1 ANSI/ANS American National Standard for Determining Meteorological Information at Nuclear Facilities R. Brad Harvey, CCM Physical Scientist Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission

2 Presentation Topics History of U.S. NRC Meteorological Monitoring Guidance History of U.S. NRC Meteorological Monitoring Guidance ANS/ANSI ANS/ANSI Potential Updates to U.S. NRC Meteorological Monitoring Guidance Potential Updates to U.S. NRC Meteorological Monitoring Guidance –3 rd Proposed Revision 1 to RG 1.23

3 Safety Guide 23 (RG 1.23) Issued in Feb 1972 Issued in Feb 1972 Guidance Topics Guidance Topics –Parameters Minimum 2 levels of wind speed, wind direction, temp Minimum 2 levels of wind speed, wind direction, temp Dew point or humidity where there is an potential for increased fogging/icing Dew point or humidity where there is an potential for increased fogging/icing –Siting Tower at same elevation as plant Tower at same elevation as plant Avoid influence of nearby structures Avoid influence of nearby structures Measurements at Measurements at –10m –Vent release height –Stack height (if applicable)

4 Safety Guide 23 (RG 1.23) Guidance Topics (cont’d) Guidance Topics (cont’d) –Data recording Dual recorders (2 digital or 1 analog/1 digital) Dual recorders (2 digital or 1 analog/1 digital) –Instrument Accuracy Wind direction: ±5° (instantaneous values) Wind direction: ±5° (instantaneous values) Wind speed: ±5mph (time average) Wind speed: ±5mph (time average) Temperature: ±0.5°C (time average) Temperature: ±0.5°C (time average) Delta-temperature: ±0.1°C (time average) Delta-temperature: ±0.1°C (time average) Dew point: ±0.5°C (time average) Dew point: ±0.5°C (time average)

5 Safety Guide 23 (RG 1.23) Guidance Topics (cont’d) Guidance Topics (cont’d) –Maintenance and Servicing 90% data recovery goal 90% data recovery goal Semiannual calibrations Semiannual calibrations –Data reduction and compilation Data averaged over 15–60 min Data averaged over 15–60 min Compiled into annual Joint Frequency Distributions Compiled into annual Joint Frequency Distributions Stability based on delta- T or sigma-theta Stability based on delta- T or sigma-theta

6 Safety Guide 23 (RG 1.23) Guidance Topics (cont’d) Guidance Topics (cont’d) –Special Considerations Additional monitoring in complex terrain Additional monitoring in complex terrain Precipitation and Solar Radiation may be desirable Precipitation and Solar Radiation may be desirable –Documentation Describe program in FSAR Describe program in FSAR

7 (1 st ) Proposed Rev. 1 to RG 1.23 Issued in Sept 1980 (post-TMI) Issued in Sept 1980 (post-TMI) Additional Guidance Additional Guidance –Siting Avoiding structure influences Avoiding structure influences Instrument boom length/orientation Instrument boom length/orientation Aspirated temperature shields Aspirated temperature shields 10m & 60m measurement heights, higher for stacks 10m & 60m measurement heights, higher for stacks Additional monitoring for coastal & valley sites Additional monitoring for coastal & valley sites

8 (1 st ) Proposed Rev. 1 to RG 1.23 Additional Guidance (cont’d) Additional Guidance (cont’d) –Data Recording Sampling rates Sampling rates CR/TSC/EOF displays CR/TSC/EOF displays –System Accuracy –Data Reduction & Compilation Hourly averages Hourly averages Hourly database submittal Hourly database submittal –Quality Assurance 10 CFR Part 50 Appendix B 10 CFR Part 50 Appendix B

9 (1 st ) Proposed Rev. 1 to RG 1.23 Additional Guidance (cont’d) Additional Guidance (cont’d) –Special Considerations for Emergency Preparedness Independent 10m backup tower Independent 10m backup tower Remote interrogation Remote interrogation

10 ANSI/ANS Approved in September 1984 Approved in September 1984 Many aspects in common with Proposed Rev. 1 to RG 1.23 Many aspects in common with Proposed Rev. 1 to RG 1.23 –Did not include “Special Considerations for Emergency Preparedness” No references to 10m backup tower or remote interrogation No references to 10m backup tower or remote interrogation Reaffirmed in 1990; withdrawn in 2000 Reaffirmed in 1990; withdrawn in 2000

11 2 nd Proposed Rev. 1 to RG 1.23 Issued in April 1986 Issued in April 1986 Endorsed ANSI/ANS Endorsed ANSI/ANS –Took exception to ANSI/ANS QA program guidance

12 ANSI/ANS Approved in February 2000 Approved in February 2000 Expanded Applicability to Nuclear Facilities in Public Sector (e.g. National Labs) Expanded Applicability to Nuclear Facilities in Public Sector (e.g. National Labs) Cooperative Effort Cooperative Effort –NUMUG –DMCC Moved ANS Subcommittees Moved ANS Subcommittees –From:ANS-2 Site Evaluation –To:ANS-3 Reactor Operations

