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RoIErW L. LEGGETT. M.C.
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Mouse of Representatiben EElasfjington, D.C. 20515 waa -a*' or*=o R,- uss RAYOURN Houst Orrect Buskome WasMINGTON, D.C.
20515 (202) 125 5718 OWEN CHAFFEE aoumin -Tura..'"^'"
March 25,1977 l
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Mr. Carlton Cammerer i
Director of Congressional Affairs United States Nuclear Regulatory Commission' Washington, D. C.
20555 Dear Mr. Cammerer.
I I have recently received inquiries as to the status of the Diablo l
Canyon nuclear.-powered generating facility at San Luis Obispo from some of my constituents who are concerned about the prospect of inter-j ruptions of electrical service in California this summer.
I It is my understanding that one unit at the Diablo Canyon facility has been ready for operation for some time, but that its l
licensing and operation have been delayed pending resolution of questions concerning earthquake safety.
I would appreciate any information you can provide concerning the current status of the Diablo Canyon facility and the procedural schedule and prospects for licensing and bringing the plant on line.
Very er y,
lOBERT L. LEGGETT t
Member of Congress R LL: ecd cc: Mr. Michael Caligiuri
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i Dockat No. 50-275 i
f NOTE TO FILE (Diablo Canyon)
SUBJECT:
MEETING AT WESTINGHOUSE NUCLFAR ENERGY CENTER, MONROEVIILE, PA.
t ON MARCH 30 CONCERNING SEISMIC RE-EVALUATION i
A meeting was held to advise the NRC of the current status of the Westinghouse and PG & E effort on seismic re-evaluation of mechanical-and electrical components. Preliminary results should be available in i
approximately one month.
i I
The philosophy being used for the re-evaluation was described. including I
scope and interfaces. The effort is concentrated on the systems need te d
l achieve and maint&&n safe shutdown.
l Attendees: Westinghouse - G. Boehm. W. Gangloff, T. Esselman, W. Sugnet I
PC & E - J. Gormley l
NRC - J. Knight, R. Bosnak l
R. J.'Bosnak, Chief Mechanical Engineering Branch Division of Systems Safety cc:
R. Heineman, SS J. Knight, SS J. Stols, PM l
I. Sihwell, SS D. Allison, PM l
P. Chen, SS Docket File 50-275 NRR Reading File DSS:MEB File
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Pacific Gas and Electric Company ATTN:
Mr. John C. Morrissey Docket Nos h h Vice President and General an:1 50-323 MAR 18 IS//
Counsel 77 Beale Street San Francisco, California 94106 Dr. Richard L. Haullin, Chairman Energy Resources Conservation and tevelopI=mt Comission 1111 howe Avenue Sacramento, California 95825 Dear Dr. Maullin I am pleased to respond to your telegram of March 10,1977, to Chairman Nowden. You described certain activities undertaken by the Energy Resources Conservation and Development Comission and its staff regarding the energy supply and water drought situation in California and inquired about the procedures to be followed by the Nuclear Regulatory Comission (NBC) in making a final determination relating to licensing of the Diablo Canyon plant for operation. Tnis case is under consider-ation by an Atorcic Safety and Licensing Doard. Since any decision or ruling by the licensing r>oard is subject to review by tne Comission, l
it would not be appropriate for the Commissioners to coment on the catter at this time. Accordingly, your telegram was referred.to me for reply.
L 2e application from the Pacific Gas and Electric Company (the licensee) for full tern (40 years from the date of the construction permits) oper-ating licenses for Units 1 and 2 of the Diablo Canyon-facility has been i
under review by the emC staff since October 1973. We basic reason that the review is not complete is the need for the licensee to cocplete a seismic reassessment program designed to determine the extent to which the plant can safely withstand a more severe seismic event than that used as a design basis for the facility at the construction permit stage.
The possible occurrence of the more severe seisade event is based upon evidence that came to light af ter issuance of construction permits for the two units in 1968 and 1970, respectively.
I
%e licensee has informed us that, except for completion of its seismic reassessment program, Unit I of the Diablo Canyon plant will be physi-cally complete and ready for operation in April or May of this year.
