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Polaris Lattice Physics for ATF Designs

Matthew Jessee

Ugur Mertyurek

Andrew Holcomb

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Polaris Overview• Fast 2-D lattice physics

• Simple Input– Assembly geometry

– Material definitions– Range of system conditions

• Output– Assembly-averaged few-group cross sections (.t16 file)– ORIGEN Isotope Library (.f71 file)

– ORIGEN Cross section Library (.f33 file) (SCALE 6.3)

• Modeling Requirements– Accurate prediction of lattice k-eff, pin power distribution, few-

group cross-sections, depletion inventories

– Relatively fast: 10,000s of transport calculations per core analysis

• https://www.ornl.gov/sites/default/files/PolarisOverview.pdf

Wide range of LWR geometry support

Polaris GENPMAXS PARCS TRACE

PART I: Polaris Overview

• https://www.ornl.gov/sites/default/files/PolarisOverview.pdf

• PWR Geometry

Part II: ATF Inputs

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ATF Inputs• Several new compositions are provided to support ATF:

– Cr2O3 – chromia used as fuel dopant– BeO – beryllia used as a fuel dopant– Al2O3 – alumina used as a fuel dopant– SiC – silicon carbide used for cladding

• System PWR and System BWR:– The dopants above are added as a property to any FUEL material, Examples– mat FUEL.1 : c_uox3 dens=10.5 : cr2o3=1000 % 1000 ppm weight percent cr2o3– mat FUEL.2 : c_uox3 dens=10.5 : al2o3=500 cr2o3=500 % 500 ppm w/o cr2o3 and 500 ppm w/o al2o3– mat FUEL.2 : c_uox3 dens=10.5 : beo3=750 % 750 ppm w/o beo

• Silicide and Nitride fuel compositions are also supported, examples– comp c_un : UN 4.5 % 4.5 % enriched UN– comp c_usi : USI 3.5 % 3.5 % enriched U3Si2– comp c_un : UN 4.5 n15enr=80 % 4.5 % enriched UN, N15 content in N is 80% enriched (100% is default)

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ATF Tutorial Problem 1 (fuel reactivity comparison)• Use wec5x5 starter input

• Operation data

– 40 MW/MTU specific power

– Burnup points: 0.1 5 10 15 20 25 30 40 50 60 70

– 900K fuel temperature, 600K (all other materials)

– Coolant is 0.6 g/cc and 600 ppm boron

• Compare lattice k-infinity vs burnup for following fuel

– (Fixed U-235 enrichment of 4.0%)

1. UOX fuel, 10.25 g/cc

2. USI fuel, 11.50 g/cc

3. UN fuel, 13.00 g/cc (100% N-15 enrichment, Polaris default)

4. UN fuel, 13.00 g/cc (0.4% N-15, natural nitrogen)

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ATF Tutorial Problem 2 (clad reactivity comparison)• Use wec5x5 starter input

• Operation data

– 40 MW/MTU specific power

– Burnup points: 0.1 5 10 15 20 25 30 40 50 60 70

– 900K fuel temperature, 600K (all other materials)

– Coolant is 0.6 g/cc and 600 ppm boron

• Compare lattice k-infinity vs burnup for following fuel

– (Fixed U-235 enrichment of 4.0%, UOX, 10.25 g/cc)

1. Zirc-4 cladding (570 micron cladding)

2. SiC cladding (570 micron cladding)

3. Zirc-4 cladding with (570 micron cladding+30 micron Cr coat)

• mat COAT.1 : Cr dens=7.19

4. FeCrAl cladding (300 microns, for pins and tubes)

• comp c_clad : WT Fe=75 Cr=20 Al=5

• mat CLAD.1 : c_clad 7.1