ML22136A110

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Presentation 1 - NRC Opening Remarks by T. Aird and C. Barr
ML22136A110
Person / Time
Issue date: 05/11/2022
From: Thomas Aird
Office of Nuclear Regulatory Research
To:
Barr C
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ML22117A070 List:
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Download: ML22136A110 (17)
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NRC Overview Presentation Second Annual Subsurface Investigations Workshop May 11, 2022 Tom Aird, NRC Office of Nuclear Regulatory Research

Workshop Motivation

  • Reactor sites are being rapidly decommissioned instead of entering SAFSTOR
  • Many complex decommissioning sites are expected to contain areas of residual radioactivity in subsurface soils and building structures
  • These complex sites will need to be investigated/surveyed and a determination made as to the need for subsurface remediation and a final decision made on license termination

Time Topic Speaker Todays Agenda NRC:

12:00 pm Logistics and Welcome Brett Klukan Jane Marshall Opening Remarks NRC:

  1. 1 NRC Opening Remarks Tom Aird Cynthia Barr 12:10 pm
  1. 2 NEI Opening Remarks NEI:

Bruce Montgomery Overview Presentations SC&A:

  1. 3 Methodologies for Optimization of Survey Design Carl Gogolak 12:40 pm #4 Statistical Methods for Subsurface Surveys to Support Decommissioning PNNL:

Deborah Fagan Jennifer Huckett 1:20 pm Discussion Period A All 2:00 pm Break

  1. 5 Utilizing the Nuclear Energy Institute (NEI) 07-07 Industry Groundwater Protection Initiative as a Foundation for Addressing Subsurface Site RSCS:

2:10 pm Assessments Matt Darois Eric Darois

  1. 6 Subsurface Basement Modeling and Survey Methods 2:50 pm Discussion Period B All
  1. 7 US DOE Challenges with Subsurface Investigation and Site-Specific DOE:

3:20 pm Case Study Amanda Anderson Brian Harcek

  1. 8 Using Electrical Resistivity Tomography (ERT) and Other Geophysical PNNL:

3:40 pm Methods to Non-Invasively Inform Subsurface Investigations Related to Tim Johnson Fred Day-Decommissioning Lewis 4:00 pm Break

  1. 9 Lessons Learned Identified during Independent Verification Activities ORAU/ORISE:

4:10 pm David King 4:30 pm Discussion Period C All 5:00 pm Adjourn

Last Years Public Workshop July 14 & 15, 2021 RES/NMSS held a public workshop on the technical basis for guidance on conducting and evaluating surveys of residual radioactivity in the subsurface soils of licensee sites. The NRC began to address this problem in NUREG/CR 7021, A Subsurface Decision Model for Supporting Environmental Compliance, issued January 2012.

https://www.nrc.gov/docs/ML2130/ML21300A378.pdf

Prior or Existing NRC Guidance

-A Subsurface Decision Model for Supporting Environmental Compliance

  • NUREG-1757, Volume 2, Revision 1 (2006)

-Consolidated Decommissioning Guidance: Characterization, Survey, and Determination of Radiological Criteria (Appendix G)

-Volume 2, Revision 2 was issued as a draft report for comment and contains updated guidance on subsurface surveys in Appendix G and J

  • NUREG-1575, Revision 1 (2000)

-Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) contains guidance on final status surveys for surface residual radioactivity

Previous and Potential New Approaches A

B C Sequence (A) Identify Potential Areas where Residual Radioactivity could be Present (B) Visualize Initial Borehole Sampling Results (C) Interpolate Data and Determine Probability of Exceeding a Threshold following Scoping (top) and Create a more Refined Map following Characterization (bottom)

Source: NUREG/CR-7021

Research Focus Areas Derived Concentration Guideline Levels for subsurface Stages of the Subsurface Decision Framework Geospatial Modeling Tools Geospatial and Statistical Methods Assessing Background and Use of MARSSIM Alternative Scenario B Evaluations of Large Soil Excavations and Soil Reuse Treatment of Uncertainty and Data Sufficiency Possible Treatment of Subsurface Elevated Areas and Hot Spots

    • Please see draft white paper Subsurface Surveys and Characterization attached to this meetings public meeting notice on NRC website.

