Information Request on Category I Masonry Walls Employed by Plants Under CP and OL Review (Generic Letter 80-32)
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.
Steven A. Varga, Acting Assistant Director
for Light Water Reactors
Division of Project Management
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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