ML17032A343
| ML17032A343 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 02/02/2017 |
| From: | Eichenberg T Nuclear Energy Institute |
| To: | Office of Nuclear Regulatory Research |
| Shared Package | |
| ML17032A338 | List: |
| References | |
| Download: ML17032A343 (15) | |
Text
DG-1327 Clarification Reactivity Initiated Accident Guidance T. W. Eichenberg EPRI Fuel Reliability Program, Reg-TAC Chair Sr. Specialist Reactor Safety Analysis, TVA January 25, 2017
- White Flint, Rockville MD 1
Overview
- Categories for Discussion
- Methods & Assumptions
- Failure Thresholds
- Release Fractions
- Miscellaneous 2
PWR vs BWR Perspective While Rod Eject / Blade Drop are Reactivity Initiated Accidents
- These different events dont share an identical topology Analytical space is different
- Every assumption isnt automatically meaningful to both PWRs and BWRs
- 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 Heating Non-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, youre 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 Failure Limits 10 http://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 cases substantiallyless than 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 doesnt 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