ML19343A321
| ML19343A321 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/17/1980 |
| From: | Ottoson H SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| IEB-80-11, NUDOCS 8009170207 | |
| Download: ML19343A321 (6) | |
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July 17, 1980 U.S. Nuclear Regulatory Commission Attention:
R. H. Engelken, Director Office of Inspection and Enforcement Region V Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Gentlemen:
Subject:
Docket No. 50-206 IE Bulletin No. 80-11, Masonry Wall Design San Onofre Nuclear Generating Station Unit 1 Your letter of May 8, 1980 forwarded the subject IE Bulletin for our action.
In particular, information identified in Items 1, 2a and 3 of the Bulletin was requested within 60 days. The requested information is provided as an enclosure to this letter.
l If you have any questions on this information, please contact me.
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RESPONSES 9
TO ITEMS 1, 2A, AND 3 OF NUCLEAR REGULATORY COMMISSICN IE BULLETIN NO. 80-11, ENTITLED " MASONRY WALL DESIGN" l
Reference:
A.
SCE letter dated April 28, 1980 to the Director of Nuclear Reactor Regulation;
Subject:
Seismic Re-evaluation Program.
Item 1:
" Identify all masonry walls in your facility which are in proximity to or l
have attachments from safety-related piping or equipment such that wall failure could affect a safety-related system. Describe the systems and equipment, both safety and non-safety-related, associated with these casonry walls. Include in your review, masonry walls that are intended to resist impact or pressurization loads, such as missiles, pipe whip, pipe break, jet impingement, or tornado, and fire or water barriers, or l.
shield walls. Equipment to be considered as attachments or in proximity l
to the walls shall include,'but is not limited to, pumps, valves, motors, I
heat exchangers, cable trays, cable / conduit, HVAC doctwork, and
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electrical cabinets, instrumentation and controls. Plant surveys, if necessary, for areas inaccessible during normal plant operation shall be performed at the earliest opportunity."
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Response
The masonry walls, which are in proximity to or have attachments from safety-related piping or equipment, at the San Onofre Nuclear Generating Station, Unit 1, are shown on the enclosed sketches (SK-S-001 through SK-S-023 The information shown on these sketches was obtained and/or verified by walkdown of the plant during the month of June,1980. All areas of the plant were accessible due to a scheduled outage, and were examined.
A specific description of the systems and equipment, both safety and ncn-safety-related, associated with these masonry walls is not available at this time. However, the enclosed sketches SK-S-001 through SK-S-023 generally describe the nature of the equipment,' conduit, cable tray, and/or piping which is attached to or in proximity to the masonry walls.
Masonry walls are also located at the northeast section of the Control-Administration Building, and adjacent to the Auxiliary Building. Since these masonry walls are not located in the proximity of safety related equipment' or piping, the review of these walls will consist of demonstration that their response or collapse would not impair the integrity or function of the Seismic Category A structures to which the walls are. attached.
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f Item 2A:
" Establish a prioritized program for the re-evaluation of the masonry walls. Provide a description of the' program and a detailed schedule for completion of the re-evaluation for the categories in the program. The completion date of all re-evaluations should.not be more than 180 days from the date of this Bulletin.
A' higher priority should be placed on the wall re-evaluations considering safety-related piping 2-1/2 inches or greater in diameter, piping with support loads due to thermal expansion greater than 100 pounds,. safety-related equipment weighing 100 pounds or greater, the safety significance of the potentially affected systems, the overall loads on the wall, and the opportunity for performing plant surveys and, if necessary, modifications in areas otherwise inaccessible. The factors described above are meant to provide guidance in determining what loads may significantly affect the masonry wall analyses."
Response
The masonry wall re-evaluation program will include the following activities:
- a. Obtaining Complete and Accurate Data.
All available drawings, specifications, purchase specifications, and related documentation for the original construction or for subsequent modifications, will be utilized as a data base for determining the structural-condition of the walls. This information will be _ verified and/or supplemented by field conducted surveys of the masonry block walls. The information obtained will include as a minimum, the following items:
the physical properties for the masonry blocks, reinforcing steel, mortar, and grout; the reinforcing bar spacing and size; the amount of grouted cells; the size and location of all wall penetrations ar.d openings; the wall boundary conditions' (i.e.. fixed, partially fixed, pinned, cantilevered, etc.); the type and physical condition of the wall support point connections; dimensions, connection locations, and loads of all significant items attached to the walls; the existing condition of the block, mortar, and grout (where possible to determine); and the location and dimensions of any structurally significant cracks, b'. Establishment of the Re-evaluation Criteria.
