ML16265A317
| ML16265A317 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/21/2016 |
| From: | Thompson R Tennessee Valley Authority |
| To: | Andrew Hon Plant Licensing Branch II |
| References | |
| Download: ML16265A317 (54) | |
Text
1 NRR-PMDAPEm Resource From:
Thompson, Russell R <rrthompson@tva.gov>
Sent:
Wednesday, September 21, 2016 9:42 AM To:
Hon, Andrew
Subject:
[External_Sender] AWA Presentation Attachments:
NRC Public Meeting - AWA Calc Presentation.pdf This is the presentation package well be using Friday.
Russell Thompson Corporate Nuclear Licensing W: 423/751-2567 C: 423/285-3405 This electronic message transmission contains information which may be TVA SENSITIVE, TVA RESTRICTED or TVA CONFIDENTIAL.
Any misuse or unauthorized disclosure can result in both civil and criminal penalties. If you are not the intended recipient, be aware that any disclosure, copying, distribution or use of the content of this information is prohibited. If you have received this communication in error, please notify me immediately by email and delete the original message.
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9/21/2016 9:41:42 AM Received Date:
9/21/2016 9:42:54 AM From:
Thompson, Russell R Created By:
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"Hon, Andrew" <Andrew.Hon@nrc.gov>
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TVACHAXCH8.main.tva.gov Files Size Date & Time MESSAGE 636 9/21/2016 9:42:54 AM NRC Public Meeting - AWA Calc Presentation.pdf 5931533 Options Priority:
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TVA Hydrology Precipitation Model Topical Report TVA-NPG-AWA16 Walk-Through Karen Carboni, TVA Bill Kappel, Applied Weather Associates LLC NRC Public Meeting September 23, 2016 Knoxville, TN
Agenda
- Introductions
- Background Information
- Overview of submittal details
- Q&A Hydrology Precipitation Model l Page l 2
Background Information Re-evaluation of PMP for TVA drainage basin started in 2014.
TVA contracted with Applied Weather Associates to update PMP.
Peer review board (Mel Schaefer Ph.D. P.E. & Barry Keim Ph.D.)
- Engaged throughout the study
& NRC Commercial dedication by ENERCON
- Classified study as safety-related
- Software controls for computer programs used (ArcGIS and SPAS)
Report issued in early 2016 Hydrology Precipitation Model l Page l 3
Probable Maximum Precipitation Definition: The theoretically greatest depth of precipitation for a given duration that is physically possible over a given storm area at a particular geographic location at a certain time of year (HMR 59, 1999)
Types of PMP studies:
Generalized (Hydrometeorological Reports)
Provides PMP values for a region HMR 51 - East of the 105th Meridian from Canada to Mexico Regional/Statewide Provide PMP values over regions with varying topography Individual basins are included in the regional/statewide results Site-Specific Provides PMP values for individual drainage basins Considers unique meteorology and topography Hydrology Precipitation Model l Page l 4
National Weather Service HMRs Coverage Hydrology Precipitation Model l Page l 5 http://www.nws.noaa.gov/oh/hdsc/studies/pmp.html
TVA Specific HMRs HMR 41 (1965)
- PMP/TVA precip above Chattanooga
- Current TVA Nuclear Plant Licensing Basis HMR 45 (1969)
- PMP/TVA precip up to 3,000sqmi, 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> HMR 47 (1973)
- Met criteria for 4 basin in Tennessee and Cumberland Rivers HMR 56 (1986)
- PMP/TVA precip, areal distribution <3000sqmi Hydrology Precipitation Model l Page l 6
How Is PMP Computed?
