ML20066A636
| ML20066A636 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 11/01/1982 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8211060153 | |
| Download: ML20066A636 (5) | |
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DUKE POWER GOMPANY P.O. HOx 33180 CHARLOTTE. N.O. 28242 IIAL 11. TUCKER reternoxe (704) 373-4531 vie e reemmen
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November 1, 1982 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: Catawba Nuclear Station Docket Nos. 50-413 and 50-414
Dear Mr. Denton:
W. O. Parker, Jr.'s letter of April 8,1982 transmitted responses to Action Items which resulted from a December 15-18, 1981 meeting with the NRC's Structural Engineering Brar:ch. Attached is a revised response to Action Item 10.
Very truly yours, FA e
/
Hal B. Tucker ROS/php Attachment cc: Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Mr. P. K. Van Doorn NRC Resident Inspector Catawba Nuclear Station Mr. Robert Guild, Esq.
Attorney-at-Law 314 Pall Mall Columbia, South Carolina 29201 g/
l Palmetto Alliance 2135b Devine Street Columbia, South Carolina 29201 Nk NN O
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Mr. Harold R. Denton, Director November 1,1982 Page 2 cc: Mr. Jesse L. Riley Carolina Environmental Study Group 854 Henley Place Charlotte, North Carolina 28207 Mr. Henry A. Presler, Chairman Charlotte-Mecklenburg Environmental Coalition 943 Henley Place Charlotte, North Carolina 28207 f
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- 10. Provide justificatior demonstrating negligible amplification assumed in vertical seismic analysis (interior structure, auxiliary building, and steel containment).
Revised Response (Steel Containment only)
During preparation of the design report for the steel containment vessel, a detailed review of all design calculations has been made.
In the course of this review, it was found that the spectra submitted in the initial response to this action item had been generated using relative acceleration time histories from the lumped mass stick model. A time history of total accelerations is the appropriate input for generation of these spectra.
The use of spectra generated using relative accelerations results in the conclusion that the vertical ground response spectrum envelopes the vertical spectrum at each point. This, in fact, may not be true when total accelera-tions are considered. Because of this, the spectra previously submitted are somewhat misleading and should be deleted from Duke's response to this action item.
A reanalysis of the vertical response of the steel containment was made. The containment vessel stick model was analyzed for vertical excitation using an input vertical base acceleration time history identical to the horizontal base acceleration time history used in the horizontal seismic analysis. All containment frequencies up to 33 hz were consicered in the analysis.
Using total acceleration time histories from this analysis, vertical response spectra were generated at the base and at mass points of interest.
A review of the results of the analysis described above was conducted to quantify the amplification in the vertical direction.
Figure 10.1 depicts the methodology used in this review.
In this figure, Spectrum "A" represents the required vertical ground response spectrum, defined in the FSAR as two-thirds of the horizontal ground response spectrum. Spectrum "1" represents the vertical ground response spectrum resulting from the input vertical base acceleration time history.
It should be noted that this spectrum enve-lopes the horizontal ground response spectrum shown in the FSAR. Spectrum "n" represents the vertical response spectrum obtained at mass point "n".
At a given period t, one point on each spectrum is defined.
j For a given frequency or period, the magnification factor H_ was defined to be the ratio of the response acceleration to the excitation acceleration.
H = a /a The digital response spectrum data was reviewed for all frequencies between 0 hz and 33.3 hz and for all applicable damping ratios.
In the general frequency range of 5 hz to 20 hz, the magnification factor H was found to be greater than 1.05, indicating a 5% or greater amplificatTon of the acceleration input at the base. At somepoints, the value of H_ reached a maximum of 1.51, indicating an amplification of the input acceleration by 51%.
e Since this amplification was felt to be potentially significant, the spectrum data was further reviewed to quantify the magnitude of the acceleration in-crease. For an input vertical base excitation equal to the required vertical ground response (Spectrum "A"), the magnitude of the increase in acceleration is given by oa = (a - a )a /aj = (H-1)aA n
j A A pointwise review of spectrum data showed the maximum amplification of acceleration to be approximately 0.06 g.
When this increase is compared to the constant gravitational acceleration of 1.0 g experienced by all attach-ments to the containment vessel, it is felt that the assumption of negligible amplification in the vertical direction is indeed justified.
It should be pointed out that the analysis in question pertains only to attach-ments to the steel containment, not the vessel itself.
In the analysis of the containment, all vertical and horizintal modes below 30 hz were considered by modeling the entire vessel and applying shock spectra at the base in both directions.
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