Reactivity and isotopic composition of spent PWR (pressurized-water-reactor) fuel as a function of initial enrichment, burnup, and cooling time

Abstract

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Calculation Uncertainties in Spent Fuel Inventory Determination

“…The results of variations in the enrichment are depicted in Figure 9. The changes in uranium isotopes content were expected because their initial content was also modified together with the enrichment [11].…”

Sensitivity and Parametric Evaluations of Significant Aspects of Burnup Credit for PWR Spent Fuel Packages

“…3. nuclides must be fixed in the fuel matrix (i.e., no credit taken for volatile elements); and 4. the predicted concentrations of selected nuclides in spent fuel must be verifiable by comparison with chemical assay measurements.…”

“…As an historical aside, early burnup credit studies [1][2][3][4][5][6][7] were often based on 23 or 24 actinides and fission products, while later (and current) calculations will be found to be based on only 22 important actinides and fission products. Originally, 24 important burnup credit nuclides were identified, based on existing and anticipated chemical assay data.…”

“…The following tables provide k values calculated for fuel enrichments of 3.0, 3.6, and 4.5 4 wt % U, for burnups of 10, 30, and 50 GWd/MTU, for various cooling times ranging from 0 to 235 200 years. General trends observed in these results are discussed and illustrated in Sect.…”

“…Since the inception of burnup credit studies at ORNL, a significant number of analyses have been performed to study the effect of various parameters on the calculated value of k " or k eff for spent fuel configurations. [1][2][3][4][5][6][7][8][9] This work has included parametric studies of the effect of factors including burnup, cooling time, initial enrichment, use of an axial burnup profile, and the number of subdivisions necessary to accurately account for this profile, reactor operating history, specific power, assembly design, and the nuclides included in spent fuel modeling. However, this earlier work was performed using a variety of baseline model configurations and different versions of the SCALE code system, and was often directed at specific technical questions.…”