NRC Public Workshop - Technical Basis for Guidance on Conducting and Evaluating Surveys of Residual Radioactivity in the Subsurface Soils of Licensee Sites

NRC Public Workshop - Technical Basis for Guidance on Conducting and Evaluating Surveys of Residual Radioactivity in the Subsurface Soils of Licensee Sites

On July 14-15, the U.S. Nuclear Regulatory Commission (NRC) is holding 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.

Workshop Format:
This will be a virtual-only meeting and attendance will be via Microsoft Teams (links to be provided at a later date). Detailed webinar information and other meeting details will be posted to the public meeting notice website: https://www.nrc.gov/pmns/mtg?do=details&Code=20210553

Workshop Agenda:
The agenda is still being developed. The current plan is to have a mix of pre-recorded presentations and open discussions. Parties interested in presenting should contact the NRC meeting organizers.
 
Workshop Topics:
The purpose of this workshop is to gather information on the subject areas below.  Discussion topics to be covered during this workshop may include:

1. Subsurface radiological surveys ranging from historical site assessments, scoping, characterization, remedial action, confirmatory, and final status surveys.

2. DCGLs for contaminants in the subsurface and use of multiple DCGLs for surface and/or subsurface layers. Evaluating elevated areas or hot spots (DCGLEMC) for potential doses to receptors including the inadvertent intruder.

3. Evaluation of sites with geospatial and statistical methods.

· Statistical methods and geospatial modeling tools and software to analyze contaminant distributions and optimize sampling and scanning of the sub-surface.

· Methods to determine the sample density, spatial distributions, depths, and volume to achieve a level of confidence and limit decision errors.

· Applicability of MARSSIM statistical tests and other alternative methods.
Treatment of uncertainty and data sufficiency.
Applicability of “composite sampling” or surrogate ratios.


4. Applicability of Scenario B for subsurface residual radioactivity and demonstrating indistinguishability from background.

5. Methods to survey large subsurface soil excavations and survey of soils for reuse in large excavations including use of conveyor belts and other methods.

The executive summary to a draft Technical Letter Report by SC&A (see link below) outlines some key issues related to sub-surface characterization and surveys for decommissioning, and in some cases suggests approaches to resolving those concerns. Attendees are strongly encouraged to have read or be familiar with the nomenclature and procedures of the MARSSIM document, as analogous terminology and many of the same concepts may be useful for subsurface surveys as well. This is already reflected in the discussion topics listed above, in NUREG/CR 7021, and the SC&A executive summary.

Key References:
Executive Summary, “Guidance on Surveys for Subsurface Radiological Contaminants,” Draft Technical Letter Report,” SC&A April 2021. ML21123A229


NUREG-1575, “Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM),” Revision 1, issued August 2000 (NRC 2000). MARSSIM Rev. 2 is soon to be issued for public comment but is available for early download at the EPA’s Science Advisory Board website: https://yosemite.epa.gov/sab/sabproduct.nsf/RSSRecentAdditionsBOARD/E1D35FEB397932FF8525854D00836CFA


NUREG/CR 7021, “A Subsurface Decision Model for Supporting Environmental Compliance,” issued January 2012.

 

Workshop Contacts:
Mark Fuhrmann, mark.fuhrmann@nrc.gov & Tom Aird, thomas.aird@nrc.gov

Thank you.
 

Anne Fream
Administrative Assistant
Nuclear Regulatory Commission
Office of Nuclear Material Safety and Safeguards
Division of Decommissionning, Uranium Recovery,
and Waste Programs
301-415-0645
anne.fream@nrc.gov