Generalization of the Livolant-Jeanpierre method of resonance self-shielding

• Published in: Annals of nuclear energy 1992-02, Vol.19 (2), p.59-63
• Main Authors: Nasr, M., Roushdy, H.
• Format: Article
• Language: English
• ISSN: 0306-4549; 1873-2100
• DOI: 10.1016/0306-4549(92)90024-6

In the formulation of resonance self-shielding of Livolant and Jeanpierre, the case of a single fuel region surrounded by a single moderator region is considered. Also a constant macroscopic flux distribution as a function of energy is adopted. This is far from validity in the case of undermoderated systems or in the case of fast reactor spectra. In the present work we started from the original formulation of Livolant-Jeanpierre, but consider that the fuel is surrounded by several moderating regions. It is found that the structure of the fine flux distribution in the resonance can be described using a series of functions which was found to be rapidly convergent. The method is applied for the calculation of multigroup effective cross-sections of 238U for pin cell rods at different moderating ratios and for annular fuel rods as well as for fast reactor lattices. Results were compared with those obtained by Livolant formalism. It has been found that the discrepancies between the two methods depend on the case treated and they reach more than 2% in the case of the effective cross-section and 1.6% in the case of the effective resonance integral.