ML19310A169
| ML19310A169 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 05/16/1980 |
| From: | Trammell C Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19310A170 | List: |
| References | |
| TAC-12369, NUDOCS 8006060219 | |
| Download: ML19310A169 (8) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION g
- j WASHINGTON, D. C. 20555 7,
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May 16,1950 Docket No. 50-344 LICENSEE: Portland General Electric Company (PGE)
FACII.ITY: Trojan Nuclear Plant
SUBJECT:
SUMMARY
OF MEETING HELD ON May 1-2, 1980 TO DISCUSS RESOLUTION OF THE TROJAN " WALL PROBLEM" On May 1-2, 1980, the NRC staff met with representatives of PGE and Bechtel Power Corporation to discuss the resolution of the Trojan " wall problem".
Attendees are listed in Enclosure 1.
Highlights of the meeting are sumarized below.
Background
While conducting investigations and analyses required by IE Bulletins 75-02 and 79-14 'in October 1979, PGE found a case wherein the wall to which a seismic anchor was attached (SA-83) was structurally inadequate to resist the earth-quake reaction forces.
This led to a complete walk-down and design verification of all walls in the facility which were constructed of concrete masory block.
Most of the problems involved walls consisting of double wythes of concrete block.
Corrective action consisted of removing piping attachments from walls or thru-bolting the attachments. Corrective actions were completed in December 1979, and, following an intensive review by the NRC staff, Trojan resumed operation.
On February 22, 1980, 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 recomended that collar joint shear stress be l
limited to 12 psi.
As a result of this consultant report, PGE embarked on a short-tem 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, and served to confirm that 40 psi is a reasonably reliable value for this type of block. The i
results for the heavy-weight block tests were much lower - about 23 psi average, as compared to the 40 psi relied upon by the staff.
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THIS DOCUMENT CONTAINS N O N M et f
F00R QUAUTY PAGES w
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Trojan Nuclear Plant,
As a result of these test results, PGE has agreed to keep Trojan out of i
service until the problem with the heavy-weight block walls is resolved to the satisfaction of the NRC staff. This meeting was the first step in
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proceeding toward a resolution of the problem.
Sumary l
The purpose of the meeting was to develop evaluation criteria for double-block concrete masonry walls and to decide on an appropriate fix where necessary.
PGE/Bechtel propose to use 10 psi as an allowable value for collar joint shear stress for heavy-weight block. Walls which exceed this value by a relatively small amount may have to be looked at on a case-by-case basis if fixing such walls involves unusual circumstances, e.g., high radiation areas, access prob 1s, unimportant wall, etc. The NRC staff agreed that 10 psi would be an appropriate allowable value.
The evaluation methods and criteria were presented in viewgraphs.
Copies of which are enclosed. These have been marked up to reflect staff coments made during the meeting.
PGE will investigate (and correct if necessary) all heavy-weight double block walls in the Control / Auxiliary / Fuel Building complex.
(At Trojan, this is equivalent to all heavy-weight double block walls at the site.)
Where collar joint mortar shear stresses exceed the allowable limit, modiff-cations will be performed by a " grouting program" to provide added assurance that the two wythes do not separate upon the application of out-of-plane loads.
This program will involve drilling 2-inch holes through one wythe of the wall and partially through the other wythe (within 1 inch of the opposite face).
Reinforcing steel or steel bar would then be inserted and grouted in place.
l As to spacing of such dowels, Bechtel presented an example for a wall with a calculated collar shear stress of 15 psi.
Four horizontal rows of dowels would be required - 2 at the top and 2 at the bottom, spaced 24" apart hori-zonta11y.
The rows would be 12" and 44" from the top and bottem of the wall.
The inherent shear capacity of the mortar would be ignored; the entire shear would be resisted by the dowels. See Enclosure 2 pp.11-14 for further details.
The NRC staff comented that dowel spacing should not exceed 24" 0.C. horizon-tally or vertically (based upon consideration of AASH0 Code requirements), and dowals should not be greater than 12" from the boundaries (horizontal or vertical) of the wall or panel.
