ML16104A387
| ML16104A387 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/13/2016 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Sreenivas V | |
| References | |
| Download: ML16104A387 (7) | |
Text
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation 1.0 Introduction Purpose of submittal YES Increase enrichment to 5 w/o License changes requested YES Summary of physical changes YES Two regions, remove cell blockers Summary of analytical scope YES New and spent fuel racks 2.0 Acceptance Criteria and Regulatory Guidance Summary of requirements and guidance YES Requirements documents referenced YES Guidance documents referenced YES Acceptance criteria described YES 3.0 Storage Rack Description New fuel storage rack description YES Nominal and tolerance dimensions YES Spent fuel storage rack description Yes Nominal and tolerance dimensions YES 4.0 Fuel Design Description Describe all fuel in pool YES Range of key parameters all past and present fuel designs Nominal and tolerance dimensions YES Describe future fuel to be covered NO None proposed Describe all fuel inserts YES Nominal and tolerance dimensions YES Describe non-standard fuel YES Describe non-fuel items in fuel cells YES Nominal and tolerance dimensions YES Bounding approximation 5.0 Overview of the Method of Analysis New fuel rack analysis description YES Storage geometries NO Single region, no blocked cells Bounding assembly design(s) YES Integral absorber credit NO Accident analysis YES Flooded & Optimum Moderation Spent fuel storage rack analysis description YES Storage geometries YES Two regions Bounding assembly design(s) YES Bounds old and new fuel designs Soluble boron credit YES Boron dilution analysis NO Previously approved analysis referenced Dominion Page 1 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation Spent fuel storage rack analysis description (contd.)
Burnup credit YES One burnup curve Decay time credit YES One burnup curve Integral absorber credit NO Other credit NO Fixed neutron absorbers NO Aging management program NO Accident analysis YES Temperature increase YES Assembly drop YES Multiple misload YES Bounding accident Boron dilution YES Other NO Fuel out of rack analysis YES Handling YES Movement YES Inspection YES 6.0 Cross Sections, Computer Codes, and Validation Code/Modules Used for Calculation of keff YES SCALE6.0/CSAS5 - KENO V.a Cross section library YES ENDF/B-VII 238 Group List all the isotopes used YES Section 8.0 Convergence checks YES Source, histories, trends Code/Module Used for Depletion Calculation YES SCALE6.0/T5-depl - KENO V.a Cross section library YES ENDF/B-VII 238 Group List all the isotopes used YES All SCALE 6.0 (T5-DEPL addnux=3)
Convergence checks YES Step size, histories, rack keff Validation of Depleted Fuel Isotopic Content YES Use ISG 2010-01 (5% burnup worth)
Validation of Code and Library YES Major Actinides and Structural Materials YES Appendix A Minor Actinides and Fission Products YES 1.5% bias (NUREG/CR-7109) 7.0 Criticality Safety Analysis of the New Fuel Rack Rack model YES Full storage area (126 cells plus structure and concrete)
Boundary conditions YES Void Source distribution NO Uniform in fissile material Geometry restrictions NO Dominion Page 2 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation Limiting fuel design Fuel density YES Bounding high Grids NO Not modeled Burnable Poisons NO No credit Fuel dimensions YES Multiple recent designs considered, bounding Axial blankets NO No blankets have been used Fuel plenum and end plug region NO No credit, modeled as moderator Limiting rack model Storage area walls YES Bound-water concrete Flooded 32° to 100°F Temperature YES Optimum Moderation 32° to 100°F Multiple regions NO New 5.0 w/o fuel allowed in all cells Flooded YES Bias and uncertainty calculated Low density moderator YES Bias and uncertainty calculated Offset all assemblies towards middle of Asymmetric fuel placement YES storage area in rack model Tolerances Fuel