ML110140233
| ML110140233 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 01/13/2011 |
| From: | Omaha Public Power District |
| To: | Office of Nuclear Reactor Regulation |
| Wilkins, L E, NRR/DORL/LPL4, 415-1377 | |
| Shared Package | |
| ML110140223 | List: |
| References | |
| Download: ML110140233 (44) | |
Text
Fort Calhoun Station Extended Power Uprate (EPU)
Project 12/13/2010 1
Spent Fuel Pool Criticality Analysis January 13, 2011
Introductions
- Bob Dulee EPU NSSS/Licensing Manager
- Carmen Ovici EPU NSSS/Licensing Supervisor
- Steve Callis EPU Senior Licensing Engineer
- Bill Hansher FCS Licensing Supervisor 12/13/2010 2
- Bill Hansher FCS Licensing Supervisor
- Bob Schomaker AREVA Project Manager
- Linda Farrell AREVA Principal Engineer
- Jeremy Dean AREVA Supervisory Engineer
Agenda
- EPU Overview - Bob Dulee
- EPU Impact on Spent Fuel Pool Criticality A
l i
Li d F ll 12/13/2010 3
Analysis - Linda Farrell
- Summary and Conclusions - Linda Farrell
- Questions
- Follow-up Actions
Project Overview
- 17% EPU: 1500 MWt to 1755 MWt 80 MWe
- Engineering & Licensing work in progress AREVA S&L d WEC
- AREVA, S&L and WEC
- Submit LAR to NRC: March 31, 2011
- Plant Modifications: 2011/2012 RFOs
- Implement EPU: Post-2012 RFO
Fort Calhoun Spent Fuel Pool Criticality Analysis Analysis Linda M. Farrell, AREVA NP
Purpose
- Allow fresh fuel of up to 5 w/o to be stored in the spent fuel racks at the Fort Calhoun Nuclear Station 12/13/2010 6
Nuclear Station
- Support Extended Power Uprate (EPU) submittal
Analysis Overview
- Methodology is similar to previous AREVA analyses
- All topics listed in DSS-ISG-2010-01 addressed
- Analysis uses
- Soluble boron credit of 500 ppm at all times 12/13/2010 7
- Burnup credit
- Equivalencing of CASMO-3 lumped fission products
- Existing burnup curve from Technical Specification
- CASMO-3 for in-core depletion
- KENO-V.a for all keffand tolerance calculations
Fuel Assembly Selection
- Bounding Fuel Assembly Description
- 14 x 14 fuel assembly
- Nominal planar average enrichment of 5 wt% U-235 (4 95 +/- 0 05 wt%)
12/13/2010 8
235 (4.95 +/ 0.05 wt%)
- No axial blankets or cutback regions
- No axial or radial enrichment zoning
- No integral burnable neutron absorber
Fuel Assembly Selection
- Bounds all existing fuel in the Spent Fuel Pool
- Currently approved for 4.5 wt%
V ifi i
f l f
l 12/13/2010 9
- Verification of legacy fuel
Depletion Analysis Overview
- In-Reactor depletion analysis
- Used NUREG/CR-6801 burnup profiles 12/13/2010 10
- Used CASMO-3 to generate isotopic number densities for burnup credit
- Treatment of CASMO-3 Lumped Fission Product
- Transferred isotopic number densities to KENO-V.a for keff calculations
Depletion Analysis Depletion Uncertainty
- Kopp 5% reactivity decrement to account for uncertainty in number densities generated by CASMO 3 12/13/2010 11 CASMO-3
- 5% of difference between fresh fuel and burnup of interest
- Calculated based on values generated by KENO-V.a
Depletion Analysis Depletion Uncertainty 12/13/2010 12
Depletion Analysis Reactor Parameters
- Values determined for 10 axial nodes and an average assembly 12/13/2010 13
- Used CASMO-3
- Parameters chosen to maximize reactivity of depleted fuel assembly
Depletion Analysis Reactor Parameters
- Fuel Temperature
- Selected to increase Pu production
- Moderator Temperature node specific
- Harden spectrum and increase Pu production 12/13/2010 14
- Harden spectrum and increase Pu production
- Soluble boron concentration (cycle average)
- Core Power - (EPU condition)
- Operating History
- No fixed/integral burnable absorbers modeled
Isotopic Number Densities
- Isotope atom densities in both CASMO-3 and KENO-V.a libraries easily transferred 12/13/2010 15
- The short lived isotopes are decayed prior to input in KENO-V.a
Lumped Fission Products
- Isotopes represented by LFP (ORNL-TM-1658) 46 Non-Saturating (401)
Ge-76 Se-78 Se-80 Br-81 Kr-84 Kr-85 Rb-85 Kr-86 Rb-87 Y-89 Sr-90 Zr-91 Zr-92 Zr-93 Zr-94 Zr-96 Mo-97 Mo-98 Mo-100 Ru-101 Ru-102 R
104 R
106 Pd 110 Cd 111 Cd 112 Cd 114 Cd 116 12/13/2010 16 Ru-104 Ru-106 Pd-110 Cd-111 Cd-112 Cd-114 Cd-116 Sn-117 Sn-119 Sn-120 Sn-122 Te-128 Te-130 Xe-132 Xe-134 Xe-136 Cs-137 Ba-138 Ce-140 Nd-144 Nd-148 Nd-150 Sm-154 Gd-156 Gd-158 15 Slowly-Saturating (402)
Se-77 Se-79 Mo-95 Tc-99 Pd-107 Pd-108 In-115 Sb-121 Sb-123 I-127 I-129 La-139 Pr-141 Nd-145 Tb-159
Lumped Fission Products
- Transfer of LFP isotopic concentrations from CASMO-3 to KENO-V.a
- For the LFP, CASMO-3 output lists
