Braidwood Generating Station

1. Braidwood Generating Station Tritium Review Presentation to RETS/REMP WorkshopJune 26, 2007

2. 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 Unit 1 – 1248 MWe Unit 2 – 1224 MWe • Number of employees 615 (Exelon)

3. 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

4. Circulating Water Blowdown Line

5. Chronology • Three significant VB leaks 1996-2000 • VB-1: 11/96, ~380K gallons • VB-3: 12/98, ~3M gallons • VB-2: 11/00, ~3M 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

6. 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

7. 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

8. 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

9. 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)

10. Regional Geology

11. Sampling and Analysis Locations

12. 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

13. 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

14. 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 2-3 VB-4,6,7

15. 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

16. Exelon Pond Pumping System

17. 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

18. 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.

19. 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

20. 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

21. 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

22. Summary of Calculated Doses

23. 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

24. 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

25. 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 1M gal/year input to radwaste • Long-term optimization • Production • Recycle • Release (electrolysis, liquid release)