PGE was requested to address relative slip compared to elastic calculations to ensure that the capacity of the pins (dowels) can be developed without excessive displacement.
Other NRC coments:
Damping for SSE calculation should be limited to 5% for the cracked condition.
a.
Trojin Hu* clear Plant *
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Past practice has been to consider ground spectra and damping together, i.e.,
modified Hausner and 5%, or Reg. Guide 1.60 and 1.61.
No case has been made for a higher damping value. The 2% damping for the uncracked condition is appropriate.
b.
Since some walls may have a calculated low frequency, PGE should investigate what impact this could have on the validity of previous piping and equipment analyses.
PGE was requested to list all walls and their corresponding frequen-cies, with a calculated frequency below about 26.Hz.
c.
Would these new considerations impact rebar strains (reported as 3 times yield)? How? Why are the new stains acceptable if increased above those pre-viously considered?
d.- A value of fy=0.9 yield is acceptable provided that the compressive stress 3
peak based on a triangular stress block is limited to 1/3 of the lesser of the compressive strength ~ of the block or mortar.
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e.
The proposed fix consisting of the steel dowels did not provide for a positive anchorage at the ends of the bars.
The Trojan plant is presently in the refueling mode, with the reactor vessel head removed and all fuel in the spent fuel pool.
PGE stated that they w,ill inves-tigate and correct walls with appropriate consideration to walls to which systems associated with mode changes are attached or in near proximity, i.e., investigate and make repairs'as needed prior to entering higher modes of operation which involve such walls whose structural integrity is in question.
PGE was requested to investigate whether or not the Technical Specifications will need to be revised to reflect the calculational methodology and criteria finally agreed upon.
As to schedule, PGE plans to evaluate all heavy-weight block first, and make all necessary corrections for SSE qualification prior to startup, per agreement reached with IE Region V.
The evaluations will take about a month to complete.
PGE plans to have all heavy-weight block Walls corrected (SSE qualified only) in time for a scheduled plant startup about July 1,1980.
l Corrective action where necessary will involve about 100 holes /doweb per wall panel and take about a week each.
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Standard weight double-block walls will be investigated to ensure that collar joint shear is less than an 18 psi allowable per the same evaluation criteria.
This will be done_on a lower priority basis, and not necessarily prior to startup.
A technical basis demonstrating that these walls have sufficient structural integrity so as not to present a safety concern will be given by PGE to sub-stantiate th'is course of action until completion of long-range testing.
PGE will i
submit a formal proposal on or about May 9,1980.
r.
There was a limited amount of discussion regarding evaluation of the walls for 1
i a 0.15g OBE.
PGE proposed to use a load factor of 1.25 for earthquake loads and use the same acceptance criteria as for the SSE.
NRC commented that the load i
factor should be 1.4 for shear walls; and damping should be limited to 2% for the OBE for both the cracked and uncracked condition.
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Trojan Nuclear Plant Whereas no final formal agreement was reached at the meeting, the NRC staff noted that NRC and PGE had reached general agreement with respect to SSE evaluation criteria sufficient for PGE/Bechtel to proceed with evaluations of the masonry walls in the plant and implementation of corrective action with reasonable assurance of their acceptability.
Detsils of a long range testing program are to be discussed and finalized at a later date.
Cri /ra C. M. Tramell, Project Manager Operating Reactors Branch #3 Civision of Licensing
Enclosures:
1.
List of Attendees 2.
Viewgraphs cc w/ enclosures 1 & 2:
See next page
. "~
Mr. Charles Goodwin, Jr.
Portland General Electric Company i
l cc: Mr. Ronald W. Johnson, Esquire Mr. John A,. Kullberg Corporate Attorney Route One Portland General Electric Company Box 250Q 121 S.W. Salmon Street Sauvie Island, Oregon 97231 Portland, Oregon 97204 1
Maurice Axelrad, Esquire Robert M. Hunt, Chairman Lowenstein, Newman, Reis, Board of County Comissioners Axelrad and Toll Columbia County Suite 1214 St. Helens, Oregon 97051 1025 Connecticut Avenue, N.W.
