ML19220C075
| ML19220C075 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/18/1976 |
| From: | Gammill W Office of Nuclear Reactor Regulation |
| To: | Deyoung R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7904280177 | |
| Download: ML19220C075 (3) | |
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CENTRAL FILE y;y 7 g.33 h'.13 READING
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DSE READING NRR READING R. C. DeYoung, Assistant Director for Light Water Reactors REV'.SION TO HTDROLOGIC ENGINEERING SLMARY PLANT NAME: Three Mile Island Nuc1 car Generating Station - Unit 2 LICENSIIM STAGE: OL DOCKET NLM3ER: 50-320 MTTMONE NUMBER: 24-32 RESPONSISLE BRANCH: LWR 2-2 REQUESTED COMPLETION DATE: May 7, 1976 REVIEW STATJS: Hydroir..ic Engineering Section (EMB) - Avaiting resolution Enclosed a.re revisions to our hydrologic engineering smry dated S pte:nbar 16, 1975, prepared by T. L. Johnson, for your use in preparing the safety evaluation rept,rt.
Revised sections include 2.4.3, 2.4.8, and 2.4.11.
The only currently outstanding irsue is a requirement to repair dasaged and missing erosion protection on the dikes. A draft of this sumnary was previously supplied to the LPM.
Original Si;ned by W. P. Gammid W. P. Gat i11, Assistant Director for Site Technology Division of Site Safety and Environ - tal Analysis
Enclosure:
As stated cc: w/o encicauze 1
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R. Boyd W. Mcdonald J. Panzarella cc: w/enclosuro-S. Banauer H. Denton ST BC's
- t. Kniel H. Silver T. Johnson
~ L. Eeller esb a
7904280l M 86 265
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DISTRIBUTION:
CENTRAL FILE IDfB READING DSE READING NRR READING
- 1. C. DeYoung, Assistant Director for Light Water Reactors REVISIONS TO HYDROLOGIC ENGIrl.ERING SDJFX PLANT NAME: Three Mile Island Nuclear Generating Station A nit 2 LICENSINC STAGE: OL DOCKET NUMBER: 50-320 MILESTONE NUMBER: 24-32 RESPONSIBLE BRANCH: LWR 2-2 y
REQUESTED COMPLETION DATE: May 7, 1976
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REVIEW STATUS: Hydrologic Engineering Section (SAB) - Awaiting resolution
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Enclosed are revisions to our hydrolopi'c engineering sumary dated Septenbcr 16, 1975, prepared by T. L. Johnson, for your use in preparing the safety evaluation report. Revised sections include 2.4.3, 2.4.8, and 2.4.11.
The only currently,4utstanding issue is a requirement to repair danaged and missing erosion protection on the dikes. A draft of this samary was previously. supplicd to the LPM.
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V. P. Ga rd11, Assistant Director for Site Technology Division of Site Safety and Environmental Analysis
Enclosure:
As stated cc: v/o enclosure R. Boyd W. Mcdonald
. Panzarella cc: v/ enclosure S. Hanauer H. Denton ST BC's K. Kniel H. Silver 86 266 T. Johnson L. Eeller frl4A DSE:HM3, DSY:Ydb 21B D E;S o,,,c s,
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_.. _.5/) 6'76 5/14/76 Form AZc 313 (Rav. 9 53) AZCM C240 2 v. s. eovsamanauf petuvine arrices iste.sae.ies
s 2.4.3 Probable Maximus Floods The Probable Maxinus Flood (PMF) for the Susquehaana River at T..ree Mile Island has a discharge of 1,625,000 cfs.
This esti= ate was furnished to the applicant by the U.S. Army Corps of Engineers.
Extensive stream channel surveys and backwater computations were perfcrmed in the site vicinity to determine water surface profiles for various flood discharges.
The stage-discharge relationships w3re developed by comprehensive backwater computations utilizing observed dsta from historic floods.
The computations show that the water level estiuates are conservative; the computed water level estimate for the 1972 discharge of 1,020,000 cfs was 1.5 feet higher than the observed level. We have reviewed this subject in detail during earlier licensing actions and conclude that the estimated PMF levels are conservative.
Wave heights and runup on safety-related structures were esti=ated by the applicant and verified by the staff and our consultant (Nunn, Snyder &
Associates). At the river water intake structure, we conclude that wave runup could cause surging inside the structure. The effects of this wave action would be mirimal, providing that the trapped air escapes, or that the pumphouse equip =ent floor of the structure is adequately designed to resist the rplift forces.
The applicant has stated that the floor of the intake structure Las been designed to withstand any uplif t forces produced by wave action on the outside of the structure.
The applicant has also stated that the flood panels which are to be =oved inco place for protection against the PM7 (see Section 2.4.10) are designed to resist the effects of wave runup. We conclude that safety related structures and equip =ent are adequately protected against flooding and associated wave action.
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2.4.8 Flooding Protection Recuirements Based on independent analyses, we have concluded that the design of the erosion protection is adequate to assure the integrity of the levee system for severe flooding and associated wave action for floods as severe as the design flood of 1,100,000 cfs.
However, based on site visits, we noted many areas of distress in the riprap protection.
It appears that the riprap has been da= aged and, in some instances, not placed to its proper design thickness and gradation. We inforned the applicant of our concerns, and tha applicant co=sitted to repairing and replacing the riprap to the proposed level of protection, as necessary. The applicant did perform some recedial work. We conclude, based on a recent site visit, that this work does not return the facility to the original design status or =eet the current design bases. We will require that additional work be perfor=ed to restore the erosion protection to its design condition.
2.4.11 Conclusions We conclude that the designs adopted for protection from flooding and local intense precipitation are adequate to protect safety-related facilities with the exception of the erosion protection, which requires further repair and replacement to conform to design requirements. We conclude that ice jams and dam failures pose no threat to safety-related facilities. We con-clude that an adequate water supply is provided for safety-related cooling and that the potential for groundwater contasinscion is low.
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