ML090980151

Summary of Pre-Application Meeting (Follow-up) with Exelon Generation Company, License Amendment Request for Lasalle County Station, Unit 2 Spent Fuel Storage Rack Modifications

ML090980151
Person / Time
Site:	LaSalle
Issue date:	04/15/2009
From:	Sands S Plant Licensing Branch III
To:	Exelon Generation Co
mahoney, m NRR/DORL/LPLIII-2 415-3867
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ML0909800214	List: ML090980151
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Download: ML090980151 (17)

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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 Apri 1 15, 2009 LICENSEE: Exelon Nuclear FACILITY: LaSalle County Station, Unit 2

SUMMARY

OF MARCH 18,2009, PRE-APPLICATION MEETING (FOLLOW UP) WITH EXELON GENERATION COMPANY, LICENSE AMENDMENT REQUEST FOR UNIT 2 SPENT FUEL STORAGE RACK MODIFICATIONS On March 18, 2009, a Category 1 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Exelon Generating Company (EGC) at the NRC Headquarters, One White Flint North, 11555 Rockville Pike, Rockville, Maryland. The purpose of the meeting was to discuss a pre-application license amendment request for Unit 2 spent fuel storage rack modifications. A list of attendees is provided as Enclosure 1.

The licensee presented information regarding the proposed design and performance of the neutron absorber NETCO-SNAP-IN Insert (See Enclosure 2). This presentation also provided details with respect to long-term spent fuel management strategy, NETCO-SNAP-IN Insert criticality analysis, spent fuel pool (SFP) criticality control, and NETCO-SNAP-IN Insert deployment strategy at the LaSalle County Station.

The NRC staff also discussed the SFP configuration with the licensee and how dry cask operations and proposed rack modifications are integrated with the spent fuel management strategy. Also discussed, was the dual-code approach, methodologies. assumptions and conservatisms used in performing the criticality analysis with the proposed rack modifications.

Members of the public were in attendance. Public Meeting Feedback forms were not received.

Please direct any inquiries to me at 301-415-3154, or SPS1@nrc.gov.

Steph Sands, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-374

Enclosures:

1. List of Attendees

2. Licensee Handout cc w/encl: Distribution via ListServ

LIST OF ATrENDEES March 18. 2009. MEETING WITH EXELON NUCLEAR PRE-APPLICATION MEETING TO DISCUSS NETCO-SNAP-IN INSERTS FOR LASALLE UNIT 2 SFP Name Organization Phone Number Stephen Sands NRC/NRRIDORLlLPLlII-2 301-415-3154 Russell Gibbs NRC/NRR/DORLlLPLlII-2 301-415-7198 Adam Levin Exelon 630-657-2193 Edward Fowles Areva 509-375-8764 Philip Hansett Exelon 815-415-3920 Greg Cranston NRCIDSS/SRXB 301-415-0546 PeterWicyk Exelon 815-415-2469 Kenneth Lindquist NETCO 845-331-8511 I

Terrence Simpkin Exelon 630-657-2800 Kenneth Nicely Exelon 630-657-2803

~lill Fisher Exelon 630-657-2165 Matt Yoder NRC/NRRIDCI/CSGB 301-415-4017 Deann Raleigh LIS Scientech 240-626-9556 Mike Mahoney NRC/NRR/DORLlLPLlII-2 301-415-3867 KentWood NRC/NRRIDSS/SRXB 301-415-4120 Emma Wong NRC/NRRlDCI/CSGB 301-415-1217 Patrick Simpson Exelon 630-657-2823 Enclosure 1

Exeli;.)n.,

Nuclear LaSalle County Station Unit 2 Spent Fuel Storage Racks Pre-Submittal Meeting March 18, 2009 Exelon..

Nuclear Opening Remarks Patrick Simpson Licensing Manager ENCLOSURE 2 1

Purpose

./ Overview LaSalle County Station (LSCS) spent fuel pool (SFP) management strategy

./ Summarize NETCO-SNAP-IN inserts criticality analysis and deployment strategy

./ Obtain NRC feedback Exelon.

