CHAPTER 5 - Enriched Reactors

Abstract

Publisher Summary This chapter discusses enriched reactors. If natural uranium fuel is enriched even to a modest degree by the addition of fissile, the design constraints are appreciably relaxed. For enriched reactors, the number of permutations and combinations of type and configuration of fuel and moderator become very large. Existing and planned reactors can be divided roughly into four main groups: (1) heterogeneous graphite-moderated gas-cooled, (2) heterogeneous water-moderated and cooled, (3) homogeneous reactors, and (4) fast (un-moderated) reactors. This chapter focuses on the reactor types within these broad groups that have been tried with some success as actual or potential power reactors, together with mention of systems that appear to be particularly attractive as future reactor types. The most conservative in principle of the enriched reactor designs is the advanced gas-cooled reactor (AGR) or Mark II reactor, which is the basis of the second generation of nuclear power reactors. Like the Magnox or Mark I reactors, AGRs are of heterogeneous design, graphite-moderated and carbon dioxide-cooled, but as the fuel contains about 2.5% of fissile material rather than 0.7%, it is possible to use high-melting-point uranium oxide rather than metallic uranium as fuel, and this allows a considerable increase in the operating temperature.