geometry Fuel pin pitch YES Fuel pellet OD YES Fuel clad ID YES Fuel clad OD YES Guide tube ID YES Guide tube OD YES Axial fuel position YES Axial Fuel Length YES Fuel content Enrichment NO 5.0 w/o is bounding Dish and Chamfer NO Included in Density Density YES Rack geometry Rack pitch YES Cell wall thickness YES Concrete Composition NO Bounding Composition Code uncertainty YES EALF extrapolation Absorber geometry and content NO No absorber credit Biases Temperature YES From code benchmarking Code bias YES EALF extrapolation Absorber geometry and content NO No absorber credit Accident analysis Flooding (water and low density moderator) YES Dominion Page 3 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation 8.0 Depletion Modeling and Burnup Effects TRITON Depletion Model Considerations Time step verification YES Adequate for isotopic convergence Convergence verification YES More neutron histories than required for depletion keff convergence Simplifications YES Described and justified (grids)
Non-uniform enrichments NO None present Nodalization YES 18 nodes depleted independently Fuel clad creep and grid growth YES Evaluated as a bias Limiting depletion parameters Past and present cycles Burnable Absorbers YES Bounding, except for Pyrex (only used in initial cycles)
Integral absorbers NO BPRA bounds WABA and IFBA (WABA plus IFBA not analyzed)
Soluble Boron YES Bounds all burnup average boron Fuel and Water Temperature YES Node-specific values based on bounding high power history fuel assembly, TS minimum flow, 18 node burnup (power) shape, SIMULATE fuel temp tables Specific power YES Includes all core power uprates, bounding high power assembly history, reduced 50% for last 40 days of depletion, proportional to 18 node burnup shape Control rod insertion NO Bounded by BPRA insertion Axial burnup shapes YES Uniform and NUREG/CR-6801 Grids YES Max. volume Zircaloy grids Depleted fuel content nuclide selection Number of nuclides YES All TRITON nuclides Volatile fission products YES Reduced based on release fractions Decay time YES 5 days (base burnup curve) and 3 years (decay time credit) 9.0 Spent Fuel Rack Analysis Rack model YES Two configurations (Regions),both infinite lattice (6x6 model with asymmetric fuel placement)
Boundary conditions YES Periodic X-Y, mirror Z Source distribution NO Uniform in fissile material Geometry restrictions YES 2 out of 4 Region 1, Region interface requirements Dominion Page 4 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation Limiting fuel design Fuel density YES Bounds all fuel batches Grids YES Min. volume Zr grids Burnable Poisons NO No credit Fuel assembly inserts YES With and without depleted BPRA Fuel dimensions YES All fuel designs in SFP considered Axial blankets NO Configurations considered YES Regions 1 (2/4 fresh 5.0 w/o fuel) and 2 (4/4 with burnup credit)
Borated YES Partial bias and tolerance calculations, extra 50 ppm boron, both regions Unborated YES Full bias and tolerance calculations for fresh fuel, most bias and tolerances calculated for depleted fuel, both regions Multiple rack designs NO All racks are the same Boraflex flux trap design Alternate storage geometry NO Axial burnup shapes Non-uniform with justification YES NUREG/CR-6801, except shape 9 Uniform YES 0 to 20 GWd/MTU Region interface effects (mixed shapes) YES Analyzed uniform and non-uniform shapes at minimum and maximum burnup Tolerances Fuel geometry Fuel pin pitch YES Fuel pellet OD YES Fresh fuel, applied to all burnups Fuel clad ID YES Fresh fuel, applied to all burnups Fuel clad OD YES Fresh fuel, creep bias for depleted Guide tube ID YES Fresh fuel, applied to all burnups Guide tube OD YES Fresh fuel, applied to all burnups Axial fuel position YES Fuel stack height YES Fresh fuel, applied to all burnups Burnup worth YES 5% of burnup worth Measured burnup YES 4% of burnup worth Fuel content Enrichment YES Dominion Page 5 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation Tolerances (contd.)
