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Non-proprietary - Presentation for September 13, 2012, Proposed License Amendment Request for Spend Fuel Pool Criticality Analysis
	ML12236A332
Person / Time
Site:	Comanche Peak
Issue date:	08/23/2012
From:	; Westinghouse
To:	; Plant Licensing Branch IV
	Singal B
References
	TAC ME8896, TAC ME8897
	Download: ML12236A332 (61)
	v • d • e

SFP Criticality Methodology for Comanche Peak Westinghouse Electric Company September 13th, 2012 Non-Proprietary attachment to CE-12-656 1

Contents

Objectives of the Comanche Peak Nuclear Power Plant (CPNPP) SFP Analysis

Methods to be used in the Analysis

- Plant Changes from Current AOR

- Depletion Calculation Inputs

- Biases & Uncertainties

- Accidents & Soluble Boron

- Interface Conditions 2

Objectives for the Comanche Peak Analysis

To provide the NRC with an analysis with appropriate conservatism to meet current NRC expectations while providing as much operational flexibility as possible to CPNPP.

- NRC concerns conveyed via the Interim Staff Guidance, and any information notices

- ISG suggestions are addressed in each individual section 3

Methodology for CPNPP Analysis

The CPNPP analysis will follow the guidance provided in WCAP-17483-P

Deviations from WCAP-17483-P guidance will be called out in the site-specific application submitted by CPNPP 4

Plant Changes from Current AOR

The following plant changes may be made which are being incorporated into the new criticality AOR

- Power: Increase from 3577 MWth to 3612 MWth

- Fuel Type: [ ]a,c

- Extension of soluble boron credit to all configurations

- Peak Assembly Average Power: 1.0 to [ ]a,c

- Cycle Ave. Boron Conc.: 1500 ppm to 900 ppm

- Configurations: Increase from 5 to a maximum of 8 5

Depletion Calculation Inputs

Depletion parameters will impact the isotopic inventory of depleted fuel

Major depletion inputs include:

- Fuel Type;

- Axial burnup and moderator temperature profiles;

- Core Power (linked to fuel temperature in PARAGON)

- Soluble boron concentration; and

- Usage of burnable absorbers/consideration of rodded operation 6

Fuel Type Input

CPNPP has gone through several fuel design changes that are significant in terms of criticality safety

[

]a,c 7

Fuel Type Input (cont)

[

]a,c 8

Axial Burnup and Temperature Profiles

[

]a,c 9

Limiting Burnup Profile Selection

[

]a,c 10

Temperature Profile Selection

Temperature profiles are based on assembly power distributions

[

]a,c 11

Burnable Absorber Assumptions

CPNPP has used:

- Pyrex and other Solid discrete B4C based absorbers;

- WABA;

- IFBA/WABA; and

- IFBA

[

]a,c 12

ISG comments on Depletion

ISG items 2b, 2c, 2d and 3a relate to depletion parameters.

- 2b- selection of depletion parameters

- 2c- selection of burnable absorber modeling

- 2d- rodded depletion

- 3a- axial burnup profile 13

ISG Section 2b The ISG states that nominal values may not be appropriate and requests discussion of the values selected

- The ISG acknowledges that some parameters cannot physically be maximized in tandem

-[

]a,c 14

ISG Section 2c & 2d Section 2c states that burnable absorber usage should be considered

- The analysis conservatively accounts for burnable absorber usage ISG Section 2d indicates that rodded depletion should be considered

- There is no sustained rod insertion during full power operation at CPNPP

[

]a,c 15

ISG Section 3a ISG Section 3a discusses selection of a limiting axial burnup profile, including justification of using either NUREG-6801 based or plant specific profiles

- [

]a,c An axially uniform profile will be considered and used at those burnups where it is limiting 16

Biases and Uncertainties

Biases and Uncertainties are included in the analysis to ensure that normal variances and real deviations from analysis conditions are accounted for.

