experience are likely to be similar in countries with well-established nuclear programs. Understanding and quantifying spent fuel isotopic uncertainties is essential to understanding operating utility predictions which ultimately are the declared shipper plutonium inventories.