bwrvip integrated surveillance program (isp) · 2018. 6. 14. · surveillance program (isp) to...

© 2018 Electric Power Research Institute, Inc. All rights reserved.

Drew Odell, Exelon/BWRVIPNathan Palm, EPRI

Heather Jackson, Structural Integrity

NRC Public MeetingJune 13, 2018

BWRVIP Integrated Surveillance Program (ISP)

Extension of Program to Address Second License

Renewal (SLR)

2© 2018 Electric Power Research Institute, Inc. All rights reserved.

Agenda

IntroductionMeeting Purpose and ObjectivesSummary of November 2016 MeetingReview of Proposed ISP for SLR ApproachData InvestigationsSpecimen PreparationNeutron Flux InvestigationsHost Plant SelectionConceptual SSLR Capsule DesignsProgrammatic AspectsFuture Actions


Introduction

Since 2002, the U.S. BWR fleet has been using an integrated surveillance program (ISP) to provide reactor vessel (RV) surveillance data and satisfy 10 CFR 50 Appendix H requirements.The ISP was designed and is managed by the EPRI Boiling Water

Reactor Vessel and Internals Project (BWRVIP).All U.S. BWRs have amended their operating licenses to

implement the BWRVIP ISP.The ISP addresses 60 years of operation and was approved by

the NRC in 2006.– Current program plan document is BWRVIP-86, Revision 1-A

BWR owners have expressed an intention to pursue SLR.Since 2015, the BWRVIP, in coordination with the EPRI Long-

Term Operation (LTO) program, has had a program to address limitations of the ISP for SLR.


Meeting Purpose and Objectives

Update the NRC on progress made on the ISP for SLR project since the November 2016 meetingProvide the NRC staff with a preview of the content of the

ISP for SLR program planProvide NRC an opportunity to provide any comments or

concerns in advance of the ISP for SLR program plan being submitted for review and approval


Summary of November 2016 Meeting


Issues Related to Original BWR Plant-Specific Surveillance Programs In the early 1990s, issues were identified with BWR plant-

specific surveillance programs:– Some surveillance materials do not match limiting vessel beltline

materials because they were designed: To earlier versions of ASTM E-185 that specified that capsules

should contain materials that represent materials from the vessel beltline region.Prior to Reg. Guide 1.99, Revision 1 (1977) when embrittling effects

of copper were not yet known.– Some surveillance materials were missing baseline data (unirradiated

Charpy data, chemistry data, and/or heat numbers).Missing or incomplete data limits the usefulness of surveillance

capsule data for predicting RPV embrittlement of vessel beltline materials.


Why Did the BWRVIP Develop an Integrated Surveillance Program? Increase overall technical quality and make most effective

use of existing BWR surveillance capsules and data– Include the BWRVIP Supplemental Surveillance Program (SSP)

capsule data (next slide)

Address regulatory concerns regarding some cases of inadequate or missing dataCollectively monitor and manage embrittlement in BWR

vessels– Share data between all BWR utilities– Avoid surprises from BWR surveillance data– Avoid excess conservatism in pressure test temperatures


Supplemental Surveillance Program (SSP)

Began in late 1980’s by the BWROG to supplement database of BWR embrittlement data9 capsules inserted into host reactors:

– Cooper (Capsules A, B, and C)– Oyster Creek (Capsules D through I)

25 materials (13 plate and 12 weld); 84 sets of weld and plate Charpy specimens, including EPRI-contributed materialsMaterial chemistries and target fluences chosen to span the

range of BWR vessel beltline materialsExcellent characterization of baseline Charpy data and

chemistryAll capsules have been tested and capsule reports have

been published and transmitted to the NRC


Current ISP Structure

Selected representative surveillance materials from the capsules of 13 host plants, plus selected materials from 9 SSP capsules, constitute the ISP– 15 representative plate heats and 15 representative weld heats

provide data for the BWR fleet– 13 host plant capsules to be withdrawn and tested during the original

plant license period– 13 host plant capsules to be withdrawn and tested during the first

license renewal period – All 9 SSP capsules were tested

The ISP Test Matrix links the representative materials to a “target” plate and weld material in each BWR RVTesting of remaining non-host BWR fleet capsules will be

deferred or designated as contingencies


Considerations for Extending Current ISP to 80 Years

GALL-SLR specifies that surveillance programs must be in place that meet 10CFR50 Appendix H, allowing for use of ISP for SLR.Extending the current ISP to address 80 years of operation

presents challenges– Total number of plants and which plants will pursue SLR are uncertain Some of the current host plants may not pursue SLR Plants electing to pursue SLR may have surveillance materials that are

not representative of other plants and are therefore not suitable as “host” plants

