1. Monitored Natural Attenuation as a Remediation Strategy for Nuclear Power Plant Applications
Sean Bushart- EPRI
Karen Kim- EPRI
NRC RIC Conference-
Panel on Subsurface Environmental Characterization, Modeling, Monitoring and Remediation
March 11, 2009

2. What is MNA? (From 1999 EPA Directive)
“The term ‘monitored natural attenuation,’ as used in this Directive, refers to the reliance on natural attenuation processes to achieve site-specific remedial objectives within a time frame that is reasonable compared to that offered by other more active methods.”
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Perception of MNR by many federal and state agencies, and the public is initially very negative. By having a reliable, scientific and engineering-based decision process that distinguishes between those sites where contaminants are controlled by processes that destroy or strongly immobilize the contaminants from sites at which MNRA is not an appropriate remedy.
It is important to note that MNR is NOT a “do-nothing” or “no action” alternative. The Science Advisory Board to the EPA advised the agency that it is an effective knowledge-based remedy where a thorough engineering analysis informs the understanding, monitoring, predicting, and documenting of the natural processes.
It’s also important to note that MNR is not a “silver bullet” that makes contaminated site management go away. But, MNR can and SHOULD be a part of active site management – removing the source and allowing attenuation to complete the job.
Please note that “MNR” and Monitored Natural Attenuation are used interchangeably through this, and more recent EPA documents.

3. Implementing MNA as a Remedial Strategy
MNA is NOT a “do-nothing” or “no action” alternative
Knowledge/science/engineering based remedy
Requires monitoring of the natural attenuation processes
Incorporates three important factors:
Risk to human health and the environment
Contaminant mobility and/or decay
Time
Appropriately implemented MNA saves remediation costs
The message from EPA is a) MNA should be considered at all sites and 2) involvement from multiple sectors of industries and experts is important.
In the end, the user will be able to 1) determine when is MNR appropriate (concentrations, source control, timeframe for recovery), 2) understand the lines of evidence needed for evaluation (historical trends, forcast models but also bioavailability, risk, degradation potential), 3) select management tools and strategies for remedy selection (how to structure RAOs, how to consider multiple remedies, property transfers).

4. Presentation Overview
Background: Industry Groundwater Protection Initiative and EPRI Role
MNA Applications for Non-Radioactive Site Contaminants and for Radioactive Contaminants
Published EPRI Report on MNA

6. EPRI Task Force for Groundwater Protection

7. EPRI Groundwater Protection Guidelines for Nuclear Power Plants (1015118)
Graded Approach
Baseline Program for all users
Toolbox of Elevated Program Elements for increased understanding of site hydrogeology.
Evaluation of Systems, Structures, Components (SSCs) and Work Practices
Risk of groundwater contamination
Design and condition of SSCs
Understanding Site Hydrogeology and Characteristics
Transport of potential groundwater contamination
Developing Conceptual Site Model
Implementing Groundwater Monitoring Program
Installing and sampling groundwater monitoring wells
Data analysis and management
Review and update of monitoring program over time

8. Examples of Structures, Systems and Components (SSCs) Evaluated in Utility Groundwater Protection Programs
These SSCs contain radioactive liquids and have the potential to contribute to groundwater contamination
Outside Storage/Transfer Areas
Spent Fuel Pool & Transfer Canal
Underground Piping
Underground Tanks

9. Relative Rank Radionuclide
Which Radionuclides are Most Important in NPP Ground Water Investigations?
Relative Rank Radionuclide
Sr-90
Cs-137
Co-60
H-3
Cs-134
I-129
Ni-63
C-14
Pu-238
Am-241
Reference: EPRI Report “Groundwater Monitoring Guidance for Nuclear Power Plants”, 2005
Ranking Based Upon:
Inventory (PWR)
Relative Dose
Solubility
Ease of Transport Through Soil (Kd)

10. Presentation Overview
Background: Industry Groundwater Protection Initiative and EPRI Role
MNA Applications for Non-Radioactive Site Contaminants and for Radioactive Contaminants
Published EPRI Report on MNA

