ML061770430
| ML061770430 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/22/2006 |
| From: | Yankee Atomic Electric Co |
| To: | NRC/FSME |
| References | |
| Download: ML061770430 (22) | |
Text
Yankee Atomic Electric Company Groundwater Closure Plan Meeting with USNRC June 22, 2006
Agenda
" Decommissioning Status
" Site End State
- Groundwater Monitoring History
- Recent Groundwater Activities
" Groundwater Closure Plan
- Fate and Transport Model
- Sampling Schedule
" Questions
Decommissioning Status
" Finalizing Remediation Activities n Establishing Final Site Grade by 9/06 UI Removing Final Structures and Piping L.Stockpiling Soil for Final Grade IJShipping Contaminated Soil n Completing Final Status Survey Field Work by 9/06
- Groundwater, Monitoring Ongoing
- Goal: Terminate NRC License for Property Outside ISFSI- by July 2007
YNPS April 2006 Site End State
- "Resident Farmer's"Well
- Offsite Down-Gradient Monitoring Wells
- Minimal Structures Will Remain Outside ISFSI L] Partial Structures - MADEP "No Detectable" Criteria LI Buried Commodities - Free Release Criteria LIISFSI Support Buildings - Free Release Criteria
" ISFSI Will Remain
Groundwater Monitoring:1997-2001
- 34 Monitoring Wells
!3 Generally Shallow Locations LI Distributed Throughout Site
- Low Levels of H-3:
CL Decreasing Trend Since 1997 L1 July 2000: Up To 5,000 pCi/L (MW-5, Under VC)
LiApril 2001 Up To 6,400 pCi/L (CB-10, Ion Exchange Pit)
- No HTD or Gamma-Emitting Nuclides
Groundwater Monitoring: 2002-2003 Data Gaps Addressed
- 12 New Wells Installed L3 7 "Bedrock" Wells
!1 5 Deep/Shallow Well Pairs E "Nested Boulder" Layer Under VC Characterized
- Extent of Down Gradient Contamination Defined
- Potable Water Well as Bedrock Background
- New Procedures For Drilling, Sampling and Analysis
Groundwater Monitoring: 2003 Summary of Results
- Tritium:
L) Generally Low Levels in Industrial Area Shallow Aquifer (2,000 - 6,000 pCi/L)
LJ Up to 46,000 pCi/L Identified in One Location Near SFP (MW-107)
" No HTD or Gamma-Emitting Nuclides
Groundwater Monitoring: 2004 Continued Improvements MInstalled 10 New Wells
!I 3 Bedrock Wells, 3 Deep / Shallow Clusters L) Bound Extent of H-3 Plume at 3 Key Locations L) Define Hydrogeological Features of Site MInstalled Data Logging Transducers MInstalled Data Logging Rain Gage
Groundwater Monitoring: 2004 Summary of Results E Tritium:
LJ Generally Low Levels in Industrial Area Shallow Aquifer (1 ,000 - 7,000 pCi/L) 1342,000 pCi/L Identified in One Location Near SFP
.(MW-1 07C)
" No HTD or Gamma-Emitting Nuclides
" Some Hydraulic Connections Noted
- 22 Wells Permanently Abandoned for D&D N SFP Emptied and Drained
Groundwater Monitoring: 2005 Focus on D&D
- Groundwater Related Activities Limited Due to D&D Activities L Source Term Areas Remediated
!I Wells Sampled in Beginning and End of 2005
- Tritium:
- 1Shallow. Locations Increased Following Uncovering of Soil and Concrete Removal Areas LJ Deeper Wells Generally Unchanged U No HTD or Gamma-Emitting Nuclides
Groundwater Monitoring: 2006 Groundwater Work Underway
- Sampling Continuing L) Quarterly Sampling
!J Selected Monthly Sampling for Tritium mAdditional Wells Installed
!I 2 Cluster Near SFP (MW-1 10, MW-1 11)
LJ 1 Cluster Down Gradient (MW-1 13)
! 2 New Wells to Define MW-1 07 Sand Lenses E Aquifer Characterization Test In Progress
- LTP Groundwater Monitoring Plan Drafted
LTP Groundwater Monitoring Plan:
Objectives
- Define Criteria for LTP Compliance Demonstration
