ML090840113

From kanterella
Jump to navigation Jump to search
Summary of Meeting with Exelon Nuclear to Discuss a Pre-application License Amendment Request (LAR) for Unit 2 Spent Fuel Storage Rack Modifications Involving NETCO-SNAP-IN Inserts
ML090840113
Person / Time
Site: LaSalle Constellation icon.png
Issue date: 04/02/2009
From: Sands S
Plant Licensing Branch IV
To:
Sands S,NRR/DORL, 415-3154
References
Download: ML090840113 (38)
v • d • e


Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 7, ?onq Exelon Generation Company FACILITY:

LaSalle County Station, Unit 2 SlIB..IECT:

SUMMARY

OF JANUARY 29,2009, PRE-APPLICATION MEETING WITH EXELON GENERATION COMPANY, LICENSE AMENDMENT REQUEST FOR UNIT 2 SPENT FUEL STORAGE RACK MODIFICATIONS On January 29,2009, a Category 1 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Exelon Generation Company (the licensee) 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 (LAR) for Unit 2 spent fuel storage rack modifications involving NETCO-SNAP-IN Inserts. A list of attendees is provided as Enclosure 1.

The licensee presented information on the proposed LAR (See Enclosure 2). This presentation provided an overview status of the LaSalle County Station LaSalle, Unit 2 spent fuel pool (SFP) storage and Boraflex degradation issue, summarized the licensee's integrated approach to spent fuel storage, and described the NETCO-SNAP-IN rack inserts and associated criticality analysis.

The NRC staff and the licensee discussed the codes which were used for the criticality analysis for use of the NETCO-SNAP-IN rack inserts with the licensee, and assumptions and conservatisms used when performing the analysis. The licensee also discussed the resolution strategy for the ability to maintain full core discharge capability at LaSalle Unit 2, with respect to dry cask storage.

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 ATTENDEES JANUARY 29,2009, MEETING WITH EXELON GENERATION COMPANY PRE-APPLICATION MEETING TO DISCUSS NETCO-SNAP-IN INSERTS FOR LASALLE UNIT 2 SPENT FUEL STORAGE RACK MODIFICATIONS Name Organization Phone Number Stephen Sands NRC/NRRlDORULPLlII-2 301-415-3154 I

Russell Gibbs NRC/NRRlDORULPLlII-2 301-415-7198 Adam Levin Exelon 630-657-2193 Greg Cranston NRC/DSS/SRXB 301-415-0546 PeterWicyk Exelon 815-415-2469 Kenneth Lindquist NETCO 845-331-8511 Terrence Simpkin Exelon 630-657-2800 Mike Mahoney NRC/NRRlDORULPLlII-2 301-415-3867 Kent Wood NRC/NRRlDSS/SRXB 301-415-4120 Emma Wong NRC/NRRlDCI/CSGB 301-415-1217 Lisa Shofield Exelon 630-657-2815 Patrick Simpson Exelon 630-657-2823

Exel n Nuclear LaSalle County Station Unit 2 Spent Fuel Storage Racks Pre-Submittal Meeting January 29, 2009 m

z

()

r o en

0 m N

c

U -f CD CD CO C-

~

Q)

(fJ r"""+'

Q 3

'< "'0

>> ~

(J)

J (J) c:

Q)

J

()

CD

~

Q)

J Q) co CD...,

Exel n Purpose Nuclear v" Overview status of LaSalle County Station (LSCS)

Unit 2 spent fuel pool (SFP) storage and Boraflex degradation v" Summarize Exelon Nuclear's integrated approach to resolution v" Describe NETCO-SNAP-IN rack inserts and criticality analysis v" Outline regulatory interactions v" Obtain NRC feedback

Exel n~\\

Nuclear Agenda

~ Opening Remarks Terry Simpkin

~ Background Adam Levin

~ Resolution Strategy Adam Levin

~ NETCO-SNAP-IN Rack Inserts K. Scot Leuenroth

~ Criticality Analysis Adam Levin

~ Regulatory Interactions Terry Simpkin

~ Closing Remarks Terry Simpkin

~ NRC Feedback NRC

z

~

ro SJ,J

~

m

)(

(I)

s

Exel nD Nuclear

Background

Spent Fuel Pool Design

../ LSCS Unit 2 SFP consists of 20 high density fuel storage racks and 43 special storage cells

