ML20247C209
| ML20247C209 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/07/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20247C206 | List: |
| References | |
| IEB-80-11, NUDOCS 8909130275 | |
| Download: ML20247C209 (3) | |
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UNITED STATES i
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SAFETY. EVALUATION.SY.THE 0FFICE.0F.WUCLEAR. REACTOR. REGULATION EVALUATION.0F. MASONRY. WALL. DESIGN..IE. BULLETIN 8041 NORTW. ANNA. POWER. STATICE UNITS.1.AND-2
1.0 INTRODUCTION
The initial staff Safety Evaluation on Masonry Wall Design for the North Anna Power Station Units 1 and 2, dated April 3, 1985, identified certain masonry walls as unacceptable based on simplified assumptions concerning their boundary conditions and the lack of physical restraints at their base mortar joint.
The staff discussed with the licensee the subject masonry walls during a telephone conversation on March 9, 1989, and further discussed Virginia Electric and Power Company's (VEPC0's) submittal of April 7,1989, during the meeting of April 19. 1989. VEPC0 comitted to identify the masonry walls previously assumed as cantilevered walls and to conduct a field inspection to ascertain the actual boundary condition. VEPCO's May 12, 1989 submittal provided the required information for staff evaluation and approval. The staff conducted a site visit on July 19, 1989 to confirm the licensee's data.
2.0 EVALUATION The original staff Safety Evaluation Report associated with IE Bulletin 80-11 on masonry walls identified the unacceptability of several masonry walls which had been evaluated as cantilevered walls without providing a boundary restraint at the cantilever support (boundary mortar joint).
VEPCO's evaluation had utilized simplified assumptions for the boundary ccnditions of the masonry walls in conjunction with the analytical tech-t niques and acceptance criteria identified in the FSAR. However, the staff had requested that a positive clamping device be provided at the joint of the assumed cantilever walls to prevent rotation at the fixed boundaries and to assure that the seismic forces would be transmitted through the cantilever support.
Based on discussions with the staff, the licensee agreed to inspect the subject walls to establish the actual boundary conditions. The licensee submittal of May 12, 1989, identified 10 walls with their specific identification number and the actual boundary conditions. These walls had been analyzed as cantilevered walls in the previous analyses.
Table I shows that the original simplified assumption of cantilever supports do not agree with the actual support conditions. The information in Table 1 indicates additional boundary supports on the sides of these walls consisting of steel channel support, mortar joints with other structural members, and masonry blocks interlocking with adjacent walls.
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The staff has concluded that the existence of these types of supports would.
remove any staff concern related to the original cantilever masonry walls without clamping support at the cantilever support. The staff site visit of July 19, 1989, has confirmed the licensee's data. Therefore, the staff considers the IE Bulletin 80-11 issues on masonry walls for North Anna Power Station Units 1 and 2 resolved.
3.0 CONCLUSI0W The licensee has resolved the original staff concern on the adequacy of the simple cantilever support for the 10 masonry walls by a field inspection as indicated in the attached Table 1.
The new information replaces the original licensee assumption that considered these walls as cantilever walls. The licensee has provided new information concerning the actual boundary conditions which has been confirmed by the staff during our site visit. Based on the new findings identified in the VEPCO's sub-mittal of May 12, 1989, and staff site visit of July 19, 1989, we consider the original issucs applicable to the cantilever masonry walls under the IE Bulletin 80-11 to be resolved.
Datedi September 7, 1989-Principal Contributor:
F. Rinaldi'
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TABLE.1 l
LIST.0F. BLOCK. WALLS.AEKET7 G.AS. CANTILEVER WALLS AND.TkII;IR. ACTUAL.SOUNDARL CONDITIONS NORTH. ANNA. POWER. STATION Item ko.
Wall. Number Actual. Boundary. Conditions 1
AB-291-3 One side encased in channel, the other side butt against enibedded steel column. (See I
DetailA, Attachment 2SH18.)
2 AB-291"3A Both sides butt against embedded steel columns.
3 AB-291-6 Both sides encased in channel.
(See Details A and B, SH 18.)
4 AB-291-9 Both sides encased in channel.
(See Details A and B, Attachment 2SH18.)
5 AB-291-13 One side encased in channel, the other side attached to channel.
(See Details C and D Attachment 2 SH 19.)
6 AB-291-16A One side encased in channel, the other side butt against embedded steel column.
(See Detail C, Attachment 2 SH 19.)
7 AB-291-17 One side free, the other side interlocked with wall AB-291-3A.
(See Detail E, SH 20.)
8 AB-291-17A One side encased in channel, the other side butt against embedded steel column.
(See DetailB, Attachment 2SH18.)
9 AB-291-18 One side encased in channel, the other side butt against embedded steel column.
(See DetailA, Attachment 2SH18.)
10 AB-291-18A Both sides butt against embedded steel columns.
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