Rack geometry Cell wall thickness YES Rack cell pitch YES Boraflex wrapper thickness YES Boraflex wrapper height YES Captured via axial fuel position variation Rack tie plate thickness and width YES Rack cell pitch YES Code uncertainty YES KENO case uncertainty YES 2 standard deviations Biases Fuel geometry Clad creep YES Grid growth (pin pitch) YES Minimum grid volume YES Minor actinides and fission product worth YES 1.5% of worth (NUREG/CR-7109)
Code bias YES Temperature YES 32 F to 170 F plus code benchmark temperature bias Low power at EOL YES Horizontal burnup tilt YES Incore thimble depletion effect YES NRC administrative margin YES 1% k Modeling simplifications Axial reflectors YES Water reflectors above and below active fuel region 10.0 Interface Analysis Region interface effects YES Calculated Region 1 interface requirements YES Specified 11.0 Normal Conditions Fuel handling equipment YES Bounding analysis Administrative controls YES Minimum boron, fuel handling restrictions, fuel qualification process, etc Fuel inspection equipment or processes YES Bounding analysis Dominion Page 6 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation 12.0 Accident Analysis Boron dilution YES 0 ppm keff < 1.0 including biases and uncertainties Normal conditions YES keff < 0.95 with minimum dilution analysis boron Accident conditions YES keff < 0.95 with TS minimum SFP boron Multiple fuel misload YES Fresh 5.0 w/o fuel in all cells Dropped assembly YES Not limiting Heavy load drop YES Not limiting Temperature YES 32 F to 212 F Seismic event NO Infinite lattice with no rack spacing credit, Region 1 contained within rack modules, benign Region boundaries 13.0 Summary and Conclusions Summary of results YES Burnup curve interpolation YES Bounding cubic equation New administrative controls NO None anticipated Technical Specification markups YES Appendix A Computer Code Validation:
Code validation methodology and bases YES NUREG 6698 Method New Fuel YES Depleted Fuel YES MOX critical YES Included for spent fuel HTC critical YES Included for spent fuel High temperature criticals YES Included, added bias Convergence YES Source, histories, trends Trends YES Bias and uncertainty YES Range of applicability YES Dominion Page 7 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation 1.0 Introduction Purpose of submittal YES Increase enrichment to 5 w/o License changes requested YES Summary of physical changes YES Two regions, remove cell blockers Summary of analytical scope YES New and spent fuel racks 2.0 Acceptance Criteria and Regulatory Guidance Summary of requirements and guidance YES Requirements documents referenced YES Guidance documents referenced YES Acceptance criteria described YES 3.0 Storage Rack Description New fuel storage rack description YES Nominal and tolerance dimensions YES Spent fuel storage rack description Yes Nominal and tolerance dimensions YES 4.0 Fuel Design Description Describe all fuel in pool YES Range of key parameters all past and present fuel designs Nominal and tolerance dimensions YES Describe future fuel to be covered NO None proposed Describe all fuel inserts YES Nominal and tolerance dimensions YES Describe non-standard fuel YES Describe non-fuel items in fuel cells YES Nominal and tolerance dimensions YES Bounding approximation 5.0 Overview of the Method of Analysis New fuel rack analysis description YES Storage geometries NO Single region, no blocked cells Bounding assembly design(s) YES Integral absorber credit NO Accident analysis YES Flooded & Optimum Moderation Spent fuel storage rack analysis description YES Storage geometries YES Two regions Bounding assembly design(s) YES Bounds old and new fuel designs Soluble boron credit YES Boron dilution analysis NO Previously approved analysis referenced Dominion Page 1 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation Spent fuel storage rack analysis description (contd.)
