3. DESCRIPTION OR FUNCTION
PWR-AXBUPRO-GKN12 contains Axial Burnup Shapes released by Siemens AG Power Generation Group. It contains data sets relative to following NPP and initial enrichment:
- NPP Neckarwestheim 1, Fuel assemblies with an initial enrichment of 3.5 wt.-% 235U
- NPP Neckarwestheim 2, Fuel assemblies with an initial enrichment of 3.5 wt.-% 235U
- NPP Neckarwestheim 2, Fuel assemblies with an initial enrichment of 3.8 wt.-% 235U
- NPP Neckarwestheim 2, Fuel assemblies with an initial enrichment of 4.0 wt.-% 235U
In each of these files the axial shapes are listed one after the other.
Each shape is characterised by
- the number of the cycle
- the number of the fuel assembly.
- axial burnup shape characteristics:
. height (in centimeter) of the nodes with respect to the active length of the fuel assemblies normalized to the cold, unirradiated state.
. the nodal burnup (in MWd/kg U).
- fuel assembly design data as well as core geometry and operating data pertinent to depletion calculations
NPP Neckarwestheim 1 (GKN1) - (square pitch lattice 15X15 - thermal Power 2497 MW)thermal Power 2497 MW)
More than 700 EOC axial shapes from cycle 18 up.
From cycle 18 to cycle 20 a change from an Out-In-Loading to an In-Out-Loading has taken place. Fuel assemblies up to number 1093 have spacer grids made of Inconel, whereas all the fuel assemblies from number 1094 up have spacer grids
made of Zircaloy.
Discharge burnups range from: 9.7 to 52.8 MWd/kg
NPP Neckarwestheim 2 (GKN2) - (square pitch lattice 18X18 - thermal Power 3850 MW) more than 500 EOC axial shapes from cycle 5 up:
- More than 170 shapes for an initial fuel enrichment of 3.5 wt.-% 235U,
discharge burnup ranges from 16.3 to 44.4 MWd/kg
- more than 170 shapes for an initial fuel enrichment of 3.8 wt.-% 235U,
discharge burnup ranges from 14.0 to 52.8 MWd/kg
- more than 180 shapes for an initial fuel enrichment of 4.0 wt.-% 235U.
discharge burnup ranges from 15.5 to 48.9 MWd/kg
PWR AXBUPRO-GKN2K contains a sample of 850 Axial Burnup Shapes released by Nuclear Power Plant Neckarwestheim II, Germany, on May 03, 2000 through Siemens AG Power Generation. All of these shapes belong to one and the same fuel assembly type, namely the Siemens Konvoi fuel assembly type FOCUS (TM). For this fuel assembly type the shapes were gathered from the cycles 5 through 12 of NPP Neckarwestheim II. All the shapes refer to EOCs. The shapes are derived from in-core 3D power density distribution measurements based on flux measurements. At 28 fuel assembly positions the flux data are monitored at 32 equidistant axial nodes. Thus, one has a total of 896 measuring points These measurements are performed every fourteenth day. The measurements are performed with the aid of the Siemens/KWU's Aeroball System which has the advantage of monitoring simultaneously all the axial nodes. The high spatial resolution and the high frequency of the measurement campaigns as well as the accuracy of the measurement result in shapes of outstanding quality. For instance, the spatial resolution suffices to discriminate the flux dips caused by the presence of the spacer grids. What regards the end effect, the presence of spacer grids in the ends of the fuel zone should attract one's attention.
The fuel assemblies to which the axial shapes under examination refer have had initial enrichments of
3.8 wt.-% and 4.0 wt.-% U-235. For the benchmark the initial enrichment is assumed to be 4.0 wt.-%.