ML20099F180
| ML20099F180 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 11/14/1984 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Harold Denton, John Miller Office of Nuclear Reactor Regulation |
| References | |
| 605, IEB-80-11, NUDOCS 8411260294 | |
| Download: ML20099F180 (2) | |
Text
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~ VIROINIA ELECTRIC AND Powan COMPANY Ricnwown,VinorxxA 20261
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' i Mr. Harold R. Denton, Director Serial No. 605 d'
V Office of-Nuclear Reactor Regulation E&C/JFK/jdm:2005N Attn: Mr. James R. Miller Docket Nos. 50-338
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Operating Reactors Branch -No. 3 50-339 Division of Licensing License Nos. NPF..
! U.S. Nuclear Regulatory Commission NPF.:b Washington, DC 20555 s
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_ ' Gentlemen:
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VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT N05. 1 & 2 3
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SUBMITTAL OF ADDITIONAL INFORMATION NRC IE BULLETIN 80-11 (MASONRY WALL D HIGN) l!
This letter provides the additional information regarding NRC IE Bulletin 80-11 (Masonry Wall Design) which was requested by your letter of October 2, 1984. Enclosure I to this letter provides the technical basis and clarification of tbc fixity condition used in the block wall analysis..
Please contact us if you have any questions or require additiarjal information.
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Very truly yours, W. L. Stewart Enclosure cc: Mr. James P. O'Reilly Regional Administrator e
Region II j,U Mr. M. B. Shymlock L9 1
l NRC Resident Inspector i
North Anna Power Station
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0411260294 841114 PDR ADOCK 05000338 4
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ENQ.0SURE I Item 1 "With respect to the boundary conditions used in the analysis, the Licensee indicated in Reference 1 that fixity was used at the base of a block wall built i
on a concrete slab. At the perpendicular intersection of two block walls, fixity was also used at those corner joints constructed of alternating courses of the running bond. The licensee is requested to provide the technical basis for assuming fixed-end conditions for these cases.
It is believed that without some clamping devices to prevent rotation of the boundary, the assumed boundary conditions may not be valid."
Answers:
In the context of tne re-evaluation criteria used in the masonry wall analysis, i
it would be more appropriate to say that the boundary conditions where the wall might be assumed as fixed were as follows:
- 1) at the base of the masonry wall where block walls were constructed with a full bed joint, and 2) at the intersecticn of two block walls whare the block walls were constructed with alternating courses of running bond and thus the block and joint interlock tied the walls together. Other types of joints were not considered adequate for the load transfer that would occur with the application of fixed boundary conditions.
The boundary conditions used in the analysis of a particular wall were dependent on the specific wall geometry, the relative stiffness of the adjoining structural elements (slab or wall), and the determination of how the wall would interact with these elements so that the load would be transferred in a manner consistent with the wall geometry specific to the wall being analyzed.
In some instances, it was determined that the boundary conditions where fixity might be assumed were not consistent with the specific wall geometry and supporting elements, and in these cases the joints described above were considered as pinned.
The appropriate boundary conditions for each case were selected to be representative of the physical condition for both the calculations of dynamic response and in the distribution of the loads which resulted. The boundary conditions used in the dynamic analysis were consistent with thos? used in the distribution of loads in each case.
Re-evaluation of masonry block walls utilized conservative assumptions, simplified analysis techniques, conventional bounJary conditions, and conservative acceptance criteria. Analysis employed conservative damping values and amplified response spectra.
Conventional boundary conditions used were siinple, fixed or pinned.
Clamping devices were not used as a means of preventing rotation at fixed boundaries because there was no assurance that such a device would behave as designed to transmit loads without damaging the masonary walls.
In lieu cf clamping devices and where moment fixity was included as a boundary condition the stresses associated with the resulting boundary moment were transmitted to supporting structures within acceptable stress limits.
76-JFK-20138-1
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