Discussion: Session 1b

W.J. MAECK

I would like to add some further comments to my Paper 5. Three methods have been consid ered for the determination of burn-up in FBR

fuels. These are :

(1) change in the isotopic composition

(2) change in the heavy element concentration

(3) fission product analysis

The fuel composition and expected sources of

fission for a 1000 MWe FBR is given in Fig.Dl.

Based on best estimate values for the cross sections and neutron spectra, the change in

the isotopic composition (Fig. D2) and the fr actional sources of fission (Fig. D3) have been calculated as a function of burn-up. Because the change in the isotopic composition