../ Unit 2 SFP has a storage capacity of 4078 fuel assemblies; 3461 storage cells are in use

../ Unit 2 fuel storage racks contain a 0.075" thick sheet of Boraflex neutron poison material and a nominal B-10 loading of 0.0238 g/cm2 between the side walls of all adjacent boxes

../ LSCS Unit 1 fuel storage racks contain BORAL neutron poison material

../ Unit 1 and 2 SFPs are cross-connected

Exel. n~)

--~.._--

Background

Monitoring Programs

¥' Silica trending in pool shows increased degradation beginning in 1999

¥' Part length and full length coupons indicate accelerated degradation in 2005

¥' BADGER testing in 2006 used to renormalize projections (RACKLIFE)

¥' Full core discharge capability will be lost in first half of 2009

00 >>

CD,

Cl.

(')

Q)

CD 0

(') 3 3 0 t""+

r 3 -'

CD (j). en <_.

(J)'"O

J

_. CD g ::J

_. t""+

J co c "

CD-Q)

J Cl.
a (D

tn 0 -..

C 0

s til......

D)

CD ca

Exel n;!)

---~

Nuclear Resolution Strategy Overview v" Implement 3-of-4 loading configuration - 2009

  • License amendment request submitted December 13, 2007 v" NETCO-SNAP-IN rack inserts - 2010
  • Neutron poison replacement for fuel storage applications
  • Requires NRC approval v" Dry cask storage - 2010
  • Implementation of dry cask storage will not eliminate the need for the other elements of strategy

Exel n~,

Nuclear Resolution Strategy Dry Cask Projections to Maintain Full Core Discharge strategy pry Casks in 2010 Dry Casks in 2011 Dry Casks in 2012 Without 3-of-4 analysis 23 11 10 With 3-of-4 analysis 9

6 6

With rack inserts and 3-of-4 analysis 2

4 5

Exel n~,

Nuclear Resolution Strategy Summary

,/ Options to manage the Boraflex degradation and maintain full core discharge capability have been evaluated

,/ Preferred resolution pathway is revision to licensing basis to use 3-of-4 loading methodology and NETCO-SNAP-IN rack inserts

,/ Results in fewer manipulations and minimizes dose, waste generation, and cost

Exel n Nuclear NETCO-SNAP-IN Rack Inserts K. Scot Leuenroth NETCO Project Manager

Exel n!.

Nuclear NETCO-SNAP-IN Rack Inserts Overview v" Refurbish the neutron absorption capability of spent fuel storage racks with degraded Boraflex v" Made of AI/B4C composite v" Extends useful storage rack life v" Minimal impact on fuel move operations

Exel n*~

Nuclear NETCO-SNAP-IN Rack Inserts

~-'-~,<

Project Overview

¥' Joint venture between NETCO and Exelon

¥' NETCO issued U.S. Patent 6,741,669 82 in 2004 for absorber insert design

¥' Clean pool prototype testing performed at Penn State in 2007

  • Full size insert, dummy cell, underwater installation

¥' Proof of concept demonstration completed at LSCS in 2007

Exel n9 Nuclear NETCO-SNAP-IN Rack Inserts

~~--~--.v Description

~ AI-1100/B4C composite, supplied by Rio-Tinto Alcan, formed into a chevron shaped rack sleeve

~ Installed via custom tool from the refueling bridge

~ Chevron is compressed during installation

  • Friction and compression forces hold insert in place

Exel n D

~~

Nuclear NETCO-SNAP-IN Rack Inserts Key Features

¥' Simplicity of NETCO-SNAP-IN

  • Standard fabrication methods demonstrated by Manufacturing Sciences Corporation with actual AI/B4C composite material

¥' Simplicity of installation tool

  • Only two moving parts
  • No electrical or hydraulic systems

¥' Once Installed, NETCO-SNAP-IN rack inserts are an integral part of the rack modules

