Potential Sources of Groundwater Contamination at Nuclear Power ...

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Potential Sources of Groundwater Contamination at Nuclear Power Plants RETS-REMP Workshop Nine Mile Point-Constellation Energy June 28-30 th , 2004 Eric Darois, CHP Robert Litman, Ph.D. Radiation Safety & Control Services, Inc. Stratham, NH

Experiences Decommissioning Sites Connecticut 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)

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

Connecticut Yankee

CY Operating History 582-Mwe Pressurized Water Reactor Construction Period 1963 - 1967 Commercial Operation Jan 1, 1968 Permanently Shut Down December 4, 1996

CY Decommissioning Update Shutdown 12/96 Large Components Removed Complete Final Survey of 400 Wooded Acres Complete 1 st GTCC Canister Located on ISFSI 4/04 Start Secondary Side Building Removal 5/04 Start Tank Farm Soil Removal 5/04 Start RCA Building Removals 7/04 Complete Fuel Transfer 4/05 Complete Physical Decommissioning 12/06 Release Non-ISFSI Areas From License Mid-2007

CY Public Interest (Circa 1998)

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

Tritium Trend

Strontium-90 Trend

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

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

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

GW Source Identification

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 amongst Containment and PAB Install Well in Area to Monitor for any Residual Contamination

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

Ongoing Groundwater Monitoring Continue Quarterly Groundwater Sampling Decommission Un-required 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

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 of Substances of Concern Preliminary Hydrogeology Evaluation Measurement Data QC Review Inventory of Nearby Water Supply Wells

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

3-D Fate and Transport Model: Task 3 Select Appropriate Simulation Code in view of Site Conditions Preliminary Conceptual Model Elements Include the Following: Aquifer System Includes Shallow Unconsolidated Formation Overlying Fractured Bedrock Large inconstancy in unconsolidated framework thickness Bedrock has all the earmarks of being anisotropic cracked framework Connecticut River is Ultimate Discharge Boundary Paired wells close to the waterway shore display upward vertical water driven inclination Consistent with the provincial idea of the stream as a release limit.

CY Lessons Learned Radionuclides DO NOT Travel Together in Aquifers Site may have Separate Aquifers Contamination can Migrate to Depths >150 feet. Long haul 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

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 day and age 1960-1980 the SFP did not have an inside stainless liner Significant IX Pit Leak - 1962 Built neighboring Sherman Reservoir in the northern Berkshires utilizing a Vapor Containment Design (the BRT) Ceased Power Operation - 1992

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

YNPS 1999 Concentration of H-3 in Ground Water Sherman Spring CB-6 CB-2 Grid N CW-7 N (True) CW-8 CW-6 44.5 Deg. CW-10 MW-6 CB-1 CB-9 CW-5 CW-9 MW-5 Monitoring Wells (x are grouted) Site Structures Fence line B-1 CW-1 MW-3 MW-2 CB-10 CW-11 CB-11A CW-3 MW-1 CW-2 CB-12 CB-7 300-3000 pCi/L B-3 CB-8 CW-4 3000-6000 pCi/L CB-3 6000-10000 pCi/L >10,000 pCi/L Approximate Scale 0 200 ft Well H-3 No. pCi/L CB-1 4210 CB-2 1280 CB-3 <MDC CB-6 666 CB-7 <MDC CB-8 <MDC CB-9 4010 CB-10 2330 CB-11A 2030 CB-12 <MDC CW-2 <MDC CW-3 <MDC CW-4 <MDC CW-5 <MDC CW-6 <MDC CW-7 <MDC CW-8 360 CW-10 <MDC CW-11 11600 MW-1 1290 MW-2 11470 MW-5 5610 MW-6 <MDC B-1 2830 Sherman Spring <MDC

Sherman Spring, YNPS Fall 2001 Concentration of H-3 in Ground Water Grid N (True) 44.5 Deg. CB-6 0 200 ft CB-2 Approximate Scale CW-7 CW-6 CW-8 CW-10 MW-6 CB-1 CB-9 CW-5 CW-9 MW-5 B-1 CW-1 MW-3 MW-2 CB-10 CW-11 CB-11A CW-3 MW-1 CW-2 CB-12 CB-7 CB-8 B-3 CW-4 CB-3

Efforts Beginning in 2003 Complete groundwater observing system built up that included: Suites of radionuclides to be dissected and significant areas in view of HSA New areas for wells in view of the site geography Intermediate Depths 60 - 200 feet) Bedrock (some as profound as 300 feet) Multiple wells at same area for three profundities Frequency for estimations which would satisfactorily screen changes in the GW

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

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

Major Lessons Learned Don't Wait MCL's Count