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© 2016 Electric Power Research Institute, Inc. All rights reserved.

Sherry BernhoftEPRI Program Manager

US NRC Regulatory Information ConferenceMarch 2016

EPRI Research for Long Term Operations

Technical Basis for SLR

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EPRI Long Term Operations Program

Leverages existing research

Systematic approach to identify research needs

International coordination and collaboration

Provides the technical basis informing decisions related tosafe, reliable and economic long term operations

Research

Operating Experience

Inspection Results

Living research programs -technical reports are updated

based on:

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Research Results in Use For Aging Management

Reactor internals inspections

Cable condition monitoring

Reactor vessel surveillance monitoring

Over 125 EPRI technical reports are referenced

in US NRC and IAEA guidance reports.

Concrete irradiation impacts

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Reactor Vessel Surveillance Monitoring

Issue: Monitor fracture toughness of the RPV and nozzles due to irradiation and other potential degradation mechanisms

BWR Integrated Surveillance Program (ISP)

– Extend program out to 80 years - 2017

– Submit for NRC review - 2018

PWR surveillance programs – will substantially increase the data points for > 60 years

– Coordinated RV Surveillance Program

– PWR Supplemental Surveillance Program

Data and trend correlations exist for LTO. Additional data will

expand and improve existing trend correlations.

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PWR Internals Inspection & Evaluation Guidelines

PWR Internals Inspection and Evaluation Guidelines (MRP-227, Revision 0) published Dec. 2008

– Currently MRP-227-A

– MRP-227, R1 published Nov. 2015

Aging Management Strategy

– Identification of components based on relevant aging mechanisms

– Inspect early in Period of Extended Operations (PEO) and every 10 years thereafter

– Component selection may be revised for SLR

– MRP-227 is a living program and updated based on research, OE and inspection results

MRP-227 aging management strategy is robust and will be validated for the SLR period

– MRP-227, R 2 - 2020

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Summary of To Date PWR Internals Inspections

15 reactors inspected, others partly complete Initial full inspections have not identified any major

issues Issues of greatest concern not seenObservations to date:

– Almost no observed austenitic SS stress corrosion cracking

– Irradiation Assisted SCC is extremely limitedCurrently limited to bolts

– No macroscopic effects of void swellingNo distortions, cracking, or excessive bolting

failure– High-strength nickel alloy clevis insert bolting

failuresHowever, not in safety function load path

– Guide card wear monitoring – guidance was updated based on OE

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Aging Management for Electrical Cables

Issue: Aging of cable insulation materials due to radiation, temperature and submergence

EPRI Technical Reports:

License Renewal Electrical Handbook

Cable Aging Reports

Low voltage thermal/radiation

Low and Medium voltage wet/submerged failure mechanisms

Medium and Low Voltage Aging Management Implementation Guidelines

Cable Testing Guidelines

In-containment Radiation and Temperature Measurements

Electrical cable systems are performing well

and tools exists for aging management.

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Condition Monitoring: Tan δ Testing Shielded Medium Voltage Cable Tan δ testing is used to evaluate shielded medium

voltage cable

Applying EPRI Tan δ acceptance criteria will identify degraded cable insulation due to water treeing or thermal damage in MV cables, cable terminations and splices

EPRI has been collecting member test data since 2009 to evaluate effectiveness

Report 1025262-June 2012 validated assessment criteria

Report 3002005321-September 2015

– Degraded cables, wet and dry, identified by tan δ

– Failure mechanism confirmation of tan δ results of cables that tested in severely degraded criteria

– No failures of cables with good or slightly degraded tan δ

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Electrical Cables Ongoing

Ongoing Projects:

Continued collection of in-containment radiation and temperature data

Enhanced condition monitoring technology

Low voltage cable susceptibility to wet (submerged) environments

Cable materials handbook

Forensic analysis of harvested cables

Service aged cables for determination of remaining qualified life

• Cable harvesting guidelines

• Testing of field returned (harvested) cables

• Determine Remaining Useful Life

Remaining useful life will inform need for

possible cable replacements for SLR.

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Aging Management for Concrete Structures

Issue: Monitoring and aging management of concrete structures due to radiation and environmental exposure

EPRI Technical Reports: Nuclear Concrete Structures Aging Reference Manual

Nondestructive Evaluation Inspection of Concrete Structures

Literature Survey of Effects of Radiation on Concrete

Expected Conditions of Reactor Cavity Concrete at 80 Years of Radiation Exposure

Boric Acid Attack of Concrete and Rebar in PWR Spent Fuel Pools

Nonlinear Ultrasound to Evaluate Integrity of Aged Concrete

Pilot Plant Augmented Containment Inspection Results

Alkali Silica Risks Ranking and Mapping

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Recent International Irradiation Data Compiled by ORNL

Data supplied

by ORNL

No appreciable impacts on biological shield wall concrete for LTO.

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Engineering Structural Evaluation:Supports designs – PWR type 1/2/3/4

Type 1 – Shoe on Bio Shield

Support of interest

Type 2 – Metal Frame

Not in Scope

Bio shield not structural

Type 3 – Shoe on Bio Shield

Not in Scope

Used only on W 4-loop units

Type 4 – Shoe on Shield Tank

Not in scope

Neutron shield tank – low fluence

- 11 units are in scope for this study (2 or 3-loop, Type 1 supports)

- Documentation of the choice of Type 1 will be included in the 2016 report.

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Engineering Structural Evaluation

Finite element analysis of the type 1 support design– Detailed drawings from a 2-loop

and 3-loop PWR

– Modeling the reduction in margin due to neutron irradiation:

Swelling of aggregates/concrete

Change in mechanical properties

– Results of the analysis will be published as an EPRI Technical Report in Q4, 2016.

Finite element modeling mesh of Type 1 RPV support

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R&D Continuing Advances to Support Aging Management

Testing materials harvested from reactors

Develop NDE techniques for concrete inspections

Determine remaining useful life of electrical cables

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Together…Shaping the Future of Electricity