– Current host plants will likely not have additional capsules available for testing in the 60 to 80 year period

– Some representative surveillance materials were in the SSP capsules only– Many BWRs, as well as ISP host plants, have lag factors as opposed to

lead factors (surveillance capsules are exposed to lower fluence than the inside surface of the RV)

Effort initiated in 2015 to evaluate options and feasibility for providing BWR RV surveillance for 80 years


Feasibility Evaluation

Task group of experts formed Options to extend or replace ISP identifiedFeasibility study performed assessing all optionsOptions ranked based on:

– Technical merit– Ease of implementation– Cost– Regulatory acceptabilityTask group developed a recommended approach to be taken for ISP for SLR


Review of Proposed Approach for Addressing Surveillance Needs of BWR Fleet in SLR


Proposed Approach

Maintain the critical elements of the ISP to the greatest extent possible, i.e., the ISP Test MatrixMake 80-year surveillance data available for the entire set of

ISP materialsUtilize existing data to the extent possible

– SSP capsules had lead factors higher than typical BWR capsules– For some materials, specimens from many capsules, exposed to a

wide range of fluence levels, have been tested

Reconstitute previously tested specimens to fill gaps in data– Specimen inserts will be irradiated prior to reconstitution (next slide)– Inserts will be placed in “Supplemental SLR Capsules”

Extend the existing ISP versus replace


Reconstitution Approach

Specimen inserts will be irradiated prior to reconstitution Inserts will be placed in

specially designed “Supplemental SLR (SSLR) Capsules”All SSLR capsules can be

irradiated in one host plantAfter irradiation is complete,

reconstituted specimens will only be fabricated and tested for those materials that are needed by plants that actually pursue SLR

Insert

End Tab

End Tab


Irradiation of Inserts Only

Irradiation of inserts prior to welding of end tabs has several advantages for the ISP for SLR– Many materials can fit into a single capsule – Cost of completing specimen fabrication is deferred Irradiation may need to begin prior to plants’ decisions to pursue

SLR being made If certain plants do not pursue SLR or shutdown early, fabrication of

specimens for some materials may not need to be completed

Although irradiating the inserts prior to specimen fabrication increases dose, it will still be less than typical PWR levels


Materials in the ISP for SLR Program

The ISP Test Matrix will remain unchanged for the ISP for SLR– The program will still consist of 15 representative plate heats and 15

representative weld heats– The limiting “target” materials for the BWR RVs will not be reevaluated

New materials will not be added to the program to address:– Materials now considered as part of the extended beltline– Changes in limiting materials as a result of potential changes in

embrittlement trend curves

The intent is to trend the embrittlement behavior of the materials in the surveillance program– Adding a new material in the SLR period and obtaining one data point will

not allow for trending of embrittlement– Several embrittlement trend curves have been considered/proposed

since the publication of RG 1.99, R2 and it is not possible to know which trend curve may be selected for the next revision or when that will occur


Benefits of Proposed Approach

Definitions of representative and target materials, as defined in approved ISP test matrix, will remain unchangedResponsibilities of utilities to implement ISP data will remain

unchangedNo changes to existing ISP test scheduleSatisfies Appendix H requirements and GALL-SLR

expectationsReduces uncertainty associated with not knowing which

plants may implement SLROnly change to ISP is addition of 80-year data where

such data does not currently exist


Data Investigations


Overview: Data Needs for SLR are Determined by Evaluating Available Data from BWRVIP ISP program80-year fluences are projected for vessel target materials.Target fluences are compared with fluences of tested

surveillance capsule materials.Gaps and additional data requirements are identified to plan

SSLR capsules.

