Dependence of LMFBR fueling requirements on plutonium isotopic composition

When the liquid metal fast breeder reactors (LMFBRs) start up, plutonium from thermal reactors will be required to enrich the reactor fuel. Neutronics analyses performed to determine the fueling requirements for an 800 megawatt electric (MWe) breeder reactor are described. This study was initiated when it was assumed that thermal reactor plutonium recycle would take place prior to the introduction of the breeder. Therefore, a range of plutonium compositions was fed into the LMFBR and the fueling requirements were determined for these various compositions. Depleted uranium was used as the diluent. The analysis were performed for two reactor designs - a reference small fuel pin design and an advanced large fuel pin design. Burnup calculations were performed to determine the compositions of the discharge plutonium