ML19319C146
| ML19319C146 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/06/1973 |
| From: | Harold Denton US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8001310506 | |
| Download: ML19319C146 (5) | |
Text
JUL 6 1973 DIST BUTION:
cket Files (50-346)
Central File, L R. C. DeYoung, Assistant Director for PWRs, L HYDROLOGIC ENGINEERING QUESTIONS Plant Name:
Davis-Besse Nuclear Power Station Licensing Stage:
OL Docket Number:
50-346 Responsible Branch:
PWR #4 Requested Completion Date:
Applicants Response Date Necessary For Next Action Planned On Project: ASAP Description of Response:
Answer Questions Review Status:
Site Analysis Branch (Hydrologic Engineering)
Awaiting Answers Enclosed are the Hydrologic Engineering questiens prepared by W. S. Bivins and L. G. Hulman for your transmittal to the applicant.
Our principal concerns are (1) the methods used to estimate the Probable Maximum surge elevation at the plant site, (2) the method used to estimate the Probable Maximum Flood (P!7) frora the Toussaint River, and (3) potentially non-conservative estimates of Probable Maximum Precipitation used to establish the PMF from the Toussaint River and to estimate the localized flooding effects on site drainage systems (including the roofs of safety-relatedbuildings).
Harold R. Denton, Assistant Director for Site Safety Directorate of Licensing
Enclosure:
As stated cc: w/o enclosure A. Giambusso W. Mcdonald cc: w/ enclosure S. H. Hanauer l
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Form AEC.H s (Rev. 9-33) AECM 0240
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HYDROLOGIC ENGINEERING QUESTIONS DAVIS-BESSE NUCLEAR POWER STATION DOCKET NO. 50-346 1.
Provide the following information (which was identified during the pre-acceptance review):
a) Describe the meteorology, surges, and waves which occurred in the region in the fall of 1972 and the spring of 1973.
Document and compare the postulated probable maximum meteorological event with the 1972 and 1973 seiche-causing storms, and discuss whether the probable maximum event is sufficiently conservative in view of the occurrence of these recent events. (2.4.2.1)*
b) Verify the probable maximum surge model by reconstituting at least the most severe of the two recent events.
(2.4.2.2) c)
Include, in your bases for wave estimates, the components attributable to waves re'fracted and reflected from and through offshore islands.
(2.4.2.2) d) Discuss and document the potential for wave-induced resonance in the intake canal at both high and low lake levels.
(2.4.2.2) 2.
Use of (your) reference 32, for probable maximum precipitation (PMP), is not considered adequate. Use " Seasonal Variation of the Probable Maximum Precipitation East of the 105th Meridian for Areas from 10 to 1000 Square Miles and Durations of 6,12, 24, and 48 Hours,' HM #33, U.S. Weather
- Suggested section of FSAR for revisions, additions, etc.
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Bureau (now NOAA).
Revise your estimates of the effects of the PMP on site j
drainage (including the roofs of safety-related structures) and the PMF on the Toussaint River.
(Also see question 9.) With respect to the PMP effects on the roofs of safety-related structures, include a discussion of i
the protection provided for roof penetrations to prevent interior flooding of safety-related systems and components.
(2.4. 2. 3, 2.4. 3.1, 2.4. 3.4, et al. )
3.
Provide a description of all penetrations, including locations, at or below elevation 585 feet, into safety-related buildings.
Include discussions of penetrations in "non-safety-related" buildings if a pathway for inleakage l
to safety-related buildings exists. Describe the methods to be employed for flood-proofing these penetrations.
(2.4.2.2) 4.
Provide the data base for the reported historical maximum surge and wave heights; include the date and source of record for the maximum recorded i
I transverse seiche.
In addition, provide a revised discussion to include the recent severe surge activity.
(2.4.2.2) 5.
Provide the design bases for, and the size of, riprap protection on the breakwater.
Identify the extent of rock protection on the intake dikes 1
and breakwater (e.g. lower elevation of riprap blanket, etc.) (2.4.2.2) 6.
Discuss and document the lake stillwater elevation plus wind-generated 1
waves and runup that will necessitate taking the cooling tower out of service.
Based on historical surge records, the design basis surge hydrograph (for rate of rise, etc.) wind-generated waves and runup, and the time 1
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' required to bring the plant to a safe and orderly cold shutdown, establish a tech spec which will ensure the plant is in a cold shutdown configuration prior to any potential loss of the use of the towers due to lake flooding.
1 (2.4.2.2 & 2.4.14) 7.
You have mixed datums throughout section 2.4.
Revise the text to either consistently use one datum throughout, or clearly identify the relation between the datums used.
(2.4) 8.
Provide map (s) of suitable scale which indicate the fetch locations and lengths used in your wind-generated wave and runup calculations. Provide cross sections from low water elevation through the plant area sufficient to allow independent verification of your runup ca3culations. Show slopes i
and types of protective cover (rock, grass, etc.) of all protective structures.
The staff does not concur with your estimate of the PMF from the Toussaint 9.
1 River.
Specifically, (i), the unit hydrograph shown on Figure 2-28 does not j
conform to generally accepted unit hydrograph theory, (ii) the rainfall (PMP)
I should be revised in accordance with the reference in question 2, above, and (iii) the time distribution of rainfall shown in Tables 2-65 and 2-66 is not considered sufficiently conservative. The time distribution of i
rainfall should be at least as severe as is indicated in EM 1110-2-1411, Standard i
i Project Flood Determinations, Corps of Engineers.
In support of your unit hydrograph, provide your working estimates of the following parameters as 1
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, defined in your reference 36: A,L,LCA, C, tp, tr, and t. Your t
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description of water level determinations is not clear. Supplement your description, with maps or other means, to document that backwater from restrictions in or blockage of the Toussaint River will not constitute a i
safety hazard at the plant.
(2.4.3) t
- 10. The experienced and projected lake levels in 1972,1973, and 1974 are, or are expected to be, somewhat higher than normal.
Provide the data base used to estimate the maximum variations in water levels in section i
2.4.2.2 and compare this estimate with the expected levels for the three years above.
Describe the effect, if any, on groundwaterwater elevations at the site. Describe the hydrostatic design bases for all safety related j
structures in relation to high lake-induced water levels.
(2.4.2.2) i i
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