Intranodal depletion effects in MOX cores - 223

The modeling of depletion-history-induced intranodal effects on important neutron physical parameters in nodal diffusion theory is addressed. Consideration is given to a situation where these aspects are of particular importance, namely, in mixed oxide cores where strong interaction between uranium and plutonium mixed oxide assemblies occur. Numerical studies on selected models are performed in order to evaluate their relative merits. It is demonstrated that intranodal effects have to be accounted for in order to obtain accurate pin power predictions. It is also found that the combined use of intranodal isotopic inventory and exposure distributions for estimating intranodal cross section behaviour significantly improves the accuracy in pin powers over the more traditional approach of utilizing exposure distributions only. (author)