The licensee estimates that the seismic reassessment program can be completed and resolved to the satisfaction of the NRC staff, the Advisory Cocnittee on Beactor Safeguards (ACRS), and the NRC Atomic Safety and p g g ?_W_
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Dr. Richard L. Haullin MR 1819//
Licensing Board so as to permit issuance of a fuel loading license in October of this year, and issuance of a full term license for power operation in January 1978. We believe that Unit 1 can oe nxie ready for operation in the spring of this year, except for final resolution k
of the seismic matter, but we believe that resolution of that matter, to the degree needed to permit a decision on fuel loading and issuance of a full term license for power operation, could require more time than predicted by the licensee. We believe that if the licensee's present schedule for submission of tne results of 'its seismic reassessment pro-gram is maintained, a decision on issuance of the full term license for Unit I would occur in the sumer of 1978.
I ne licensee estimates that Unit 2 will be physically complete in-Decencer 1977, except for resolution of the seismic matter, and that the seisnic matter will be resolved on a time scale that will permit fuel loading and issuance of a full term license a few months after similar actions are taken for Unit 1.
He believe that a decision on fuel loading and issuance of a full term license for Unit 2 could occur a few nonths af ter a decision on Unit 1, but that the decision wi13 likely occur in the latter half of 1978.
There is a possible alternative approach that could result in an NFC decision on an interim (as distinguished from full term) operating license for operation of Diablo Canyon Unit 1 before the end of 1977, if action is initiated procptly. The authority to grant such a license is set forth in Section 50.57 of 10 CPR Part 50, in conjunction with other regulations addressing radiological safety and environmental matters associated with the issuance of licenses. This approach would generally consist of the following:
l (1) An appropriate request by the licensee for an interim license, pending final resolution of the seismic matter through corpletion of the attendant adjudicatory proceedings for a full term licenso by the Atomic Safety ard Licensing Board. Tne request would
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need to demonstrate the need to consider such an action.
( 2) Sutraittal of information and analyses by the licensee to demcw-strate that the requisite level of safety would oe assured during the period of the interim license. Tnic information should include all available results of the seismic reassessment program, supported by:
(a) a realistic assessment of the probability of large earth-quakes in the site environs and the probability of the plant to withstand such earthquakes without failures of structures and equipment sufficient to lead to unacceptable radiological' con-sequences to the public; (b) a comitment by the licensee to make
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f Dr. Richard L. Haullin g4g y g any changes to the design determined to be necessary on the basis of the continuing seismic reassessment program; and (c) an evalu-ation of the practicality of making the needed changes to a plant which has been in operation during the term of the interim license.
If adequate information were provided by the licensee on these issues, the staff would be preparea to promptly develop a Safety ' Evaluation Report setting forth its conclusions.on the acceptability of such an interim license for consideration by the ACRS and by the Atcnic Safety arr3 Licensing Board.
(3) Review and a report on the proposed interim license by the ACRS.
(4) Consideration of interim licensing by the ktomic Safety and Licensing I
board.
As noted previously, the approach described above has the potential of l
1eading to an Imc decision on issuance of such an interira license for I
l Diablo Canyon Unit 1 in the latter part of 1977 if action is initiated i
l promptly by the licensee and is supported by the timely submittal of l
l requisite technical information and analyses.
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In sunraary, we believe that, if the licensee's present application for a full term license continues to be prosecuted vigorously, an tsC 6ecision on Diablo Canyon Unit I will be reached about the middle of next ycer. However, it appropriate application is made and justified, we believe it is possible that a decision on whether to issue an interin license could be reacned by the end of this year.
I hope that this resoonae to your telegram of March 10 is of assistance to your Cocraission in its deliberations.
Sincerely, Original Sigaod by j
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Ben C, Rusche p
Q WM Ben C. Rusche, Director h
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4 MEMORA!iDUt1 FOR:
J. P. Knight, Assistant Director-i for Engineering i
Division of Systems Safety j
1 FRO'i:
- 1. S. Sibweil. Chief I
Structural Engineering Branch Division of Systems Safety
SUBJECT:
REVIEW 0F DIABLO CANYON REEVAltlATION (SEB:1111) i Due to the expected increase of the level of SEB activity on the subject matter, I have assioned David Jeng to be a co-reviewer with K. Kapur.
Both Ken and Dave have been instrumental in establishing our seismic l
design criteria and I am confident that together they will carry the revie,v to a successful conclusion.
