NRC Generic Letter 80-32, Information Request on Category I Masonry Walls Employed by Plants Under CP and OL Review

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GL80032

APR 21 1980

TO ALL CONSTRUCTION PERMIT AND OPERATING LICENSE APPLICANTS

SUBJECT: INFORMATION REQUEST ON CATEGORY I MASONRY WALLS EMPLOYED BY PLANTS UNDER CP AND OL REVIEW

In Licensee Event Report 79-15, dated November 4, 1979, Portland General Electric Company stated that some piping supports and restraints at the Trojan Nuclear Plant were supported off masonry walls not designed to carry these loads. Subsequently, these conditions were corrected.

A meeting between the NRR staff and the staff of Portland General Electric Company and Bechtel Corporation including their consultants, was held on December 11, 1979. In the meeting the philosophy of the analysis and design of masonry walls, in general, was examined and the structural safety of the masonry walls at the Trojan Plant was discussed. Subsequent to the meeting Bechtel Power Corporation, the Architect/Engineer for the Trojan Plant, conducted a survey of another thirteen plants whose project spans overlapped that of the Trojan Plant. This survey revealed that six of the thirteen plants had some Category I large pipe (2-1/2* and larger) supports attached to reinforced masonry walls. This was reported in a letter from Bechtel to NRC, dated November 15, 1979. Based on this finding, we believe that masonry walls are probably being used or are intended to be used in other unsurveyed plants to support Category I piping and components.

Since present standard review plans do not explicitly provide acceptance criteria for analysis, design, construction and quality control applicable to Category I masonry walls, there is a need to determine the extent of usage of such walls in plants under construction, to ascertain what criteria are actually being used, to establish the acceptance criteria for concrete and reinforcing steel used in these walls and to be informed on the procedures used for the analysis and design of such walls. In order to develop the aforementioned information and to assure the design adequacy of masonry walls and the support anchors for piping equipment hung from such walls, we have prepared a list of questions to which it is requested that all applicants whose dockets are tinder CP and OL review respond.

This request for generic information was approved by GAO under blanket clearance number B180225 (R0072). This clearance expires July 31, 1980.

Sincerely,

Steven A. Varga, Acting Assistant Director for Light Water Reactors Division of Project Management

Enclosure:

As statedENCLOSURE REQUEST FOR INFORMATION ON THE USE OF CATEGORY I MASONRY WALLS

1. Are there any concrete masonry walls being used in any of the Category I structures of your plant? If the answer is "No" to this question there is no need to answer the following questions.
2. Indicate the loads and load combinations to which the walls were designed to resist. If load factors other than one(1) have been employed, please indicate their magnitudes.
3. In addition to complying with the applicable requirements of the SRP Sections 3.5, 3.7 and 3.8, is there any other code, such as the "Uniform Building Code" or the "Building Code Requirements for Concrete Masonry Structures" (proposed by the American Concrete Institute) which was or is being used to guide the design of these walls? Please identify and discuss any exceptions or deviations from the SRP requirements or the aforementioned codes.


4. Indicate the method that you used to calculate the dynamic forces in masonry walls due to earthquake, i.e., whether it is a code's method such as Uniform Building Code, or a dynamic analysis. Identify the code and its effective date if the code's method has been used. Indicate the input motion if a dynamic analysis has been performed.
5. How were the masonry walls and the piping/equipment supports attached to them designed? Provide enough numerical examples including details of reinforcement and attachments to illustrate the methods and procedures used to analyze and design the walls and the anchors needed for supporting piping/equipment (as applicable).
6. Provide plan and elevation views of the plant structures showing the location of all masonry walls for your facility.
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