ML20028G050
| ML20028G050 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 01/11/1983 |
| From: | Brey H PUBLIC SERVICE CO. OF COLORADO |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| P-83022, TAC-42925, NUDOCS 8302070352 | |
| Download: ML20028G050 (3) | |
Text
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p pul> lie Service Company *ff Odanydle P. O. Box 840, Denver, Colorado 80201 January 11, 1983 Fort St. Vrain Unit No. 1
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fjf e7fl Mr. Robert A. Clark, Chief *f 'g g g @ l Operating Reactors Branch #3 Division of Licensing y, __
l Nuclear Regulatory Commission
SUBJECT:
Masonry Block Walls
REFERENCE:
G-82377 i Gentlemen:
t The following is Public Service Company of Colorado's response to your letter of November 19, 1982 requesting additional information on masonry block walls.
ITD4 1 Since no quality assurance records are available the Licensee is requested to confinn that Dur-0-Wall exists in the walls as specified in the design. Also provide available data to justify the yield strength of Dur-0-Wall used in the analysis. In addition, provide verification to assure proper anchoragt of Dur-0-Wall at the boundary and proper bonding between Dur-0-Wall and mortar. Further, justify the use of Dur-0-Wall as a reinforcing element considering the fact that this is not normally used in such capacity. Include applicable test data in your justification.
PSC RESPONSE All of the 22 walls, which were qualified by relying on the strength of Duro-0-Wall, were investigated to verify that Dur-0-Wall does exist. A total of 17 walls had Dur-0-Wall as originally speci fied. This was verified by means of a metal detector and by removing mortar in various locations to check the Dur-0-Wall size and b
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bond. A total of five walls were noted to have discrepancies with the installation of the Du r-0-Wal l from what was originally specified.
Each of the walls and the corresponding discrepancies are as follows:
Wall 49 Dur-0-Wall was missing from one course of block Wall 51 Dur-0-Wall was missing from the upper half of the masonry block wall.
Wall 95 Dur-0-Wall was missing from the lower half of the masonry block wall.
Wall 100 Dur-0-Wall was not found.
Wall 101 Dur-0-Wall was found to be missing from one course.
Reanalysis of wall number 51, which has a very short span length, showed that there is adequate strength in the masonry to resist the various loads and that Dur-0-Wall, in fact, would not be required as originally specified to maintain wall integri ty. The remaining walls, numbers 49, 95, 100, and 101 will require modifications to provide aden,uate reinforcement.
The yield strength of the Dur-0-Wall can be justified since a maximum stress of 40,000 psi was used in the analysis of the Dur Wall steel. The normal cold-drawn steel wire used for Dur-0-Wall nas a minimum yield point strength of 64,000 psi (See Ref. 2 below).
Therefore, the values used in the masonry block wall analysis are conservative, and justifiable. No test data on the Fort St. Vrain Dur-0-Wall reinforcing is available.
No credit was taken for the Dur-0-Wall at the boundary support.
The shear strength of mortar is sufficient in resisting the seismic loads. An evaluation of the bond be tween the boundary and the masonry block mortar joint is currently being perfonned by PSC.
Results of this evaluation will be available upon review and evaluation by PSC.
The bonding be tween the Dur-0-WalI and mortar was found to be sufficient through engineering judgement upon inspection of the walls in which mortar was removed to expose the Dur-0-Wall.
Dur-0-Wall is justified as a reinforcing element in the following references:
- 1) Reinforced Masonry Engineering Handbook. By James Anrhein, 1973 Edition, Page 242.
e P-83022 Pag 2 3 g 2) A Comprehensive Data File on Masonry Wall Reinforcement, By
- W.H. Bartlett,1962, Page 33.
Based on this information, PSC feels that it is justifiable to use Dur-0-Wall as a reinforcing element.
ITEM 2 Provide data to justify the strength of the bar straps used in wall modifications.
PSC RESP 0t4SE PSC feel s that data is not required to justify the strength of the bar straps used in the wall modifications since ASTM A36 steel was used in the analysis. ASTM A36 is a low strength steel and any steel used would have as a minimum the tensile strength properties of ASTM A36 steel .
ITEM 3 Veri fy whether load conbinations used are in conpliance with the plant FSAR.
d PSC RESP 0tiSE_
The FSAR does not address load conbinations on masonry block Wdils, however, Design Criteria: Structures - General (System 70) discusses concrete load conbinations which were used in the analysis of the masonry block walls.
ITEM 4 Indicate the number of walls which were qualified by relying on the strength of Dur-0-Wall and that of bar straps. Also, provide the status of wall modifications.
PSC RESPONSE Twenty-two masonry block walls were originally qualified by relying on the strength of Dur-0-Wall. Sixteen masonry block walls were qualified by use of bar straps attached to the walls.
All wall modifications with regard to the 16 masonry block walls requiring bar straps were conpleted approximately one year ago. The modifications to the four walls which had dur-o-wall discrepancy will be conpleted by March 15, 1983.
Very truly yours, N Arru x, D ~
- 11. L. Brey, Manager Nuclear Engineering Division HLB:pa
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