13 ANSI/ANS Guidance Topics Guidance Topics –Meteorological Measurements –Siting of Meteorological Instrumentation –Data Acquisition –Data Base Management –System Performance –Appendixes (for information only)

14 ANSI/ANS Approved by ANS December 2005 Approved by ANS December 2005 –Awaiting approval by ANSI before publishing Updates/Enhancements Updates/Enhancements –System calibration methods –System accuracy calculations –Editorial and clarity changes

15 ANSI/ANS Meteorological Monitoring System Meteorological Monitoring System –Basic Meteorological Measurements Wind speed, wind direction, temp, precip Wind speed, wind direction, temp, precip –Supplemental Meteorological Measurements Moisture, solar/net radiation, pressure, mixing height, etc. Moisture, solar/net radiation, pressure, mixing height, etc. –Remote Sensing Technologies Sodar, radar wind profilers, NEXRAD, satellite data, etc. Sodar, radar wind profilers, NEXRAD, satellite data, etc. –Sources of Other Surface Observations –Meteorological Observation Towers –Stability Class Determination Delta-T, sigma theta, sigma phi, Monin-Obukhov length, etc. Delta-T, sigma theta, sigma phi, Monin-Obukhov length, etc.

16 ANSI/ANS Instrument Siting Instrument Siting –Topographic Effects Flat terrain, mountain, and shoreline sites Flat terrain, mountain, and shoreline sites –Instrument Orientation Aerodynamic effects of obstacles, diabatic effects Aerodynamic effects of obstacles, diabatic effects –Optional Site Selection Techniques Remote sensing, tracer studies, numerical modeling, physical modeling, etc. Remote sensing, tracer studies, numerical modeling, physical modeling, etc.

17 ANSI/ANS Data Acquisition Data Acquisition –Recording Mechanisms Primary system: digital Primary system: digital Optional backup system: analog or digital Optional backup system: analog or digital –Sampling Frequencies Averaging: At least 30 samples at intervals no longer than 60 sec spaced over not less than 10 min period Averaging: At least 30 samples at intervals no longer than 60 sec spaced over not less than 10 min period Standard Deviation: more frequent sampling Standard Deviation: more frequent sampling –Data Processing min averages for display in CR/TSC/EOF min averages for display in CR/TSC/EOF Hourly averages for climatic and dispersion analyses Hourly averages for climatic and dispersion analyses

18 ANSI/ANS Data Base Management Data Base Management –Representative Site Data Bases 3-5 yrs of onsite data for dispersion calculations 3-5 yrs of onsite data for dispersion calculations –Data Validation Techniques Compare to expected range of values, redundant sensors, other tower levels, other data sources, etc. Compare to expected range of values, redundant sensors, other tower levels, other data sources, etc. –Data Substitution From redundant sensors, other tower levels (adjusted for change in height), linear interpolation for short periods of missing data, etc. From redundant sensors, other tower levels (adjusted for change in height), linear interpolation for short periods of missing data, etc.

19 ANSI/ANS Data Base Management (cont’d) Data Base Management (cont’d) –Data Recovery Rates 90% annually, individual channels and composite WS/WD/DT joint frequency distributions 90% annually, individual channels and composite WS/WD/DT joint frequency distributions –Data Archiving Retain raw data for 5 years, valid hourly data for life of facility Retain raw data for 5 years, valid hourly data for life of facility –Data Reporting Annual joint frequency distributions Annual joint frequency distributions

20 ANSI/ANS System Performance System Performance –System Accuracy Wind Speed: ±0.2 m/s or 5% of observed; Wind Speed: ±0.2 m/s or 5% of observed; Wind Direction: ±5° Wind Direction: ±5° Temperature: ±0.5°C Temperature: ±0.5°C Delta-T: ±0.1°C Delta-T: ±0.1°C Dew Point: ±1.5°C Dew Point: ±1.5°C Time ±5 min Time ±5 min Etc. Etc.

21 ANSI/ANS System Performance (cont’d) System Performance (cont’d) –System Calibrations Encompass entire channel (from sensor to display/recorder) Encompass entire channel (from sensor to display/recorder) Preoperational and 6-month intervals thereafter Preoperational and 6-month intervals thereafter Document “as-found” and “as-left” results Document “as-found” and “as-left” results Field versus laboratory calibrations Field versus laboratory calibrations –System Protection, Maintenance & Service Protect against electrical faults, severe environmental conditions, etc. Protect against electrical faults, severe environmental conditions, etc. –Quality Assurance and Documentation

22 ANSI/ANS Appendixes (for information only) Appendixes (for information only) –Supplemental Measurements –Tower Siting in Complex Terrain –Stability Class Determination –Optional Site Selection Techniques –Wind Computations –Calibration Practices

23 3 rd Proposed Rev. 1 to RG 1.23 Part of ongoing overall effort to update regulatory guidance to support expected new reactor applications Part of ongoing overall effort to update regulatory guidance to support expected new reactor applications May include consideration of guidance provided in ANSI/ANS May include consideration of guidance provided in ANSI/ANS –Tower and instrument siting criteria –System accuracy –Data processing, recording, and displays