ML19344D268

Forwards Info Re Values for Ultimate Compressive Strength of Masonry Assemblies.No Violation of Tech Specs Occurred as Result of Values Used in Accordance W/Uniform Bldg Code

ML19344D268
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	03/06/1980
From:	Goodwin C PORTLAND GENERAL ELECTRIC CO.
To:	Schwencer A Office of Nuclear Reactor Regulation
References
TAC-07551, TAC-11299, TAC-12369, TAC-7551, NUDOCS 8003110617
Download: ML19344D268 (4)

Text

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March 6, 1980 Trojan Nuclear Plant Docket 50-344 License NPF-1 Director of Nuclear Reactor Regulation ATTN:

Mr. A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D. C.

20555

Dear Sir:

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The attachment to this letter, entitled "Masonary Compressive Strength (fd)",

documents information provided orally to your staff concerning values for the ultimate compressive strength of masonry assemblies (f;) at the Trojan Nuclear Plant.

In summary, it is Licensee's judgment that strict application of the UBC definition of f5 would not change the original design calculations for the Plant, the comparisons made for interim operation or the results of the evaluations performed pursuant to LER 79-15. Therefore, no safety questions are presented by the identification of the variance in the values used for fi from those given by the UBC, and Licensee is of the opinion that FSAR Section 3.7, which through reference to FSAR Section 3.8, requires that masonry structr.res be constructed in accordance with the UBC, has not been violated as a result of the use of a value for f& greater than 1500 psi.

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Mr. A. Schwencer March 6, 1980 Page 2 Thus, no violation of the Trojan Technical Specifications has occurred in this regard.

If Licensee proposes to rely on a value of f4 greater than 1500 psi, information substantiating that value will be developed and submitted to the NRC.

Sincerely, f

C. Goodwin, Jr.

Assistant Vice President Thermal Plant Operating and Maintenance CG/4sa10B18

Attachment:

Masonry Compressive Strength (ff), 2 pages, dated March 6,1980 c:

Mr. R. H. Engelken, Director U. S. Nuclear Regulatory Commission Region V Mr. Lynn Frank, Director State of Oregon Department of Energy Control Building Service List

e e,

A. Schwsnc r March 6, 1980 Page 1 of 2 MASONRY COMPRESSIVE STRENCTH (f&)

By reference to ASTM Standard C-90, the specification for masonry at Trojan required that the masonry units used in the construction of Category I structures be tested in accordance with ASTM Standard C-140 to assure that the masonry units met the design strength values used in design. Appropriate standards were also specified for testing the other materials used in construction. Accordingly, the masonry block units, the grout cell fill and the mortar used in the construction of masonry walls were tested individually in accordance with appropriate standards during the construction of Trojan. The average values obtained are as follows:

Average Material Compressive Strength Heavyweight block units 4100 (net)*

2050 (gross)

Lightweight block units 2700 (net)*

1350 (gross)

Grout cell fill

>6000 Mortar

>3500 l

In a response dated August 17, 1978 to questions from the NRC Staff con-cerning the as-built Control Building and in Table B-6 of " Trojan Control Building Supplemental Structural Evaluation, September 19, 1978", Bechtel compared these values to similar values for materials used in two test programs (the Berkeley and Schneider tests) in order to establish the 1

applicability of the data from such programs to the walls at Trojan. In tables provided with these documents the values reported for the compres-sive strength of the block units alone (both at Trojan and for the referenced test programs) were characterized as being values for ff.

In common usage, the term f4 is sometimes used both as an expression for the compressive strength of individual masonry units and for the compressive strength of assemblies which consist of the materials which constitute the wall (i.e., mortar, grout and block units)(see e.g.,

J. E. Amrhein, Reinforced Masonry Engineering Handbook). However, the UBC definition of fs is more specific. Section 2404 of that code provides that if tests are not performed on the masonry assembly in accordance with paragraph 2, the value for f& should be taken from

• Since approximately one-half of the grcss area of the block consists of the open cells, to arrive at a value of strength for the net area the test value for the gross area is multiplied by two.

e, A. Schwsncsr March 6, 1980 Page 1 of 2 the table provided in paragraph 3 of Section 2404. Since such tests were not performed, reference is made to that table which indicates that a value of 1500 psi for f& could be assumed for both the lightweight and heavyweight block at Trojan. Therefore, designation of the compres-sive strengths of individual masonry units in the comparison provided to the NRC Staff as being values for fi was inconsistent with the UBC definition of fa. Nevertheless, since all of the values presented were for tests only of individual units, the comparisons remain valid, and the test results from the two test programs are applicable to the walls at Trojan.

The term fa did not otherwise enter into the analysis on which Licensee based its conclusions that the as-built Complex could safety withstand an SSE level of 0.25g.

Thus, the use of the term f& to refer to material strength beyond the UBC definition did not affect the results of calcu-lations and analyses performed by Licensee nor could it have affected the conclusions reached by the Licensing Board in Phase I of the Control Building proceedings.

Table A3-2, Rev. O, of PGE-1020 also contained the notation fa. That table provided test values for the individual masonry block units used in the testing program described in Appendix A of PGE-1020. As explained above, that notation is not consistent with the UBC definition of fa.

Nevertheless, the comparison of the strength of blocks used in the tests to the blocks at the Plant remains valid. PGE-1020 has been modified in Revision 4 to remove the f& notation.

Licensee has conducted a review to determine all other instances where a value of f& was used in calculations or analyses for Trojan.

In the design of the Plant (before data was available from the ASTM tests) the value of f& used for masonry walls was 1500 psi.

In the evaluations pursuant to LER 79-15, a value for f4 of 2000 psi was used. Licensee is not aware of any other instances where a value of fd entered into its calculations or analyses for Trojan.

J Although tests were not performed to establish a value for fa consistent with the UBC definition, it is Bechtel's judgment that the value of 2000 psi used in the LER 79-15 evaluations represents a.. appropriate estimate of the value that would have been obtained if such tests had been performs.d.

Licensee concurs in this judgment.

Bechtel has also reviewed the analyses performed pursuant to LER 79-15 to determine whether use of a value of 1500 psi for f& in the analyses would have adversely impacted the results or conclusions based on such analyses. The value of f& did not govern any portione of the analyses other than in the determination of a wall's frequency. The frequency calculations for all single and mortared double block walls carrying significant piping and equipment reaction forces have been reviewed and Bechtel has concluded that the maximum change in wall frequency due to use of a value for fi of 1500 psi would be on the order of 15 percent.

This level of change would not affect any of the conclusions reached by Licensee with respect to resolution of the LER 79-15 vall problem.

LWE/sa/4mg10B21