- Two-group fluxes
- Cross sections 12/13/2010 17
- Cross sections
- Number density
- Determined isotope that has an absorption rate ratio similar to the LFP fast-to-thermal absorption rate ratio
- Determined an equivalent isotopic concentration for input to KENO-V.a
Equivalencing
- Total absorption cross section is defined as 2
1 a2 2
a1 1
total a
)
/
(
)
(
)
(
+
+
+
=
12/13/2010 18 Where:
1 - group 1 flux 2 - group 2 flux a1, a2, - absorption cross sections for groups 1 and 2 for each isotope 2
2 1
a2 a1 2
1
/
)
(
)
/
(
+
+
=
Equivalencing
- Derive an equivalent amount for the two pseudo-isotopes by deriving an equivalent macroscopic cross section
X
X
X
+
=
12/13/2010 19 Where:
X - atomic number density for each isotope eq a
402 a
402 401 a
401 eq 402 a
402 401 a
401 eq a
eq
)
X
(X X
or
X
X
X
+
=
+
=
Equivalencing Equivalent isotopic concentration is calculated by orig 2
orig
-1 2
1 402 2
402
-1 2
1 402 401 2
401
-1 2
1 401 eq
)
/
(
)
)
/
((
X
)
)
/
((
X X
+
+
+
+
=
12/13/2010 20 This value is then added to the concentration determined by CASMO-3 and the total used in KENO-V.a calculations This approach yields conservative results within CASMO-3 calculations, and is thus appropriate
- Compared LFP kinfinity to Equivalent kinfinity
Depletion Analysis Burnable Absorbers & Rodded Operation
- As previously discussed 12/13/2010 21
Criticality Analysis Axial Burnup Profile
- Used NUREG/CR-6801
- Used axial burnup shapes for all burnups
- Reviewed axial burnup shapes from 7 cycles of 12/13/2010 22
- Reviewed axial burnup shapes from 7 cycles of operating and planned future cycles
- Included one case at 3.5 wt% and 24.1 GWD/MTU to verify axial burnup shape is conservative and appropriate in 10-30 GWD/MTU range
- Burnup shapes from NUREG/CR-6801 are valid
Criticality Analysis Rack Model 12/13/2010 23
Criticality Analysis Rack Model Three Regions:
- Region 1 of-4 loading U-235 enrichments less than or equal to 5.0 wt% with no burnup credit
- Region 2 of-4 loading U-235 enrichments less than or equal to 5.0 wt% and burnup credit 12/13/2010 24 wt% and burnup credit
- Region 2 peripheral cells of-4 loading U-235 enrichments less than or equal to 5.0 wt% and (lower) burnup credit
- Region 2 and Region 2 peripheral cells dimensions are effectively identical, the peripheral cells do not have neutron absorber between the assembly and the concrete wall
- Region 2 peripheral established due to gamma heating analysis
Criticality Analysis Rack Model
- No degradation of installed neutron absorber (Boral)
Nominal B 10 loading = 0 0151 g/cm2 12/13/2010 25
- Nominal B-10 loading = 0.0151 g/cm2
- Modeled B-10 loading = 0.014 g/cm2
- Fuel extends above Boral plate by 1.3
Criticality Analysis Rack Model
- The K95/95 is calculated using:
K95/95 = keff+biasm+ksys+[C2(k 2+m 2+sys 2+tol 2)+ktol 2]1/2+kBu k = the KENO V a calculated result 12/13/2010 26 keff= the KENO-V.a calculated result biasm= the bias associated with the calculation methodology ksys= summation of k values associated with the variation of system and base case modeling parameters C= confidence multiplier based upon the number of benchmark cases k, m, sys= standard deviation of the calculated keff, methodology bias, and system ktol. tol= statistical combination and standard deviation of statistically independent k values due to manufacturing tolerances kBu= Burnup credit penalty to account for depletion reactivity uncertainty
Criticality Analysis Interfaces
- Interaction effects between Regions 1 and 2 evaluated
- All cases run with 5 wt% U-235 and 4-of-4 loading pattern Evaluated at both 0 ppm and 500 ppm soluble boron 12/13/2010 27
- Evaluated at both 0 ppm and 500 ppm soluble boron
- Both 7/8 and 2 separation distances evaluated
- If keff increases above the maximum of the two individual regions, then there is an interaction effect
- No interaction effect was demonstrated
Criticality Analysis Normal Conditions System Effects
- Moderator Temperature
- Rack-to-rack interactions
- Non Fuel Bearing Components
- Fuel Tolerance Effects
- Theoretical Density
- Pellet OD
- Clad Inner Dimension Cl d O Di i
12/13/2010 28 Rack Tolerance Effects
- Centered to Off-Centered Assembly in Fuel Cell
- Cell Inner Dimension
- Absorber Thickness
- Absorber Width
- Region 1 Cell Pitch x & y
- Region 2 Cell Pitch x & y
- Clad Outer Dimension
- Guide Tube Dimension, ID
- Guide Tube Dimension, OD
- Rod Pitch
- Active Fuel Height
Criticality Analysis Accident Conditions
- Used 500 ppm soluble boron
