Storm Drain Tritium Discharges RETS/REMP Workshop Roger Tolbert Grand Gulf Jim Key Key Solutions, Inc.

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1 Storm Drain Tritium Discharges 2005 RETS/REMP Workshop Roger Tolbert Grand Gulf Jim Key Key Solutions, Inc.

2 The Issue Discovery of Measurable H-3 Levels in Yard Storm Drains Not Routine Release Pathway NRC IE Bulletin Requires Evaluation To Be Performed

3 Tritium Concentrations (pci/l) Location Collection Date 12/09/04 12/15/04 12/27/04 01/05/05 01/13/05 1 E Turbine Yard MH MH MH MH MH MH Catch Basin MH MH MH-8 < MH-6 < Outfall <

4 The Problem UFSAR Assumed All Liq Rad Waste Releases via Radwaste Line Into Mississippi River Release To Environment Did Not Take Place Though Normal Effluent Discharge Pathway Became Necessary to Develop Pathway Specific Dilution Factors

5 Yard Drain Release Pathway

6 Yard Drain to Culvert

7 Culvert 1 to 014 Basin 014 Basin Culvert 1

8 Culvert Basin to Hamilton Lake to Mississippi River

9 Assess Dose At Lake (Not Mississippi River) Highest Long Term Environmental Concentrations Would Occur in Lake First Body of Water With Sufficient Size to Sustain Year Round Fish or Invertebrate Population Assessment at This Location Insures Dose to Public Unlikely to be Substantially Underestimated

10 Assess Dose At Lake Most Likely Real Exposure Only After Reaching Mississippi River Substantial Additional Dilution Would Occur Assessment at Lake = Conservative Assessment

11 Recommendations Revise UFSAR New Release Pathway New Dose Estimates for Liquid Releases Revise ODCM Update Definition of Dilution Factor to Include Releases to Lake Change Liquid Surveillance Requirement to Include Releases From Storm Drains

12 Surveillance Recommendations Provide Monthly Grab Sample at 007 Outfall Could Monitor 007 Outfall at Effluent LLD Better Choice - Monitor 007 Outfall at Environmental LLD Uncontrolled Release Directly to Environment Lower Monitoring Level Allows for Trending and Early Warning Demonstrates Increased Diligence

13 Monitor and Trend 007 Outfall Tritium Concentrations 007 Outfall Discharge Flow Rate 007 Outfall Discharge Volume Site Precipitation Determines Dilution Volume Examine Correlation Between Precipitation and 007 Tritium Concentrations

14 Determination of New Discharge Pathway Dilution Factor and Dose Assessment

15 1 s t Dilution Point Assumed Dilution Points 2nd Dilution Point

16 Assumed Future Monitoring Would Take Place at 007 Outfall Environmental Concentrations Would Be Difficult to Predict Based on Measurements From Plant Yard 007 Outfall Represents Single Entry Point to Environment Preferred Monitoring Location

17 Area Drainage Basins

18 Discharge Pathway Drainage Basins Discharge Pathway Drainage Basin B Discharge into Basin 014 via Culvert 1 Drainage Basin Description Approximately 0.35 square miles of Drainage Basin B discharges through Culvert 1 (UFSAR section ). Drainage Basin Surface Area (acres) 224 Basin 014 Discharge into Hamilton Lake Remainder of Drainage Basin B (0.26 square miles) plus 2.8 square miles drained by Drainage Basin A. All discharge into Hamilton Lake 1960

19 Assumptions for Derivation of Dilution Factor Releases to the Environment Would Only Be Significant During Rain Fall Ignored Dilution of Hamilton Lake Environmental Dilution Driven Only By Runoff From Drainage Basins

20 Total Drainage Basin Runoff Depends On Total Rainfall Runoff Drainage Area Type of Cover on Drainage Area

21 USDA Natural Resources Conservation Service (NRCS) Old Soil Conservation Service Field Engineering Handbook Chapter 2 Estimating Runoff and Peak Discharges NTIS Doc No.PB

22 Runoff [ inches] = ( ) 2 P 0.2* S ( P + 0.8* S ) P = Precipitation in Inches S = Maximum Potential Retention S = ( 1000 CN ) 10 CN = Runoff Curve Number

23 Retention Depends On Cover Type Cover Treatment Crop Type and Cultivation Hydrologic Condition Impervious Areas Urban and Industrial Hydrologic Soil Group

24 USDA Runoff Curves

25 Curve Numbers for Agricultural Land USDA - NRCS Engineering Field Handbook

26 Curve Number Selection - Natural Area Hydrologic Soil Group from UFSAR Chapter 2 Type A and B Soils Most Conservative Lowest Runoff Potential (Type A ) Wooded Area Lowest Dilution Volume

27 Curve Numbers for Urban Area USDA - NRCS Engineering Field Handbook

28 Curve Number Selection Plant Area Most Conservative Paved Parking Lot Highest Runoff Potential Highest Waste Volume

29 Dilution Factor Outfall to Culvert 1 DF 1 = WA + PY PY DF 1 = Dilution factor for Dilution Pathway 1. WA = Annual runoff from wooded area around plant. PY = Annual runoff from plant yard discharging through 007 Outfall.

30 Runoff from 007 Outfall into Culvert 1 Dilution Factor (DF 1 ) Location P CN Runoff (inches) Drainage Area (acres) Runoff ft 3 /yr x 10 6 Wooded Area Lowest Annual Rainfall (1978) Plant Yard Total Culvert 1 Runoff 19.7 Average Annual Wooded Area Rainfall Plant Yard Total Culvert 1 Runoff 35.8

31 Dilution Factor 2 Culvert 1 to Hamilton Lake DF 2 = ( B + B ) A R CV1 + CV1 DF 2 = Dilution factor for Dilution Pathway 2. B A = Annual runoff from Basin A. B R = Annual runoff from Basin B R. CV1 = Annual runoff from Culvert 1.

32 Runoff from Culvert 1 into Hamilton Lake Dilution Factor (DF 2 ) Location P CN Runoff (inches) Drainage Area (acres) Runoff ft 3 /yr x 10 6 Culvert 1 Exit Flow Lowest Annual Rainfall Basin A + Basin B R Total Runoff Into Hamilton Lake Average Annual Rainfall Culvert 1 Exit Flow Basin A + Basin B R Total Runoff Into Hamilton Lake 289.6

33 Dilution Factors for Discharge from 007 Outfall into Hamilton Lake DF Outfall to Culvert 1 DF 2 Culvert 1 to Hamilton Lake DF HL 007 Outfall to Hamilton Lake Lowest Annual Rainfall Average Annual Rainfall

34 Dose Assessment Assumptions 007 Outfall to Hamilton Lake DF = 10 Pathways Potable Water Ingestion Fish Ingestion Invertebrate Ingestion Age Groups Child Teen Adult

35 Calculated Doses Concentration Level Max Observed 007 Outfall Concentration Potable Water Environmental LLD Non-Potable Water Environmental LLD Liquid Effluent LLD Annual Concentration at 007 Outfall Resultant Annual Dose (mrem) pci/l uci/ml Child Teen Adult E E E E-04 2, E E E E-04 3, E E E E-04 10, E E E E-03

36 Calculated Doses Concentration Level Potable Water Environmental Reporting Level Potable Water Environmental Reporting Level 10 CFR 20 Effluent Concentration Limit Annual Concentration at 007 Outfall Resultant Annual Dose (mrem) pci/l uci/ml Child Teen Adult 20, E E E E-03 30, E E E E-03 1,000, E E E E-01

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