黒鉛減速ガス冷却炉におけるプルトニウムリサイクルの研究, (I)

Abstract

The IBM 704, 709 or 7090 computer code developed at the M. I. T. has been used to analyze the fuel-cycle performance of a gascooled, graphite-moderated reactor. For the first time this code has been used to treat plutonium recycle study in a thermal reactor. Fuel feed cases studied consist of natural uranium, 1.0 _??_ or 1.3_??_ enriched uranium blended with recycle of all, 90%, 75% or none of the plutonium produced in the reactor. The two methods of managing fuel which were studied were simple batch irradiation and bidirectional fuel management.Use of bidirectional fuel management and plutonium recycle greatly increases the amount of energy that can be liberated from a given amount of uranium fuel of specified enrichment. For example, the number of MWd of energy that can be obtained from a metric ton of 1.0 _??_ enriched uranium fuel with various methods of fueling are:Batch irradiation, no recycle 4, 616Batch irradiation, total recycle 7, 660Bidirectional irradiation, no recycle 11, 352Bidirectional irradiation, total recycle 15, 191 Even with natural uranium feed, bidirectional fueling and total recycle of plutonium permits production of 9, 274MWd/t. of uranium.The high burn-up attainable with plutonium recycle is advantageous also in flattening the power density distribution in the core. This permits operation of the reactor at a higher total power when steady state plutonium recycle conditions have been reached than when the reactor is first charged with fuel of uniform composition.Poisoning due to the build-up of 242Pu is less severe than had been expected and could be controlled by-bleeding off and not recycling 1025% of the plutonium.