11. Original MNA Work: Based upon Biological Decay of Hydrocarbons
Ex. For USTs containing BTEX (benzene, toluene, ethylbenzene, xylene)
Benzene will biologically decay under the proper conditions:
C6H O2 → 6CO2 + 3H2O
(aerobic biodegradation* of benzene)
* Biodegradation... a coupling of an oxidation (electron donor) to a reduction (electron acceptor) to gain energy for the organism

12. Example: Total BTEX Projection from MNA Site*
8/93
7/94
9/95
1,450 ft
Modeled Projected Extent
of Plume with
Advection,
Dispersion,
and Sorption Only
Biodegradation Omitted
3,300 ft
* Reference: AFCEE

13. MNA Applications for Radionuclides
DOE:
Sandia Labs: A Natural Attenuation Toolbox for Metals and Radionuclides
Decision-Making Framework Guide for the Evaluation and Selection of MNA Remedies at DOE Sites
IAEA:
Applicability of Monitored Natural Attenuation at Radioactively Contaminated Sites (STI/DOC/010/445, 2006)
EPA:
2007: Monitored Natural Attenuation of Inorganic Contaminants in Ground Water, Volume 1: Technical Basis for Assessment
Radionuclides, particularly those relevant to NPPs, can be good candidates for MNA due to their known half lives and in some cases their biogeochemical behaviors

14. Presentation Overview
Background: Industry Groundwater Protection Initiative and EPRI Role
MNA Applications for Non-Radioactive Site Contaminants and for Radioactive Contaminants
Published EPRI Report on MNA

15. Why a Utility MNA Compendium?
EPRI Report ( ) “Technical Guidance for MNA at Nuclear Power Plants”
Why a Utility MNA Compendium?
Put in Place a Guidance Document Useful to Utility Site Managers
Need Consistent Utility-Industry Approach
MNA is Global Across Utilities:
Media
Soil-groundwater-surface water-sediments
Contaminants
PAHs, NAPL, metals, PCBs, and other inorganics
Waste Streams
Oil, combustion by-products, coal tars, transformer oils, solvents
First and foremost, a guidance document tailored to helping your site managers understand and manage their specific sites – be it an MGP site, plant decommissioning and property transfer, coal or fossil fuel combustion byproducts.
This would include MNR strategies for different waste streams, different media and pathways.
Would house and/or reference the numerous EPRI reports that have dealt with components that are germane to MNR ranging from identification of organic attenuation factors for NAPL or fossil fuel sources in groundwater to physical and hydraulic properties of coal and/or oil combustion by-products, to models that have been developed including the MARS, MYGRT groundwater transportation code, or databases such as the Combustion By-Product Environmental Analysis System. EPRI recently completed a 3-year study to assess arsenic and selenium attenuation from field leachates at CCP management sites. EPRI recently hosted a sediments-water interactions symposium.
EPRI, Guidance for the selection of monitored natural attenuation as a remedial measure.
EPRI. Conducted a 3-year study on arsenic and selenium attenuation.
EPRI, What does an MGP candidate site look like for MNA.
Integrating these documents/reports, with practical field applications and experience derived from cases studies yields an integrated set of tools that includes....READ FROM SLIDE

16. Monitored Natural Attenuation for Nuclear Power Plants
ATTENUATION PROCESS
Biological Chemical Volatilization Sorption Dispersion Dilution Radioactive Decay
U.S. EPA & DOE
Guidance for Superfund RCRA/CERCLA Sites:
Hanford Lawrence Livermore Savannah River
DOE Implementation of MNA for Radionuclides
EPA Guidance
EPRI Environment Sector
Guidance for Manufactured Gas Plants
Monitored Natural Attenuation of Chlorinated Solvents, U.S. EPA REMEDIAL TECHNOLOGY FACT SHEET
Inter-EPRI Collaboration
EPRI Nuclear Sector
Technical Guidance for Monitored Natural Attenuation for Nuclear Power Plants