Agenda

./ Opening Remarks. . . . . . . . . . . . . . . . . . . .. Pat Simpson

./ Long-Term Spent Fuel Management. Adam Levin Strategy

./ NETCO-SNAP-IN Insert Criticality Ed Fowles Analysis

./ SFP Criticality Control Phil Hansett

./ NETCO-SNAP-IN Insert Deployment Adam Levin Strategy

./ Closing Remarks. . . . . . . . . . . . . . . . . . . . . . Pat Simpson

./ NRC Feedback NRC

2

Exelon~

Nuclear Long-Term Spent Fuel Management Strategy Adam Levin Director, Spent Fuel and Decommissioning Exel~n Nuclear Spent Fuel Management Objectives

./ Maintain keff :0:; 0.95 if fully flooded with unborated water, which includes an allowance for uncertainties

./ Comply with 8.5.b storage configuration requirements

./ Maintain full core discharge capability

• Based on good operating practice; there is no licensing basis requirement 3

Strategic Elements Single Unit Full Core Discharge Capability

./ SFPs are cross-connected and have the ability to move spent fuel between Units 1 and 2 to fully discharge core

• Requires 764 plus -300 open locations (Le., full core plus reload)

• Full core discharge capability may be needed for maintenance (e.g., jet pump maintenance and fuel support piece replacements)

./ Currently there are 947 available locations and 645 unusable locations due to Boraflex degradation Exelon.

Nuclear Strategic Elements Management of Boraflex Degradation ---.

./ RACKLIFE projections (Le., six-month look ahead)

• Project additional 200 cells to be declared unusable on July 1,2009

./ BADGER testing - July 2009

./ Pool water chemistry and temperature 4

Exelon.

Strategic Elements 3-of-4 Storage Configuration

../ Needed as soon as possible to restore full core discharge capability

../ With dry cask storage and f\lETCO-SNAP-IN insert deployment

• Best case: 3-of-4 storage configuration no longer required after delivery of first insert batch (September 2010 target)

• Worst case: some 3-of-4 storage configuration required through 2016

../ Rapidly growing population of fuel channels and other Class BIC low-level radioactive waste (LLRW) irradiated hardware

• 513 fuel channels stored in unusable locations

• Additional 160 fuel channels may be discharged in February 2010

• Channels relocated to cells with blocking devices,~a;>.Rg~j91~(:7ci)w:.j Exelt~n.

Strategic Elements 3-of-4 Storage Configuration (cont.)

./ Fuel assembly management

• Restore flexibility in fuel shuffles for refueling outages

• Restore flexibility in meeting B.5.b requirements

./ Plans for Class BIC LLRW management under development

• Onsite dry storage systems in design

• Potential deployment in late 2010 or early 2011 5

Exel~)n.

Strategic Elements Dry Cask Storage and Rack Inserts

,/ Dry Cask Storage

• Target date for operation is November 2009

• Improvement from 2011 original plans when BADGER testing revealed accelerated degradation in 2006

• Plan to load six dry casks to regain 408 locations in 2009

• Load six systems each year (minimum) through at least 2012

• Annual refueling operations at dual-unit sites results in limited windows for dry cask storage operations

,/ NETCO-SNAP-IN Inserts

• Target date for operation is September 2010

• Driven by licensing, manufacturing, and materials testing schedules

• First-of-a-kind large-scale deployment

• Field demonstration completed successfully in October 2007 Exelon" Nuclear NETCO-SNAP-IN Insert Criticality Analysis Edward Fowles AREVA NP Inc.

6

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Criticality Analysis with 1~c1ear Major Analysis Assumptions '-.....

./ There is no longer any Boraflex in the spent fuel storage racks

./ A chevron shaped neutron absorbing insert has been installed in the corner of each "accessible" storage cell Exelr~n.

NETCO-SNAP-IN Insert 7

Exelon.

Nuclear Criticality Analysis with Inserts Computer Codes

.,/ CASMO-4

• Approved at LSCS for use with MICROBURN-B2 for in-core licensing calculations

• Used to establish maxim um reactivity lattices

• Used for comparison calculations to establish manufacturing uncertainties

• Shown by Studsvik to produce reliable in-rack results relative to criticality experiments

.,/ KENO V.a (SCALE 4)

• Benchmarked against critical experiments to establish a code bias and uncertainty

• Major contributor in defining the final kef! used for comparison to the 0.95 regulatory limit Exeh!.m.