The analysis will account for:

- [

]a,c 17

ISG Comments on Biases & Uncertainties

ISG Sections 2a, 3b and 4 relate to biases and uncertainties

- Section 2a- Depletion Uncertainty

- Section 3b- Rack Models

- Section 4- Code Validation 18

ISG Section 2a

ISG Section 2a discusses the use of the 5% decrement method as a depletion uncertainty and what the NRC believes the uncertainty is meant to represent

- The analysis will utilize the EPRI depletion uncertainty methodology to either develop an appropriate depletion uncertainty or support the 5% depletion uncertainty

- [ ]a,c 19

ISG Section 2a (cont)

EPRI Methodology will be used to justify the depletion uncertainty used in CPNPP analysis

- [

]a,c 20

ISG Section 3b

ISG Section 3b discusses the modeling of SFP Racks including geometry and neutron absorbers

- [

]a,c

- CPNPP credits BORAL in the Region 1 racks, the Region 1 racks were described previously

- [

]a,c

- CPNPP credits no fixed neutron absorbers in the Region 2 SFP racks and is not impacted by the neutron absorber efficiency issue 21

ISG Section 4

ISG Section 4 discusses the validation of codes used in SFP criticality analyses

- The analysis incorporates a code validation suite which addresses the concerns brought up in Section 4 of the ISG

- [

]a,c 22

Accident Conditions & Soluble Boron

[

]a,c 23

ISG Comments on Accidents & Soluble Boron Credit

The ISG requests that all normal operation be considered to determine the limiting precursor to an accident

- This analysis will consider normal operation scenarios 24

Interface Conditions

Interface conditions exist at the boundaries of fuel configurations, SFP regions, and rack modules

- [

]a,c 25

ISG Comments on Interfaces

The ISG comments that the maximum set of biases and uncertainties from the configurations making up the interface needs to be used

- [

]a,c 26

Questions?

27

Spent Fuel Pool Criticality License Amendment Request Pre-Submittal Meeting S t b 13, September 13 2012

SFP Meeting Agenda

Introductions

Purpose

CPNPP Spent Fuel Pool Criticality Background and Status

CPNPP Fuel Assembly Configuration Control P

Program O Overview i

Westinghouse Analysis Introduction*

Meeting Summary and Conclusion

Will contain proprietary information 1

Introductions

Luminant Power Company Dave Goodwin Director, Projects Engineering Fred Madden Director, Oversight and Regulatory Affairs Tim Hope Manager, Nuclear Licensing Ji Jimmy S Seawright i ht C Consulting lti E Engineer i - Regulatory R l t Aff Affairs i

Matt Weeks Manager, Core Performance Engineering Cody Lemons Core Performance Engineer 2

Introductions

Westinghouse Electric Company Andrew Blanco Criticality Analyst Darrin Smith Project Manager for Criticality Ed Mercier U.S. BWR & Criticality Manager Ki C Kris Cummings i F l Licensing Fuel Li i Manager M

EPRI Albert Machiels Senior Technical Executive 3

Purpose To provide the NRC an overview of the upcoming Spent Fuel Pool criticality analysis License Amendment Request to update the Comanche Peak Technical Specifications regarding Spent Fuel Pool Storage configurations and receive NRC comments on the planned submittal.

4

Licensing Actions License Amendment Request for revised Spent Fuel Pool Criticality Analysis

Submitted in August 2007 (with Uprate)

Credit additional margins in the spent fuel pool (such as decay time)

Increase spent fuel storage capacity.

Request was withdrawn Aug 2009 Uprate Amendment Request approved in 2008

U1C14 - October 2008 to April 2010

U2C12 - October 2009 to March 2011 Dry Cask Storage 5

Comanche Peak Spent Fuel Pool C fi Configuration ti Controls Presented by Cody Lemons Core Performance Engineering

Topics for Discussion Current CPNPP Inventory and Limits Current Configuration Control methods Proposed Configuration Controls to support revised Technical Specifications p

7

Background Information The Comanche Peak Nuclear Power Plant (CPNPP)

Two Unit Station - Westinghouse 4 Loop PWRs

Initial License

Unit 1 - February 8, 1990

Unit 2 - February 3, 1993

Current Operating Cycles (18 Month)

Unit U it 1 - Cycle C l 16

Unit 2 - Cycle 13 8

CPNPP Wet Fuel Storage The two Spent Fuel Pools are connected by a Transfer Canal, and each pool is divided into 2 Regions

Region I

441 total storage locations

BORAL neutron absorbers and Flux Trap geometry

Analysis of Record demonstrates keff < 0.95 for fresh fuel while flooded with unborated water 9

CPNPP Wet Fuel Storage

Region II

2932 total storage locations

No fixed neutron absorbers

Boraflex was p physically y y removed p prior to installation of the racks

Developed cell design (no flux trap)

Technical Specifications require configuration be maintained for criticality controls

1 of 4, 2 of 4, 3 of 4, 4 of 4 configurations

Dependent upon Initial Enrichment and Burnup

Credit for soluble boron to demonstrate Keff < 0.95 10

Dry Storage Activities Accelerated Dry Storage of Spent Fuel Five Years.