Target vessel materialRepresentative

(surveillance) material Host plant


Methodology for Projecting BWR Target 80-year Fluences

1/4T fluence values for ISP target plate and weld materials were taken from the latest docketed P-T curve reports, or from updated fluence evaluations for tested ISP capsules.Fluence was estimated by projecting linearly from the

reference fluence (e.g. 32 or 54 EFPY) to 72 EFPY.The projected 72 EFPY fluences were compared with

fluences of capsules that will be tested by the ISP prior to the end of the 60-year license renewal period.Where gaps exist, data needs were identified for extending

the ISP for SLR to bound the fleet.


72 EFPY 1/4T Fluence Projections for BWR Target Plates

7 plates < 1x1018 n/cm2

5 plates > 5x1018 n/cm2

22 plates > 1x1018 n/cm2and < 5x1018 n/cm2


72 EFPY 1/4T Fluence Projections for BWR Target Welds

9 welds < 1x1018 n/cm2

4 welds > 5x1018 n/cm2

21 welds > 1x1018 n/cm2and < 5x1018 n/cm2


Target 80-year Fluences are Compared with Fluences for ISP Surveillance CapsulesData for 15 plate and 15 weld materials are available from

25 existing capsules tested under the ISP and individual plant programs and 9 SSP capsules.Data not included for 6 ISP capsules tested in 2016-2025.Testing of 13 ISP(E) capsules is planned during the license

renewal period.Fluences for tested ISP and SSP capsules are obtained from

published capsule test reports.– All ISP and SSP capsules have been evaluated using the RAMA

fluence methodologyProjected fluences for remaining ISP capsules and ISP(E)

capsules are obtained from BWRVIP-86, Rev. 1-A.– Matching of projected vessel fluence and surveillance capsule fluence

shows that some materials are already covered and the remaining materials can be grouped by fluence needed to catchup to the vessels


Fluences of Tested and Planned ISP Capsules Bound 13 Target Plates and 17 Target Welds for 80 years

Tested Capsule Fluence as a % of Target SLR Fluence

Number of Target Plates

Number of Target Welds

< 50% 16 1350-99% 10 12≥ 100% 8 9

Projected ISP(E) Capsule Fluence as a % of Target

SLR Fluence

Number of Target Plates

Number of Target Welds

< 50% 5 150-99% 16 16≥ 100% 13 17

When ISP(E) capsules are considered, an additional 5 plates and 8 welds are bounded

Existing ISP data bounds 8 target plates and 9 target welds for 72 EFPY


To Bound all Target Heats for 80 years, Additional Surveillance Data is Needed for 13 Representative Plates and 10 Representative Welds

Needs additional surveillance data?

Number of Representative

Plates

Number of Representative

WeldsYes 13 10No 2 5

Total 15 15


Methodology for Planning Proposed Supplemental SLR CapsulesFor each representative plate and weld material for which

additional surveillance data is needed:– The tested capsule having the highest fluence is identified.– Some representative heats represent multiple target vessels. The

corresponding target heat with the bounding projected 72 EFPY 1/4T fluence is identified.

– The needed “catchup” fluence is determined by:

Catchup fluence for each

representative heat

Bounding 1/4T fluence projected for 72 EFPY for corresponding target vessels

Highest fluencetested capsule–=


Representative Materials Needing Additional Data are Grouped Based on the Range of Additional Fluence Needed

GroupCatchup Fluence Needed

(n/cm2, E > 1 MeV) Number of Materials

1 < 1x1018 72 > 1x1018 n/cm2 and < 5x1018 n/cm2 83 > 5x1018 n/cm2 8

Groupings show fluence targets for selection of materials and design of Supplemental SLR capsules.

Three Supplemental SLR capsules are proposed with catchup fluences that bound all target plates and welds for 80 years.

This approach is a natural extension of the existing ISP program to fill in needed data.


Conclusions of Data Investigations

80-year fluence needs can be met with a small number of SSLR capsules, with materials grouped based on “catchup” fluence8 of 34 target plates and 9 of 34 target welds are bounded

for 80 years by existing ISP data13 of 34 target plates and 17 of 34 target welds will be

bounded for 80 years by ISP capsules tested during the license renewal periodAdditional data is needed for 13 of 15 representative plates

and 10 of 15 representative welds to meet projected fluence needs for 80 years


Specimen Preparation


ISP Repository

All specimens tested under the ISP and SSP are maintained in a single repository Specimens are stored in a highly organized manner

