ML060170269
| ML060170269 | |
| Person / Time | |
|---|---|
| Site: | Fermi, Boiling Water Reactor Owners Group  |
| Issue date: | 12/13/2005 |
| From: | General Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| Honcharik M, NRR/DPR/PSPB, 301-415-177 | |
| Shared Package | |
| ML060240100 | List: |
| References | |
| BWROG-05032, TAC MC8714 | |
| Download: ML060170269 (41) | |
Text
BWROG-05032 Enclosure 2 GE Presentation Regarding Decay Ratio Adder Removal for BWROG Stability Solution Options I-D and II Redacted and Non-Proprietary Information
Decay Ratio Adder Removal Option I-D/Il Exclusion Region Licensing Methodology Presentation to NRC - Closed Session December 13, 2005 imagination at work 1/
DR Adder Removal NRC Presentation /
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Agenda
- Purpose
- Background
- Proposal
- Recent Instability Events
- Justification to Remove 0.15 DR Adder
- Demonstration Analysis-
- Summary of ODYSY LTR Changes
- Conclusion imagination at work 2/
DR Adder Removal NRC Presentation I 12/13/2005
Pu rpose
- Provide justification for removal of 0.15 core decay ratio adder from Options l-D and 11 exclusion region licensing methodology
- Provide description of proposed changes relative to approved ODYSY LTR imagination at work 3/
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=
Background===
- BWROG Stability Long-Term Solutions (LTS) defined in NEDO-3 1960
- Enhanced Option I-A (EIA)
- Option l-D
- Option 11
- Option Ill
- LTS must meet GDC-12
- Prevent oscillations from occurring, or
- Detect & suppress oscillations, or
- Both prevent and detect & suppress imagination at work 4/
DR Adder Removal NRC Presentation I 12/13/2005
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Background===
- EIA
- Prevention solution applicable to all plants
- Oscillation prevention provided by analytically determined exclusion, restricted regions protected by automatic scram, rod block (respectively)
- ODYSY approved for region generation and validation in NEDC-32339P Supplement 1
- Option Ill
- Detect & suppress solution applicable to all plants
- Oscillations automatically detected & suppressed by new plant hardware imagination at work 5/
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Background===
- Option l-D
- Prevention and detect & suppress solution
- Applicable to plants with small cores where only core-wide mode oscillations are possible
- Existing flow-biased APRM flux scram detects and suppresses core-wide mode oscillations
- Oscillation prevention provided by analytically determined, administratively controlled exclusion region
- Buffer region defined outside of exclusion region
- Stability monitor required imagination at work 6/
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Background===
- Option I-D Stability Monitor
- Stability monitor must be operational to enter Buffer Region
- Calculated decay ratios must be below specified stability criterion to operate in Buffer Region
- If decay ratios above criterion, immediate exit from Buffer Region required
- If inadvertent entry into Buffer Region and stability monitor not operational, immediate exit required
- Plants do not normally operate in Buffer Region imagination at work 7/
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Background===
- Option 11
- Prevention and detect & suppress solution
- Applicable to BWR/2 plants
- Existing quadrant based flow-biased APRM flux scram detects and suppresses both core-wide and regional mode oscillations
- Oscillation prevention provided by analytically determined, administratively controlled exclusion region imagination at work 8/
DR Adder Removal NRC Presentation 12/13/2005
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Background===
- Original (FABLE) exclusion region licensing methodology approved in NEDO-31960
- ODYSY exclusion region licensing methodology for Options I-D/Il approved in NEDC-32992P
- ODYSY methodology includes 0.15 core decay ratio (DR) adder
- 0.15 is added to the calculated ODYSY core DR to yield a "procedure" core DR
- Procedure core DR is compared to 0.80 stability criterion to determine exclusion region boundary
- 0.15 adder effectively makes stability criterion 0.65 imagination at work 9/
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Background - Stability Criteria Map 1.0 0.9 0.8 0.7 Core 0.6 Decay Ratio 0.5 0.4 0.3 0.2 0.1 0.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Channel Decav Ratio
()imaginationat work 10/
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Background===
- ((
- ODYSY LTR did not take credit for methodology improvement to expedite licensing approval imagination at work 11/
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Background===
- ODYSY methodology improvements include:
-rr
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imagination at work 12 /
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Proposal
- Option I-D/Il exclusion regions becoming larger due to high energy core designs
- Affects plant operation
- 0.15 Adder adds unnecessary conservatism to exclusion region methodology for Option I-D/Il
- Demonstrated by recent instability event analyses and operational experience
- BWROG proposes to remove 0.15 Adder to yield more acceptable regions and avoid unnecessary operational challenge
- Requires NRC review and approval imagination at work 13/
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Increasing Exclusion Region Size for representative plant (with 0.15 DR Adder) 100 90 Cycle 23 80 I-70 0
a.