17. EPRI Report (1016764) “Technical Guidance for MNA at Nuclear Power Plants”
Includes Guidance on:
Mechanisms for Migration and Retention of Radionuclides
Evaluating Site Suitability for MNA
Remediation Objectives and Site Remediation
Monitoring Attenuation
Assessing MNA Progress and the Contingency Plan
First and foremost, a guidance document tailored to helping your site managers understand and manage their specific sites – be it an MGP site, plant decommissioning and property transfer, coal or fossil fuel combustion byproducts.
This would include MNR strategies for different waste streams, different media and pathways.
Would house and/or reference the numerous EPRI reports that have dealt with components that are germane to MNR ranging from identification of organic attenuation factors for NAPL or fossil fuel sources in groundwater to physical and hydraulic properties of coal and/or oil combustion by-products, to models that have been developed including the MARS, MYGRT groundwater transportation code, or databases such as the Combustion By-Product Environmental Analysis System. EPRI recently completed a 3-year study to assess arsenic and selenium attenuation from field leachates at CCP management sites. EPRI recently hosted a sediments-water interactions symposium.
EPRI, Guidance for the selection of monitored natural attenuation as a remedial measure.
EPRI. Conducted a 3-year study on arsenic and selenium attenuation.
EPRI, What does an MGP candidate site look like for MNA.
Integrating these documents/reports, with practical field applications and experience derived from cases studies yields an integrated set of tools that includes....READ FROM SLIDE

18. EPRI Report (1016764) “Technical Guidance for MNA at Nuclear Power Plants”
Evaluating Site Suitability for MNA
Site conceptual model integrating:
plant layout
potential contaminant sources
site operating history
site hydrogeology
Site characterization to evaluate:
nature and extent of the radioactive contamination in soil and groundwater
hydrogeological and geochemical features of the site
a stable or diminishing groundwater plume
Evaluation of near-site receptors and near-site land and water use
First and foremost, a guidance document tailored to helping your site managers understand and manage their specific sites – be it an MGP site, plant decommissioning and property transfer, coal or fossil fuel combustion byproducts.
This would include MNR strategies for different waste streams, different media and pathways.
Would house and/or reference the numerous EPRI reports that have dealt with components that are germane to MNR ranging from identification of organic attenuation factors for NAPL or fossil fuel sources in groundwater to physical and hydraulic properties of coal and/or oil combustion by-products, to models that have been developed including the MARS, MYGRT groundwater transportation code, or databases such as the Combustion By-Product Environmental Analysis System. EPRI recently completed a 3-year study to assess arsenic and selenium attenuation from field leachates at CCP management sites. EPRI recently hosted a sediments-water interactions symposium.
EPRI, Guidance for the selection of monitored natural attenuation as a remedial measure.
EPRI. Conducted a 3-year study on arsenic and selenium attenuation.
EPRI, What does an MGP candidate site look like for MNA.
Integrating these documents/reports, with practical field applications and experience derived from cases studies yields an integrated set of tools that includes....READ FROM SLIDE

19. EPRI Report (1016764) “Technical Guidance for MNA at Nuclear Power Plants”
“Triggers” for Assessing MNA Progress
Are radioactive contamination levels decreasing at rates that meet or exceed predictions?
Migration of contaminants beyond established plume or compliance boundaries
Contaminants detected at locations that potentially will pose unacceptable risks to receptors
Contingency soil and groundwater remediation options should be evaluated
Triggers should be set so as to ensure that seasonal fluctuations or sampling variability do not trigger a contingency unnecessarily
First and foremost, a guidance document tailored to helping your site managers understand and manage their specific sites – be it an MGP site, plant decommissioning and property transfer, coal or fossil fuel combustion byproducts.
This would include MNR strategies for different waste streams, different media and pathways.
Would house and/or reference the numerous EPRI reports that have dealt with components that are germane to MNR ranging from identification of organic attenuation factors for NAPL or fossil fuel sources in groundwater to physical and hydraulic properties of coal and/or oil combustion by-products, to models that have been developed including the MARS, MYGRT groundwater transportation code, or databases such as the Combustion By-Product Environmental Analysis System. EPRI recently completed a 3-year study to assess arsenic and selenium attenuation from field leachates at CCP management sites. EPRI recently hosted a sediments-water interactions symposium.
EPRI, Guidance for the selection of monitored natural attenuation as a remedial measure.
EPRI. Conducted a 3-year study on arsenic and selenium attenuation.
EPRI, What does an MGP candidate site look like for MNA.
Integrating these documents/reports, with practical field applications and experience derived from cases studies yields an integrated set of tools that includes....READ FROM SLIDE

