ML063170153
| ML063170153 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 11/06/2006 |
| From: | Susquehanna |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML063170153 (12) | |
Text
Susquehanna Steam Electric Station Extended Power Uprate Proposed License Amendment I
Agenda
- Introduction
- Initial Staff Comments
- Objectives
- Overview of Changes
- Steam Dryer Analysis
- Comments from Public
- Conclusions and Closing Remarks L M11111 1
Objectives Describe why the dryer analysis techniques employed will provide a final dryer that:
- Adequately defines and applies loads
- Comprehensively analyzes the loads
- Is benchmarked to actual Susquehanna plant data
- Is robust and has a strong technical basis
- Requires stress intensities to conform to ASME design limits.
I S'-' Submittal Change Overview
- Addresses several areas in original submittal that NRC identified as lacking sufficient information Removed Standby Liquid Control proposed changes
" NRC approval is now requested for a change to the FSAR
- PPL evaluation results indicate that a trip of a feedwater pump or condensate pump may result in a unit scram.
I II 17-I 2
Sumittal Change Overview
- Updated information:
- Description of TS changes currently undergoing NRC review
- Updated PRA analysis results I . Detailed Dryer Analysis now provided.
I I-
~) ISusquehanna Steam Dryer Analysis Approach
- Determine if an acoustic resonance will be present after EPU implementation.
- Develop a design basis for cyclic stresses which include EPU conditions.
- Develop required actions to bring the steam dryer design into conformance with the cyclic stress design basis.
L 3
I
- I Susquehanna Steam Dryer IF Susquehanna Main Steam Line Configuration i -T, 141-4
Steam Dryer Analysis
- Acoustic Resonance and Acoustic Loading
- MSIV Closure Testing
- Analysis Methods
- Uncertainty Evaluation
- Analysis Results
- Needs I
Ir coustic Resonance Prediction I
LI 5
Vt,, MSIV Closure Testing MSIVs Slow Closed at 75% CLTP
- Simulates 100% CLTP flow through remaining open steam lines.
- Used to benchmark strain gauge data for composite load I methodology for EPU cases.
- Simulates 113% OLTP (first EPU step) flow through the remaining open steam lines.
- Used to determine presence of acoustic resonances and steam line vibration levels at the first EPU step.
- Strain gauge data used to develop ACM steam dryer loading for the first EPU step.
I
~iV1am Steam Line Strain Gauge 47 Test Results RMS Spectrum Waternll Plot SSES Uinit1, 37% - 107%, MSL-A-Upper, Ch 49
- _ II 0.2 -
V7I r 0
0.05-Ii F-7 ii11 L I Freq [Ftj Power [%]
6
7
- ~Steamn Dryer Analysis Methods
- Main steam line strain gauges used as inputs to ACM.
- Structural Integrity Associates provided strain to pressure conversion factors.
° Steam dryer load definition generated using CDI acoustic circuit methodology (ACM).
- GE model used 1% Raleigh damping factor.
- GE performed + 10% frequency shifts to bound structural uncertainty.
Stress intensities were scaled as a result of the benchmarking effort.
The ASME stress intensity design limit of 13;600 PSI for 304 stainless steel was applied to the finite element analysis stress intensity results.
i 8
F
,--Uncertainty Considerations Precision Uncertainty Component Symbol Bias (Note 1) (Note 2)
Acoustic Pressure Measurement U1 0% +/-6.2%
Difference in MSL Strain Gauge Locations Between U2a 0% +16.9%
Susquehanna and Quad Cities Unit 2 Ability of ACM to Determine Acoustic Dryer Pressure U2b -
Loads Measurement of Dryer Pressures in 1985 U3a 0% +10%
Susquehanna Measurements Ability of ACM to Determine Spatial Distribution of U3b 0% +-7.6%
Non-Acoustic Pressure Loads Use of a Two-Second Time History in FE Calculations U4a -2% 0%
_7 Ability of FE Model to Represent Dryer Structure U4b (*) (I)
Determination of CPPU Scale Factor U5a (M) ()
Conservatism in 113% OLTP Load Definition U5b +24% 0%
Bias / Precision - Totals +22% +/-22.8%
9
Uncertainty Considerations Notes to Uncertainty Table:
- 1) Negative bias values indicate an under-prediction of the dryer loads or stress intensities and a positive bias value indicates an over-prediction.
- 2) The precision value indicates either an over-prediction or an under-prediction of the dryer loads or stress intensities.
- 3) NA indicates that an uncertainty value is not applicable for this uncertainty component.
(*) Indicates proprietary information, as provided in PPL letter to the NRC PLA-6076.
II M Significant To Uncertainty Contributors
" Structural uncertainties applied at the component level.
" Conservatism In 113% OLTP Load Definition
- + 24% Over prediction (Positive Bias) 0 Ability of ACM to Determine Spatial Distribution of Non-Acoustic Pressure Loads
- Non-Acoustic Loads Developed Based On Benchmark Of 1985 Instrumented Dryer Test
" Overall Approach Results In A Conservative Estimate Of End-To-End Uncertainty Evaluation Of Dryer Stresses 0I I
10
4}Finite Element Analysis Results Two steam dryer components exceeded allowable design peak stress intensities (13,600 PSI) prior to applying structural and analytic uncertainties.
I .Four additional steam dryer components have insufficient peak stress intensity margin to cover uncertainties.
I Summary,
" Analysis shows no acoustic resonances are expected to exist at full EPU conditions.
" Steam line testing demonstrates that no acoustic resonances will exist at the first EPU step.
- Steam line testing demonstrates that the main steam lines and attached equipment will be subject to low levels of vibration at the first EPU step.
" Analysis techniques are comprehensive and utilize actual Susquehanna plant data.
" The steam dryer analysis method was benchmarked against measured Susquehanna strains.
- The EPU steam dryer design will conform to the ASME design criteria ensuring the steam dryer will maintain it's structural integrity.
I 11
Needs A decision to modify or replace the steam dryer by end of November.
We would like feedback on steam dryer analysis methodology.
I 12