60 1i 50 40 30 20 10 0
0 10 20 30 40 50 60 70 80 90 100 Core Flow (%)
imagination at work 14/
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Recent Instability Events Exclusion and Buffer regions calculated for two plants with recent instability events
- Nine Mile Point 2 - July 24, 2003
- Recirc pumps downshift and FCV runback
- Flow reduction: 94% to 28%, power: 100% to 35%
- FW temperature equilibration raised power to 45%
- Slow growing oscillations developed
- Perry - December 23, 2004
- Recirc pumps downshift
- Flow reduction: 99% to 33%, power: 100% to 44%
- FW temperature equilibration raised power to 55%
- Slow growing oscillations developed C imagination at work 15 /
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[I 17 /
I' imagination at work DR Adder Removal NRC Presentation /
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DR Adder Removal NRC Presentation I 12/13/2005
Recent Instability Events
- Exclusion regions calculated with 0.80 DR Criterion (no adder) provide significant margin to power/flow conditions where instability events occurred
- Buffer region adds significant additional margin
- Exclusion regions calculated with 0.65 DR Criterion (0.15 adder) contain excessive margin 0.15 DR Adder excessively conservative for Option I-D/Il exclusion region application imagination at work 20/
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Justification to Remove 0.15 DR Adder
- Detect and suppress solution element provides direct SLMCPR protection
- Conservative plant-specific analysis performed each cycle to demonstrate margin to SLMCPR (described in NEDO-32465) imagination at work 21/
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Justification to Remove 0.15 DR Adder
- Exclusion Region provides additional measure of protection (i.e., defense-in-depth)
- Prevention solution element provides additional, indirect SLMCPR protection
- Standard approved ODYSY uncertainty (20%)
applied to evaluation is appropriate and sufficient
- Events near boundary not anticipated, not significant and unlikely to approach SLMCPR
- Region generated based on limiting analysis conditions (Haling depletion, longest cycle exposure analyzed, limiting cycle exposure used)
- Different (larger) exclusion region generated for reduced feedwater temperature operation imagination at work 22/
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Justification to Remove 0.15 DR Adder
- Exclusion Region conservatism demonstrated by comparison to actual events
- Buffer Region further reduces likelihood of instability for Option I-D plants
- Stability monitor required and operating at all Option l-D plants for additional protection
- Flow-biased APRM flux trip has been lowered for both Option 11plants and several Option l-D plants to offer timely scram in case THI oscillations develop imagination at work 23 /
DR Adder Removal NRC Presentation 12/13/2005
Justification to Remove 0.15 DR Adder
- ODYSY is best-estimate stability code
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- Significant theoretical improvement over FABLE
- ODYSY used in conservative procedure to produce reasonably limiting exclusion region
- Protects against reasonably limiting events 0.15 DR Adder excessively conservative for ODYSY exclusion region procedure I imagination at work 24/
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Proposed ODYSY Procedure 1 rr 0
2.
0 0
a imagination at work 25 /
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Proposed ODYSY Procedure
- 3. [
4.
0 0
5.
6.