Burnup credit YES One burnup curve Decay time credit YES One burnup curve Integral absorber credit NO Other credit NO Fixed neutron absorbers NO Aging management program NO Accident analysis YES Temperature increase YES Assembly drop YES Multiple misload YES Bounding accident Boron dilution YES Other NO Fuel out of rack analysis YES Handling YES Movement YES Inspection YES 6.0 Cross Sections, Computer Codes, and Validation Code/Modules Used for Calculation of keff YES SCALE6.0/CSAS5 - KENO V.a Cross section library YES ENDF/B-VII 238 Group List all the isotopes used YES Section 8.0 Convergence checks YES Source, histories, trends Code/Module Used for Depletion Calculation YES SCALE6.0/T5-depl - KENO V.a Cross section library YES ENDF/B-VII 238 Group List all the isotopes used YES All SCALE 6.0 (T5-DEPL addnux=3)
Convergence checks YES Step size, histories, rack keff Validation of Depleted Fuel Isotopic Content YES Use ISG 2010-01 (5% burnup worth)
Validation of Code and Library YES Major Actinides and Structural Materials YES Appendix A Minor Actinides and Fission Products YES 1.5% bias (NUREG/CR-7109) 7.0 Criticality Safety Analysis of the New Fuel Rack Rack model YES Full storage area (126 cells plus structure and concrete)
Boundary conditions YES Void Source distribution NO Uniform in fissile material Geometry restrictions NO Dominion Page 2 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation Limiting fuel design Fuel density YES Bounding high Grids NO Not modeled Burnable Poisons NO No credit Fuel dimensions YES Multiple recent designs considered, bounding Axial blankets NO No blankets have been used Fuel plenum and end plug region NO No credit, modeled as moderator Limiting rack model Storage area walls YES Bound-water concrete Flooded 32° to 100°F Temperature YES Optimum Moderation 32° to 100°F Multiple regions NO New 5.0 w/o fuel allowed in all cells Flooded YES Bias and uncertainty calculated Low density moderator YES Bias and uncertainty calculated Offset all assemblies towards middle of Asymmetric fuel placement YES storage area in rack model Tolerances Fuel geometry Fuel pin pitch YES Fuel pellet OD YES Fuel clad ID YES Fuel clad OD YES Guide tube ID YES Guide tube OD YES Axial fuel position YES Axial Fuel Length YES Fuel content Enrichment NO 5.0 w/o is bounding Dish and Chamfer NO Included in Density Density YES Rack geometry Rack pitch YES Cell wall thickness YES Concrete Composition NO Bounding Composition Code uncertainty YES EALF extrapolation Absorber geometry and content NO No absorber credit Biases Temperature YES From code benchmarking Code bias YES EALF extrapolation Absorber geometry and content NO No absorber credit Accident analysis Flooding (water and low density moderator) YES Dominion Page 3 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation 8.0 Depletion Modeling and Burnup Effects TRITON Depletion Model Considerations Time step verification YES Adequate for isotopic convergence Convergence verification YES More neutron histories than required for depletion keff convergence Simplifications YES Described and justified (grids)
Non-uniform enrichments NO None present Nodalization YES 18 nodes depleted independently Fuel clad creep and grid growth YES Evaluated as a bias Limiting depletion parameters Past and present cycles Burnable Absorbers YES Bounding, except for Pyrex (only used in initial cycles)
Integral absorbers NO BPRA bounds WABA and IFBA (WABA plus IFBA not analyzed)
Soluble Boron YES Bounds all burnup average boron Fuel and Water Temperature YES Node-specific values based on bounding high power history fuel assembly, TS minimum flow, 18 node burnup (power) shape, SIMULATE fuel temp tables Specific power YES Includes all core power uprates, bounding high power assembly history, reduced 50% for last 40 days of depletion, proportional to 18 node burnup shape Control rod insertion NO Bounded by BPRA insertion Axial burnup shapes YES Uniform and NUREG/CR-6801 Grids YES Max. volume Zircaloy grids Depleted fuel content nuclide selection Number of nuclides YES All TRITON nuclides Volatile fission products YES Reduced based on release fractions Decay time YES 5 days (base burnup curve) and 3 years (decay time credit) 9.0 Spent Fuel Rack Analysis Rack model YES Two configurations (Regions),both infinite lattice (6x6 model with asymmetric fuel placement)
