ML19260E189
| ML19260E189 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 04/24/1979 |
| From: | Bennett J LOS ALAMOS NATIONAL LABORATORY |
| To: | Tokar M Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19260E190 | List: |
| References | |
| 1-13:79:110, NUDOCS 8002130635 | |
| Download: ML19260E189 (2) | |
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N LOS ALAl'!;OS SCIENTIFIC LABOhlATORY Post Cflice Box 1663 Los Alamos, Ne'v Mexico 87545 in repiy refer to: Q-13 : 79 : 110 Maa stoo: 576 April 24, 1979 Dr. Michael Tokar Nuclear Regulatory Commission Phillips Building 7020 Norfolk Avenue Bethesda, Maryland 20014 Cear Mike:
F.nclosed is our final report on the effect of installing the core region constraint devices into the Fort St. Vrain reactor with regard to seismic response. Re report is unchanged from the draft version with the exception that we have co-ected a few typo's and have cleaned up the figures.
We have not incorporated any response to the comments by the NRC structural engineering branch at this time. We have reviewed these ec= cents, however, and we offer the following response:
1.
Regarding comment (1), the assu=ptions conct.rning thm end restraint produced by the RCDs and resulting frequency increase produced by them (Pg. 3 of Appendix), we agree that the ratios may be high.
Obviously, the lower limit is when the RCDs will not change the en:i condition at all, in which case the expected chear forces in a column will Se the same with or without RCDs. While the assumptions of a pinned or fixed end conditions may not be realistic, the assumption does allow us to quantitatively evaluate the effect of stiffening the core in ter s of the directions tha: the shear forces take (i.e.,
they decrease with stiffening rather than increase). Clearly for the " intuitive" stiffening sus;ested in co= ment (1) the shear forces will still decrease, but not as much as those shown in the tables.
2.
Regaraing coc=ent (2), the axial stiffness was included only as a "what if" case and in fact the entire range of calculated frequencies was bounded from above and below wiu the same conclusion.
3.
Regarding comment (3), our analyses of core block i= pact and con-clusions regarding the FSV core system were not made with total dis-
_egard to vertical effects. Our studies with FYSMCD, a generic com-puter codel of core blocks for a core of this type, s'.cws tha: the general magnitudes of impact forces in a system of this type are relatively unaffected by the presence of the vertical component, (though the motion is so=ewhat dif#erent). 3ecause there is, on the average, as much increase in f riction as there is decrease, the u e.,w.. w,aa m mm.n..e.
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Q-13:79:110 April 24, 1979 maximum relative velocities in the system renain about the same.
Thus, since the maximum hori: ental impact forces are proportional to the hori: ental velocities, then their magnitudes are about the same as those in a strictly hori:entally excited system.
For your information, I am enclosing a portion of a quarterly report LA-NUREG-6579-PR in which we reported and discussed a portien of this work.
In particular, I draw your attention to the general conclusions (2) and (3) and Figures 15 and 16 of this report.
We feel that, while with more time, we can do an extensive analysis of the effect of the RCDs on the FSV core seismic response, our conclusions will remain unchanged.
Let us know of your wishes in this regard, and please call me if you have any questions regarding these comments.
Sincerely,
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vJoelG.Bennett, Q-13 Reactor and Advanced Heat Transfer Technology
Enclosure:
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