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FRAPCON Statistical Package

FRAPCON/FRAPTRAN Users Group Meeting

September 7, 2012

Paul CliffordDivision of Safety Systems

Office of Nuclear Reactor Regulation

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Statistical Package

• FRAPCON-3.4 designed to provide best-estimate predictions. NRC needed ability to perform independent fuel rod design calculations.

• FRAPCON statistical package performs the following tasks:– randomly samples among specified distributions of manufacturing

tolerances, modeling uncertainties, and rod power uncertainties,– creates multiple FRAPCON input decks,– executes each of these unique cases, and – compiles the results (e.g., plots, 95/95 UTL, data files).

• Statistical package also allows introduction of a power ramp to existing rod power history.– User specifies ramp magnitude (KW/ft), time duration, and burnup

time step.

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Statistical Package (cont.)

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Manufacturing Tolerances

• Manufacturing tolerances may be defined as a variety of distributions including uniform and normal.

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Modeling Uncertainties

• FRAPCON calibration modeling uncertainties defined in NUREG/CR-7022, Volume 2.

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Usage

• NRC using FRAPCON statistical package to perform independent fuel rod design calculations.– End-of-life rod internal pressure.– LOCA initialization (stored energy).– AOO overpower cladding strain.– AOO overpower fuel power-to-melt.

• FRAPCON confirmatory calculations may support review of a variety of licensing applications.– New fuel rod designs.– Fuel vendor transitions.– Power uprates.– Condition reporting (e.g., fuel thermal conductivity degradation).– Review of new fuel performance models/methods.

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PWR 16x16 – UO2 Rod 1

Calculated end-of-life rod internal pressure (500 cases):

Nominal = 1676 psia

95/95 with sampled TOL = 1847 psia

95/95 with sampled TOL + FGR = 1873 psia

95/95 with sampled TOL + FGR + POW = 2015 psia

0

1

2

3

4

5

6

7

8

9

0 5 10 15 20 25 30 35 40 45 50

Rod

Ave

rage

Pow

er (K

W/ft

)

Rod Average Burnup (GWd/MTU)

Limiting 2nd Cycle

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PWR 16x16 – UO2 Rod 2

Calculated end-of-life rod internal pressure (500 cases):

Nominal = 1809 psia

95/95 with sampled TOL = 1977 psia

95/95 with sampled TOL + FGR = 2088 psia

95/95 with sampled TOL + FGR + POW = 2332 psia

0

1

2

3

4

5

6

7

8

9

0 10 20 30 40 50 60

Rod

Ave

rage

Pow

er (K

W/ft

)

Rod Average Burnup (GWd/MTU)

Limiting 3rd Cycle

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PWR 14x14 – UGdO2 Rod

Calculated end-of-life rod internal pressure (500 cases):

Nominal = 1319 psia

95/95 with sampled TOL = 1463 psia

95/95 with sampled TOL + FGR = 1785 psia

95/95 with sampled TOL + FGR + POW = 1820 psia

0

1

2

3

4

5

6

7

8

9

0 200 400 600 800 1000 1200

Ro

d A

vera

ge

Po

wer

EFPD

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Conclusions

• FRAPCON statistical package provides a robust tool for performing independent fuel rod design calculations.

• During the past 12 months, NRC has completed confirmatory calculations to support the following licensing actions:– Calvert Cliffs Units 1 &2 fuel transition (CE 14x14).– Turkey Point Units 3 & 4 extended power uprate (W 15x15).– St. Lucie Unit 1 extended power uprate (CE 14x14).– St. Lucie Unit 2 extended power uprate (CE 16x16).

• NRC will continue to utilize statistical package to support licensing actions.