Boundary conditions YES Periodic X-Y, mirror Z Source distribution NO Uniform in fissile material Geometry restrictions YES 2 out of 4 Region 1, Region interface requirements Dominion Page 4 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation Limiting fuel design Fuel density YES Bounds all fuel batches Grids YES Min. volume Zr grids Burnable Poisons NO No credit Fuel assembly inserts YES With and without depleted BPRA Fuel dimensions YES All fuel designs in SFP considered Axial blankets NO Configurations considered YES Regions 1 (2/4 fresh 5.0 w/o fuel) and 2 (4/4 with burnup credit)
Borated YES Partial bias and tolerance calculations, extra 50 ppm boron, both regions Unborated YES Full bias and tolerance calculations for fresh fuel, most bias and tolerances calculated for depleted fuel, both regions Multiple rack designs NO All racks are the same Boraflex flux trap design Alternate storage geometry NO Axial burnup shapes Non-uniform with justification YES NUREG/CR-6801, except shape 9 Uniform YES 0 to 20 GWd/MTU Region interface effects (mixed shapes) YES Analyzed uniform and non-uniform shapes at minimum and maximum burnup Tolerances Fuel geometry Fuel pin pitch YES Fuel pellet OD YES Fresh fuel, applied to all burnups Fuel clad ID YES Fresh fuel, applied to all burnups Fuel clad OD YES Fresh fuel, creep bias for depleted Guide tube ID YES Fresh fuel, applied to all burnups Guide tube OD YES Fresh fuel, applied to all burnups Axial fuel position YES Fuel stack height YES Fresh fuel, applied to all burnups Burnup worth YES 5% of burnup worth Measured burnup YES 4% of burnup worth Fuel content Enrichment YES Dominion Page 5 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation Tolerances (contd.)
Rack geometry Cell wall thickness YES Rack cell pitch YES Boraflex wrapper thickness YES Boraflex wrapper height YES Captured via axial fuel position variation Rack tie plate thickness and width YES Rack cell pitch YES Code uncertainty YES KENO case uncertainty YES 2 standard deviations Biases Fuel geometry Clad creep YES Grid growth (pin pitch) YES Minimum grid volume YES Minor actinides and fission product worth YES 1.5% of worth (NUREG/CR-7109)
Code bias YES Temperature YES 32 F to 170 F plus code benchmark temperature bias Low power at EOL YES Horizontal burnup tilt YES Incore thimble depletion effect YES NRC administrative margin YES 1% k Modeling simplifications Axial reflectors YES Water reflectors above and below active fuel region 10.0 Interface Analysis Region interface effects YES Calculated Region 1 interface requirements YES Specified 11.0 Normal Conditions Fuel handling equipment YES Bounding analysis Administrative controls YES Minimum boron, fuel handling restrictions, fuel qualification process, etc Fuel inspection equipment or processes YES Bounding analysis Dominion Page 6 of 7 4/26/2016
North Anna Power Station Criticality Analysis Checklist New Fuel Storage Rack and Spent Fuel Pool Proposed License Amendment Request Subject Included Justification / Explanation 12.0 Accident Analysis Boron dilution YES 0 ppm keff < 1.0 including biases and uncertainties Normal conditions YES keff < 0.95 with minimum dilution analysis boron Accident conditions YES keff < 0.95 with TS minimum SFP boron Multiple fuel misload YES Fresh 5.0 w/o fuel in all cells Dropped assembly YES Not limiting Heavy load drop YES Not limiting Temperature YES 32 F to 212 F Seismic event NO Infinite lattice with no rack spacing credit, Region 1 contained within rack modules, benign Region boundaries 13.0 Summary and Conclusions Summary of results YES Burnup curve interpolation YES Bounding cubic equation New administrative controls NO None anticipated Technical Specification markups YES Appendix A Computer Code Validation:
Code validation methodology and bases YES NUREG 6698 Method New Fuel YES Depleted Fuel YES MOX critical YES Included for spent fuel HTC critical YES Included for spent fuel High temperature criticals YES Included, added bias Convergence YES Source, histories, trends Trends YES Bias and uncertainty YES Range of applicability YES Dominion Page 7 of 7 4/26/2016