Nuclear Criticality Analysis with Inserts Reactivity Limits for LSCS Fuel Assemblies

./ CASMO-4 lattice comparisons at maximum in-rack reactivity levels using temperatures between 4°C and 100°C

./ All assemblies used and proposed to date were evaluated, including GE 8x8, GE-14, ATRIUM-9, ATRIUM-10, and ATRIUM 10XM leads (J)

./ Bounding ATRIUM-10 fuel lattices defined to be more reactive than the legacy fuel and expected future assembly designs

• A1OT-4.57L1OG38 from 96" to 150"

• A1OB-4.57L1OG60 from 0" to 96" 8

Exelon.

Nuclear Criticality Analysis with Inserts REBOL Lattices

./ REBOl means reactivity equivalent at beginning of life

• Sometimes called REFFE - reactivity equivalent fresh fuel enrichment

• Necessary because KENO V.a does not perform depletion calculations

./ Defined using CASMO-4 to be at least 0.010 ilk more limiting than the bounding top and bottom ATRIUM-10

..-' lattices

./ Each lattice is defined using a single U235 enrichment level and no Gd 20 3 Exelt~n.

Nuclear Criticality Analysis with Inserts Evaluated Normal Conditions

./ Depletion at bounding moderator void levels

./ Actual assembly geometry modeled

./ Assemblies modeled using beginning of life mechanical parameters

./ Storage with or without a fuel channel

./ Uniform versus distributed enrichment

./ Rack and assembly manufacturing tolerances

./ Mixed assembly types

./ Locations without insert and without an assembly

./ Spacers not modeled 9

./ Misplaced assembly

./ Missing insert (most limiting accident)

./ Dropped cC)sembly

./ Limiting assembly position conditions

./ Limiting assembly orientation conditions

. ..~ .._ Exelon.

~

Nuclear Criticality Analysis with Inserts Modeling Conservatisms

./ All lattices of all assemblies are at maximum reactivity ".

./ REBOL lattices are at least 0.007 ~k more reactive than the maximum reactivity lattices supported by this analysis

./ Conservative assumptions have been made throughout this ana.lysis (e.g., water temperature, insert modeling, spacers neglected, fuel rod pitch, no natural uranium, infinite array boundary conditions, etc.)

10

Exelon.

Nuclear Criticality Analysis with Inserts Conclusions

,/ All assemblies manufactured for use in the LSCS reactors, and ATRIUM-10 assemblies that do not exceed the stated reactivity limitations, meet the 0.95 keff regulatory limit when stored in the Unit 2 SFP Exelon~.

Nuclear SFP Criticality Control Phil Hansett Senior Reactor Engineer 11

Exelon.

SFP Criticality Control

./ Analysis demonstrates that regulatory requirement to maintain keff~ 0.95 is met

./ Current additional margin to criticality

• Criticality analyses

- Core resident - maximum uncontrolled, cold, in-core k.., = 1.252

- Pool resident - maximum uncontrolled, cold, in-core k.., = 1.275

- - Bounding future design - maximum uncontrolled, cold, in-core k..,=1.275

• Only five assemblies total are near peak reactivity

• 8.5.b requirements make it unlikely that fuel near peak reactivity in core will be placed near each other, or other peak reactivity assemblies in pool Nuclear N ETCO-SNAP-I N Insert Deployment Strategy Adam Levin Director, Spent Fuel and Decommissioning 12

Exel~""n.

Deployment Strategy

./ Delivery of inserts expected to begin in July 2009

• Initial batch of 182 expected

• Extensive dimensional and tolerance receipt inspections

./ Monthly deliveries scheduled from August 2009 through January 2010, and again from March 2010 through June 2010

./ By June 2010, total of 1875 inserts expected onsite

• -1245 storage locations will be unusable as of July 1, 2010

• All unusable cells will be recovered by summer 2010

• Cells will not be available for use until NRC approval is granted

./ Delivery of 400 inserts per year scheduled from 2011 through 2016

• Stay ahead of unusable cells due to Boraflex degradation (Le., 400 per year)

• Sufficient backlog in the event degradation accelerates Exel~n.

