ML15348A340

RAI Regarding NTTF 2.1 - Flooding

ML15348A340
Person / Time
Site:	Robinson
Issue date:	12/14/2015
From:	Uribe J F Japan Lessons-Learned Division
To:	Guill P F, Maysam A Duke Energy Corp
Uribe, Juan NRR/JLD 415-3809
References
Download: ML15348A340 (1)

Text

From: Uribe, Juan To: "Maysam, Al"; Paul.Guill@duke-energy.com

Subject:

Robinson RAI regarding NTTF 2.1-Flooding Date: Monday, December 14, 2015 9:52:00 AM Al, Paul: As previously discussed, here is the info need that will be docketed as an RAI as part of the review.

Please reference this email as the source in the response letter.

Thanks Robinson Info Needs-12/14/2015

1. Starting Water Level for the Robinson Dam Overtopping Failure in HEC-RAS

NRC staff's review of the HEC-RAS dam failure file revealed that the breach starting elevation is set to the top of the embankment elevation of 229.075 ft NAVD88.

However, this assumption does not consider the time needed to erode the downstream face of the dam and is also

not supported by the NWS BREACH model output data.

USACE Guide (TD-39, "Using HEC-RAS for Dam Break Studies," August 2014, p.9) states that "the HEC-RAS breach start time is considered to be when the erosion process has mitigated to the upstream face of the

dam." Provide additional information that justifies selecting a breach starting elevation set to the top of the embankment elevation.

JUAN F. URIBE PROJECT MANAGER NRR/JLD/JHMB 301-415-3809 l O-13F10 l Juan.Uribe@nrc.gov U.S. Nuclear Regulatory Commission Please consider the environment before printing this e-mail

From: Uribe, Juan To: "Maysam, Al"; Paul.Guill@duke-energy.com

Subject:

Robinson RAI regarding NTTF 2.1-Flooding Date: Monday, December 14, 2015 9:52:00 AM Al, Paul: As previously discussed, here is the info need that will be docketed as an RAI as part of the review.

Please reference this email as the source in the response letter.

Thanks Robinson Info Needs-12/14/2015

1. Starting Water Level for the Robinson Dam Overtopping Failure in HEC-RAS

NRC staff's review of the HEC-RAS dam failure file revealed that the breach starting elevation is set to the top of the embankment elevation of 229.075 ft NAVD88.

However, this assumption does not consider the time needed to erode the downstream face of the dam and is also

not supported by the NWS BREACH model output data.

USACE Guide (TD-39, "Using HEC-RAS for Dam Break Studies," August 2014, p.9) states that "the HEC-RAS breach start time is considered to be when the erosion process has mitigated to the upstream face of the

dam." Provide additional information that justifies selecting a breach starting elevation set to the top of the embankment elevation.

JUAN F. URIBE PROJECT MANAGER NRR/JLD/JHMB 301-415-3809 l O-13F10 l Juan.Uribe@nrc.gov U.S. Nuclear Regulatory Commission Please consider the environment before printing this e-mail