Reference:

ML22088A219 **

Proposed Methodologies for Subsurface Survey Design and Data Analysis

--supporting remedial and license termination decision making--

Subsurface Survey Subsurface Sampling Design Modeling Tools/Software Bayesian SADA ELLIPGRID Objective: add and test these Visual Markov (or other) statistical sampling techniques with existing Sampling Bayes and subsurface modeling tools Plan (VSP)

Cokriging Other??

Figures: NUREG/CR-7021

Contact Information Tom Aird, NRC/RES Thomas.aird@nrc.gov Cynthia Barr, NRC/NMSS Cynthia.barr@nrc.gov

Subsurface Guidance Development Cynthia Barr, Senior Risk Analyst, Office of Nuclear Material Safety and Safeguards Division of Decommissioning, Uranium Recovery, and Waste Programs Presentation at the 2nd Annual Subsurface Soils Workshop May 11, 2022

Current Technical Information and Guidance NUREG/CR-7021, A Subsurface Decision Model for Supporting Environmental Compliance Draft NUREG-1575, Rev. 2, Draft NUREG-1757, Volume Multi-Agency Radiation Survey and 2, Rev. 2, , Consolidated Site Investigation Manual (or Decommissioning Guidance:

MARSSIM--used for surface soils Characterization, Survey and and building surfaces only) Determination of Radiological Criteria 11

Major Changes to NUREG-1757, Vol.

2, Rev. 2

  • Dose modeling updates Dose modeling considerations and exposure scenarios for buried residual radioactivity (Appendix J)

Development of subsurface DCGLs (Appendix G)

Consideration of cumulative dose from multiple sources including surface and subsurface soils (Appendix G)

Radiological survey and dose modeling integration (Appendix G) 12

Major Changes to NUREG-1757, Vol. 2, Rev. 2

  • Radiological surveys updates
  • Surveys of open excavations or substructures (Appendix G)
  • Surveys of soils/materials planned for reuse (Appendix G)
  • Use of composite sampling (Appendix O) 13

NUREG-1757, Volume 2, Rev. 2, Final Issuance Volume 2, Rev. 2, issued for public comment December 2020 Final publication is expected summer 2022 Guidance was added to address comments on need for additional subsurface guidance, including first workshop findings Interim subsurface investigations guidance to be developed late 2022 or early 2023 Interim guidance will be issued for public comment prior to finalization Interim guidance will be folded into the next revision of NUREG-1757, Volume 2 (Rev. 3) 14

Guidance Gaps

  • Development of derived concentration guidelines levels (DCGLs) or clean-up levels for subsurface residual radioactivity
  • Evaluation of the importance of subsurface elevated areas and need for derivation of DCGLEMCs
  • Evaluation of geospatial data analysis and modeling tools including GIS and geostatistical tools
  • Development of a technical approach for optimization of subsurface survey design, and to facilitate remedial and compliance decision-making
  • Development of a technical approach for evaluation of soil excavations, basement substructures, and materials planned for reuse

Interim Subsurface Guidance Development and VSP Code Improvements

  • Subsurface investigations interim guidance will consider Need for update of current guidance SC&As technical white paper and proposed methodologies PNNLs scoping of Visual Sample Plan tools Other technical information
  • Visual Sample Plan (VSP) computer code improvements Data analysis tools for continuously collected data Statistical test parameters and power calculations 16

Final thoughts

  • Guidance is available on subsurface surveys and dose modeling to derive clean-up levels in NUREG-1757, Volume 2, Rev. 2
  • Additional interim guidance is being developed
  • Contracts to address remaining data gaps are being but in place (e.g., surveys of exposed surfaces in the subsurface)
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