ML20209D416

Discusses Review of Facility Masonry Wall Design,Per .Outstanding Issues Identified in Working Stress Approach & Nonlinear Analysis Method.Audit of Design Calculations Suggested

ML20209D416
Person / Time
Site:	Diablo Canyon
Issue date:	10/02/1984
From:	Lear G Office of Nuclear Reactor Regulation
To:	Knighton G Office of Nuclear Reactor Regulation
Shared Package
ML17083B484	List: ML20209C687 ML20209C692 ML20209C725 ML20209C729 ML20209C734 ML20209C742 ML20209C774 ML20209C779 ML20209C786 ML20209C810 ML20209C853 ML20209C869 ML20209D170 ML20209D204 ML20209D416 ML20209D421 ML20209D450 ML20209D560 ML20209D649 ML20209D703 ML20209D864 ML20209D903 ML20209E021 ML20209E030 ML20209E037 ML20209E052 ML20209E145 ML20209E211 ML20209E268 ML20209E506 ML20209F952 ML20209G177 ML20210E664 ML20210E745 ML20210E799 ML20210E811 ML20210E916
References
FOIA-86-197 TAC-60090, NUDOCS 8410150140
Download: ML20209D416 (6)

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4.....' 00r 0 21984 Docket No. 50-275 MEMORANDUM FOR: C_.r  ; m Jn, Chief Licensing Branch #3 Division of Licensing FROM: George Lear, Chief Structural and Geotechnical Engineering Branch Division of Engineering

SUBJECT:

DIABLO CANYON - MASONRY WALL DESIGN

Reference:

Letter from J. O. Schuyler of Pacific Gas and Electric (PG & E) to G. W. Knighton of NRC, dated August 7, 1983.

We have reviewed the information provided by the licensee in the referenced letter.

Our review indicates the licensee's re-evaluation criteria contains two basic elements: (1) working stress design approach; and (2) a non-linear analysis method, " energy balance approach". As noted in the enclosure, we have identified some outstanding issues with both elements of the criteria.

In order to expedite the resolution of the issues related to the working stress design approach, we suggest that we audit the licensee's design calculations to assess whether the differences between the staff's working stress criteria and those of the licensee's have any significant impact on the re-evaluation program. It has been cur past experience that such differences are quite often efficiently resolved through a direct audit review rather than via time consuming debates of technical merit and adequacy of a particular criterion.

l The second item pertains to the use of energy balance method. As'noted in the enclosure, use of this method may. require a test verification proaram.

l SONGS-1 completed a test program to qualify their walls and the results of l this program art currently under review. Construction techniques at SONGS-1 and Diablo Canyon appear to be different in some significant aspects; therefors.

a plant unique test verification program may be reeded for Diablo Canyon. We suggest that we discuss this issue with the licensee during the audit. .If possible, we suggest that you make arrangements for the audit in the first week of October 1984.

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we George . Lear, Chief l Structural and Geotechr.ical Engina ring Branch Division of Engineering cc: See next page.

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Knighton

Enclosure:

As stated cc: J. Knight T. Novak D. Jeng H. Schierling L. Yang N. Chokshi CONTACT: Li Yang, x28179 N. Chokshi, x28967 1

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l MASONRY WALL REVIEW PACIFIC GAS AND ELECTRIC C0.

DIABLO CANYON POWER PLANT, UNIT 1 DOCKET N0. 50-275 STRUCTURAL AND GE0 TECHNICAL ENGINEERING BRANCH STRUCTURAL ENGINEERING SECTION A WORKING STRESS APPROACH The staff has reviewed the information provided by the licensee in a letter dated August 17, 1983. For the wall qualified by the working stress design approach, the staff has noted several differences between it acceptance criteria and the licensee's re-evaluation criteria. The licensee should assess the program and provide this information for the staff's review.

1. The licensee's criteria specify 5% damping for uncracked situation while the staff's criteria allow 4% damping for OBE evaluation.

2. The staff criteria specify the increase factor of 1.3 for the shear carried by the masonry, the licensee's criteria includes a factor of 1.67.

3. The staff criteria permit the maximum rebar stress of 0.9 fy, while licensee's allowable stress is the tested average fy.

ENERGY BALANCE TECHNIQUE, With regards to the use of energy-balance technique, the NRC staff with the assistance of Franklin Research Center and its consultant have conducted an exhaustive review of the available information on this technique over the last two years. It-is the staff's position that the mere use of the energy balance technique in qualifying walls without test verification is

_2 not acceptable. This is due to the lack of the test data to establish the load-deflection _hysteretic behavior, ductility ratios and the post yield envelopes for different material properties and also due to the known differences in construction details as well as available experimental data between masonry walls and reinforced concrete walls in nuclear power plants.

The statf may, therefore, require a confirmatory testing program of a sufficient scope and specificity such that the applicability of the energy-balance technique to the masonry walls at Diablo-Canyon can be demonstrated.

For detail discussion and definition of such a testing program, if the applicant wishes to pursue the testing approach, we suggest that direct meetings between the NRC staff and the applicant be arranged to expedite resolution of the issue.

. Diablo Canyon, Unit 1 AE00 found 51 LERs and six revisions in the NRC Document Control System for the January 1,1983 to June 30, 1984 assessment period. Fifty-two percent of the events'were attributed to personnel errors. Four percent were due to design, manufacturing, or construction errors. Twelve percent were a result of deficient or erronedbs procedures, and twenty percent were due to component failure.

Twelve percent were placed in the "other" category and none were due to external causes. Twenty-six preliminary notification of occurrence reports (PN0s) were submitted and four special reports were found. Based on our review of the available reports, our findings are as follows:

1. LER Completeness

a. Was the information given sufficient to provide a good understanding.of the event?

Yes, enough information was given to clearly and adequately describe each event.

b. Were the LERs coded correctly?

Yes, all of the entries reviewed appeared to be correct. No discrepancies or inconsistencies were found.

c. Was supplementary information provided when needed?

Thirty-seven of the fifty-one LERs submitted included supplemental informa-tion. In each case, the additional information added to the clarity and completeness of the.LER.,

d. When follow-up reports are promised, are they delivered?

Follow-up information was promised for three events and in each case it was delivered.

e. Were'similar occurrences adequately referenced?

l-l Yes, similar occurrences were always referenced.

2. Multiple Event Reporting in a Single LER No cases of reporting multiple occurrences in an LER when separate reports i

should have been submitted were found.

3. Prompt Notification Follow-uo Reports No Prompt Notification reports were found. Twenty-six PM0s were found and three were followed-up by LERs. It does not appear that follow-up reports were required for the others.

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Diablo Canyon, Unit 2 AE00 found seven PN0s applicable to Unit 2 and no LERs. Unit 2 is still under construction.

In conclusion, our review indicates that, based on the stated criteria, the licensee provided adequate event reports during the assessment period. Although the licensee reported a very large percentage of events due to personnel errors compared to other plants, no specific areas which required improvement were found.

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