ML14058A063

Jocassee Overtopping Notes

ML14058A063
Person / Time
Site:	Oconee
Issue date:	02/04/2014
From:	Office of Nuclear Reactor Regulation
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References
FOIA/PA-2012-0325
Download: ML14058A063 (2)

Text

Jocassee Overtopping Notes NRC Data Using 1940 - 2000 data of all types and sizes of dams with inadequate flow out of spillways:

0 There were 134 failures in 1.37 x 106 dam-years producing a rate of 9.78 x 10- per year.

a Of the spillway failures, 5 were in earthen dams.

0 No spillway failures seen in rockfill dams.

e There were 17 gate failures for all dams with 2 of them resulting in dam failure producing a failure rate of 1.46E-6 per year.

Duke

" Cameras monitor level staff gage and forebay.

" Monitoring in Jocassee control room and at the Charlotte, NC office.

" The dam has sufficient freeboard. Top of dam is at 1125-ft msl.

" The dam has regular inspections with weekly visual checks of gate mechanism.

• Spillway design would allow spillover before the main dam overtops.

• During a PMF event, the spillway Tainter gates are required to be fully opened with 3-out-of-4 hydro-turbines for adequate relief.

• Tainter gates have backup motive power from portable air compressors.

FE R Identified conservatism in 18 CFR 12D repord (b)(7)(F)

Conclusions

• Dam failure data is too sparse to make decisions on constituent failure modes.

• Statistically overtopping cannot be completely ruled out but, given the above information, it appears to have a low likelihood as a major contributing failure mode for Jocassee.

" Piping and foundation failures still need to be addressed.

References

[1]. Operation Report, "Jocassee Development of Keowee-Toxaway Project", Federal Energy-Regulatory Comrmission,".August 23, 2007_

WI. Supporting Technical Information Document, "Jocassee Pumped Storage Project", STI No. 2503-JO-03, Duke Power, December 3, 2004.

[3]. Part 12 Inspection Report, "Jocassee Development of Keowee-Toxaway Project",

NATDAM ID# SC00529, Findlay Engineering Inc., December 2004.

[4]. Emergency Action Plan Dam Failure Inundation Study, "Jocassee Hydro Project",

Duke Power Company, December 10, 1992.

[5]. Letter from D. Baxter (Duke Energy) to J. Gilter (US NRC), "Response to 10 CFR 50.54(f) Request, September 26, 2008.