ML17032A343

NEI-EPRI Slides. DG-1327 NRC Meeting

ML17032A343
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Site:	Nuclear Energy Institute
Issue date:	02/02/2017
From:	Eichenberg T Nuclear Energy Institute
To:	Office of Nuclear Regulatory Research
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DG-1327 ClarificationReactivity Initiated Accident GuidanceT. W. EichenbergEPRI Fuel Reliability Program, Reg

-TAC ChairSr. Specialist Reactor Safety Analysis, TVAJanuary 25, 2017 *White Flint, Rockville MD 1

Overview*Categories for Discussion

-Methods & Assumptions

-Failure Thresholds

-Release Fractions

-Miscellaneous 2

PWR vsBWRPerspectiv e*While Rod Eject / Blade Drop are Reactivity Initiated Accidents-

-These different events don't share an identical topology

• Analytical space is different

-Every assumption isn't automatically meaningful to both PWR's and BWR's-Example from item 2.2.5

• (a) is PWR speak

• (b) is BWR speak-Example item 2.2.10

• Muddy regarding BWR 3

Methods & Assumptions

• Approved Models

-What does "account for calculational uncertainties mean"?

-Realistic / Risk Informed methods to be allowed?-Expecting a full RG 1.203 process?

4 Methods & Assumptions

• 5% power DNB/CPR threshold?

-Value is below TS monitoring power level.

• Correlation range of applicability may not extend that low

-DNB/CPR may not be appropriate metric relative to very fast transient condition 5

Methods & Assumptions

• Misc. Assumptions

-Are "sensitivity" studies going to be plant and cycle specific?

-What is NOT a "major reactivity feedback?"

• Direct Moderator HeatingNon-Eq. T-H-What is meant by "manufacturing tolerances?"

• Plant , fuel type, and/or cycle specific.As-built vs bounding tolerance

-Accounting for something vs. sensitivity/parametric evaluation.

6 Methods & Assumptions

• Misc. Assumptions

-What is meant by "wider operating conditions"?

-Effectively, you're saying the determination of limiting conditions is non

-linear.*When does the search stop? To "survey a larger population" implies a realistic assessment.

-What is "sufficient parametric study"?

7 Methods & Assumptions

• Misc. Assumptions

-Why do advanced methods need to implement artificial conservatism to compare against failure criteria?

-Extensive focus on bounding assumptions

• Seems incompatible with implications of 2.2.4 (limiting scenario tied to non

-linear effects, not artificial conservatisms) 8 Methods & Assumptions

• Misc. Assumptions

-Approved hydrogen pickup model is explicit

-Need for an approved hydride orientation model is not as obvious. Need to validate the failure curve utilized.-Is the use of RG 1.224 account for hydride orientation issue?

9 Failure Thresholds

• EPRI Test Program

-Why Revision 1

• MBT Data / NSRR corrections

-Temperature Effects

-Pulse Effects

-Power History Effects

-Hydrogen > 300ppm

-Elongation

-FailureLimit s 10http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000003002005540 Failure Thresholds

• Best Estimate?

-Yes, in the sense that curve fits are relative to nominal data.

-No, in the sense that the shape of curve fits displays negative impact in areas without failures*Low Hydrogen region

-No, in the sense that correlation coefficients are in some casessubstantiallylessthan 1 11 Release Fractions

• Appropriate Location

-Keep information in one place; remove from DG

-1327-Locate to 1.183, 1.195, etc. (sign of a bigger problem)*Example: Changing dose method constitutes an AST/TID backfit?

12 Release Fractions

• Transient Fission Gas Release-Database doesn't represent low burnup 13 Miscellaneous

• Logistical Issue

-Approved Analytical Methods must Exist

• Method reviews in a timely manner?

• Potential New Method Elements

-Transient Fission Gas Release / Mechanical aspect

-Corrosion/Hydrogen Uptake/Crud

-Hydride Characterization

-FCI Impact if Centerline Melt Allowed

-Contribution of Fission Gas Release to Pressure Surge 14 Questions?? / Discussion 15