– Each capsule has a unique storage container– Broken Charpy halves from an individual specimen are stored

together in their own labeled container– An ISP repository inventory report is maintained and updated on a

yearly basis

Previously tested specimens are readily retrievable to support the ISP for SLR effort


Specimen Etching – Background and Objectives

Etching of broken ISP weld and HAZ specimens performed to determine if enough weld material is available in Charpy specimens halves to support fabrication of inserts for reconstitution– Original weld surveillance specimens contain a varying amount of weld and plate

material– Original HAZ specimens are roughly one half base metal and one half weld metal

For reconstitution, ASTM E1253 specifies an insert width of 18 mm, but this requirement may be relaxed if:– It can be experimentally or analytically shown that the plastic deformation zone in

subsequent testing will not extend into the heat affected zones produced by reconstitution and,

– Heat input during welding shall be controlled such that no part of the volume of the central 10-mm portion of the reconstituted Charpy-sized specimen exceeds the prior metal irradiation temperature at any time during welding

Target for SSLR capsules is to have14 inserts of each weld material– 12 per ASTM E-185-82– 2 Spare


Specimen Etching – Results

Etching completed on 9 of 10 weld heats (one heat to be used will come from Peach Bottom Unit 2 capsule to be withdrawn in fall 2018)– 3 heats have more than adequate material to obtain 14 inserts of an

18mm width– 3 heats will require the use of smaller insert sizes to obtain 14 inserts Some specimens with an insert width of 15mm, which will be tested in the

transition region or lower shelf As many as 3 specimens with an insert size of 12mm that will be tested on

the lower shelf and lower portion of transition curve only– 3 heats will require the use of smaller insert sizes and as few as 10

specimensTechnical bases and procedures for using smaller insert

sizes and specimen quantities will be provided in the ISP for SLR program plan


Basis for Use of Smaller Specimen Insert Sizes

Although ASTM E1253 identifies an insert size of 18mm, use of smaller inserts is permitted, as discussed on slide 31.– ASTM E1253 further provides reference to test programs have shown

acceptable Charpy results using shorter inserts– The multi-lab RESQUE program (ASTM STP 1418) concluded: 12mm inserts can be tested in the transition region 15mm inserts can be tested at any energy

– Other studies (ASTM STP 1204) have also shown acceptability of using 15mm inserts on the upper shelf


Basis for Use of Smaller Specimen Quantities

Although it is desirable to be in compliance with ASTM E185-82 by having 12 specimens, current BWR capsules often contain only 8 specimens– Capsules were designed to earlier versions of E185– The BWRVIP has had no issues developing high quality Charpy

curves with only 8 specimens

For all materials tested under the ISP for SLR Program, at least 2 capsules will have been previously tested– Embrittlement behavior of materials has been characterized– Previous test results can be used to inform selection of appropriate

test temperatures


Material Identification and Reconstitution

Positive identification of the inserts will be maintained during the irradiation period by only including one material per packet.Arc stud welding will be performed for all of the SLR weld

inserts in accordance with ASTM E1253 proceduresEnd-tabs will be oversized so that they can be EDM

machined in plane with the irradiated insert


Neutron Flux Investigations


Fluence vs. Flux and Lead Factor Considerations

The primary objective for obtaining additional surveillance data is to achieve a fluence exposure that is equal to or greater than 80-year RV fluenceCatchup fluences cannot be achieved prior to the end of 80

years of operation using typical BWR surveillance capsule flux rates– Catchup fluences must be reached in a reasonable timeframe - ~10

years or less– An accelerated flux rate is needed

Concerns were identified at the November 2016 public meeting regarding flux embrittlement effects and ASTM E185 lead factor recommendationsA balanced perspective is needed concerning fluence, flux,

and lead factor – some compromise is needed


ASTM E185 Lead Factor Recommendations

ASTM E185-82 recommends that surveillance capsule lead factors be in the range between 1 and 3ASTM E185 is written for the development of a plant-specific

surveillance program– The ASTM E10.02 committee is currently considering an annex to the

standard for integrated surveillance programs

Lead factor is not a meaningful consideration for integrated surveillance programs– The data from one surveillance capsule is representative of materials

in multiple reactor vessels and a different lead factor exists for each

For planning of the ISP for SLR, lead factor will not be considered. Target flux and fluence will be the primary considerations.


