OPTIMIZATION AND ANALYSIS OF LOW-LEAKAGE CORE MANAGEMENT FOR PRESSURIZED WATER REACTORS
Abstract
Low-leakage extended-burnup fuel management is a promising pressurized water reactor (PWR) improvement which yields better neutron economy than the traditional out-in fuel management scheme with resulting economic savings and a likely reduction in vessel fast neutron fluence. This reduction in leakage is accomplished by locating as many of the fresh assemblies as is practical in the core interior rather than on the periphery. The Commonwealth Edison Zion Unit-1 reactor was selected as representative of current operating PWRs and analyzed. A major objective was to develop and analyze optimum transition loading arrangements leading from present out-in management to the desired low-leakage scheme. The wet BP design, which yields a lower reactivity penalty than the dry BP design, was implemented in our calculational model which was generally based on various modules in the Electric Power Research Institute Advanced Recycle Methodology Program (ARMP). However, a direct search scheme was developed to optimize the loading pattern. The objective function of this search was the initial boron concentration which would correspond to a maximized cycle length for a given number of loaded fresh assemblies. Transition cycles from the current three-batch out-in scheme to the desired four-batch low-leakage pattern were developed using this direct search scheme which included some zoning features to accelerate the calculation. At the equilibrium cycle, 32 out of 48 fresh assemblies are loaded in the core interior, with a requirement for 384 wet BP rods for each cycle. A 6.4 percent savings in fuel cycle costs is thereby realized compared with a three-batch out-in strategy, and a 3.8 percent savings in fuel cycle costs compared with a four-batch out-in strategy. Therefore, the low-leakage option is a promising improvement and further detailed calculation should be considered.
Degree
Ph.D.
Subject Area
Nuclear physics
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.