CORE AND FUEL ASSEMBLY OF PRESSURIZED-TUBE REACTOR (ALTERNATIVES) Russian patent published in 2001 - IPC

FIELD: nuclear reactors. SUBSTANCE: reactor core incorporating fuel assemblies with nuclear fuel in the form of uranium dioxide and erbium oxide pellets should have rated mass fraction of U-235 constituting at least 2.4 mass percent. Erbium content of fuel is chosen from following formula: Er = 0.4 mas.% + 0.5 x (Cact + 0.2 x Cpr + 2.4) mas.%, where Er is mass fraction of erbium in nuclear fuel, mas.%; Cact is actual mass fraction of U-235 in nuclear fuel charged into fuel elements during their manufacture, mas.% ; Cpr is mass fraction of U-236 in nuclear fuel charged into fuel elements during their manufacture mas. %; Cact = 0 at Cpr <0.1 mas.%; K is variable chosen between +0.1 and +0.1 mas.%. Fuel elements used for pressurized-tube reactors should have definite proportion of rated mass fractions of U-235 and erbium oxide in nuclear fuel so as to improve reactor safety and to facilitate its servicing. Provision is made for maintaining steam void coefficient of reactivity for pressurized-tube reactor using additional absorbers. EFFECT: enhanced burnup fraction at reduced maximal heat power of fuel assembly and linear load on fuel elements. 6 cl