ML18275A272

Enclosure 2 - River Bend Station Spent Fuel Pool Criticality Analysis of Boraflex Storage Racks with NETCO-SNAP-IN Rack Inserts

ML18275A272
Person / Time
Site:	River Bend
Issue date:	09/13/2018
From:	Global Nuclear Fuel
To:	Office of Nuclear Reactor Regulation
Shared Package
ML18284A174	List: ML18275A272 ML18275A276 ML18283B940
References
KGO-ENO-LD1-18-120
Download: ML18275A272 (12)

Text

ENCLOSURE 2 KGO-ENO-LD1-18-120 River Bend Station Spent Fuel Pool Criticality Analysis of Boraflex Storage Racks with NETCO-SNAP-IN Rack Inserts Non-Proprietary Information IMPORTANT NOTICE This is a non-proprietary version of Enclosure 1, from which the proprietary information has been removed. Portions of the enclosure that have been removed are indicated by an open and closed bracket as shown here (( )).

Non-Proprietary Information Global Nuclear Fuel River Bend Station Spent Fuel Pool Criticality Analysis of Boraflex Storage Racks with NETCO-SNAP-IN Rack Inserts

Non-Proprietary Information Regulatory Requirements 10 CFR 50.68 (b) (4)

The k-effective of the spent fuel storage racks loaded with fuel of the maximum fuel assembly reactivity must not exceed 0.95, at a 95 percent probability, 95 percent confidence level, if flooded with unborated water.

General Design Criterion 62, Appendix A to 10 CFR 50 Criticality in the fuel storage and handling system shall be prevented by physical systems or processes, preferably by use of geometrically safe configurations.

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Non-Proprietary Information Methodology Overview

• Consistent with NEI 12-16 Revision 3, Guidance for Performing Criticality Analyses of Fuel Storage at Light-Water Reactor Power Plants.

• Peak reactivity analysis with most limiting (bounding) lattice in every rack cell location.

• No credit for the Boraflex neutron absorber (modeled as water).

• B-10 areal density used for rack insert analysis (0.0115 g B-10/cm2) is 10%

less than the certified minimum areal density (0.0129 g B-10/cm2).

• Quantification of credible normal and abnormal conditions with consideration of biases, rack/fuel tolerances and computational uncertainties.

• Covers current and future (GNF3) fuel product lines at River Bend Station.

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Non-Proprietary Information Analysis Uncertainty Quantification

/

The contribution from the biases are:

The contribution from the tolerances are:

The contribution from the uncertainties are:

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Non-Proprietary Information Computer Code Calculations TGBLA06 a MCNP-05P b

• NRC-approved lattice physics code

• Monte Carlo N-Particle code used for in (NEDE-30130-P-A). rack reactivity (keff) calculations.

• TGBLA solves Two-Dimensional (2D)

• Uses point-wise (i.e., continuous) ENDF/B-diffusion equations with diffusion VII cross-section library, and all reactions parameters corrected by transport in a given cross-section evaluation are theory to provide system considered.

multiplication factors and perform * ((

burnup (depletion) calculations.

• Uses ENDF/B-V cross-section data.

• Performs coarse-mesh, broad- ))

group, diffusion theory calculations; * ((

including thermal neutron scattering with hydrogen using an S(,) light water thermal scattering kernel.

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a) (( b) MCNP-05P is the GNF controlled production version of the Los Alamos National Laboratory code MCNP5.

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Non-Proprietary Information Boraflex Rack Cell Model with Inserts

((

• No credit taken for Boraflex neutron absorber.

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• Assumes every rack cell contains a design basis bundle with the worst rack reactivity suppression capability (i.e., highest rack efficiency) ((

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• ((

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• Stainless steel rack modeled.

• B-10 areal density used in the rack insert model is 10% lower than the certified minimum (95/95).

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Non-Proprietary Information Design Basis Bundle

(( * ((

)) bounds current and future fuel types at River Bend Station.

• Design basis bundle is selected to be the bundle with the worst rack reactivity suppression capability (i.e., highest rack efficiency) ((

))

• The design basis bundle is used to:

Define the nominal in rack keff result.

Used for performing all biases, manufacturing tolerances, computational uncertainty calculations, and all credible abnormal/accident condition calculations.

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Non-Proprietary Information Fuel Storage Conditions Analyzed Credible Normal Conditions Credible Abnormal Conditions

• ((

• Dropped/Damaged assembly

• Misloaded or mislocated fuel assembly

• Missing insert

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• No inserts along the rack periphery 8

Non-Proprietary Information Analyzed Tolerances and Biases Bundle and Rack Tolerances Fuel Depletion Bias

• (( * ((

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• Rack pitch

• (( ))

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Non-Proprietary Information Analysis Uncertainties

• ((

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Non-Proprietary Information Summary

• Analysis complies with requirements in 10 CFR 50.68 and GDC 62.

• Follows guidance in NEI 12-16 Revision 3.

• Consideration given to all credible abnormal conditions, manufacturing tolerance implications, and computational uncertainties in determining maximum in-rack eigenvalue.

• The analysis resulted in a storage rack maximum k-effective less than the 0.95 limit from 10 CFR 50.68 for normal and credible abnormal operation with tolerances and computational uncertainties taken into account.

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