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Impact of Revised 10 CFR 50.46(b)ECCS Acceptance Criteria

2009 Regulatory Information Conference

Rockville, MD

March 12, 2009

Mitch Nissley

Westinghouse Electric Company

© 2009 Westinghouse Electric Company LLCAll Rights Reserved

Westinghouse Non-Proprietary Class 3

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Topics

● Plant Safety

● Impact of Rule Change on Operating Plants

● Implementation Steps

● Recommendations

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Are Operating Plants Safe? YES!● Significant Conservatisms Exist, Even with Realistic Evaluation Models

– Worst Single Failure– Loss of Offsite Power Considered– Technical Specification Limits Considered (PWRs typically operate

with peak linear heat rates 25% below limit)– Limiting Break Location Only– Other Conservatisms in Inputs & Codes

● Depletion of Fissionable Isotopes Limits Achievable Power Beyond ~ 30,000 MWD/MTU– High burnup fuel cannot lead the core

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Impact on Plant Operations

● Additional Reload Checks and/or Analyses, e.g.,– Burnup-dependent corrosion limits– Burnup-dependent peaking factor limits (may

impact Limiting Conditions for Operation)

● Core Design Impacts, e.g.,– Number of feed assemblies– Enrichment and burnable poisons

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Expectation of Full Scope Implementation Requirements

● Assumptions– All operating reactors will need to demonstrate

compliance– Most will need to perform new small and large break

LOCA analyses to do so– Most or all vendor LOCA Evaluation Models (EM) will

need to be revised to demonstrate compliance– Most Tech Spec Administrative Controls sections will

need to be revised to reference new EM (or other basis for demonstrating compliance)

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Expectation of Full Scope Implementation Requirements

● Vendor Updates EM and Re-submits– Treatment of ID oxygen uptake, burnup

methodology, addition of Cathcart-Pawel

● NRC Reviews and Approves– Methodologies likely to differ among vendors– Each vendor maintains multiple EMs

● Licensee Obtains New Analyses from Vendor

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Expectation of Full Scope Implementation Requirements● Licensee Prepares and Submits License Amendment Request

(LAR) to Revise EM Reference in Tech Specs– New burnup-dependent peaking limits may be required

● NRC Reviews and Approves LAR

● Licensee Implements Revised Tech Specs, Updates UFSAR

● Licensee and Vendor Monitor Compliance with Limits on Continuous Cycle-by-Cycle Basis– Corrosion & peaking factor burndown vary cycle by cycle

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Future Reload Monitoring● Reload Limits Established by Initial LOCA Re-analysis

– Different limits may be required for first, second, third cycle fuel

● Core Designers Verify Peaking Factor Limits Met Throughout Cycle for All Fuel in Core

● Fuel Rod Designers Verify Corrosion/Hydrogen Limits Met Throughout Cycle for All Fuel in Core

● Changes from Previous Cycle May Require Core Re-design or LOCA Re-analysis

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Cost Estimates● Testing Costs (Per Vendor, Per Alloy)

– Hydrogen-charged ring compression tests ~ $1M– Expanded hot cell database ~$10M– Potential periodic testing (not defined) - ?

● Cost to Vendors and Licensees to Re-license EM, Re-analyze Most Plants, Update Licensing Bases, and Monitor Cycle-by-Cycle Compliance– Estimated as several hundred $M

● Cost to NRC in Terms of Resource Requirements– Estimated at 10-50 man-years for entire US fleet

Need to Balance with Regulatory Needs

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Recommendations● Avoid Additional Excessive Conservatisms, e.g.,

– Double-sided oxidation away from burst over-estimates any ID oxygen pick-up effect

● Allow Alternative Temperature and Oxidation Limits– High burnup fuel cannot lead the core– Allowable oxidation expected to increase at lower temperatures

● Employ Phased Submittals and/or Reduced Scope Implementation – Not possible/practical for industry to prepare, or NRC to review,

~100 LAR without a coordinated approach