ML101930544

Ground Water Communication Supplemental Information Questions and Answers

ML101930544
Person / Time
Site:	Oconee
Issue date:	02/08/2010
From:	- No Known Affiliation
To:	Office of Information Services
References
FOIA/PA-2010-0209
Download: ML101930544 (6)

Text

Oconee Ground Water Communication Supplemental Information Questions and Answers

.2/8/2010

1. Q: When were the wells sampled?

A: Most of the Oconee ground water monitoring wells are sampled quarterly. The wells were last sampled during the week of January.25, 2010.

2. Q: When were results received?

A: Analysis results were received Feb. 8, 2010.

3. Q: How long have you known about elevated tritium concentrations?

A: Tritium concentrations atone well were elevated during'sampling in January 2009 but samples have been below the nuclear industry communication threshold of 20,000 picocuries per liter until the latest sample results received on Feb. 8.

Two wells were installed at this location in 2007 and a third deeper well was installed in December 2009 as part of response to the initial elevated readings. The Feb. 8 sample results were the first samples from this newer well (see question 17 for well depths).

4. Q: if you have known about elevated levels since last year what has ONS been doing to correct the situation?

A: We~have been investigating potential sources todetermine if this is an on-going leak or an old leak that was detected by our new groundwater wells. We have performed the following activities:

Two of the Chemical treatment Ponds were lined about 1 1/2 years ago in response to low levels of tritium being detected in some of the original monitoring wells; Tritium levels in these wells were about 1/2 of the limit and have been trending down since the ponds were lined.

The yard drain piping leading fromrthe Chemical Treatment Ponds was slip lined. These ponds and associated piping lead to a larger on-site pond that is part of Oconee's NRC licensed effluent release pathway.

Liquid waste discharge line has been pressure tested and soil samples have been collected along the suspect area along the discharge line. No leak was detected during the pressure test and the soil samples are still being evaluated.

Some underground drain piping has been inspected. Potential leak pathways were identified, and the discharge from the drain piping was rerouted to on-site chemical treatment ponds 1 & 2 (CTP A&2). The turbine building sumps normally discharge to the east side yard drains, but due to the concern that this yard drain piping may be leaking LA tký avAS

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Oconee Ground Water Communication Supplemental Information Questions and Answers 2/8/2010 the sumps were realigned to CTP 1&2. There is a nuclear industry underground piping initiative underway. All underground piping will be identified, risk ranked and inspection plans developed.

In addition to the initial 26 monitoring wells thatwere installed in 2007, 14 new wells (with 5 more in progress) have been installed around the plant site to further determine the extent of the elevated tritium levels.

5. Q; Where are the two wells with elevated levels located?

A: These Wells are located between the turbine building and one of our switchyards (525 kV on the east side of the plant. It i's approximately 1/2 mile from the wells to the Keowee River and 1.5 milesto a private well'that Duke samples regularly.

6. Q: Where does the ground water go?

A:. The groundwater flow direction in the area where the wells are located discharges to Chemical Treatment.Pond 3 (CTP3) or the conveyance system directly below CTP3. The conveyance. is a monitored surfacewater discharge point to the Keowee River and listed as Outfall"002 under the station's NPDES permit (SC00005i5). Four of the new wells are located on the south-side of CTP 3 and the conveyance closer to the site boundary. Tritium has not been detected in these Wells indicating that groundwater from theaffected area is not moving.

beyond CTP 3 and the conveyance.

7. Q: What sources are suspected?

A: Underground piping carrying liquid waste from the plant and the yard drain piping are. two possible sources that are being investigated.. No other likely sources have been identified to.

date, but the investigation is continuing.

8. Q: What changes have been made to. plant operations in response to the ground water samples?

A, Discharges though the yard drains on the east side of the.plant were stopped in falt of 2008.

9. Q: What is the dose from 35,400 picocuries perliter?

A: This water is not..used for drinking purposes. However, if it were to be;consumed, the maximum dose would be approximately'7 millirem peryear (using EPA assumptions). The average annual dose to a member of the public is 360 millrem per year (due to natural, medical, and consumer products).

