OPTIMIZATION OF CORE RELOAD DESIGN FOR LOW-LEAKAGE FUEL MANAGEMENT IN PRESSURIZED WATER REACTORS

YOUNG JIN KIM, Purdue University

Abstract

A new method has been developed to optimize pressurized water reactor core reload design for low-leakage fuel management, a strategy recently adopted by most utilities to extend cycle length and mitigate pressurized thermal shock concerns. The method consists of a two-stage optimization process which provides the maximum cycle length for a given fresh fuel loading subject to power peaking constraints. In the first stage, a best fuel arrangement is determined at the end-of-cycle in the absence of burnable poisons. A direct search method is employed in conjunction with a constant power, Haling depletion. In the second stage, the core control poison requirements are determined using a linear programming technique. The solution provides the fresh fuel burnable poison loading required to meet core power peaking constraints. An accurate method of explicitly modeling burnable absorbers was developed for this purpose. The design method developed here was implemented in a currently-recognized fuel licensing code, SIMULATE, that was adapted to the CYBER-205 computer. This methodology was applied to core reload design of cycles 9 and 10 for the Commonwealth Edison Zion, Unit-1 Reactor. The results showed that the optimum loading pattern for cycle 9 yielded almost a 9 percent increase in the cycle length while reducing core vessel fluence by 30 percent, compared with the reference design used by Commonwealth Edison. Cycle length increase is a direct measure of economic savings for a given fuel loading. The results of cycle 10 optimization produced similar improvements. The research represents the first use of an accurate, commercially acceptible neutronics modeling method in an automated optimization procedure which also incorporates burnable absorber design strategy.

Degree

Ph.D.

Subject Area

Nuclear physics

COinS