Storm Based Approach-Deterministic
- Maximize storms
- Transposition storms
- Combine into PMP design storm
- By storm type Subjective decisions involved Data is key
- Both quantity and quality Hydrology Precipitation Model l Pagel 7
PMP History HMRs have become out-of-date Based on outdated methods and techniques
- Better understanding of meteorology Storm datasets not up to date
- Most recent TVA HMR more than 30 years old Many processes subjective and not reproducible Several inconsistencies between each report Not clear how storm data used to develop the PMP values Limited working papers/notes Limited to no external/independent review Quantification of topographic effects improved Better spatial representation of rainfall today
- NEXRAD/PRISM/NOAA Atlas 14
- Better documentation
- Independent review Hydrology Precipitation Model l Page l 8
PMP Improvements Used Today
- NEXRAD weather radar Very important for spatial distribution Must be calibrated first
- GIS
- Computing power/speed
- Updated understanding of rainfall
- Updated understanding of topographic effects
- Updated climatology for maximization 40+ years of updated data included Hydrology Precipitation Model l Page l 9
Current PMP Work Many PMP studies completed last 30 years Private industry-numerous site-specific, statewide, regional studies Need for updating PMP to better design/update spillways Understand flood hydrology/PMF State dam safety, FERC, NRC main users Bureau of Reclamation, Corps of Engineers (RIDM)
NWS no longer involved Hydrology Precipitation Model l Page l 10
AWA Project Locations Hydrology Precipitation Model l Page l 11
Current PMP Work
- Objective not to reduce the values, but to make them as accurate as possible given current understanding of meteorology
- Coordination with Nuclear Safety/Dam Safety/Users Understand how developed Aware of subjectivity/uncertainty Better information to make more informed decisions
- Results are used in place of HMRs Hydrology Precipitation Model l Page l 12
TVA Overall Basin Analyzed Hydrology Precipitation Model l Page l 13
TVA PMP Development Steps Total Adjustment Factor
=
IPMF x MTF x OTF Hydrology Precipitation Model l Page l 14
TVA Mean Annual Precipitation Hydrology Precipitation Model l Page l 15
NOAA Atlas 14 Precip Frequency 100-yr 24-hr, Point Values Hydrology Precipitation Model l Page l 16
TVA Storm Search and Storm Development Storm search included All relevant HMR storms Storms greater than 100yr in-place Significant flood events Previous/ongoing studies Results in most complete storm database possible Able to be continually updated All storms used for PMP analyzed with SPAS Hydrology Precipitation Model l Page l 17
TVA Storm Analysis Using SPAS
- SPAS produces Hourly gridded rainfall Depth-Area-Duration data Mass curves at each grid
- SPAS extensively peer reviewed Numerous independent review boards FERC, state dam safety, USACE SPAS has been through nuclear QA V&V Hydrology Precipitation Model l Page l 18
TVA Storm Search Domain l 19 Hydrology Precipitation Model l Page
TVA Short List Storm Locations-All Types Hydrology Precipitation Model l Page l 20
Hydrology Precipitation Model l Page l 21 TVA Storms-General Storm Type
TVA Storms-Tropical Storm Type Hydrology Precipitation Model l Page l 22
TVA Storms-Local Storm Type Hydrology Precipitation Model l Page l 23
Storm Maximization and Adjustments
- Total Adjustment Factor = IPMF x MTF x OTF
- Calculate the In-Place Maximization Factor (IPMF) for each storm
- Use dew point if available
- Use Sea Surface Temperature if no dew point available Hydrology Precipitation Model l Page l 24
In-Place Maximization Factor Development
- Identify moisture source region
- Define appropriate time frame associated with given storm
- Dew Point climatology most closely reflecting main rainfall period used 6, 12, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />
- Analyze x-hour average dew points in the source region to define value
- Use SST if not dew point data available Hydrology Precipitation Model l Page l 25
Air Mass Source Region Identification HYSPLIT very helpful Hydrology Precipitation Model l Page l 26
Storm Representative Value Identification Hydrology Precipitation Model l Page l 27
