ML20213C824
| ML20213C824 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 11/29/1978 |
| From: | Bivins W Office of Nuclear Reactor Regulation |
| To: | Lynch M Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-0240, CON-WNP-240 NUDOCS 7812150317 | |
| Download: ML20213C824 (4) | |
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Docket No. 50-397
.NOV 2 91978 l
MEMORANDUM FOR:
M. D. Lynch Light Water Reactors Branch f4, DPl!
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i FROM:
William S. Bivins, leader i
Hydrologic Engineering Section Hydrology-Meteorology Branch, DSE
SUBJECT:
WNP-2 HYDROLOGIC ENGINEERING QUESTIONS (Q-1s)
PLANT NAME: WPPSS Nuclear Project 2 LICENSING STAGE: OL DOCKET NUF3ER: 50-397 REQUESTED COMPLETION DATE: November 21, 1978 REVIEW STATUS: Hydrologic Engineering Section (h"'8) -
Awaiting Responses i
Enclosed are hydmlogic engineering questions (0-1s) for the subject plant, prepared by T. Johnson. There were incomplete responses to acceptance review questions, and some of the information previously requested was not provided. In addition, detailed and legible maps were not provided to determine certain basic information needed for the analysis of Probable Maximum Flood conditions. We would there-fore expect that additional questions will be forthcoming after the r
i site visit, as a result of obtaining more infomation about the i
physical characteristics of the site. area. At the.present tine, due to the poor maps and information provided, the situation is unclear l
regarding various hydrologic parg1 1P31 Signed by; ters.
UT 8 31111a= S Bivins l
7 81215 03)((k ie William S. -Bivins, Leader Rydrologic EngineeHng Section Hydrology-Feteorolooy Branch t
Division of Site Safet and j
Environmental Analy s
Enclosure:
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l As Stated DISTRIBUTION:
DOCKET FILES (50-3., )
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l 1.
As requested during acceptance review questions, provide a i
detailed post-construction topographic map of the plant area.
The map should show the locations of streams, ditches, and s
i drainage Structures. Where any drainage structures, including roof openings, are relied upon to convey runoff from the local FMP, provide pertinent details of the structures, such as size, slope, elevation, cross-sectional area, etc.
2.
Your analysis of the Probable Maximum Flood (PMF) discharge on the stream with the 38.5-square-mile drainage a'rea is not complete.
Further document the~ analyses used and the bases for the PMF hydro-graph shown in Figure 2,4-12, including (a) verification of l
historical flood flows, if applicable, (b) time of concentration (c) duration of rain' fall for the unitgraph, and (d) all other assumptions.
1 3.
Your analysis of PMF water surface profiles for the 38.5-square-mile basin is not clear and uses some assumptions which may not be conservative. Slope-area computations are not necessarily conservative when computing water-surface profiles. Since the design basis flood condition (within three feet of safety-related structures) is produced by a PMF on this stream, provide water surface profiles computed using a method which utilizes standard step
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computational solutions to gradually varied flow.
(HEC-2 Corps i
of Engine 6rs, is one acceptable method). More then three cross-sections (inadditiontothoseenFigure2.4-10)willbeneeded for this revised analysis.
4.
A Manning's 'n' value of.026 is not considered conservative for c9mouting water surface cle;/ations for any typical stream.
Unless you can occument the conservatism of an 'n' value of
.025, it is our position that an 'r.' value of.05 be used for this stream.
In additio% analyt;es should be provided to test the sensitivity of a change in
'n' values on the water surface
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If credit is, take, for reservoir and stream storage in your 5.
r caleclations of the PMF profile (as discussed on p.2.4-11 and p.2.4-12), the ba:;es for the flow routings must be provided, including all applicable routing coefficients, inflow-outflow relationships, and area capacity curves. Alternatively, you shculd assume that the computed peak flow' occurs without any attenuation.
6.
It is not clear h.3w a may.ir,um wave height of only one foot (p.2.4-13) was. computed using an effective fetch'of 1.5 miles and an overwater wind speed of 45 mph. Please reconfirm your calculations.
In addition, provide the effective fetch diagram, and the depth of water assuned.
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Provide the bases;for your estimate of'O.6 fact of wave runyp.
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s Provide the slope,used.(1.on 2, vert.i:a1 wall, etc) and the composition of the slope (riprap, concrete wall etc-)c f
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