9.183. The peaking factor design approach for liquid-metal-cooled fast breeder reactors, i. e., LMFBRs (§15.51), is inherently similar to that used for water-cooled reactors, but differs in some respects [26]. In PWRs and BWRs, hot-channel factors are used primarily as part of the determination of design margins in relation to a boiling crisis. In LMFBRs, however, the factors and subfactors are used together with computer codes to identify operating margins in relation to a variety of other thermal and hydraulic design limits, e. g., those affecting cladding temperature and the structural integrity of the core internals. Fuel failure propagation is also of concern. A statistical treatment is generally used to analyze the entire core rather than to identify a single hot channel. An objective is to determine the number of channels that approach design limits within specified confidence ranges in a manner analogous to the PWR statistical approach described in §9.172 et seq.

INTRODUCTION

10.1. Reactor fuel management is concerned with those activities in­volved in the planning for and design of the fuel loading for a nuclear power plant. Planning activities include fuel procurement over a period of years as required for future reload batches and consideration of utility operational strategy that may affect the energy production of the given generating unit. Fuel loading design requires not only the development of specifications for a new fuel batch, but also the determination of the core location for fuel assemblies from previous batches which will be reinserted. The nature of these activities will become clearer to the reader as the relevant topics are presented.

10.2. The nuclear fuel cycle is the path followed by the fuel in its various states, from mining the ore to the disposal of the final wastes. At one time, the fuel “cycle” envisioned the recycling of recovered fissile and fertile material from spent fuel. However, in the United States, the prospect of this being implemented in the near future is remote. Therefore, from the viewpoint of an electric utility operating a nuclear power plant, major
interest is in the fuel burnup stage and associated fuel management. In fact, without plutonium recycle, as practiced in Europe, the objective in the United States is to obtain as much energy as possible at minimum cost using a once-through cycle. We will therefore cover the pre-reactor fuel cycle steps in only enough detail so that fuel procurement is understand­able. Post-reactor operations and waste management are treated in Chapter 11.

10.3. Economic considerations play a significant role in fuel manage­ment. Although a comprehensive discussion of nuclear power economics is beyond our scope, some background is essential for an understanding not only of core management but of many aspects of plant system design and operation. Nuclear energy-generating expenses normally include costs associated with the capital investment required, the cost of fuel, and op­eration and maintenance charges. Later in this chapter, a brief introduction to these cost categories will be given. In Chapter 14 we will show how the relative cost contributions affect plant operation strategy.