Transcript Design- and Operating Bases Regional Meteorological Conditions

13th Nuclear Utility Meteorological Data Users Group Meeting
Lessons Learned From Establishing
Design- and Operating-Basis
Regional Meteorological Conditions
For Permitting New Nuclear Power Plants
in the United States
Ping K Wan
Bechtel Power Corporation
October 2009
Introduction
• Highlight significant climate characteristics
• Establish Design- & Operating-Basis
Meteorological Criteria
• Discuss Lessons Learned
– Areas of concern
– Guidance needed to fill gaps
– Ways could expedite/improve application
review process
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Significant Site Climate Characteristics
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Ambient temperature & humidity statistics
Maximum rainfall rates
Maximum snowfall rates
Tornado parameters
Basic wind
The UHS Meteorological conditions
Regional Air Quality
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Establishing Design Criteria
• Design-Basis for SSCs (safety-related)
Consider the most severe natural phenomena historically
reported for the site and surrounding area with margin
sufficient to account for the limited accuracy, quantity,
and period of time which the data have been
accumulated.
• Operating-Basis for SSCs (nonsafety-related)
Consider the statistic of meteorological averages and
extremes collected onsite and/or at nearby
representative stations with sufficient length of reliable
records available.
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Plant Heat Dissipation System Design
Ambient Temperature & Humidity
The 0%, 1%, and 2% Annual/Seasonal
Exceedance Values for:
• Minimum ambient dry bulb temperature
• Maximum ambient
– Dry-bulb temperature
– Wet-bulb temperature (coincident)
– Wet-bulb temperature (non-coincident)
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Building Roof Design
Maximum Rainfall & Snowfall Rates
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Maximum Rainfall Rate
Maximum Short-Term Rainfall Rate
Maximum Snowfall Rates & Snowpack
48-Hour Probable Maximum Winter
Precipitation
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Structural Design
Tornado and Extreme Wind
• Tornado Parameters
– Maximum wind speed
(maximum rotational & translational speed)
– Radius of maximum rotational speed
– Pressure drop & rate of pressure drop
• Basic Wind Speed
– 3-Sec Wind Gust
– Fastest Mile
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Ultimate Heat Sink (UHS) Design
Meteorological Conditions resulting in:
• Maximum evaporation and drift loss of
water,
• Minimum water cooling
• Potential for water freezing in the UHS
water storage facility, if applicable
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Requests for Additional Information
• SER documents NRC’s technical review of an
applicant’s SAR
• RAIs are a tool to help the NRC Staff reach the
conclusions presented in the SER
NRC Project
Manager
Technical
Reviewer
Branch Chief
COL
Applicant
Technical
Editor
and
Licensing
Assistant
Office of
General
Counsel
NRC Project
Manager
NRC June 2008
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Meteorology-Related RAIs
Repetitive requests for information in 3 basic
areas identify a need for additional
guidance:
• Information and analysis deficiencies
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Incomplete data
Unidentified data sources
Inconsistent application of values
Questionable technical approach
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Meteorology-Related RAIs (cont.)
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Data quality & representativeness deficiencies
– Representativeness for specific site
– Interpretation of data
– Misapplication of NCDC storm events database
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Deviation from guidance or inconsistency with
DCD
– Seasonal versus annual exceedance for
temperatures
– Site characteristic values versus DCD values
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Meteorology-Related RAIs (cont.)
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Potential Climate Change Impacts
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Related to meteorological site characterization for
establishing site suitability for possible future
construction/operation of a NPP at the site
Early Site Permits are valid for 10 to 20 years and can be
renewed for an additional 10 to 20 years.
ACRS and NRC were specifically interested in the impacts
of climate change on design-basis hurricane and designbasis temperatures
In general, just analyzing past trends is not sufficient.
Forecasts of climate change need to be examined.
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Guidance—In Progress
• COL/DC-ISG-7 (draft) issued to identify
combinations of winter precipitation to
assume for determining snow loads on
building roof.
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Guidance—In Progress
• ANS 2.21 (in development) to provide
criteria for assessing atmospheric effects
on the ultimate heat sink.
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Guidance—Still Needed
• Appropriateness of non-site specific data sets for
use in applications
• Risk-based approach to exceedance of
meteorological parameters for plant design
• PPE-type approach to guide site selection efforts
• Seasonal vs. annual exceedance values for dry- and
wet-bulb temperatures
• Climate change impacts—identifying and applying
trends
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Selection of Reactor Type Guided By
Meteorological Parameters
Extreme Wind
Basic Wind Speed:
100-yr mean recurrence interval for SR
50-yr mean recurrence interval for NSR
Tornado
Max rotational speed
Max translational speed
Max pressure drop
Rate of Pressure Drop
Radius
Precipitation
Maximum rainfall rate
Maximum snow load
Weight of 48-hour PMWP
Ambient Design Temperature
0%, 1%, 2% Exceedance
Maximum Dry Bulb
Maximum Wet Bulb
–coincident
–non-coincident)
Minimum Dry Bulb
Site
Values
ABWR
AP1000
ESBWR
U.S.
EPR
APWR
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Expedite/Improve Review Process
• Adherence to regulatory guidance
• Avoidance of weakness identified in
previous applications
• Guidance development
– Cooperation between industry & NRC with
respect to scope and approach
– Consistency in content and conclusions
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In Closing
• Adherence to regulatory and industry guidance.
• Design- and Operating-basis regional
meteorological conditions must be complete and
sufficiently conservative.
• Consistently apply the established parameters for
the chosen reactor technology.
• Leverage RAIs Lessons Learned Experience fully.
• Guidance development should be closely
coordinated between industry and U.S. NRC.
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