10 Q: What is the NRCpublic dose limit?

A: 100 mrem/year 2

Oconee Ground Water Communication Supplemental Information Questions and Answers 2/8/2010

11. Was SC DHEC aware of this before now?

A: Yes. The State was informedof the original sample results as a courtesy in Jan. 2008 and has been briefed as new data has been acquired.. They Were also briefed on the results of the detailed groundwater site characterization-repOrt that was produced using the data from the existing and new groundwater monitoring wells This report discusses the Oconee. site hVdrogeology, ground water flow. direction, flow speed, etc.

12. What about the other wells you monitor?

A: We are sampling 54 on-site monitoring wells. All. of the other wells havetritium levels less than the reportinglevel.

We have also sampled a private well about 1.5 miles from the plant site. We have not seen elevated tritium levelsfrom this well. The well is located in Pickens County. This well is sampled quarterly.

13. Can tritium at these levels migrate into any drinking water supplies? Whatwill prevent itfrom reaching, my property and my well?

A. Ground water from the affected area flows south into CTP 3 and the conveyance which enters the Keowee River as surface water through a licensed.and monitored release discharge point. See question 6.

14. Should I have my well sampled? Do you have any plans to test private wells?

A. We do not plan to test individual wells, as all results indicated that tritium is not migrating.

off-site through the ground water.

If a resident wants to~have their well water tested, they may contact the South Carolina Dept. of Health and Environmental Control (DEHC) at 1-800-476-9677. This number is the agency's "response and public information"' line.

15. Are you prepared to test for tritium beyond the plant's property boundary?

A.. We have an extensive.ground water monitoring program in place in addition to our environmental monitoring program. Data from our ground water samples do not show radioactivity from this plume migrating off-sitethrough the groundwater.

16,. Is there a health or safety hazard for people living nearthe plant or working. at the plant?

A. No. The tritium found in the monitoring wells~does not pose a health or safety hazard to the public or plant employees and it is not available for consumption.

17. Howdeep are the wells with the elevated tritium and what are their associatedtritium levels?

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Oconee Ground Water Communication Supplemental Information Questions and Answers 2/8/2010 A. GM-7R is approximatley 65 feet deep and had a trit ium level of 24,400 picocuries per liter.

GM-7DR is approximately 150 feet deep and had a tritium level of 35,400 picocuries' per liter.

18. Is there a way to remove tritium* from the groundwater?

A. Tritium cannot be easily. removed from water since it is part of the water itself. In some cases the best strategy is to monitor the groundwater and allow it to naturally dissipate through radioactive decay and dilution.. This strategy works well when the source of tritium has been eliminated and the groundwater is not flowing in a direction that could affect drinking waterwells.

Another strategy is to pump the groundwater for monitoring and discharge to a permitted discharge pathway.

19. How long have you been puttingtritium into the environment?

A. All nuclear power plants release tritium into the environment through NRC permitted discharge.

pathways. These discharges.are conducted using NRC approved plant procedures and are monitored by the NRC and state agencies. These releases are part of the normal plant operating program.

20. Do you measure tritium as part of the dose to your workers?

A. Yes, air and liquid samples are collected in the plant to assure workers are not exposed to levels of:tritium that Would require dose to be calculated and assigned. We carefully. monitor and control any employee's exposure to radiation, and have Very strict limits for annual exposure.

21. What will this do to my property value?

A. It is impossible. for us to speculate on future property values due to various factors involved, which do not involve the Oconee Nuclear Plant.

22. How much will the monitoring and investigation cost and will these costs get passed along to your customers?.

A. No final costs are available since we are still investigating.

23. What istritium?

A. Tritium (chemical symbol H-3) is a radioactive isotope of the element hydrogen (chemical symbol H). Tritium is produced naturally in'the upper atmosphereWhen cosmic rays strike air molecules. It is also.a byproduct of the production of electricity in nuclear reactors and is used commercially in.concentrated quantities in self-luminescent devices, such as exit signs, gun sights and wristwatches. It is commonly found in water and is generally not considered hazardous.

24. Are low levels of tritium in water safe?

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Oconee Ground Water Communication Supplemental Information Questions and Answers 2/8/2010 A. Yes. The U.S. Environmental Protection Agency sets standards for acceptable public drinking water. Under these standards, any concentration of tritium up to 20,000 picocuries per liter is safe to.drink. According to EPA figures, a person who drinks two liters of water per day with tritium of 20,000 picocuries per literwould receive four millirem of radiological exposure from the tritium.

