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.
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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.
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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 LI coustic Resonance Prediction I
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Vt,,
M SIV 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 methodology for EPU cases.
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- 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.
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~iV1am Steam Line Strain Gauge 47 Test Results RMS Spectrum Waternll Plot SSES Uinit 1, 37% - 107%, MSL-A-Upper, Ch 49 II 0.2 -
V7I r
0 0.05-Ii F-7L ii11I Power [%]
Freq [Ftj 6
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- ~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).
Load definition input into GE ANSYS finite model of SSES steam dryer.
- 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.
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,--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%
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%
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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 Contributors To Uncertainty
" 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 0II 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.
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.Four additional steam dryer components have insufficient peak stress intensity margin to cover uncertainties.
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- 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.
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Needs A decision to modify or replace the steam dryer by end of November.
We would like feedback on steam dryer analysis methodology.
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