Selection of Target Flux

In order to obtain the needed catchup fluences of the ISP for SLR program in 10 years, a flux of at least 2.4E+10 n/cm2-s is neededThe embrittlement trend curve in the Alternate PTS Rule,

10CFR50.61a, contains a breakpoint value for flux of 4.39E+10 n/cm2-s for consideration of flux effects– 4.39E+10 n/cm2-s will be used as an upper limit on flux for the SSLR

capsules

2.4E+10 n/cm2-s < TARGET FLUX < 4.39E+10 n/cm2-s


Neutron Flux Investigations

Project initiated to investigate neutron flux values for SSLR capsules– Provide data for use in selection of potential host plants– Determine possible positions for placement of capsules

Candidate host plants selected for evaluation based on similarity to other BWR designs– Increase potential for capsule transferability, if needed– Parameters evaluated for similarity included shroud inner diameter

(ID), shroud thickness, annulus width, core size– Four BWR/4 units selected for evaluation

Flux values calculated at varying azimuthal, axial, and radial positions within the reactor annulus


Neutron Flux Investigation Conclusions

Target flux values for SSLR capsulescan be obtained by a combinationof the following:– Locating the capsules at a core “flat”

(0°, 90°, 180°, and 270° positions)– Offsetting the capsules from the

shroud by several inches– Positioning the capsule lower in the core

(although the flux profile is less uniformacross the capsule in this region)

Optimal location:– Several inches radially from the core shroud toward the reactor vessel– Within +/- 5° of the 0° and 180° positions Low flux locations Free from jet pump obstructions

– Between 60” and 100” from the bottom of the active fuel Flux profile will be relatively uniform over height of capsule


Flux Investigation Results - Azimuthal


Flux Investigation Results - Axial


Neutron Flux Investigation Methods

The 4 candidate SLR plants are current ISP host plants and have been previously evaluated using the RAMA fluence methodologyTo evaluate the potential flux of the SSLR capsules:

– Previously developed RAMA transport solutions for the most recent available operating cycle (actual or projected) were used as a starting point

– RAMA models were modified to include representative capsules in the annulus region where the SSLR capsules may be placed

– 3D interpolation was performed to produce axial, aziumthal, and radial flux profiles

To evaluate the flux spectrum, RAMA inputs were modified to analyze flux on a group-by-group basis


Neutron Flux Spectrum Comparison

Evaluation performed to compare neutron spectrum at potential SSLR capsule location and that at position of typical BWR capsulesSSLR capsule positioned at:

– 0° azimuthal position– Axial position where flux profile is “flat”– Radial position corresponding to a flux of 4.39E10 n/cm2-s

Comparisons made for energy groupings between 1Mev and 17MeVFlux normalized for each grouping by dividing by total fluxFour candidate SLR host plants evaluatedMaximum difference in flux between SSLR capsule and a typical

BWR capsule for all energy groupings is less than 2.5%Small difference in neutron flux spectrum between typical

BWR capsule and SSLR capsules


Neutron Flux Spectrum Comparison - Example


Host Plant Selection


Candidate Host Plant Selection

Intent is to identify multiple plants in the ISP for SLR program plan as candidate host plants for the SSLR capsules– Addresses the contingency planning requirements of 10 CFR 50

Appendix H for cases of plant shutdown– Provides flexibility for changes that may occur between time of program

plan development and capsule insertion (~3 to 4 years from today)Several plants selected for consideration based on the following:

– Similarity to other plant designs In case relocation of SSLR capsules and holder becomes necessary

– End of 60-year license dates Provides enough time for SSLR capsules to be installed and obtain

needed fluence levels– Existing quality fluence model Needed in order to determine potential flux values for SSLR capsules

– Existing ISP host plant Familiar with existing ISP host plant responsibilities


Conceptual SSLR Capsule Designs


SSLR Capsule Design

Each SSLR capsule will contain 8 packets– Each packet will contain the inserts for one material– One capsule containing only 7 materials will include a “filler” packet so

that all capsules can have the same dimensions

Dosimetry– Flux wires of high-purity iron, nickel, copper, and niobium will be

included in each packet– Wire length in the horizontal direction is sufficient to overlap each

weld insert in the packet, so that any azimuthal variation in flux can be measured if required