Isa S. Sihweil. Chief l
Structural Engineering Branch Division of Systems Safety cc:
D. Rusche R. Ifeiner:an F. Schroeder t).
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.. Gaanill D. Allison C. Stepp K. Kapur P. Jene DISTRIBUTION:
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4 NOV 2 4 1976 l
j MEMORANDUM FOR:
H. R. Denton, Director, Division of Site Safety and Environmental Analysis i
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THRU:
W. P. Cammaill, Assistant Director for Site.
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Technology, DSE J. C. Stepp, Chief, Geology and Seismology Brtach, 'DSE l
FROM:
R. B. Hofmann, Leader, Geology Section,l CSB, DSE
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SUBJECT:
RECOMMENDATIONS CONCERNING POSSIBLE COURSES OF ACTION REGARDING DIABLO CANTON j
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The following are some ' approaches which I' think will help clarify Tor -
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the ACRS technical issues concerning reevaluation of the Diablo Canyon
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1.
Review all the basic considerations that went into tta decision j
to accept the USGS magnitude 7.5 earthquake on the Hosgri fault J
l offshore from Diablo Canyon. This will result in our esposing alternative views to those which were finally presented by the I
USGS as their formal stance. We can conclude that the USGS ppsition in therefore a conservative one which we have accepted.
Ttfe o'th'er viewpoints are much less conservative and I think well founded ind may ease the minds of those on the ACRS who are not knowledgeable of these details.
l 2.
The unpublished paper which Dr. Trifunac refers to in proposing that much higher g value anchor points must be used than the.75 ge(Newmark).
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or perhaps evenpeaks proposed by the Geological Survey is predicated upon a direct extrapolation of small earthquakes ~ occurring near the i
l source or large earthquakes occurring at a distance. Under both of these circumstances the source appears tc. the recording location
'j as approximating. a point source.- A strike-slip fault movement on
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the 11osgri fault for a magnitude 7.5 earthquake however would be many tens of miles long. The distance from the Hosgri fault to i
Diablo Canyon is 3 miles. The energy which is effective in creating i
peak accelerations at a site is limited to the length of fault-equal to distance away from it to the recording site..This is shown
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by a mathematical term call the directivity function. It has been-
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4 used in wave propagation studies of ~ several-types 'and.was used l
by Dr. Brune in his study some years ago in an attempt to define the peak acceleration that could occur at 0 distance'from a fault. ~I i
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_n o. believe that this concept is well accepted.
Dr. Trifunac has.not g.y/f
. extrapolated response spectra to the source. Unfortunately he py %)
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has followed the same route as the early investigators who extra--
( 4 polated peat accelerations to the source and round extremely nign er Fie r *
.... values _....Tho...rempanaa spettra. ara...nuhjhet to. tha a-rules indicated by the directivity functi)n es is peak acceleration.
This aspect
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has not been analyzed 5 the literature at this time. There is j
a good chance someone will do e following the publication of Dr. Trifunac's paper in which he finds that the O period spectral anchor values are as high as he is predicting. I believe his paper is in error and that this error could be pointed out to the board. We could at this point engah a consultant or PG&E could engage a consultant to develop mathematically the effect of the f
directivity function upon design spectra as a large earthquake source is approached. The design spectral anchor values will be i
l such lower - approximately 1/3, I suspect.
j 3.
The work which was outlined in our recent meeting by Dr. Stepp which had been developed by Don Bernreuter of the Lawrence Liver-more Laboratory could be'more fully documented and sent to the i
ACRS. We could more fully develop in clear language that aspect presented by Don Bernreuter; that is to clarify what he has said a
in his report for the ACRS and to perhaps engage a statistical I
consultant or have PG&E engage a statistical consultant to broaden the implications of his result. That result being that an increase I
in magnitude beyond magnitude 6.5 does not increase design spectral anchor valuas but does increase the longer period design responses.
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4.
One very telling argument by Dr. Trifunac which was repeated several times in the testimony of the ACRS meeting before last.
