DESIGN AND EXPERIENCE OF HEU AND LEU FUEL FOR WWR-M REACTORS

Thin-walled WWR-M5 fuel elements were designed and manufactured and ha ve been used successfully for 16 years; they contain twice as much ura nium-235 as the WWR-M2 and WWR-M3 fuel elements. The fuel elements hav e been optimized with regard to their neutron physics and thermal-hydr aulic parameters and fuel consumption has been minimized. The mean spe cific power in the core of the WWR-M reactor was raised to 230 kW l(-1 ), the measured maximum volume thermal specific power was 900 +/- 100 kW l(-1) and the surface specific power was 136 +/- 15 cm(-2). The WWR -M5 fuel elements enable the power of the WWR-M pooltype reactor to be raised to 30 MW while cm simultaneously increasing the number of cell s in the core available for experimentation by a factor of approximate ly two and reducing fuel element consumption. Reactor tests of WWR-M f uel elements with reduced fuel enrichment (36 and 21%) were carried ou t for a meat uranium density up to 2-3 g cm(-3). Conversion of WWR-SM- type reactors to these fuel elements did not lead to a loss in reactiv ity and enabled their power to be increased to 20-30 MW. (C) 1998 Publ ished by Elsevier Science S.A. All rights reserved.