Analysis Methods for Thermal Research and Test Reactors
PERTURBATION-INDEPENDENT METHODS FOR
CALCULATING RESEARCH REACTOR KINETIC PARAMETERS
Argonne National Laboratory
Argonne, IL 60439-4841 USA
The analysis of research reactor transients depends on the effective delayed neutron fraction (beff), its family-dependent components (beff,i), the prompt neutron lifetime (lp), and the decay constants (li) for each delayed neutron family. Based on ENDF/B-V data, methods are presented for accurately calculating these kinetic parameters within the framework of diffusion theory but without the need for a perturbation code. For heavy water systems these methods can be extended to include the delayed photoneutron component of beff which results from fission product gamma rays energetic enough to dissociate the deuteron. However, a separate calculation is needed to estimate the fractional loss of fission product gamma rays from leakage, energy degradation, and absorption in fuel and structural materials. These methods are illustrated for a light-water Oak Ridge Research Reactor (ORR) LEU core and for a heavy-water Georgia Tech Research Reactor (GTRR) HEU core where measured and calculated values of the prompt neutron decay constant (beff/lp) are found to be in good agreement. In addition, the calculated beff,i values compare favorably with results obtained from a 3D perturbation code.
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Manuel M. Bretscher
Argonne National Laboratory – 362
9700 South Cass Avenue
Argonne, IL 60439 USA
Phone: (630) 252-8616
Fax: (630) 252-5161
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