The criteria will address the governing code provisions, loads, and load. combinations, material properties, the evaluation methods, allowable design stresses and acceptance criteria,'and design spectra to be employed in the evaluation of the masonry walls.
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'. c. Development of the Methodology to be Employed.
In general, the masonry walls at San Onofre Unit 1 provide varicus functions. Some walls serve as' load bearing shear walls, while other walls are non-load bearing which provide radiation shielding or architectural functions and are either supported by or connected to structures of non-masonry construction.
The development of the re-evaluation methodology to be employed will reflect consideration of the various functions, and configurations of the masonry walls, as well as a review of the various analytical methods which are available.
- d. Evaluation of the Masonry Walls.
The design adequacy of the masonry walls will be re-evaluated in accordance with the established masonry wall re-evaluation criteria.
The analytical methods to be employed will be consistent with the criteria and will provide for adequate representation of the behavior of the structure when subjected to the design loads.
A re-evaluation priority for the masonry block walls has' been prepared based upon the following factors:
o the overall loads on the wall and the potential stress level within the wall.
the wall support which is provided to safety-related items or o
equipment (in. general,'very-little piping is supported by the masonry walls).
the potentially affected equipment ite=s and systems in proximity to o
the masonry walls.
The resultant re-evaluation priority for the masonry walls is shown in Table 1.
It is our intention.to proceed with the program as described above including the non-seismic evaluations such that a submittal of the program data and evaluation results can be provided on or about November 8, 1980. This submittal will address the following items:
- a. Responses to Item 2b(1) and Item 2b(ii) of IE Bulletin 80-11.
- b. Program re-evaluation criteria (including justification for the criteria employed)
- c. Re-evaluation report addressing the results of the program's non-seismic evaluations.
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I' With respect to the seismic evaluations, reference A provides a I
description of the program which has been initiated for the seismic
_re-evaluation of the San Onofre Unit 1 balance of plant structures.
In general, the masonry walls which are. subject to this bulletin are connected to, supported by, or constitute a portion of, the structures which will be re-evaluated in the Reference A program. Accordingly, the re-evaluation of seismic design adequacy of the masonry walls will be performed in conjunction with the conduct and schedule of the Reference A program. Therefore, the report addressing the results of the IE Bulletin evaluation of the seismic design adequacy of masonry walls will be provided about April, 1981. If these evaluations can be further expedited we will let you know.
Item 3:
" Existing test data or conservative assumptions may be used to justify the re-evaluation acceptance criteria if the criteria are shown to be conservative and applicable for the actual plant conditions. In the absence of appropriate acceptance criteria a confirmatory masonry wall l
test program is required by the NRC in order to quantify the safety margins inherent in the re-evaluation criteria. Describe in detail the actions planned and their schedule to justify the re-evaluation criteria used in Item 2.
If a test program is necessary, provide your commitment l
for such a program and a schedule for submittal of a description of the l
test program and a schedule for completion of the program. This test program should address all appropriate loads (seismic, tornado, missile, etc.).
It is expected that the test program will extend beyond the 180 day period allowed for the other Bulletin actions. Submit the results of the test program upon its completion."
Response
Justification for the re-evaluation criteria will be submitted with the criteria.
It is not anticipated that a test program will be necessary. This matter will be reassessed, however, in conjunction with the preparation of the re-evaluation critieria to be employed.
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I TABLE 1 SAN CHOFRE NUrLEAR GENERATING STATION, UNIT 1 NASONRY WALL RE-EVALUATION PRIORITY WALL #
BUILDING OR AREA TB-12 Turbine Area Enclosure Wall FB-1 through 10 Fuel Storage Building TB-1, 7, and 11 Turbine Area Enclosure Walls AB-3 Control-Admin Building TB (remaining walls)
Turbine Area Enclosure Walls VB-1 through 4 Ventilation Building AB-1 and 2 Control-Admin Building SB-1 through 7 Reactor Auxiliary Building AB-4, 5, and 6 Control-Admin Building
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