This is slightly less than the amount of exposure a person would receive in one chest x-ray. which is 6-10 millirems.

25. What did Oconee do when it found the. tritium?

A, We began a thorough investigation and we continue to investigate the source. Once We received samples withelevated levels we shared the information with the Nuclear Regulatory Commission, SC DHEC, local officials, plant employeesand local media.

26. Why haveyou, not found the source after 2 years of looking?

A. Work has been on-going to determine the source of the radioactivitysince it was first discovered.,

Temporary wells were installed and sampled in spring of 2008. Testing of the release pipe was performed in February of 2008. Releases through one of the suspected pipe were discontinued in the fall of 2008.. The trend in GM-7R was identified the first quarter of 2009. A plan to install an additional 19 wells was approvedin November of 2009.

27. What will you do if it does reach the drinking supply?

A. We have every reason to believe that drinking water wells will not be affected by tritium in ground water. See question 6 & 13;

28. How does tritium affect people's. health?

A. The levels of tritiumfound in the areasýidentified do notpose a health or safety hazard to the public or plant workers. Tritium enters the body by drinking water, absorption through the skin or breathing. Tritium emits Very.weak radiat ion and leaves the body relatively quickly through normal waste streams. Radioactivity is~part of ourenvironment and is present naturally in our bodies from the food we eat. For example, we receive approximately 15 millirem annually just from radioactivity in foods such as bananas and potatoes. (Table 3.14, NCRP 160)

29. What will prevent this tritium from reaching the Keowee River?

A. All nuclear power plantsrelease tritium into the environment through NRC permitted discharge pathways. These! discharges are conducted using NRC approved plant procedures and are monitored bythe NRC and state-agencies. These releases :are part of the normal plant operating program. Through our environmental monitoring, program wesample the Keowee River to ensure that radioactivity levels are below all release limits.

30. Is it safe to eat fish from ILake KeoWee?

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Oconee Ground Water Communication Supplementalilnformation Questions and Answers 2/8/2010 A. Based on routine radiological sampling of fish and water, it is safe to eat fish from Lake Keowee.

31. Have tritium leaks been discovered at other Duke Energy nuclear plants? What did they do about it?

A. Because tritium is naturally occurring andis a by-product of nuclearoperations, we have detected low levels of tritium in-groundwater at our other nuclear stations. These levels are attributable to station operations and do not pose any health or safety hazards. We have also placed additional monitoring wells in service at our other two stations.to further enhance our monitoring program.

In October 2007, Catawba Nuclear Station, reported elevated levels of tritium of 42, 335 picocuries per liter in a sample from one of the station's on-site environmental monitoring wells. The tritium was contained on the plant's property. The SC DHEC'sampled 27 residential wells surrounding Catawba. Results from these samples.did not find any evidence thatthe tritium had movedoff the plant property.. The source of the elevated tritium was a leak from 2006 that hadbeen repaired. The monitoring well which, had the elevated tritium was installed to get better information about the leak.

32. If you finda. leak will you fix it?

Yes.

33.. Where can Ifind more information about tritium?

A. The Nuclear Regulatory Commission and the.Environmental Protection-Agency provide detailed information on their websites: http://wwW.nrc.gov/reactors/operating/ops-experience/grndwtr-contam-tritium.html http://www.epa.gov/radiation/radionuclides/tritium.htm. The. SC Department of Health and Environmental Control also has information on their website: http://www.sc.dhec.gov

34. How are you communicating about the tritium?

A. Oconee is dedicated to keeping'the:community informed, and will provide the most accurate information as it becomes available. Oconee commits to open dialogue on this subject, and will continue to:

" Engage in ongoing conversations with inquiring residents.

" Release new information as appropriate

" Continue conversation with local officials regarding new information.

" Participate in ongoing discussions and with various regulatory agencies including the State, Environmental Protection Agency, and the Nuclear Regulatory Commission.

Duke Energy's highest concern is the safety and well-being of our employees, the public and the environment; 6