ML16267A029

SFP Pre-Submittal Meeting Slides - BWR Storage Rack Inserts, Updated NCS Analysis at Harris Nuclear Plant

ML16267A029
Person / Time
Site:	Harris
Issue date:	09/29/2016
From:	Duke Energy Corp
To:	Office of Nuclear Reactor Regulation
Barillas M
References
Download: ML16267A029 (12)

Text

LAR Pre-Submittal Meeting 09/29/2016 BWR Storage Rack Inserts, Updated NCS Analysis at Harris Nuclear Plant

Background/LAR Objective BWR fuel from Brunswick Nuclear Plant currently stored at Harris Nuclear Plant Some BWR fuel stored in racks with Boral neutron absorber material Some BWR fuel stored in racks with Boraflex neutron absorber material (focus of this LAR)

Boraflex poison is degrading Boraflex BWR storage racks are being monitored through the Duke Energy corrective action program Current status: operable but degraded License Amendment Request Remove credit for Boraflex in BWR storage racks Update nuclear criticality safety (NCS) analysis for these racks Contracted Holtec International to design and manufacture storage rack inserts for these racks Metamic neutron absorber material Contract includes updated NCS analysis 2

Holtec International Dream Insert for BWR Racks Simple design: L-shaped, full length inserts Only fuel movement will be rotations to line up bail handles Robust material: Metamic Insert design new for BWR racks, but similar installed previously in PWR racks (Turkey Point)

Ample neutron absorption Minimum, Nominal B4C content 21, 25 (wt.%)

Minimum, Nominal B-10 areal density 0.0130, 0.0146 (g/cm2)

Coupons will accompany inserts, supporting surveillance program 3

Updated NCS Analysis of Record for the BWR Boraflex Racks Overall philosophy: multiple layers of conservatism No burnup credit Minimal boron credit: 500 ppm (normal), 1000 ppm (accident) - consistent with PWR racks at HNP Tech Spec minimum: 2000 ppm Fuel assembly tolerances treated as biases No prescriptive loading patterns for fuel: all qualified fuel can be stored throughout the racks Metamic insert in every cell Design basis model has center insert missing Bounding (low) SFP temperature used in design basis model Eccentric fuel/insert position treated as biases Design basis fuel assembly: GE7 Static fuel population (GE3-GE7)

Administrative restriction on GE8 and later models to be stored in SFP C ONLY 4

Updated NCS Analysis of Record for the BWR Boraflex Racks (continued)

Conservative accident scenarios modeled Misload accident fuel assembly: GE13 (scenario analyzed for GE13 in every cell)

Mislocation of PWR 17x17 fuel assembly beside the rack Multiple coincidental missing inserts Significant k-effective margin for normal conditions Ongoing discussion of k-effective margin for accident conditions 5

Addressing DSS-ISG-2010-01 Items

1. Fuel Assembly Selection As mentioned, all different fuel types currently stored in the BWR Boraflex racks were compared. GE7 chosen as design basis assembly For all physically possible assembly types in rack, GE13 most reactive, and, therefore, chosen as accident condition (misload, multiple misload)

2. Depletion Analysis Not applicable for this application (no burnup credit)

Some PWR isotopic information pulled from previous Holtec analysis, only for model completeness

3. Criticality Analysis 3.b. - Rack Model - Analysis follows guidance in the ISG 3.c. - Interfaces - Analysis addresses potential interfaces between rack types 3.d. - Normal Conditions - some typical normal conditions are not so for these racks, since the fuel is not expected to be moved or manipulated until removal from the SFP environment.

3.e. - Accident Conditions - As mentioned previously, conservative accident conditions modeled in the analysis 6

Addressing DSS-ISG-2010-01 Items (continued)

4. Criticality Code Validation MCNP5-1.51 - criticality code; CE cross-sections based on ENDF/B-VII, incorporate NJOY adjustments (temperature dependence)

Criticality code, neutron cross-section data, and analysis methods used have been benchmarked against a variety of critical experiments 4.a. - Area of Applicability - developed and discussed in the NCS report 4.b. - Trend Analysis - performed for bounds of the analysis 4.c. - Statistical Treatment - aligns with ISG expectations 4.d. - Lumped Fission Products - not included 4.e. - Code-to-Code Comparisons - not used to validate criticality code

5. Miscellaneous 5.a. - Precedents - none cited 5.b. - References - appropriate and used within proper context 5.c. - Assumptions - bounding, conservative assumptions as appropriate 7

References/Methodology DSS-ISG-2010-01, Staff Guidance Regarding the Nuclear Criticality Safety Analysis for Spent Fuel Pools - most recent NRC guidance NEI 12-16, Guidance for Performing Criticality Analyses of Light-Water Reactor Power Plants

- pending industry guidance document Review NEI 12-16 Criticality Analysis Checklist (Appendix C of latest revision) for potential issues with this application NEI 16-03, Guidance for Monitoring of Fixed Neutron Absorbers in Spent Fuel Pools -

pending guidance on neutron absorber monitoring 8

Technical Specification Notes/Changes T.S. 3.7.14 - Fuel Storage Pool Boron Concentration No changes (minimum 2000 ppmB)

T.S. 5.6.1.3 - BWR Storage Racks in Pools A and B (Design Features)

Sub-divide for BWR Boraflex storage racks (with inserts) and BWR Boral storage racks Add restriction for storage of fuel types GE8 through GE13 in the BWR Boraflex storage racks T.S. 6.8 - Procedures and Programs Add BWR Boraflex Storage Racks - Metamic Rack Insert Monitoring Program Level of detail similar to Tech Spec Task Force Traveler TSTF-557-T Applied to Metamic inserts only 9

Implementation Strategy Inserts to be shipped to HNP late 2016/early 2017 Inserts installed through 10 CFR 50.59 process Installation scheduled January - October 2017 LAR submission to take credit for inserts: 1st quarter 2017 Request 12 month review from NRC Update operability evaluation if necessary prior to SE Incorporate updated Tech Specs, clear operability evaluation, incorporate other changes once SE is received 10

Questions/Comments/Feedback 11

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