Dry Storage Status:

Nine ((9)) Casks completed p in 2012

Nine (9) Casks scheduled in 2013 Currently 288 Fuel Assemblies in Dry Storage

Approximate discharge volume from 3 cycles of operation 11

Current CPNPP Fuel Storage Controls Current Method for Configuration Control:

A Technical Specification Surveillance Report is generated when needed (typically each refueling outage)

This report may be used as the basis for multiple fuel move plans, since enrichment/burnup values are static

Burnup/Enrichment values for input are obtained from the database used for Special Nuclear Material Reporting (TracWorks' Fuel Data Management System database)

Software is used to determine Maximum Allowable Storage Configuration (MASC) by comparing Enrichment / Burnup to the Technical Specification limits TracWorks, the TracWorks logo, and ShuffleWorks are trademarks or registered trademarks of Westinghouse Electric Company LLC, its Affiliates and/or its Subsidiaries in the United States of America and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited. Other names may be trademarks of their respective owners."

12

Current CPNPP Fuel Storage Controls Software Requirements:

for initial implementation or software revision, testing and d

documentation t ti is i performed f d by b an independent i d d t reviewer i

configuration controls ensure integrity of executable files and data files

cyber security controls prevent tampering / inadvertent changes Database Requirements:

All database updates are independently reviewed and approved

Administrative controls provide method for users to ensure integrity of database prior to utilizing the data 13

Current CPNPP Fuel Storage Controls Example TS Surveillance Report Initial Enrichment and Burnup values are input from the TracWorks database.

database MASC (Maximum Allowable Storage Configuration) determined by software based on input inp t values.

al es 14

Results are plotted graphically versus the TS limits to assist in identifying errors. (Based on internal OE regarding a violation of TS limits)

(reference LER-04-001, ML041260217) 15

Current CPNPP Fuel Storage Controls Prior to any fuel movement within Region II, a color coded map of the new planned configuration is created

Map is color-coded using the MASC from the Surveillance Report

Acceptability of planned configuration is verified visually Administrative procedural controls are in place to ensure TS configuration is maintained during the sequence, and for any alterations to the planned sequence sequence.

16

17 Verification Methods Currently, verification of TS compliance relies on a manual review.

This method is effective due to the simplicity of the current limits:

All fuel falls into one of 4 homogeneous categories

The vast majority of all fuel stored in Region II is limited to a 3 of 4 configuration g

The small number of 2 of 4 and 4 of 4 assemblies are verified, then the remainder of the pool can be reviewed to ensure a 3 of 4 pattern is maintained 4

Region II Interface requirements from the AOR can be simplified down to two requirements:

No 1 of 4 assemblies adjacent to the Region I racks

For any 2x2 array containing an assembly, the number of assemblies in the array is < the assemblys MASC (i (i.e.

e 3 3 of 4 or 4 of 4) 18

Verification of TS Interface Requirements Example of SAT Configuration - Location D2 ( )

All potential 2x2 arrays containing this location satisfy the TS required checkerboard pattern.

pattern 19

Verification of TS Interface Requirements Example violation of 3 of 4 requirement 4 assemblies in 2x2 for assemblies at array, limit is 3 of 4 KK4, LL4, and MM4 Example violation of 2 assemblies bli in i 2x2 2 2 1 of 4 requirement array, limit is 1 of 4 for assembly at S2 20

Controls to support revised Technical Specifications The proposed new TS Limits will be more complex than the current limits, potentially crediting:

Neutron Absorbing Inserts (i.e.

