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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© 2009 Electric Power Research Institute, Inc. All rights reserved.
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.”
3© 2009 Electric Power Research Institute, Inc. All rights reserved.
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
4© 2009 Electric Power Research Institute, Inc. All rights reserved.
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
5© 2009 Electric Power Research Institute, Inc. All rights reserved.
2002 2013
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Nuclear Industry Groundwater Events
EPRI Groundwater Protection Projects
June 2007NEI 07-07 Finalized
August 2005
Indian Point 2September 2002
Salem
September 2005
Groundwater Monitoring Guidancefor Nuclear Power Plants
(1011730)
NEI 07-07 Industry Groundwater
Protection Initiative
June 2006
Callaway
November 2007
EPRI Groundwater ProtectionGuidelines for
Nuclear Power Plants(1015118)
September 2005
1st Annual EPRI GroundwaterProtection Workshop
(Decommissioning TechnicalInformation Workshop)
December 2005
1st GroundwaterAssessment
20132008
2009 2010 2011 2012
March 2006
Braidwood
June 2006Industry Groundwater Protection
Initiative Announced
2012
Technology Demonstration:Tritium Separation Pilot Plant
Advanced Technologies for Groundwater Protection
2009 - 2010
Groundwater Data Managementand Modeling Tools
Demonstration at Southern Hatch PlantSeptember 2008
MNA Guidance forNuclear Power Plants
(1016764)
2009
Atmospheric Deposition of Tritium
2010 - 2011
Revision 1EPRI Groundwater Protection Guidelines
2009
Technology Innovation:Soil Vapor Extraction System
Pilot Testing
2007
Groundwater Protection for New Plants
6© 2009 Electric Power Research Institute, Inc. All rights reserved.
EPRI Task Force for Groundwater Protection
Challenge:Contaminant Characterization
& Mitigation
Challenge:Root Cause Determination
ANT Program:Incorporating lessons learned
to new plant design.
Equipment Reliability Program:Leak integrity improvement.
LLW-RM Program:Tritium Modeling
Groundwater AssessmentsGroundwater Protection
Guidelines
Decommissioning:Capturing experiences
Environment Group:Capturing experiencesGroundwater Modeling
RemediationData Management
Materials Group:Stress corrosion cracking
Leakage mechanism determination
NDE Center:System / Component
Inspection
7© 2009 Electric Power Research Institute, Inc. All rights reserved.
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© 2009 Electric Power Research Institute, Inc. All rights reserved.
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© 2009 Electric Power Research Institute, Inc. All rights reserved.
Which Radionuclides are Most Important in NPP Ground Water Investigations?
Relative Rank Radionuclide
1 Sr-90
2 Cs-137
3 Co-60
4 H-3
5 Cs-134
6 I-129
7 Ni-63
8 C-14
9 Pu-238
10 Am-241
Reference: EPRI Report 1011730 “Groundwater Monitoring Guidance for Nuclear Power Plants”, 2005
Ranking Based Upon:
•Inventory (PWR)
•Relative Dose
•Solubility
•Ease of Transport Through Soil (Kd)
10© 2009 Electric Power Research Institute, Inc. All rights reserved.
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© 2009 Electric Power Research Institute, Inc. All rights reserved.
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:
C6H6 + 7.5O2 → 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© 2009 Electric Power Research Institute, Inc. All rights reserved.
Example: Total BTEX Projection from MNA Site*
Modeled Projected Extentof Plume with
Advection,Dispersion,
and Sorption OnlyBiodegradation Omitted
8/93 7/94 9/95
1,450 ft
3,300 ft
* Reference: AFCEE
13© 2009 Electric Power Research Institute, Inc. All rights reserved.
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© 2009 Electric Power Research Institute, Inc. All rights reserved.
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© 2009 Electric Power Research Institute, Inc. All rights reserved.
EPRI Report (1016764) “Technical Guidance for MNA at Nuclear Power Plants”
• 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
Why a Utility MNA Compendium?
16© 2009 Electric Power Research Institute, Inc. All rights reserved.
Monitored Natural Attenuation for Nuclear Power Plants
Monitored Natural Attenuation of Chlorinated Solvents, U.S. EPA REMEDIAL TECHNOLOGY FACT SHEET
http://www.clu-in.org/download/remed/chl-solv.pdf
Biological Chemical Volatilization Sorption Dispersion Dilution Radioactive Decay
Guidance for Superfund RCRA/CERCLA Sites:
Hanford Lawrence Livermore Savannah River
ATTENUATION PROCESS
U.S. EPA & DOE
Guidance for Manufactured Gas Plants
EPRI Environment Sector
Technical Guidance for Monitored Natural Attenuation for Nuclear Power Plants
EPRI Nuclear Sector
DOE Implementation
of MNA for Radionuclides
EPA Guidance
Inter-EPRI Collaboration
17© 2009 Electric Power Research Institute, Inc. All rights reserved.
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
18© 2009 Electric Power Research Institute, Inc. All rights reserved.
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
19© 2009 Electric Power Research Institute, Inc. All rights reserved.
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
20© 2009 Electric Power Research Institute, Inc. All rights reserved.
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© 2009 Electric Power Research Institute, Inc. All rights reserved.
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
23© 2009 Electric Power Research Institute, Inc. All rights reserved.
EPRI Groundwater Protection/Remediation Guidance and Other Key MNA References
• Technical Guidance for Monitored Natural Attenuation at Nuclear Power Plants 1016764, EPRI, Sep.08
• Groundwater Protection Guidelines for Nuclear Power Plants: Public Edition 1016099, EPRI, Jan. 08
• Groundwater Monitoring Guidance for Nuclear Power Plants 1011730, EPRI, Dec. 05
• EPA 1999. Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage Tank Sites. Directive 9200.4-17P. U.S. Environmental Protection Agency. April 1999
• EPA 2007. 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 2006. Applicability of Monitored Natural Attenuation at Radioactively Contaminated Sites. International Atomic Energy Agency. Technical Reports Series No. 445.
• Sandia 1999. Site Screening and Technical Guidance for Monitored Natural Attenuation at DOE Sites. SAND99-0464. 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). 1995.
24© 2009 Electric Power Research Institute, Inc. All rights reserved.
Monitoring MNA Biogeochemistry(for advanced investigations)
Reference: USEPA: Site Characterization for MNA of Radionuclides in Ground Water
Dominant Terminal Electron Accepting ProcessDominant Terminal Electron Accepting ProcessDominant Terminal Electron Accepting ProcessDominant Terminal Electron Accepting Process
+10+10+10+10
0000
-10-10-10-10
Electron AcceptorsElectron AcceptorsElectron AcceptorsElectron Acceptors
pEpE
AerobicRespiration
AerobicRespiration
O2O2
OrganicsOrganics
O2O2
SO4-SO4-
SulfateReduction
SulfateReduction
SO4-SO4-
H2SH2S
MethanogenesisMethanogenesis
CO2CO2
CH4CH4
H2H2
DenitrificationDenitrificationDenitrificationDenitrification
NONO33--NONO33--
NONO33--NONO33--
Iron (III)ReductionIron (III)
Reduction
Fe (III)Fe (III)
Fe (II)Fe (II)
Chemical SpeciesChemical SpeciesChemical SpeciesChemical Species
Eq
uiv
alen
tsE
qu
ival
ents
Eq
uiv
alen
tsE
qu
ival
ents
MNA BiogeochemistryMNA BiogeochemistryMNA BiogeochemistryMNA Biogeochemistry
PCE/TCE
Mn (IV)
Cr (VI)U (VI)
Reference: DOE LBNL VIMSS Institute