ML18312A087

Clinch River: Draft ACRS Slide Presentations for 2.3, 2.4 and Chapter 11

ML18312A087
Person / Time
Site:	Clinch River
Issue date:	11/08/2018
From:	Kevin Quinlan NRC/NRO/DLSE
To:	Mallecia Sutton NRC/NRO/DLSE
Sutton M
References
Download: ML18312A087 (15)

Text

Staff Presentation to ACRS Subcommittee Clinch River Early Site Permit Application SER Chapter 2, Site Characteristics Section 2.3 - Meteorology Kevin Quinlan

Chapter 2, Section 2.3 - Meteorology Involves site specific information such as:

• regional climatology (2.3.1)

• local meteorology (2.3.2)

• onsite meteorological measurements program (2.3.3)

• short-term atmospheric dispersion estimates for accidental releases (2.3.4)

• long-term atmospheric dispersion estimates for routine releases (2.3.5) 2

2.3.1 Regional Climatology Staff performed review and analysis for the following -

• Tornado/Hurricane Wind Speeds and Associated Missiles

• Staff confirmed the applicants site characteristic values were appropriately derived from RG 1.76 and RG 1.221

• 100-year return Wind Speed (3-second gust)

• Staff confirmed the applicants site characteristic values were appropriately derived using ASCE/SEI 7-05

• Maximum Winter Precipitation

• Staff confirmed the applicants site characteristic values were appropriately derived using DC/COL-ISG-007 methodology

• Ambient Air Temperature and Humidity

• Staff independently confirmed the applicants site characteristic values using NWS data from Chattanooga, TN

• Staff concludes that the identification and consideration of the climatic site characteristics are acceptable and meet the requirements of 10 CFR 52.17(a)(1)(vi), 10 CFR 100.20(c), and 10 CFR 100.21(d) 3

2.3.2 Local Meteorology

• Staff reviewed and verified that the local meteorological data provided by Clinch River are representative of the site area as impacted by local topography.

• NRC Staff reviewed the Clinch River analysis of the following atmospheric phenomena recorded at the CRN site:

• Onsite wind speed and direction

• Atmospheric stability

• Ambient temperature and humidity

• NRC Staff also confirmed information recorded at offsite locations (such as National Weather Service reporting stations)

• Precipitation

• Fog

• Air quality and potential influence of the plant and related facilities on local meteorology 4

2.3.2 Local Meteorology (contd)

• Staff concludes that the applicants identification and consideration of the meteorological, air quality, and topographical characteristics of the site and the surrounding area meet the requirements of 10 CFR 100.20(c),

and 10 CFR 100.21(d), and are sufficient to determine the acceptability of the site.

5

2.3.3 On-site Meteorological Measurements Program

• Staff held an audit at the Clinch River site and surrounding area on May 15-17, 2017

• Audit topics related to meteorological monitoring included:

• Location and exposure of previously sited meteorological instrumentation and tower

• Instrument maintenance

• Data quality assurance program

• NRC staff completed a quality assurance review of the onsite meteorological database submitted by TVA as part of the ESP application.

• Staff confirmed that the TVA meteorological tower conformed to RG 1.23 criteria for siting of the tower in relation to the proposed Clinch River site 6

2.3.3 On-site Meteorological Measurements Program

• The SSAR used vector-averaged wind direction data as input to the straight-line Gaussian dispersion models (such as PAVAN and XOQDOQ). The applicant chose an alternative method to the best practice guidance cited in RG 1.23 and ANSI Standard 3.11-2005 which states that the transport wind direction for straight-line Gaussian models should be based on the scalar mean (or unit vector) wind direction.

• TVA voluntarily provided a submittal on April 9, 2018 (ML18100A950),

which evaluated the effects of having used vector-averaged wind directions in lieu of using scalar-averaged wind directions for the accident and routine release atmospheric dispersion estimates and the resulting doses presented in SSAR Chapters 15 and 11.

• TVAs analysis showed that the dose modeling results were bounding based on the use of vector-averaged wind directions. However, the applicant acknowledged that atmospheric dispersion and deposition factors for routine radiological releases were greater in some directions and lower in others when compared to using scalar-averaged wind directions.