Packet Design

(14x)


SSLR Capsule Holder Design

Specialized holder design is needed for SSLR capsules– One holder capable of containing three capsules for the three catchup

fluence groupings– Allow for the removal of capsules from the holder independently– Attach to core shroud to obtain needed flux– Allow for transfer to an alternate host plant, if needed

Conceptual capsule holder designs are being developed for the candidate host plantsPrimary intent of conceptual design effort is to ensure that

capsules can be installed in locations that provide needed fluxDetailed capsule holder design effort will occur after NRC

approval of ISP for SLR program plan


Conceptual SSLR Capsule Holder Design


Conceptual SSLR Capsule Holder - Installed


Programmatic Aspects


Project Administration and Implementation

The ISP for SLR program plan will maintain the following elements of the current NRC approved ISP (exceptions as noted):– Project Management Responsibilities– Capsule Data EvaluationDeviation from 10CFR50 Appendix H timeliness requirements will

be requested – materials will be reconstituted and tested once it is known that a plant will be pursuing SLR and data will be needed

– Fluence and Dosimetry– Plan for Ongoing Vessel Dosimetry Three options are currently provided for dosimetry for those plants

not withdrawing and testing capsules– Data Sharing– Data Utilization


Future Actions

Completion of ISP for SLR program plan in late 2018Submittal of ISP for SLR program plan in early 2019 for NRC

review and approvalRespond to NRC requests for additional informationPost NRC approval activities

– Final host plant selection– Capsule holder design finalization and fabrication– Capsule insertion and irradiation– Capsule withdrawal, specimen reconstitution, and testing– Use of data by BWRVIP members


Together…Shaping the Future of Electricity

BWRVIP Integrated Surveillance Program (ISP)�Extension of Program to Address Second License Renewal (SLR)AgendaIntroductionMeeting Purpose and ObjectivesSummary of November 2016 MeetingIssues Related to Original BWR Plant-Specific Surveillance ProgramsWhy Did the BWRVIP Develop an Integrated Surveillance Program?Supplemental Surveillance Program (SSP)Current ISP StructureConsiderations for Extending Current ISP to 80 YearsFeasibility EvaluationReview of Proposed Approach for Addressing Surveillance Needs of BWR Fleet in SLRProposed ApproachReconstitution ApproachIrradiation of Inserts Only Materials in the ISP for SLR ProgramBenefits of Proposed ApproachData InvestigationsOverview: Data Needs for SLR are Determined by Evaluating Available Data from BWRVIP ISP programMethodology for Projecting BWR Target 80-year Fluences72 EFPY 1/4T Fluence Projections for BWR Target Plates72 EFPY 1/4T Fluence Projections for BWR Target WeldsTarget 80-year Fluences are Compared with Fluences for ISP Surveillance CapsulesFluences of Tested and Planned ISP Capsules Bound 13 Target Plates and 17 Target Welds for 80 yearsTo Bound all Target Heats for 80 years, Additional Surveillance Data is Needed for 13 Representative Plates and 10 Representative WeldsMethodology for Planning Proposed Supplemental SLR CapsulesRepresentative Materials Needing Additional Data are Grouped Based on the Range of Additional Fluence NeededConclusions of Data InvestigationsSpecimen PreparationISP RepositorySpecimen Etching – Background and ObjectivesSpecimen Etching – ResultsBasis for Use of Smaller Specimen Insert Sizes Basis for Use of Smaller Specimen QuantitiesMaterial Identification and ReconstitutionNeutron Flux InvestigationsFluence vs. Flux and Lead Factor ConsiderationsASTM E185 Lead Factor RecommendationsSelection of Target FluxNeutron Flux InvestigationsNeutron Flux Investigation Conclusions Flux Investigation Results - AzimuthalFlux Investigation Results - AxialNeutron Flux Investigation MethodsNeutron Flux Spectrum ComparisonNeutron Flux Spectrum Comparison - ExampleHost Plant SelectionCandidate Host Plant SelectionConceptual SSLR Capsule Designs�SSLR Capsule DesignPacket DesignSSLR Capsule Holder DesignConceptual SSLR Capsule Holder DesignConceptual SSLR Capsule Holder - InstalledProgrammatic Aspects�Project Administration and ImplementationFuture ActionsSlide Number 58

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