ML19331D081

Summary of 800624 Site Visit & 800619-20,25-28 Meetings W/ Util & Bechtel in Bethesda,Md, & San Francisco,Ca, Respectively,Re Masonry Wall Problem Per IE Bulletins 79-02 & 79-14

ML19331D081
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	07/03/1980
From:	Trammell C Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
Shared Package
ML19331D082	List: ML19331D081
References
IEB-79-02, IEB-79-14, IEB-79-2, TAC-12369, NUDOCS 8008270230
Download: ML19331D081 (5)

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f July 3, 1980 Docket No. 50-344 FACILITY: TROJAN NUCLEAR PLANT LICENSEE: PORTLAND GENERAL ELECTRIC COMPANY (PGE)

SUMMARY

OF MEETINGS AND SITE VISIT HELD ON JUNE 19, 20, 24-28, 1980 TO DISCUSS THE TROJAN MASONRY WALL PROBLEM On June 19 and 20,1980 the NRC staff net with representatives of PGE and Bechtel Power Corp. in Bethesda, Paryland to discuss the resolution of the Trojan masonry wall problem. See Enclosure 1 for a list of attendees at this meeting.

On June 24,19S0, the NRC staff visited the Troja.: site.

Those attending are listed in Enclosure 2.

The purpose of the visit was to inspect the repairs made to ten masonry walls and to conduct a tour of masonry walls in general throughout the plant.

On June 25-28, 1980, the NRC staff met with PGE and F achtel at Bechtel offices in San Francisco to conclude resolution of the. mas;nry wall problem.

Tnose attending are listed in Enclosure 2.

Backcround The " wall problem" The " wall problem" originated in October 1979 while PGE was conducting inves-tigations and analyses required by IE Bulletins 79-02 (Concrete expansion anchor bolts) and 79-14 (Seismic support as-built verification).

PGE found that a certain seismic anchor (SA-83) was inadequately attached (by anchor bolts) to a concrete masonry wall.

In pursuing an adequate "fix", PGE explored the possibility of thru-bolting. However, analysis disclosed that the wall itself had inadequate structural integrity to resist earthquake reaction forces from the attachc) piping. Therefore, the "fix" involved removing this support from the wall and anchoring it elsewhere.

This discovery led to a detailed piant walk-down and verification of the ade-quacy of the structural design of all walls in the plant which were constructed of concrete masonry block. Most of the problems requiring modification involved walls consisting of double "wythes" of concrete block.

As a result of this discovery, IE:V issued an "imediate action letter" docu-menting an agreement reached between PGE and IE:V that Trojan operation would not resume until the problems with Trojan's walls had been corrected.

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Trojan PGE pursued corrective action in October, November, and December 1979.

Absent this problem, the plant would have been in operation. Corrective action consisted mostly of removing piping attachments from walls or thru bolting the attachments.

Partly in respense to these problems, on November 30, 1979, the ASLB in the Trojan Control Building proceeding ordered Trojan to not resume operation pending further order.

The Licensing Board held a special hearing on this and other matters on December 28 and 29,1979. At the conclusion of this hearing, the Board lifted its shutdown order, and left the wall problem to the staff for resolution.

Following an intensive review by the NRC staff, Trojan resumed operation on December 31, 1979.

On February 22, 1950, the NRC staff filed its SER related to this matter.

In this SER, the NRC relied on a collar joint (inter-wythe) shear ultimate capability of 40 psi, and an allowable value of 18 psi, based on the information available at the time (which was not directly applicable to the Trojan design). At the same time, Dr. James Colville, an NRC consultant retained to assist with the Trojan problem, filed his evaluation and recom-mended that collar joint shear stress be limited to 12 psi.

He also raised questions regarding the adequacy of the method used oy PGE and relied upon by the NRC in its SER, to evaluate wall flexibility.

As a result of this consultant report, PGE embarked on a short-term test program to measure the shear capacity of the collar joint.

PGE conducted 4 in-situ tests.

Results for the standard weight block were about 70 and 93 psi. The results for the heavy-weight black tests were much lower - about 23 psi average, as compared to the 40 psi relied upon by the staff.

As a result of these test results, another imediate action letter was sent to PGE from IE:V indicating FGE's agreement to keep Trojan out of service until the problem with the heavy-weight concrete block walls l

is resolved to the satisfaction of the NRC staff.

This letter was introduced into evidence by the NRC staff at the conclusion of the Trojan Control Building preceeding on April 17, 1980.

Conclusion l

In the course of the review of the reevaluations of the double wythe heavy weight block walls, NRC concerns arose over the potential nonconservative assessments l

of flexibility for all walls, as relied upon in its February 1980 SER. As a result of the meetings described above, evaluation criteria acceptable to the NRC l

staff for all types of masonry walls were developed and documented in a letter from PGE to NRC (IE Region V) dated June 28, 1980 (Enclosure 3).

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. Trojcn Based on the NRC staff review and these criteria, the NRC staff concluded that these revised criteria would provide reasonable assurance that all safety-related systems attached to or near masonry block walls at Trojan will function for earthquakes up to and including the safe shutdown earthquake.

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Charles M. Tramell, Project Manager Operating Reacters Branch =3 Division of Licensino

Enclosures:

1.

List of Attendees-Bethesda Mtg.

2.

List of Attendees-Site Visit 3.

PGE 6/28/80 Ltr.

cc w/ enclosures:

See last 2 pages of this report

o LIST OF ATTENDEES TROJAN WALL PROBLEM MEETING BETHESDA, MARYLAND - JUNE 19 & 20. 1980 NRC PGE T. Novak W. Lindblad F. Schauer D. Broehl P. T. Kuo A. Carr, Jr.

H. Wong B. Sresler

.r H. Lee R. Johnson.

V. Noonan M. Axelrad S. Treby L. Erickson

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J. P. Knight-T. Bushnell D. G. Eisenhut M. Holley, Jr.

j R. Vollmer G. Lainas BECHTEL K. Wichman W. Tseng

'K. Herring P. Chang-Lo C. Tramell W. White R. Anderson D. Halligan K. Buchert B. Churchill l

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i LIST OF ATTENDEES TROJAN SITE VISIT i

d JUNE 24,1980 i

NRC PGE C. Tramell T. Bushnell i

K. Herring D. Broehl J. Colville J. Perry J. P. Knight 4

P. T. Kuo LIST OF ATTENDEES TROJAN WALL PROBLEM MEETING 4

BECHTEL/ SAN FPANCISCO 8

i NRC PGE BECHTEL C. Tramell-U. Lindblad J. O' Leary 1

K. Herring D. Eroehl R. Anderson J. P. Knight T. Bushnell P. Chang-Lo G. Lainas R. Johnson W. White J. Colville L. Erickson B. Sarkar P.~T. Kuo B. Bresler W. Tseng P. Porrill M. Holley, Jr.

D. Sternberg I

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