Storm Representative Value Identification Hydrology Precipitation Model l Page l 28
Moisture Transposition Factor Development
- Total Adjustment Factor = IPMF x MTF x OTF
- Compare climatological 100-yr moisture availability between source and target
- Horizontal comparison only
- How much more or less moisture would be available to a storm in one location versus another Hydrology Precipitation Model l Page l 29
Moisture Transposition Factor Development Hydrology Precipitation Model l Page l 30
Moisture Transposition Factor Map Hydrology Precipitation Model l Page l 31
Moisture Transposition Factor Map Hydrology Precipitation Model l Page l 32
TVA Topography and Orographics
- Total Adjustment Factor = IPMF x MTF x OTF
- Utilize precip frequency data between source and each grid
- TVA HMRs
- Topography not addressed in reproducible manner
- Many subjective judgments
- For low resolution used Hydrology Precipitation Model l Page l 33
Elevation Across TVA Domain Hydrology Precipitation Model l Page l 34
Transposition Regions Hydrology Precipitation Model l Page l 35
Orographic Transposition Factor
- Calculated by comparing the precipitation frequency data at the source location vs the target location
- Assume precip frequency data representative of topography
- Assume if transpositionable, then similar meteorology/topography between two locations
- Duration used reduces mixed population issues Hydrology Precipitation Model l Page l 36
Orographic Transposition Factor
- Same as discussed in WMO 2009, Section 3.1.4 Since precipitation-frequency values represent equal probability, they can also be used as an indicator of the effects of topography over limited regions. If storm frequency, moisture availability, and other precipitation-producing factors do not vary, or vary only slightly, over an orographic region, differences in precipitation frequency values should be directly related to variations in orographic effects.
Hydrology Precipitation Model l Page l 37
Orographic Transposition Factor SPAS Rainfall entered as x value in y = mx + b Result becomes orographically adjusted rainfall Ratio of this result vs original SPAS rainfall becomes OTF SPAS 24-hour rain = 18.39 P0 =.73(18.39) + 0.19 P0 = 13.61 OTF = 13.61/18.39 = 0.74 10 year 25 year 50 year 100 year 200 year 500 year 1000 year SOURCE (X-axis) 5.01 5.89 6.61 7.35 8.12 9.18 10.00 TARGET (Y-axis) 3.81 4.51 5.06 5.61 6.18 6.92 7.47 24-hour Rainfall Frequency Depths (in)
Hydrology Precipitation Model l Page l 38
Orographic Transposition Factor Hydrology Precipitation Model l Page l 39
Total Adjustment Factor
- TAF = IPMF x MTF x OTF
- Each factor analyzed individually for each storm for each grid
- PMP Calculated at numerous area sizes and durations Hydrology Precipitation Model l Page l 40
Example PMP-General Storm Hydrology Precipitation Model l Page l 41
Example PMP-Tropical Storm Hydrology Precipitation Model l Page l 42
Example PMP-Local Storm Hydrology Precipitation Model l Page l 43
PMP Results-LIP
- LIP calculated for all locations
- 1-hr 1-sqmi PMP for every grid
- Standard output because hourly PMP available from 1-through 72-hours Hydrology Precipitation Model l Page l 44
Example PMP-1-hr 1sqmi Hydrology Precipitation Model l Page l 45
PMP Comparisons
- Compare to precip frequency
- Should be 2 to 5 times as large Hydrology Precipitation Model l Page l 46
PMP Comparisons
- Develop PMP for Test Basins
- Compare to Previous PMP values Hydrology Precipitation Model l Page l 47
PMP Comparisons-Test Basins Hydrology Precipitation Model l Page l 48
PMP Comparisons-Test Basins Hydrology Precipitation Model l Page l 49
Seasonality of PMP by Storm Type
- Analyzed dates of occurrence of storm on short list
- Utilized storm data relevant to TVA to derive seasonality of PMP Hydrology Precipitation Model l Page l 50
Conclusions Storm based approach utilized Data base updated with storms through completion of study Sensitivity and uncertainty discussed Utilized excellent work available from previous HMRs Higher confidence in results Explicit quantification of values All data independently peer review and checked Data used for hydrologic analyses PMF/IDF LIP All data and calculations contained within PMP GIS Tool Hydrology Precipitation Model l Page l 51