(i e discharged Control Rods)

Decay Time

Differences in reactivityy based on fuel type yp / fuel history y

Non-homogeneous configurations (or high/low configurations)

A pattern may contain separate reactivity limitations for A and B locations 21

Controls to support revised Technical Specifications Safety and efficiency with the increased complexity requires:

Updated / new software:

Technical Specification Surveillance Reports which document acceptability for each configuration

Graphical G p output p to assist in the review process p for these reports

Verification of planned Fuel Move Sequences AND Configurations

Visual aid maps (color coded), for review and fuel move planning purposes

Detailed procedures for implementation 22

Controls to support revised Technical Specifications Example Surveillance Report:

Example based on 6 storage configurations.

A01 could be stored in 4 4 of 4 4 ONLY in a configuration which credits RCCAs (in either A or B location).

T89 in 3 of 4:

Could only be in B location with NO RCCA

Could be in either location in a configuration with RCCA credit.

23

Controls to support revised Technical Specifications Example of Graphical Output which may aid in discovering outliers within the data.

The assembly with over 10,000 MWD/MTU excess b

burnup is i in i error.

24

Controls to support revised Technical Specifications Verification of planned Fuel Move Sequences and Configurations

CPNPP uses ShuffleWorks software program for fuel move planning.

TS verification ifi ti software ft will ill utilize Sh ffl W k data tili ShuffleWorks d t files to determine the acceptability of fuel move sequences q

This software will tie together the fuel move plans (from ShuffleWorks) with the TS Allowed Configurations (from the Surveillance Report)

A report will be generated demonstrating acceptability or identifying id tif i failures f il 25

Controls to support revised Technical Specifications Visual aid maps (color coded) coded), for review and fuel move planning purposes:

E Example l Planning Pl i Map M for f 3 off 4 No N RCCA Credit C dit configuration fi ti During fuel movement planning, planning it is desired to move an assembly to location FF16 (an A location). A blue blue assembly would be selected based on the planning map.

After the sequence is planned planned, the software would verify the acceptability of the move.

26

Controls to support revised Technical Specifications Fuel Assembly Inserts

If credited in the analysis, the Technical Specifications apply to fuel inserts, as well as fuel assemblies

Fuel insert moves are controlled via the same procedures d andd software, ft and d treated t t d with ith the th same level of control as fuel moves

CPNPP has a damaged RCCA which has a disconnected rodlet. This RCCA will NOT be flagged as a TS creditable insert within the database 27

Controls to support revised Technical Specifications Unplanned alterations which occur during fuel / insert movement will be administratively controlled:

It will be preferred to move the assembly to Region I.I This will likely be the fastest method to continue fuel movement.

Alternatively, a detailed checklist will be utilized to ensure the li it ti limitations are met.

t

This checklist will involve obtaining the Surveillance Report, and manually ensuring TS limits are satisfied for the assembly and all surrounding assemblies (or insert).

All fuel movement alterations require Reactor Engineering and Fuel Handling SRO approval prior to placing the fuel or fuel insert.

28

BORAL Monitoring Program Per 2012 EPRI Report Strategy for Managing Long Term Use of BORAL in Spent Fuel Storage Racks The CPNPP Monitoring Program will track industry BORAL experience as well as utilize conservative assumptions for g

degradation within the analysis.

y 29

Summary CPNPP Current Limits are relatively simple, which allows relatively simple methods to maintain configuration control.

Proposed changes to the Technical Specification limits will result in a higher level of complexity.

CPNPP recognizes that the increase in complexity requires more robust b t methods th d to t maintain i t i configuration fi ti control.

t l New tools will be necessary to ensure TS limits are maintained during all fuel movement with the Spent Fuel Pool.

Procedural controls

Software 30

Questions / Comments?

31

SFP Criticality Methodology for Comanche Peak 32

Summary and Conclusions Current Schedule Overview

September 2012 - complete scoping studies and determine configurations

December 2012 - complete technical analysis

Februaryy 2013 0 3 - complete p CPNPP C specific p WCAP C

March 2013 (tentative) - submit LAR to NRC Based on Westinghouse Topical Report and EPRI Depletion Uncertainty

WCAP-17483-P - Westinghouse Methodology (ML-11364A066)

EPRI DDepletion l ti Uncertainty U t i t Report R t Questions / Open Discussion 33

v t e Letter Sequence Request
TAC:ME8896, (Open) TAC:ME8897, (Open)
Initiation Request Acceptance... Administration Meeting, Meeting, Meeting, Meeting, Meeting Questions Answers Results Approval... Other:
MONTHYEAR2012-11-05 [Table View]

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