Calculation of the reactivity worth for TRIGA core fuel elements by means of the two-dimensional, two-group perturbation theory

A two-dimensional, two-group perturbation theory calculation method has bee n proposed for the rapid and accurate calculation of the reactivity worth f or. TRIGA core fuel elements. The method requires shorter computation times and provides almost the same level of accuracy as a conventional direct ei genvalue calculation method using the CITATION code. Values for changes in macroscopic cross-sections and diffusion coefficients are obtained from cel l calculation The reactivity worth for each individual fuel element is calc ulated on the basis of the above-mentioned changes, by means of the two-gro up, first older perturbation method using normal and adjoint neutron fluxes calculated beforehand for a normal core. The method was applied to a 250 k W TRIGA Mark-II reactor. The results of the calculations are in agreement w ith the experimental values for fuel elements in the locations C3, D8, E7 a nd F4. The reactivity worth for the TRIGA core fuel element placed in locat ion B2 calculated by means of this method is approximately 5% greater than that calculated by means of the CITATION code which is based on a conventio nal direct eigenvalue calculation method.