High conversion ratio plutonium recycle in pressurized water reactors

Abstract

About 2000 MTU/year of reprocessing capacity is expected to be available by 1978. Additional capacity probably will not be added until 1982. At this rate of recovery, some 10,000 kg of plutonium might be available each year from 1979 through 1981. At that time, demandfor reprocessingcapacity should increase rapidly. Indeed, even should this rate of reprocessing be achieved, the expected backlog of discharge fuel is some 6000MTU containing about 30,000 kg of plutonium by 1981. Efficient utilization of the large quantities of plutonium to be generated in light water reactors is clearly in the best interest of the nation during the time period required to develop a base for a large commercial fast breeder industry. This development may well take 20 ya at the current rate of progress. In any event, I believe there is a strong incentive to use plutonium light water reactors in such a way as to minimize the depletion of plutonium needed for future use and to reduce to a much greater extent, than heretofore envisioned, the projected demands for uranium ore and enrichment capacity, while at the same time accelerating the growth of nuclear power generation capacity. Fuel utilization in pressurized water reactors can be measurably improved by using a tightly packed lattice of fuel rods. Conversion ratios in the range 0-8 to 0.9 appear to be feasible. These should be compared with conversion ratios of about 05 in plutonium recycle designs using the fuel to water volume ratios of current operating PWK's. A conceptual design for the Babcock & Wilcox Company reactors (Duke Power Co., 1969) now in operation is presented for illustrative purposes. In order to obtain the potential benefits of an improved plutonium recycle core as early as possible, mechanical design changes are restricted to the components within the existing core baffles and above the lower grid plate. No changes to the control drive mechanism including the coupling to the control rod assembly and the location of the in-core instrumentation appear to be necessary. Thus, it is quite possible to implement the mechanical changes in the core design of the concept presented in this paper with a minimum disruption of power generation.