Deployment Strategy Considerations

../ With deployment Percellbg* *FP Locotloll. Wit.. III**' "

strategy working as envisioned, LSCS can maintain full core discharge capability 10% Jk--------,

without reliance upon 40%

3-of-4 storage configuration

../ If all cells were 0%

2010 2011 2012 2013 2014 2011 2011 declared unusable today, insert installation would cover 100% of iocations by 2017 13

Deployment Strategy Considerations (cant.)

./ Risks to insert deployment and the need to maintain the capability of a 3-of-4 storage configuration through 2016

• Near term need to restore full core discharge capability

• Dry cask storage initial campaign

• Additional accumulation of Class BIC LLRW in pools (e.g.,

channels)

• NETCO-SNAP-IN insert manufacturing and deployment capability

• NETCO-SNAP-IN insert licensing

./ Partial delays in dry cask storage and/or insert deployment will lead to need for some 3-of-4 storage configuration; however, the goal is to minimize this impact Exel("n~

Nuclear Closing Remarks Patrick Simpson Licensing Manager 14

Closing Remarks

~ Goal is to restore and maintain full core discharge A

• capability

~ Exelon plans to submit a license amendment request to reflect use of NETCO-SNAP-IN rack inserts

~ Criticality analysis demonstrates compliance with applicable regulatory requirements Nuclear NRC Feedback 15

April 15, 2009 LICENSEE: Exelon Nuclear FACILITY: LaSalle County Station, Unit 2 SUB..IECT:

SUMMARY

OF MARCH 18, 2009, PRE-APPLICATION MEETING (FOLLOW-UP)

WITH EXELON GENERATION COMPANY, LICENSE AMENDMENT REQUEST FOR UNIT 2 SPENT FUEL STORAGE RACK MODIFICATIONS On March 18, 2009, a Category 1 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Exelon Generating Company (EGC) at the NRC Headquarters, One White Flint North, 11555 Rockville Pike, Rockville, Maryland. The purpose of the meeting was to discuss a pre-application license amendment request for Unit 2 spent fuel storage rack modifications. A list of attendees is provided as Enclosure 1.

The licensee presented information regarding the proposed design and performance of the neutron absorber NETCO-SNAP-IN Insert (See Enclosure 2). This presentation also provided details with respect to long-term spent fuel management strategy, NETCO-SNAP-IN Insert criticality analysis, spent fuel pool (SFP) criticality control, and NETCO-SNAP-IN Insert deployment strategy at the LaSalle County Station.

The NRC staff also discussed the SFP configuration with the licensee and how dry cask operations and proposed rack modi'fications are integrated with the spent fuel management strategy. Also discussed, was the dual-code approach, methodologies, assumptions and conservatisms used in performing the criticality analysis with the proposed rack modifications.

Members of the public were in attendance. Public Meeting Feedback forms were not received.

Please direct any inquiries to me at 301-415-3154, or SPS1 @nrc.gov.

IRA!

Stephen Sands, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-374

Enclosures:

1. List of Attendees

2. Licensee Handout cc w/encl: Distribution via ListServ DISTRIBUTION:

PUBLIC RidsOgcRp Resource K. Wood, NRR lPl3-2 rtF RidsRgn3MailCenter Resource E. Wong, NRR RidsAcrsAcnw_MailCTR Resource R. Gibbs, NRR S. Campbell, EDO Region 3 RidsNrrDor1lpl3-2 Resource M. Mahoney, NRR C. Tucci, NRR RidsNrrPMSSands Resource M. Yoder, NRR RidsNrrlATHanis Resource G. Cranston, NRR ADAMS Accesslon . No. PKG ML090980214 Mto. NarIce ML090630536 MtIO. S ummarv w1 SI'd 1 es: ML090980151 OFFICE DORULPL3-2/PM DORULPL3-2/LA DORULPL3-2/BC NAME SSands THarris CGratton for RGibbs DATE 04/14/09 04/14/09 04/15/09 OFFICIAL RECORD COPY