ML19317D248
| ML19317D248 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 09/13/1977 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 7911190628 | |
| Download: ML19317D248 (5) | |
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l Septerber 13, 1977 Docket Nos. 50-269/270 and 50-287 Duke Power Company ATTN: Mr. William 0. Parker, Jr.
Vice President Steam Production P. O. Box 2178 422 South Church Street Charlotte, North Carolina 28242 Gentlemen:
We are reviewing your submittal dated October /,1976, which provided infonnation identifying the details of the seismic design of the over-head emergency path through the 230 KV switchyard at Oconee and your submittal dated April 13, 1977, which responded to our request for information dated February 23, 1977.
We find that before we can complete ou review, additional information as indicated in the enclosure is necessary.
It is requested that you provide the information within 45 dvs of receipt of this letter.
Sincer d
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,y A. Schwencer, Chief Operating Reactors Branch fl l
Division of Operating Reactors
Enclosure:
Request for Additional Information cc w/ enclosure: See next page i
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Duke Power Company September 13,1977 cc: Mr. William L. Porter Duke Power Company P. O. Box 2178 422 South Church Street Charlotte, North Carolina 28242
- 1. Michael McGarry, III, Esquire
'.leBevoise & Libernen 100 Shoreham Building 806-15th Street, NW.,
Washinpan,D.C. 20005 Oconee Public Library 201 South Spring Street Walhalla, South Carolina 29691 s.--..
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REQUEST FOR ADDITIONAL INFORMATION 9.
In your response to Rlb* it is indicated that passive earth pressure has been relied upon to resist sliding and overturning effects.
For shallow foundation embedment in backfill material, it is unconserva-tive to rely upon the passive earth resistance.
For those cases of deep embedment, factors of safety against sliding should be cal-culated in such a way that slip circle failure due to shear stress is prevented.
One of the acceptable methods of calculating the factor of safety against overturning is given in BC-TOP-4A.
If it should be noted that the original intent of this request was to detennine to what extent the effect of the foundation interaction with the surrounding soil modifies the freefield seismic motion, Provide a discussion indicating in each case how soil-structure interaction was accounted for. Also provide a statement indicating that the factors of safety against sliding and overturning for each foundation meet the acceptance criteria stated in Section 3.8.5.II.5 of the Standard Review Plan.
10.
In your response to Rle indicate that the effects of one horizontal and one vertical earthquake components are combined on the basis of the absolute sum method.
11.
In your response to Rif, the reference to SA.3 of the Appendix SA to the FSAR is not satisfactory.
Indicate your intent to qualify each foundation to meet the load combinations and acceptance criteria per Section 5A.2.2 of the Appendix EA to the FSAR.
12.
In your response to R2 it should be noted that the National Electric Safety Code (NESC) heavy loading provides for ice and wind loading, and does not include the effects of seismic loading. Since the load combinations referred to in section 5A.2.2 of the Appendix 5A to the FSAR are not applicable to the transmission line and the towers, appropriate load combinations and the corresponding acceptance criteria should be chosen frem the sections 3.8.4.II.3 & 5 of the Standard Review Plan, and clearly identified in your response. The modal analysis for the tower, in an unloaded condition, to predict the seismic loading is not acceptable. The effect of seismic loading consists of two parts:
(1) the effect of inertia loading on both
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the towers and the transmission line; for the towers the input may i
l Note: Rlb is request lb of our April 13, 1977 letter.
Other similar abbrevations (R _) in this RFAI refer to other requests in that letter.
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, be the ground response spectra, but the input for the lines should be the appropriate amplified response spectra corresponding to the attachment point, (2) the effect of ground displacement; the ground displacement would cause stretching of the lines and this in turn would impose corresponding loading on the towers. The stresses from (1) and (2) above should be combined by the absolute sum method to obtain the seismic loading which in turn should be used in appropriate load combinations along with other loads.
Provide specific responses to the previous R2 including the concerns expressed in the clarifications detailed above.
13.
In your response to R2 failure of secondary bracing members is predicted.
In combination with R12 above, it should be noted that wnenever members are predicted to fa;1, subsequent analyses must be perfonned on the model that exludes the failed members, and the resulting stresses and displacements must meet appropriate acceptance criteria.
14.
In your response to R3a it is stated that seismic loads were generated as prescribed on page SA-3 of the FSAR. The referenced page simply provides the ground response spectra. However, in order to obtain the seismic loading of the Relay House a dynamic analysis of its mathematical model should be performed. Therefere, provide the specific infonnation requested in R3a and provide a stress sumary of the critical sections.
15.
In your response to R3b it is stated that a seismic force of 0.36g has been assumed to be applied to equipment supported on the foundation and the structural steel framed building.
Floor response spectra for points of attachment provide the maximum resconses for a range of natural frequencies. When the equipment ha' more than one degree of freedom, the effective acceleration is uually greater than the response from the predominant mode.
De onstrate the conservatism of the 0.369 static coefficient through a comparison of response obtained from a dynamic analysis of the multimode equipment subjected to floor response spectra.
s 16.
In your response to R4, note that the Section 5A.2 of the FSAR simply states that where the analysis is difficult the highest acceleration from the response _ spectrum curve is to be used.
For 2". damping this value is approximately 0.36g.
Provide justifications for ignoring contributions from higher modes (see your own discussion in note CC in response to R7).
17.
In your response to R6 it should be noted that the power circuit breakers must be verified by at least prototype testing for demonstration of operability in the seismic environment.
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3-18.
Provisions for periodic inspection and testing of electrical power systems are called for in 10 CFR 50 Appendix A General Design Criterion 18 and in the Regulatory Guide 1,118 entitled
" Periodic Testing Of Electrical Power And Protection Systems".
Provide the details of a program of inservice inspection and test-ing that would be consisted with these provisions.
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