Exel n S)

NETCO-SNAP-IN Rack Inserts

~~~~-

Application Installation Locations for the LSCS Demonstration vi' When placed in each Nuclear storage location, the NETCO-SNAP-IN rack inserts mitigate the positive reactivity effect associated with degraded Boraflex vi' Installation will be done as-needed at LSCS by onsite fuel handlers vi' Once installed, fuel can be moved in and out of the storage locations as usual HI?

WW~l)

VV5~

N

Exel n~,

---~~-

Nuclear

,-.....~

NETCO-SNAP-IN Rack Inserts LSCS Demonstration

¥' Three inserts were installed in the LSCS Unit 2 fuel storage racks the week of October 22, 2007

¥' Ease of installation was well received by Exelon fuel handlers

¥' Drag testing with a new fuel channel was performed in each location to test clearances

¥' No clearance issues were encountered during testing

Exel n~,

Nuclear NETCO-SNAP-IN Rack Inserts Installation v' Insert being installed in location B17 of the LSCS Unit 2 SFP

Exel n~!

Nuclear NETCO-SNAP-IN Rack Inserts

"""'-.~--~..

Installed Insert N

View Looking Into Locations VV59 and B17 After Installation of a NETCO-SNAP-IN Rack Insert

Exel n s; Nuclear NETCO-SNAP-IN Rack Inserts

-......-...-~

Borated Aluminum Material

../ Evaluation of Alcan and similar materials

  • Comparison of Alcan material with BORAL
  • Review of wet storage experience with BORAL
  • Accounting of NETCO's experience in materials qualification including NRC reviewed evaluations

../ Accelerated corrosion testing

  • Pre-test characterization
  • Accelerated corrosion environment
  • Post-test characterization
  • 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> and 4000 hour0.0463 days <br />1.111 hours <br />0.00661 weeks <br />0.00152 months <br /> test results
  • Accelerated corrosion testing (6000 hour0.0694 days <br />1.667 hours <br />0.00992 weeks <br />0.00228 months <br />, 8000 hour0.0926 days <br />2.222 hours <br />0.0132 weeks <br />0.00304 months <br />)

Exel n Nuclear NETCO-SNAP-IN Rack Inserts

---~~..

Fast Start Coupon Surveillance Program

../ Provide early performance data on the composite material in the LSCS Unit 2 SFP environment

../ Series of 24 coupons (nominal 16 vol% boron carbide) cut from composite material produced for the LSCS demonstration have been installed

../ Exelon plans to place fast start coupons in a cell surrounded with freshly discharged fuel (i.e., center of 3x3 array) following each Unit 2 refueling outage to maximize gamma energy disposition and temperatures

../ Exelon plans to remove two coupons approximately every six months for testing and inspection (i.e., post-test characterization) at a qualified laboratory

Exel n~:,

Nuclear NETCO-SNAP-IN Rack Inserts Long-Term Surveillance Program

../ Specially designed surveillance tree with 24 coupons (nominal 17 vol% boron carbide) attached to each side of a four-sided structure (96 total)

../ Surveillance tree will be installed during the first insert installation campaign and will reside there as long as the fuel racks continue to be used

../ Coupons will be periodically removed and sent to a qualified laboratory for testing

  • Quantify long-term corrosion, including pre-and post-examination
  • Track effects along bend radii
  • Trend galvanic corrosion with 30488, Inconel 718, and Zircaloy coupons

00_. ::t>

CD...,

Q.

(')

Q)

CD 0

(') 3 3 0 r-+

r 3......,

CD 0;' (j) <_.

(/)"'0

J

_. CD g ::::J

_. r-+

J

(.Q

-" c CD-Q)

J Q.

n.._.... -.

n m -_...

J=:s S>> -

fA_.

fA m

z 111

~

n (1)

~ :::s

'"""'t

(~)

Exel n i:,

~~_.~_.,._--~--

Nuclear Criticality Analysis

¥' Reactivity results meet the 0.95 K-eff acceptance criteria including uncertainties and worst case abnormal and accident conditions

¥' Analysis takes no credit for any neutron absorption of the Boraflex

