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

1

Potential Sources of Groundwater Contamination at Nuclear Power

Plants RETS-REMP Workshop

Nine Mile Point- Constellation EnergyJune 28-30th, 2004Eric Darois, CHP

Robert Litman, Ph.D.

Radiation Safety & Control Services, Inc.Stratham, NH

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)

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Hydrogeological Terms

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

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Connecticut Yankee

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CY Operating History

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

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CY Decommissioning Update

• Shutdown 12/96• Large Components Removed Complete• Final Survey of 400 Wooded Acres Complete• 1st 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

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CY Public Interest(Circa 1998)

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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 – 1st 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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114

= Well Location - No Detectable Plant Related Radioactivity over 1 mRem/yr

= Well Location - Detectable Tritium over 0.015 mRem/yr (400pCi/L)

= Well Location - New Well

= Shallow and Deep Well Location

100( )

506

505

503

504 507

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112

113

Pennisula(3 Wells)

Rifle Range(9 Wells Total, 8 P revious and

1 New Well)

EOF(1 Well)

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AST

101( )

CONNECTICUT RIVER

105( ) 106( ) 107 ( )

110( )

115

102( )

104

123

103( )

502

501

508

124

120

118

119 121

125

122

109( )

= Well Location - Detectable Tritium over 0.015 mRem/yr and Strontium over 0.2 mRem/yr (2 pCi/L for Sr-90)

Note: 1) Samples analyzed to a Minimum Detection Sensitivity of 1 mRem/yr for Individual Nuclides 2 ) Cs-137 in Well #103S was at 0.8 mRem/yr (13.5 pCi/l)

Status as of December 2003 Sample Round Rev 3 3/8/04

GROUNDWATER MONITORING Summaryas of December 2003

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Tritium TrendNRC Criteria (25 mrem/yr) = 652,000 pCi/LEPA Drinking Water Standard = 20,000 pCi/l

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05

Co

nce

ntr

atio

n in

pC

i/L

MW-105S

MW-109D

MW-102D

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Strontium-90 TrendNRC Criteria (25 mrem/yr) = 251 pCi/lEPA Drinking Water Standard = 8 pCi/l

0

50

100

150

200

250

6/01 8/01 10/01 12/01 2/02 4/02 6/02 8/02 10/02 12/02 2/03 4/03 6/03 8/03 10/03 12/03

Co

nc

en

tra

tio

n in

pC

i/L

MW-105SMW-103SMW-106S

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Bias Detection

-10

-5

0

5

10

0 10 20 30 40

Rank Order

Co

nc

en

tra

tio

n (

pC

i/L)

0

2

4

6

8

10

12

14

16

18

20

-6.18 -4.64 -3.09 -1.55 -0.01 1.53 3.08 4.62 6.16

Concentration (pCi/L)

Fre

qu

ency

-4 -3 -2 -1 0 1 2 3 4

Standard Normal Quantile

Observed Distribution

Normal Distribution

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

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

-10

-5

0

5

10

15

20

0 5 10 15 20

Rank Order

Co

nc

en

tra

tio

n (

pC

i/L)

0

1

2

3

4

5

6

7

8

9

-6.54 -3.64 -0.74 2.16 5.06 7.96 10.86 13.76 16.66

Concentration (pCi/L)

Freq

uen

cy

-4 -3 -2 -1 0 1 2 3 4

Sigma

Observed Distribution

Normal Distribution

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Bias Detection

-15

-10

-5

0

5

10

15

0 5 10 15 20

Rank Order

Co

nc

en

tra

tio

n (

pC

i/L)

0

1

2

3

4

5

6

7

8

9

-27.01 -21.46 -15.91 -10.36 -4.80 0.75 6.30 11.85 17.40

Concentration (pCi/L)

Freq

uen

cy

-4 -3 -2 -1 0 1 2 3 4

Sigma

Observed Distribution

Normal Distribution

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

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GW Source Identification

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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

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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

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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

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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

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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

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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.

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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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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 1960-1980 the SFP did

not have an interior stainless liner• Significant IX Pit Leak - 1962• Built adjacent to Sherman Reservoir in the

northern Berkshires using a Vapor Containment Design (the BRT)

• Ceased Power Operation - 1992

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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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CB-7

CB-12

CB-3

B-3CB-8

CW-4

Sherman Spring

CW-7

CW-8CW-6

CB-2

CW-10

CB-6

CW-5

CW-1CW-9

MW-6

MW-3

CB-9

MW-5

CB-1

CB-11ACW-11

MW-2

B-1

CB-10

MW-1CW-2

CW-3

0 200 ft

YNPS 1999 Concentration of H-3 in Ground Water

Monitoring Wells(x are grouted)

Site StructuresFence line

Approximate Scale

Grid N

44.5 Deg.

N(True)

300-3000 pCi/L

3000-6000 pCi/L

6000-10000 pCi/L

>10,000 pCi/L

3131

CB-7

CB-12

CB-3

B-3CB-8

CW-4

Sherman Spring,

CW-7

CW-8CW-6

CW-10

CW-5

CW-1CW-9

MW-6

MW-3

CB-9 CB-1

CB-11A

CW-11

MW-2

B-1

CB-10

MW-1

CW-2CW-3

YNPS Fall 2001 Concentration of H-3 in

Ground Water

MW-5

CB-2

CB-6

0 200 ft

Approximate Scale

Grid N

44.5 Deg.

N(True)

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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 60 -200 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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36

37

38

39

40

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42

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Additional Investigations

• More Wells to Further Bound Plume

• Step Draw Down Test to Understand Aquifer Connections

• Install Network of Level Transducers

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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

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Major Lessons Learned

Don’t WaitMCL’s Count