Washington, D. C.
20036 Columbia County Courthouse Law Library, Circuit Court' Room Richard M. Sandvik, Esquire St. Helens, Oregon 97051 Frank W. Ostrander, Jr.
Counsel for Oregon Dept. of Director, Oregon Department of Energy Energy Labor and Industries Building, Room 111 500 Pacific Building Salem, Oregon 97310 520 S.W. Yanhill Portland, Oregon 97204 Dr. Hugh 0. Paxton 1229 41st Street Mr. David B. McCoy Los Alamos, New Mexico 87544 348 Hussey Lane Grants Pass, Oregon 97526 Michael Malmros, Resident Inspector U. S. Nuclear Regulatory Comission William Kinsey, Esquire Trojan Nuclear Plant 1002 N.E. Holladay P. O. Box 0 Portland, Oregon 97232 Rainier, Oregon 97048 Ms. Nina Bell Dr. Kenneth A. McCollom, Dean 728 S.E. 26th Street Division of Engineering, Portland, Oregon 97214 Architecture and Technology Oklahoma State University Mr. Eugene R. Rosolie Stillwater, Oklahoma 74074 Coalition for Safe Power 215 S.E. 9th Avenue Portland, Oregon 97214 O
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i Mr. Charles Goodwin, Jr.
Portland General Electric Company cc: Marshall E. Miller, Esquire, Chairman Atomic Safety and Licensing Board U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Atomic Safety and Licensing Board Panel U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Docketing ?.nd Service Branch (7)
Office of the Secretary U. 3. Nuclear Regulatory Commission Washington, D. C.
20555 Alan S. Rosenthal, Esquire Atomic Safety and Licensing Appeal Board U. S. Nuclear Regulatory Connission Washington, ". C.
20555 Dr. John H. Buck Atomic Safety and Licensing Appeal Board U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Dr. W. Reed Johnson Atomic Safety and Licensing Appeal Board U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Atomic Safety and Licensing Appeal Panel (5)
U. S. Nuclear Regulatory. Commission Washington, D. C.
20555 9
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~ LIST OF ATTENDEES PGE/BECHTEL MEETING May 1-2,1980 BECHTEL NRC K. Green C. Trammell D. Persinko W. Tseng K. Buchert J. Fair B. Sarkar K. Herring K. Wichman P. Chang-Lo W. White P. T. Kuo R. Anderson J. Ma H.' Lee B. Churchill (counsel)
H. Polk-K. Lee D. Jeng H. Wong J. Gray (counsel)
J. Costello PGE C. P. Tan J. Colville (consultant)
T. Bushnell D. Broehl W. Lindblad M. Axeirad (counsel)
M. Holley, Jr. (consultant) l l
l mmem--e
6 h
MEETING
SUMMARY
DISTRIBUTION (W/ ENCLOSURE 1 ONLY)
Licensee:
Mr. Charles Goodwin, Jr.
Assistant Vice President Portiand General Electric Company 121 SW Salmon Street Portland, Oregon 97204 H. Denton E. G. Case Docket File NRC PDR t/encis. 1 & 2 L PDR I
h NSIC
.ORBB4 Rdg NRR Rdg DEisenhut RTedesco TNovak Glainas ORB Branch Chiefs (5)
ORB Project Manager -CTrammell w/encls.1 & 2 ORB Licensing Assistant AE0D IE RFraley, ACRS-16 Program Support Branch Meeting Summary File NRC Participants W/ Enclosures 1 & 2:
DPersinko-P. T. Kuo D. Jeng JFair J. Ma H. Wong kNerring H. Lee J. Costello KWichman H. Polk C. P. Tan J. Gray J. Colville i
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