  • Boraflex material replaced with water in rack model

¥' All NETCO-SNAP-IN rack inserts are assumed to be loaded in the same orientation through the pool so all stored fuel assemblies "see" a face of the inserts wing

Exel nD Nuclear Criticality Analysis yI' Criticality analysis performed by AREVA

  • CASMO-4 for determination of differential reactivity associated with manufacturing tolerances
  • KENO V.a for absolute SFP rack reactivity calculations yI' Base analytical model assumes one insert and one bounding reactivity ATRIUM-1 0 assembly in each spent fuel storage cell yI' Base analysis performed at the most limiting temperature of 4°C

Exel n~,

-,,-~--_._~,-

Nuclear Criticality Analysis 1/" Reactivity uncertainty for the following manufacturing uncertainties included:

  • Fuel rod pitch
  • U02 fuel pellet density
  • Channel bulge
  • Pellet diameter
  • Clad diameter
  • Pellet volume
  • Gadolinia concentration
  • Areal B-10 density
  • NETCO-SNAP-IN insert thickness
  • Stainless steel wall thickness
  • Storage cell pitch
  • Storage cell inside dimension

Exel n!)

Criticality Analysis Nuclear

¥' Criticality analysis documentation quantitatively demonstrates the bounding reactivity nature of the ATRIUM-10 design used in criticality analysis relative to all past fuel used at LSCS (GE8x8, ATRIUM-9, ATRIUM-10, and GE14)

¥' Appendix in analysis report compares in-rack K-inf values of bounding reactivity ATRIUM-1 0 design (with installed insert) to the most limiting fuel of past designs (GE8x8, ATRIUM-9, ATRIUM-10, and GE14)

Exel n9 Nuclear Criticality Analysis

~ Resultant rack reactivity using the bounding design is 0.940 K-eff

  • This includes these major components:

- 0.918 rack K-eff

- 0.01 L1K manufacturing reactivity uncertainty

- 0.0035 L1K impact associated with the accident condition of a single insert missing from the interior of the storage rack

~ Analysis specifically incorporates the reactivity effect associated with those assemblies loaded on the periphery being enclosed by only two or three wings of an insert

~ Analysis specifically demonstrates the SFP reactivity decreases when storage cells contain neither an insert nor a fuel assembly

Exel n9 Nuclear Criticality Analysis

'-~-_.,

Summary

../ Calculation performed in accordance with Standard Review Plan

../ Analysis takes no credit for any neutron absorption of the Boraflex

../ Results show maximum K-eff < 0.95

../ Unit 2 SFP may at times contain individual rack configurations that reflect the originally installed Boraflex configuation, 3-of-4 configuration, and rack insert configuration

  • Each of these unique configurations individually meet the criticality acceptance criteria
  • A SFP containing a combination of these configurations also meet the criticality acceptance criteria

Exel n Nuclear Regulatory Interactions Terry Simpkin Regulatory Assurance Manager

Exel n!:,

---~--,-,,~

Nuclear Regulatory Interactions

../ Plan to submit license amendment request to reflect use of NETCO-SNAP-IN rack inserts in first quarter 2009

  • Request approval by first quarter 2010

../ If approved, the rack inserts will be installed and credited to maintain SFP criticality requirements

n o -

en_.

~

c.a

a ft) 3m

~

en

Exel nD Nuclear Closing Rel11arks

../ Ultimate goal is to maintain full core discharge capability v" Proposed resolution involves several elements

  • 3-of-4 loading configuration
  • NETCO-SNAP-IN rack inserts
  • Dry cask storage

../ Exelon plans to submit a license amendment request to reflect use of NETCO-SNAP-IN rack inserts in first quarter 2009

z n

~

tD tD.,.a.

G) n

ML090840113 OFFICE DORULPL3-2/PM DORULPL3-2/LA DORULPL3-2/BC NAME SSands THarris RGibbs DATE 04/2/09 04/2/09 04/2/09

Retrieved from "https://kanterella.com/w/index.php?title=ML090840113&oldid=5318442"