7

2.3.3 On-site Meteorological Measurements Program

• TVA concluded that for normal and accident gaseous release dose assessments, the existing dose analyses included in the ESP application, which are based on vector-averaged wind directions and scalar-averaged wind speeds, is conservative and remains the basis of the CRN Site ESP application.

• NRC staff conducted an audit of this voluntary submittal (ML18248A113) to evaluate the potential implications of the applicants use of vector-averaged wind directions as input to the dispersion modeling analyses and wind-related data summaries.

• Staff audited CRNS atmospheric dispersion and dose analyses and agrees with the applicants conclusion.

• The staff concluded that the onsite meteorological monitoring system provides adequate data to represent onsite meteorological conditions as required by 10 CFR 100.20 and 10 CFR 100.21 8

2.3.3 On-site Meteorological Measurements Program The staff proposed COL Action Items as stated below:

COL Action Item 2.3-2: An applicant for a COL or a CP referencing this ESP should verify that the onsite meteorological measurement system, including the instrument tower, expected at the site prior to operation, is as described in SSAR Section 2.3.3. Any differences in instrumentation, exposure, or siting should be identified and discussed in order to demonstrate that the meteorological measurements program continues to meet the guidance provided in RG 1.23.

COL Action Item 2.3-3: An applicant for a COL or a CP referencing this ESP should verify whether the operational phase of the onsite meteorological measurements program will include wind data averaging on the basis of scalar or vector averages.

COL Action Item 2.3-4: An applicant for a COL or a CP referencing this ESP should identify and justify the wind speed and direction averaging approach(es) (either vector or scalar) to be used in the COL or CP:

• for modeling accident-related Control Room and Technical Support Center (TSC) atmospheric dispersion; and

• to be used during the operational phase to support emergency planning.

9

2.3.4 Short-Term (Accident)

Diffusion Estimates

• Staff performed an independent verification of the applicants accident diffusion estimates

• Staff created a Joint Frequency Distribution (JFD) from the onsite meteorological data for input to the PAVAN atmospheric dispersion computer model

• Staff executed its PAVAN computer model and generated offsite dispersion estimates (X/Q) values for all sectors along the uniform analytical Exclusion Area Boundary (EAB) (1100 feet) and the Low Population Zone (LPZ) (5279 feet) boundary

• The staff found the applicants EAB & LPZ site characteristic X/Q values acceptable

• The staff concludes that the applicant has established site characteristics and design parameters acceptable to meet the requirements of 10 CFR 52.17(a)(1)(ix), 10 CFR 100.21(c)(2), and 10 CFR 100.20(c) 10

SSAR Figure 2.3.4-1. Effluent Release Boundary with Analytical EABs 11

2.3.5 Long-Term (Routine)

Diffusion Estimates

• Staff performed an independent verification of the applicants routine release diffusion estimates

• Staff created a JFD from the onsite meteorological data for use as part of the input into the XOQDOQ atmospheric dispersion computer model

• Staff executed the XOQDOQ computer model and generated atmospheric dispersion and deposition estimates (X/Q and D/Q) for receptors of interest

• Staff concludes that representative atmospheric dispersion and deposition conditions have been calculated for receptors of interest. The characterization of atmospheric dispersion and deposition conditions meet the requirements of 10 CFR 100.21(c)(1) and are appropriate for the evaluation to demonstrate compliance with 10 CFR Part 50, Appendix I.

12

Conclusion

• All regulatory requirements for Section 2.3 have been satisfied

• No open items

• Three confirmatory items 13

Questions?

14

Acronyms

• ASCE - American Society of Civil Engineers

• CFR - Code of Federal Regulations

• COL - combined license

• CP - construction permit

• DC/COL-ISG - Interim Staff Guidance for design certifications and combined licenses

• D/Q - atmospheric deposition factor

• EAB - exclusion area boundary

• ESP - early site permit

• JFD - joint frequency distribution

• LPZ - low population zone

• RG - Regulatory Guide

• SSAR - Site Safety Analysis Report

• TVA - Tennessee Valley Authority

• X/Q - atmospheric dispersion factor 15