- Analyzed conditions
- Drop of a fresh fuel assembly outside the rack 12/13/2010 29
- Drop of a fresh fuel assembly outside the rack
- Misload of a fresh assembly into unapproved location
- Boron dilution
- Straight deep drop accident
Criticality Code Validation Introduction
- NUREG/CR-6698 general methodology utilized
- Benchmark configurations
- 100 International Handbook configurations 12/13/2010 30
- 100 International Handbook configurations
- 145 actinide HTC configurations (NUREG/CR-6979)
- 28 fission product configuration from International Handbook
- Complete trend analysis
- Statistical treatment
- Lumped Fission Products
- No code-to-code validation necessary
Criticality Code Validation Area of Applicability
- Experiments fully cover the range of the Fort Calhoun system, thus no extrapolation required
- The most significant physical parameters affecting criticality:
12/13/2010 31
- the fuel enrichment
- the absorber materials
- the lattice spacing
- Other parameters have a smaller effect but have also been included in the analysis
- Sufficient number of experiments to be statistically significant
Criticality Code Validation Area of Applicability 12/13/2010 32
Criticality Code Validation Trend Analysis
- Results analyzed to identify any trends in the bias
- Linear regression analysis used
- Trending Parameters:
12/13/2010 33
Criticality Code Validation Trend Analysis
- Analysis of data
- Weighted and non-weighted linear regression analysis
- Goodness-of-fit tests
- Coefficient of determination 12/13/2010 34
- Students T-distribution
- Test residuals of the regression for trends indicated by Students T-distribution
- Results of the trending analysis
- Very small slopes with no statistical validity, with the exception of the non-weighted trend for fissile isotopic content
- Single-sided lower tolerance band used to establish the bias and uncertainty for fissile isotopic content
- Lower tolerance limit (KL) is conservative
Criticality Code Validation Trend Analysis
- Removal of 11 MOX cases analyzed to determine if they influence bias in non-conservative direction 12/13/2010 35 conservative direction
- Inclusion of cases determined to be insignificant
Criticality Code Validation Statistical Treatment
- Performed two separate trending analysis/bias calculations
- 100 Benchmark Cases 173 (HTC ti id d fi i d
t )
12/13/2010 36
- 173 cases (HTC actinides and fission products)
- Bias and bias uncertainty established
- Bias uncertainty uses variation of population about the mean
- Used 95/95 single-sided tolerance limits for confidence factor
Criticality Code Confirmation Lumped Fission Products
- Replacement of lumped fission product with equivalent
- Cross-code comparison of CASMO-3/KENO-V.a using equivalencing show method is acceptable 12/13/2010 37 equivalencing show method is acceptable 5.00 wt%, 42.3 GWd/mtU 4.20 wt%, 32.161 GWd/mtU CASMO-3:
0.90972 0.92371 KENO-V.a:
0.9109 +/- 0.0004 0.9230 +/- 0.0004
- Note: KENO-V.a is 3D versus CASMO-3 2D
- KENO-V.a incorporates axial leakage and reflection, CASMO-3 does not
Criticality Code Validation Summary
- The bias and its uncertainty
- Used 95/95 weighted single-sided tolerance limit
- Used methodology presented in NUREG/CR-6698 12/13/2010 38
- Took into account the possible trending of keff
- These results support the criticality analysis of the Fort Calhoun spent fuel pool.
- Equivalencing method supported by both equivalent cross-section data and CASMO/KENO-V.a comparisons
Additional Information
- Spacer grid modeling
- Analyzed for including versus not including spacer grids
- Four different soluble boron concentrations 12/13/2010 39 Four different soluble boron concentrations (0, 850, 1700, 2500)
- Overall results are statistically insignificant
- Acceptable to not model the spacer grids
Additional Information
- Geometry changes during irradiation
- Results show negative k - no additional uncertainty is warranted 12/13/2010 40 uncertainty is warranted
Conclusions
- All acceptance requirements are met
- No change to burnup loading curve in existing Technical Specification 12/13/2010 41
- 500 ppm soluble boron during normal conditions
- Very simple loading pattern of-4 for all storage locations
Conclusions
- Margin to limits
- 0.0069 k margin for the boron dilution events
- 0.0028 k margin for misload conditions at 500 ppm of boron 12/13/2010 42 ppm of boron
- Analysis meets requirements for NRC Acceptance for Review
Questions?
Meeting Follow-up Actions