Braidwood Generating Station Tritium Review Presentation to RETSREMP

Braidwood Generating Station Tritium Review Presentation to RETS/REMP Workshop June 26, 2007 1

Braidwood Station Background • • Dual-unit Westinghouse pressurized water reactors Construction permit December 1975 Unit One operation July 1988 Unit Two operation October 1988 (Initial operating licenses good for 40 years) • Generation capability • Number of employees Unit 1 – 1248 MWe Unit 2 – 1224 MWe 615 (Exelon) 2

Circulating Water Blowdown Line • Station exchanges clean water with Kankakee River for cooling lake through circulating water make up and blowdown lines • In addition, blowdown line caries periodic discharges of liquid radioactive waste – Tritium is principal component; other activity is significantly reduced via radwaste system (filters, demineralizers, RO) – Prior to 11/05, discharges 2 -3 times per week – Discharge concentration limits contained in offsite dose calculation manual (ODCM) • 10 times limits in 10 CFR Appendix B • For tritium, concentration limit is 1 E+7 pico-curies/liter • Non-radiological aspects of discharge regulated by NPDES permit 3

Circulating Water Blowdown Line 4

Chronology • Three significant VB leaks 1996 -2000 – – VB-1: 11/96, ~380 K gallons VB-3: 12/98, ~3 M gallons VB-2: 11/00, ~3 M gallons Inadequate response at the time • IEPA questions raised regarding Godley; sampling initiated - 3/05 • Environmental contractor engaged to install sampling wells - 6/05 -11/05 • Identified elevated groundwater tritium concentrations near site border - 11/05 • Ceased liquid radioactive releases – 11/05 • Formed issues management team and root cause team – 11/05 5

Issues Management Team Role • Characterize source and extent of contamination • Develop and implement remedial action • Coordinate/support external response efforts – – – Public outreach/media response Regulatory Government Legal Real estate • Support root cause team 6

Regulatory Issues • NRC – Violations for failure to document and assess impact of releases • Low to moderate safety significance (white) – Oversight of characterization and remediation efforts • Illinois EPA – Lead agency is Bureau of Water – Violation Notices for exceeding IEPA groundwater quality standard and non-degradation standard – Exelon community relations plan • Jurisdictional issues for regulation of radioactive releases 7

Key Learnings • Historic insensitivity to blowdown spills • Lack of knowledge of State groundwater regulations • Exelon functional area gaps for radiological spills • IEPA sensitivity to “Right to Know” • Issues management process 8

Description of Sites • Areas for focused site characterization reports – – – Areas near VB 1 and VBs 2, 3 VB 4 VB 6 VB 7 West side of turbine building • Other areas investigated - no tritium identified – Blowdown line between VB 1 and 3 – River screen house (past VB 11) 9

Regional Geology 10

Sampling and Analysis Locations 11

Additional Studies • Comprehensive water level measurements • Area wide well inventory • Review release logs to estimate curies released from VB leaks • Tritium dating study in VB 2, 3 plume area • Chemical analysis of groundwater/blowdown water • Pipe integrity test • Modeling of transport 12

Regional Groundwater Use • Wells are screened as follows – Shallow aquifer (25 -30 feet) • Private wells – Shallow bedrock (80 -100 feet) • Private wells – Deeper bedrock (600 -700 feet) • Some private wells • Municipal wells – Deepest bedrock (1400 -1600 feet) • Municipal wells 13

Key Conclusions • Tritium in groundwater is consistent with historical releases from VBs • Migration will not result in impact on private wells above the groundwater standard • Additional conclusions and observations VB-1 VB-4, 6, 7 VB 2 -3 14

VB 2, 3 • Objectives – Prevent migration into uncontaminated areas – Recover contaminated groundwater – Use a method that can be implemented quickly, with already licensed and permitted disposal methods • Currently pumping from pond on Exelon property (Exelon Pond) – Most immediate effect on northward migration • Will supplement this action with additional remediation actions based on modeling 15

Exelon Pond Pumping System 16

Blowdown Line Integrity • • • Operate line water solid Sealed bottom of VB vaults Installed continuous leak detection system Hydraulic transient analysis of line Weekly inspections of blowdown line corridor 17

Action to Suppress VB-1 Plume • VB-1 plume is leaching into site perimeter ditch • Installed temporary weir in ditch to raise level of surface water – – Installed in 3/06 Stop partially penetrating influence of ditch Result - slow downward trend in sample results at weir Removed in fall of 2006 after successful implementation of remediation system • Installed remediation system consisting of 3 wells. 18

Dose Assessment • Performed by independent three member team with significant industry experience – Independent review – Dr. John W Poston • Methodology highlights – Multiple exposure pathways considered – Results include past, current, and hypothetical future dose – Methodology consistent with Regulatory Guide 1. 109 (1977) – Volumes and concentrations released based on plant release logs and soil samples 19

VB-2, VB-3 Related Scenarios • Private Well 8 Potable Water – Well Drinking Water – Garden Irrigated with Well • Exelon Pond – – Swimming Eating Fish Living In Pond Eating Deer Drinking From Pond Eating Goose Drinking from Pond • Smiley Ditch VB-2, VB-3 – Eating Deer Drinking from Smiley Road Ditch – Direct Dose from Smiley Road Ditch • Spill Water at VB-3 – Deer drinking water eating contaminated vegetation 20

VB-3 Multiple Nuclide Scenarios • Deer drinking ponded spill water, eating contaminated vegetation around vacuum breaker pit. • Direct shine to members of public on Smiley Road from potential soil contamination in ditch. • No direct sample data from 1998 spill – Soil sample data from 2001 50. 75 (g) available – Tank release data from 1998 21

Summary of Calculated Doses 22

Root Cause Analysis • Responses to spills varied; none were adequate – 1996 and 1998 spills treated as water spills; no sampling or cleanup – 2000 spill was sampled and cleaned up; no consideration of impact on ground water • Root cause is lack of integrated procedural guidance – Environmental spill response procedures not intended for radioactive spills – Radiological documentation procedure does not consider impacts on groundwater, hydrology, groundwater regulations • Additional root cause is lack of management oversight – Review of condition reports – Inadequate follow-through for 2000 spill 23

Root Cause Corrective Actions • • • Develop integrated spill response procedure Develop methodology for future releases Increase rigor in issues management process Case study for management aspects Other actions address training, procedure enhancements • Previous actions to prevent catastrophic VB failures – Appear effective based on performance since 2000 – Did not address small VB leaks – Action to consider alternate methods for releases 24

Release Reduction • Recycle modifications – Clean up radwaste to primary grade water • Reverse osmosis/demineralizers – Use existing primary water storage tanks • Volume reduction modifications – Condensate re-route (chillers and aux steam) – Floor drain re-route (reduces organic input) – Reduction of over 1 M gal/year input to radwaste • Long-term optimization – Production – Recycle – Release (electrolysis, liquid release) 25