Tracking the Source of I-131 in the Cape Fear River

1. Tracking the Source of I-131 in the Cape Fear River Greg Barley Supervisor-Chemistry Services

2. “You take all the experience and judgment of (men) over 50 out of the world and there wouldn't be enough left to run it.” Henry Ford

3. Background Information • Shearon Harris Nuclear Plant 900 MWe Westinghouse PWR • Liquid effluents discharge to Harris Lake via cooling tower blowdown line • Harris Lake discharges (ultimately) to Cape Fear River

4. Background Information (Cont’d) • Water composite sample collected upriver where Deep River and Haw River form the Cape Fear River (control location) • Water composite sample collected downriver at water treatment plant for town of Lillington (indicator location)

6. History • Medical applications result in environmental releases of I-131 from municipal sewage treatment facilities • City of Durham, NC, sewage treatment discharges to Haw River (tributary to Cape Fear River) • Prior to March 2006 there were a few events where I-131 was detected at the control location, but the indicator location showed <MDA

7. Problem Description • March 2006, I-131 detected at both indicator and control locations on the Cape Fear River • Similar concentrations observed at both locations • No discharge from Harris Lake occurring (low rainfall) • Water samples from Harris Lake showed <MDA for I-131 • Low rainfall reducing dilution water to Cape Fear River

8. Key Point #1 • I-131 NOT result of plant operation • I-131 present at both indicator and control locations at similar concentrations • No discharge from Harris Lake to Cape Fear River • No detectable I-131 in Harris Lake

9. Key Point #2 • Impact on the Radiological Environmental Monitoring Program • Identify source • Determine if program modifications are warranted

10. Key Point #3 • Communication, Public Relations • Detectable I-131 in public drinking water supply (Lillington) • Meeting held with NC Dept of Radiation Protection • Source is not plant operation • NC evaluate public impact • Communicate plan to identify source • Receive information from state personnel on potential sources • Critical in light of recent industry events regarding groundwater communication

11. Source Identification • Sample Tributaries • Haw River (Jordan Lake Dam), Deep River • Special sampling required special safety precautions • Where sampling was visible to public, informed local rangers (Jordan Lake Dam) • Special grab samples from control and indicator locations • Monitor the trend via “snapshots”

14. Observations • Source of I-131 is upriver of Jordan Lake along Haw River, likely Durham sewage treatment facility • Integrated concentrations at control and indicator locations very similar due to low dilution (dry weather, low river flow)

15. Conclusion #1 • No need to change REMP control location • Want to retain current control location in event I-131 detected at indicator location in future • Since infrequent occurrence, no new control location required

16. Conclusion #2 • Add enhancements to REMP • When I-131 detected at indicator location • Consider special sampling • Initiate lower I-131 MDA for Harris Lake Spillway water sample analyses • Revise procedure to require compensatory grab sampling when composite sampler is out of service

17. Conclusion #3 • Communication with regulatory officials is of tremendous importance • Information sharing two ways • Regulatory officials able to respond to public inquiries • Creates good will between licensee and regulators • Huge success!

18. Questions?