Spallation-Fission Symbiosis

Abstract

<p>The search for an enhancement of nuclear energy suggests that breeding of fissile fuel from fertile materials as well as the rejuvenation of spent nuclear fuel is of major importance. With the development of linear accelerator breeders it is possible, in principle, to enrich depleted nuclear fuel and to reenrich spent thermal reactor fuel for continued burnup without reprocessing. The management of separated fissile isotope is thus largely avoided.</p> <p>The symbiotic nuclear reactor system analyzed here consists of a linear accelerator breeder and a conventional nuclear converter reactor capable of burning natural uranium fuel. With repeated breed-burn cycles the system nuclear fuel can be brought to fuel burnups of up to and exceeding 27 times the conventional system once-through fuel burnup.</p> <p>The analysis undertaken here shows considerable potential for uranium based fuel cycles relative to that for thorium fuel cycles for the case of low fuel burnup rejuvenation without reprocessing. Consequently uranium-plutonium fuel cycles are analyzed for schemes with periodic chemical fuel reprocessing as well as without reprocessing.</p> <p>This analysis involves the development of a detailed symbiotic system dynamic mass-energy conservation formulation, yielding results ranging from detailed system isotopic concentration histories to general system fuel mass flow and energy flow. A comparison is made between the major parameters of the symbiotic reactor system and its equivalent conventional system.</p> <p>Optimum symbiotic system characteristics are generally obtained for net accumulated fuel burnups below 9 times the conventional once-through fuel burnup. For the presently estimated fuel to capital-operational cost fraction a marginally favorable symbiotic system is only obtained with an energy self-sufficient breeder subsystem. For increased fuel cost fractions, however, the symbiotic system shows, highly improved system characteristics even for net power consuming breeder subsystems.</p>