" Identify Activities Required to Gather Additional Modeling Information
- Define Process to Demonstrate Groundwater Concentrations Comply with LTP
" Identify Completion Schedule and Documentation Requirements
LTP Groundwater Monitoring Plan:
Closure Criteria
- Tritium Concentrations <20,000 pCi/L in Resident Farmer Well L3 0.7 gpm From Highest Tritium Location LI Use Aquifer Characterization Testing and Numerical Model Results
- Tritium Trends Acceptable LI Resident Farmer Demonstration Not Affected LI Down Gradient Offsite Wells <20,000 pCi/L
" Site Radionuclides (Excluding Tritium) Do Not Exceed Amendment No. 158 Limits
LTP Groundwater Monitoring Plan:
2006 Activities
" Perform. Aquifer Characterization Test "J Identify Hydraulic Connections Between Aquifers
" Determine Hydrogeological Parameters
" Develop Fate and Transport Model
" Continue Sampling and Analysis U3 5 Quarterly Samples (Includes Two Spring Seasons)
LJ Consider Reducing Analyses for Certain Nuclides
" Demonstrate Yield and Radiological Water Quality of "Resident Farmer" Well
Fate and Transport Model:
YNPS Groundwater Model
" Uses 3-D MODFLOW/MODPATH/MT3DMS
" Includes Large Area on Both Sides of River
" Assumes Finer Grid On and Near Site
" Assumes 15 Layers LZ Glaciofluvial(1)
LJ Till (3 sand layers sandwiched between 4 till layers)
!3 Glaciolacustrine (2 sand layers sandwiched between 3 Glaciolacustrine layers)
LJ Upper bedrock El Lower Bedrock
Fate and Transport Model:
Use of Model
" Match Pressure Transient Tests by Varying Continuity of Sand Lenses LJ Pressure Transient Tests June 2006 L Pumping Test MW-107C June 2006
" Simulate Historical Rates of Tritium Movement
- Revise Conceptual Site Model
" Predict Fate and Transport of Tritium Plume
Fate and Transport Model:
Data for Model Development
" Base Maps JI 1997 Orthophotos; DEM10; YAEC land 5'-contour L 1974 10 foot bathymetric contour map of Reservoir
" Geology
- i Original borings and seismic
- i 1977-82 borings, testpits, mapping and seismic LI 1993-2006 borings and monitoring wells
- Water levels Li Approx. quarterly since 1993 Li Datalogger records 2003-2006
Fate and Transport Model:
Data for Model Development
" Physical Tests on Soil LI Seismic Refraction and Shear Wave Velocities l3Tests on Undisturbed Till from 1977 Testpits LJ GeoTesting Express Soil Testing 2003
- Water Quality Data
!3 Radiological (Particularly Tritium) from 1965 on LJ Boron 2003-2004; 2006 LAnion/Cation Summer 2006
Fate and Transport Model:
Model Calibration
- Match Avg Annual Historical Water Levels Under Plant Operating Conditions
- Match Vertical Groundwater Gradients
" Match Response to Rainfall
" Match Rate of Tritium Movement in Glacial Drift; Downward in Glacial Till
" Match Pressure Transient and Pumping Tests from 2006
Groundwater Closure Plan.:
Documentation of Results E Mid-2006 Groundwater Report LI Well Characteristics lAquifer Characterization Results 0 2006 Groundwater Report LI Numerical Model Results LJ Resident Farmer Demonstration
- 1Q 2007 Supplemental Report to Confirm LTP Criteria Met.
Groundwater Closure Schedule Quarterly Sampling Ongoing Monthly H-3 Sampling Ongoing Aquifer Characterization Test June-July 2006 2Q 2006 Sampling Round June-July 2006 2006 Interim Report September 2006 3Q 2006 Sampling Round September 2006 4Q 2006 Sampling Round December 2006 2006 Groundwater Report February 2007 1Q 2007 Sampling Round March 2007 Summary Letter April 2007 License Termination July 2007