I imagination at work 26/
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Proposed ODYSY Procedure
- E[
27/
imagination at work DR Adder Removal NRC Presentation I 12/13/2005
Demonstration Analysis
- Exclusion regions generated for two new plants and three plants from original ODYSY LTR
- New: Plant 1, Plant 2
- Original: Plant 3, Plant 4, Plant 5
- Regions generated with and without DR adder
- Core DR criterion: 0.80, 0.65
- Regions generated for reduced feedwater temperature for Plant 1
- Nominal, -30F,-60F
( imagination at work 28/
DR Adder Removal NRC Presentation 12/13/2005
Demonstration Analysis Plant BWR Core Core Loading Cycle Inlet Type Size by Fuel Type Length Orifice Original (MWd/ST) Diameter Licensed (in) Power 1 4 548 1Ox10 - 100% 12,930 2.22 100.0 2 3 580 10x10 - 81% 13,150 2.21 106.1 9x9- 19%
3 4 560 10x10 - 34% 13,868 2.09 104.1 9x9 - 64%
8x8 - 2%
4 4 368 8x8 - 100% 10,775 2.09 104.1 5 4 368 9x9 - 30% 10,425 2.22 100.0 8x8 - 70%
I imagination at work 29/
DR Adder Removal NRC Presentation /
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Plant 1 Demonstration Exclusion regions with and without 0.15 DR Adder 100 90 80 I
0 70 CL 0~
60 E
Is 50 40 30 20 10 0
0 10 20 30 40 50 60 70 80 90 100 Core Flow (%)
imagination at work 30/
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Plant 1 Demonstration
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imagination at work 31 /
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Plant 1 Demonstration Er imagination at work 32 /
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Plant 2 Demonstration Exclusion regions with and without 0.15 DR Adder 100-90 -
DR-O 65 80 DR=0.80
~70 p~60 o50 40 30 20 10 0 10 20 30 40 50 60 70 80 90 100 Core Flow (%)
imagination at work 33,/
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Plant 3 Demonstration Exclusion regions with and without 0.15 DR Adder 100 A 90 -
80 70 60 10
- 0 50 40 30 20 10 0
0 10 20 30 40 50 60 70 80 90 100 Rated Core Flow (%)
imagination at work 34 /
DR Adder Removal NRC Presentation /
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Plant 4 Demonstration Exclusion regions with and without 0.15 DR Adder 100.
90 80 70 DR=0.65 DR=0.80 o 60 D M 50 40 30 20 10 0 10 20 30 40 50 60 70 80 90 100 Rated Core Flow (%)
( EGO imagination at work 35/
DR Adder Removal NRC Presentation /
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Plant 5 Demonstration Exclusion regions with and without 0.15 DR Adder 100-90- -
80 - DR=0.65 70 0:
60 50 40 30 20 10 0
0 10 20 30 40 50 60 70 80 90 100 Rated Core Flow (%)
1 imagination at work 36/
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Demonstration Analysis Conclusions
- Analysis performed for plants of different size, varying exclusion region sizes, 8x8 - lOx1O fuel
- [I imaginationatwork 37 /
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Summary of ODYSY LTR Changes
- Removal of 0.15 Core DR Adder
- Removal of comparison to FABLE
- Outdated and unnecessary to include
- Explicit treatment of feedwater temperature
- Separate region generated for reduced FW temp
- Addition of recent instability event analysis
- Addition of two new plants (with new fuel/core designs) to demonstration analysis
- E((
imagination at work 38/
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Conclusions
- 0.15 Core DR Adder introduces unnecessary conservatism that may affect operations and should be removed from Option I-D/Il exclusion region methodology
- New, standalone ODYSY LTR (NEDC-33213P) will be submitted for NRC review
- Basis no longer includes comparison to FABLE
- Title will reflect ODYSY application for Option I-D/I1 imagination atwork 39/
DR Adder Removal NRC Presentation I 12/13/2005
NRC Feedback
- Questions?
- Comments?
a ~imagination at work 40/
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