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1 Potential Sources of Groundwater Contamination at Nuclear Power Plants RETS-REMP Workshop Nine Mile Point- Constellation Energy June 28-30 th, 2004 Eric.

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Presentation on theme: "1 Potential Sources of Groundwater Contamination at Nuclear Power Plants RETS-REMP Workshop Nine Mile Point- Constellation Energy June 28-30 th, 2004 Eric."— Presentation transcript:

1 1 Potential Sources of Groundwater Contamination at Nuclear Power Plants RETS-REMP Workshop Nine Mile Point- Constellation Energy June th, 2004 Eric Darois, CHP Robert Litman, Ph.D. Radiation Safety & Control Services, Inc. Stratham, NH

2 2 Experiences Decommissioning Sites –Connecticut Yankee –Yankee Rowe Groundwater Dose Contribution to License Termination (LT) Criteria NRC LT Criteria (10CFR20 Sub E, 10CFR50.82) –25 mrem/year + ALARA All Pathways Resident Farmer Typically Used –GW Contamination Requires Site Specific Dose Modeling (NUREGS)

3 3 Hydrogeological Terms Packer Testing Hydraulic Conductivity Pieziometric Surface Slug Test Pump Test Mud and Wash Drilling Rotosonic Drilling Glaciolacustrine Transmissivity Overburden

4 4 Connecticut Yankee

5 5 CY Operating History 582-Mwe Pressurized Water Reactor Construction Period Commercial Operation Jan 1, 1968 Permanently Shut Down December 4, 1996

6 6 CY Decommissioning Update Shutdown12/96 Large Components Removed Complete Final Survey of 400 Wooded AcresComplete 1 st GTCC Canister Located on ISFSI4/04 Start Secondary Side Building Removal5/04 Start Tank Farm Soil Removal5/04 Start RCA Building Removals7/04 Complete Fuel Transfer4/05 Complete Physical Decommissioning12/06 Release Non-ISFSI Areas From LicenseMid-2007

7 7 CY Public Interest (Circa 1998)

8 8 CY Groundwater Investigation History Evidence of GW Contamination During Operation –Potable Wells –CTMT Mat Sump – H-3 (~24,000,000 pCi/L) –Confirmed RWST Leak –Possible SFP Leak – Not Confirmed 1997/1998 – 1 st Monitoring Wells Installed –Initial Sampling H-3 and Gamma Only –143,000 pCi/L H-3 Formal Hydrogeological Investigation Plan –CT DEP –2 Phases – Includes Quarterly Sampling –Sr-90 Identified GW Dose Model Developed for LTP 2004 – Commitment to DEP –All Contaminants < EPA’s MCLs 20,000 pCi/L H-3 8 pCi/L Sr-90

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10 10 Tritium Trend

11 11 Strontium-90 Trend

12 12 Bias Detection Case 1: No Bias, Mn-54 March 2002 Data Set

13 13 Bias Detection Case 2: + Bias, Tc-99 March 2002 Data Set

14 14 Bias Detection Case 3: - Bias, Pu-241 March 2002 Data Set

15 15 GW Source Identification

16 16 Soil Remediation Plans Remove Soil from Areas Containing Elevated Contamination to Bedrock – Target Area is Groundwater Source: –Tank Farm Area including Structures –East of Resin Storage Facility –Area between Containment and PAB Install Well in Area to Monitor for any Residual Contamination

17 17 Groundwater Characterization Activities Conduct Routine Groundwater Monitoring Review and Document Existing Information - Phase II Plan, Task 1 Characterize Site-specific Hydrogeologic Conditions – Phase II Plan, Task 2 Develop Contaminant Fate and Transport Model – Phase II Plan, Task 3

18 18 Ongoing Groundwater Monitoring Continue Quarterly Groundwater Sampling Decommission Un-needed Wells Installed Water Level Monitoring System –33 Monitoring Points, Including Shallow and Deep Zones –Include Surface Water Points at Storm Water Pond, River, and Canal

19 19 Phase II Hydrogeologic Work Plan: Task 1 Conceptual Site Model Elements Review of Existing Hydrographs/Water Level Data Assessment of Apparent Contaminant Source Areas Catalog of Well and Boring Logs Description and Mapping of Bedrock Features Hydrogeologic Cross Sections Preliminary Groundwater Geochemistry Evaluation Evaluation of Substances of Concern Preliminary Hydrogeology Evaluation Measurement Data QC Review Inventory of Nearby Water Supply Wells

20 20 Phase II Hydrogeologic Work Plan: Task 2 Implement Improved Bedrock Packer Tests Install Bedrock Monitoring System Based On Packer Test Results Assess Aquifer Hydraulic Conductivity –Packer Test Measurements –Mat Sump Observations - Long-term Groundwater Extraction –Slug Test Measurements - Localized Measurements Assess Tidal Influence on Groundwater Install Additional Monitoring Wells as Needed Collect Other Supplemental Site-Specific Information to Support Fate and Transport Modeling

21 21 3-D Fate and Transport Model: Task 3 Select Appropriate Simulation Code based on Site Conditions Preliminary Conceptual Model Elements Include the Following: –Aquifer System Includes Shallow Unconsolidated Formation Overlying Fractured Bedrock Large variability in unconsolidated system thickness Bedrock appears to be anisotropic fractured system –Connecticut River is Ultimate Discharge Boundary Paired wells near the river shore exhibit upward vertical hydraulic gradient Consistent with the regional concept of the river as a discharge boundary.

22 22 CY Lessons Learned Radionuclides DO NOT Travel Together in Aquifers Site may have Separate Aquifers Contamination can Migrate to Depths >150 feet. Long Term Trends Are Important –Bias Detection –Seasonal Fluctuations –Rain Events Consider Level Monitoring –Correlate to RainFall Develop Conceptual Hydrogeologic Site Model –Well Placement –Bedrock Geophysics –Overburden Characteristics

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24 24 YR Operational History PWR, Operated from 1960 to 1992 Initially 485 Mwt, Uprated to 600 Mwt in 1963 Fuel Clad for ~14 years was Stainless Steel During the time period the SFP did not have an interior stainless liner Significant IX Pit Leak Built adjacent to Sherman Reservoir in the northern Berkshires using a Vapor Containment Design (the BRT) Ceased Power Operation

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27 27 Yankee Rowe Potential Groundwater Contaminating Events Unlined SFP IX Pit Leak 1962 Outside Storage Of Contaminated Materials –Refueling Equipment –Waste Redistribution of Soil Contamination –RCA Snow Removal –Rain – Storm Drains –Wind RX Head Impact – Outside Soil Contamination Underground PVC Drain Pipe Leak

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30 30 Well H-3 No. pCi/L CB CB CB-3

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33 33 Efforts Beginning in 2003 Complete groundwater monitoring program established that included: – Suites of radionuclides to be analyzed and relevant locations based on HSA –New locations for wells based on the site geology Intermediate Depths feet) Bedrock (some as deep as 300 feet) Multiple wells at same location for three depths –Frequency for measurements which would adequately monitor changes in the GW

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43 43 Additional Investigations More Wells to Further Bound Plume Step Draw Down Test to Understand Aquifer Connections Install Network of Level Transducers

44 44 Yankee Rowe Lessons Learned EPA MCLs Selected for Criteria Prior Investigations Not Rigorous –Little Regulatory Involvement Involve All Stakeholders Analyze for Wide Suite of Radionuclides Include Non-Rad Constituents Long Term Trends Important

45 45 Major Lessons Learned Don’t Wait MCL’s Count


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