A pressurized water reactor plutonium incinerator based on thorium fuel and seed-blanket assembly geometry

摘要

A pressurized water reactor (PWR)fuel cycle is proposed, whose purpose is the elimination and degradation of weapons-grade plutonium. This Radkowsky thorium-fuel Po incinerator(RTPI) cycle is based on a core and assemblies retrofittable to a Westinghouse-type PWR. The RTPI assembly: however. is a seed-blanket unit. The seed is supercritical, loaded with Pu-Zr alloy as fuel in a high moderator-to-fuel ratio configuration. The blanket is subcritical, loaded mainly with ThO2, generating and burning U-233 in situ. Blankets are loaded once every 6 yr. The seed fuel management scheme is based on three hatches, with one-third of the seed modules replaced every year. The core generates 1100 MW(electric). Equilibrium conditions are achieved with the second seed lending. For equilibrium conditions, the annual average of disposed (loaded) Po is 1210 kg, of which 702 kg are completely eliminated, and 508 kg are discharged but with significantly degraded isotopics (i.e., with a high percentage of even mass isotopes). Spontaneous fissions per second in a gram of this degraded Pu are similar to 500 resulting ill significantly increased proliferation resistance, Every 6 yr the blanket discharge contains 780 kg of U-233 (including Pa-233) and 36 kg of U-235. However, the blankets are initially loaded,with all amount of natural uranium selected such that these U fissile isotopes constitute only 12 of the total U discharge, a percentage equivalent to 20 U-235 enrichment; hence, both the discharged uranium isotopics satisfy proliferation-resistant criteria. The RTPI control variables, namely, the moderator temperature coefficient, the reactivity per ppm boron, and the control rods worth, are about equal to those of a PWR. The RTPI spent-fuel stockpile ingestion toxicity over a period often million years is about the same as the counterpart toxicities of a regular, or a mixed-oxide (MOX), PWR. Compared with known PWR MOX variants, the RTPI is, per 1000 MW(electric) and per annum, a significantly more efficient incinerator of weapons-grade plutonium. References: 8