20. Summary: Monitored Natural Attenuation for Nuclear Power Plants
Benefits of MNA for NPPs
Effective, technically sound remediation methodology
Relatively low cost compared to traditional remediation methods (i.e. excavation and soil replacement)
Does not produce secondary waste
Applications of MNA at NPPs
Decommissioning
Yankee Rowe, Connecticut Yankee
Operating Plants

21. Conclusions: Implementing MNA as a Remedial Strategy
MNA is NOT a “do-nothing” or “no action” alternative
Knowledge/science/engineering based remedy
Requires monitoring of the natural attenuation processes
Incorporates three important factors:
Risk to human health and the environment
Contaminant mobility and/or decay
Time
Appropriately implemented MNA saves remediation costs
The message from EPA is a) MNA should be considered at all sites and 2) involvement from multiple sectors of industries and experts is important.
In the end, the user will be able to 1) determine when is MNR appropriate (concentrations, source control, timeframe for recovery), 2) understand the lines of evidence needed for evaluation (historical trends, forcast models but also bioavailability, risk, degradation potential), 3) select management tools and strategies for remedy selection (how to structure RAOs, how to consider multiple remedies, property transfers).

22. BACKUP SLIDES

23. EPRI Groundwater Protection/Remediation Guidance and Other Key MNA References
Technical Guidance for Monitored Natural Attenuation at Nuclear Power Plants , EPRI, Sep.08
Groundwater Protection Guidelines for Nuclear Power Plants: Public Edition , EPRI, Jan. 08
Groundwater Monitoring Guidance for Nuclear Power Plants , EPRI, Dec. 05
EPA Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage Tank Sites. Directive P. U.S. Environmental Protection Agency. April 1999
EPA Monitored Natural Attenuation of Inorganic Contaminants in Ground Water, Volume 1 – Technical Basis for Assessment. EPA/600/R-07/139. U.S. Environmental Protection Agency. October 2007.
IAEA Applicability of Monitored Natural Attenuation at Radioactively Contaminated Sites. International Atomic Energy Agency. Technical Reports Series No. 445.
Sandia Site Screening and Technical Guidance for Monitored Natural Attenuation at DOE Sites. SAND Sandia National Laboratories. March 1999.
Technical Protocol for Implementing Intrinsic Remediation with Long-Term Monitoring for Natural Attenuation of Fuel Contamination in Groundwater, Volume I and Volume II. Air Force Center for Environmental Excellence (AFCEE)

24. Monitoring MNA Biogeochemistry (for advanced investigations)
Reference: USEPA: Site Characterization for MNA of Radionuclides in Ground Water

25. Dominant Terminal Electron Accepting Process
MNA Biogeochemistry
Aerobic
Respiration O2
Organics
Chemical Species H2
Iron (III)
Reduction
Fe (III)
Fe (II)
SO4-
Sulfate
Reduction
H2S
Equivalents
Denitrification
NO3-
Methanogenesis
CO2
CH4
+10
Electron Acceptors
PCE/TCE
Mn (IV)
Cr (VI)
U (VI) pE
-10
Dominant Terminal Electron Accepting Process
Reference: DOE LBNL VIMSS Institute

26. Together…Shaping the Future of Electricity