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.