was that Dr. Newmark's proposed spectra for Diablo Canyon for a j
magnitude 7.5 earthquake at a distance of 31/2 miles (5 kilometers) l i
is about the same as that actually recorded at Pacoima Dam for the i
San Fernando earthquake where the distance to the main rupture
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was about 3 kilomsters. It has been pointed out by Drs. Newmark, j
Blume, and, I believe, in our summary of supporting position in-formally present&d to the ACRS, that this recording was an unusual one because of topographic affects and possible response of the rock on which the recording site was located. Michel Bouchon of MIT completed a doctoral thesis en June of 1976 in which he developed mathematical procedures to model the topographic affects of the ridge and other characteristics of the environment of the Pacoima i
Dam recording site. This was also done previously by Boore,1972
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and by trifunac,1973, both of whom also agreed that topography amplified the peak acceleration. Bouchon's thesis dif fers in that j
he separates out the effect of the site on the various modes of wave propagation and provides an estimate of the relative frequency content of the various modest.In his thesis he shows that the peak acceleration from Pacoima Dam (upon which is based the recommenda-tiors by the USGS) is caused by a Raleigh phase. The Raleigh phase travels horizontally along the surface'of the earth. Bouchon l
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i points out that the P and S phases contain lower frequency infor-i 4
mation and are amplified greatly by the topography, so much so it
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l appears, that the' computational capability available to him was not j
able to define quantitatively the amount of amplification. He has synthetically reproduced with a fair degree of. accuracy the Pacoima l
Das strong motion seismogram. This shows that a-technique is avail-l able for modeling the effects of source to site.
In either the Bernreuter approach or this approach, we must assume j
a certain effective stress. We can assume the effective stress j
which was determined for the Pacoima Dem earthquake, and argue that a strike slip fault should have a less or reduced effective stress.
j Bouchon indicates as a by-product of his research,however, that the corner frequency of Fourier spectra developed for seismograms j
recorded at a distance is greatly influenced by topography and I
stratigraphy in the locale of the source. Hence, it may be that effective stresses which have been determined to date based on I
corner frequencies are greatly in error. This is an aside, however, l
and I believe that an effective stress similar to that of the Pacoima l
l Dam earthquake can successfully be argued as an upper limit to be l
used as a model of a Diablo Canyon-Hoagri situation.
Bouchon might l
be hired by us or by PG&E to proceed with modeling the Hosgri-1 Diablo Canyon situation, which is vastly different from the Pacoima Dam situation, for a magnitude 7.5 earthquake with a similar effec-tive stress to that for the San Fernando earthquake of 1971.
Sensitivity calculations could also be made to determine the effect of changing effective stress on both the level of acceleration and spectral shape. This procedure would be very similar to that pro-posed by Stewart Smith (TERRA) for calculating design spectra for San Onofre.1/ In their case, however, they must go through the pro-cedure that Bouchon has already gone through, and prove that they can replicate already recorded strong motion seismograms. Either approach I believe would be effective in supporting Dr. Newmark's spectra, or perhaps showing that it should be altered in some manner.
These approaches are all theoretical, but offer an effective method of assessing the effect of various parameters on the level and slope of strong ground motion. The modeling performed by Bouchon or that proposed by Stewart Smith also could be used to predict the effect of a large base mat in reducing accelerations. We do not have an-adequate number of seismograms recorded under various circumstances to provide the same convincing test of validity for base mat effects l
ss we can for the design spectra, but I believe it would be one more l
piece of evidence that could help resolve the problem. The Bouchon i
procedure I am sure will be effective in this respect.
I am not familiar enough with the procedures proposed by Dr. Smith to know if his procedures would be as effective in estimating the so-called Tau effect.
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Finally, consideration should be given to a probabilistic approach.
In such an approach, all event sizes would be considered to have a finite probability of occurring and their locations would be' a h
probabilistic value also. It is possible, using methodologies which are reasonably easily developed, to compute a spectrum which would j
have a uniform probability cf being exceeded in the lifetime of the l
plant.
i l-In amemary, there are ' five possible procedures which we can follow, which
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would provide more technical input to the ACRS to help them make a 7
j decision. It may require the use of all 5 to provide the Board with sufficient information to convince it on a technical basis that our approach is reasonable and correct. I believe that we are going to be 1
l faced with a confrontation between ACRS, consultants and ultimately with l
individuals within the USGS in any event, and that the best procedure j
l st this time, if the' ACRS will not respond to the concept of Dr. Newmark's
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l judgment being the best available that probably all five procedures will I
be required to justify what we are attempting to do before the ACRS and perhaps the regular court system. We have in effect abrogated our responsibilities and have left them with the Geological Survey. I don't argue that this is a bad position, but if it is our position then I believe it should be clarified.and that they should take the responsibility for the technical decisions which they have made for us rather than requiring the NRC to try to defend them when they are essentially i
untenable.
I Renner B. Hofmann, Leader Geology Section Geology and Seismology Branch Division of Site Safety and j
Environmental Analysis Office of Nuclear Reactor Regulation DISTRIBUTION:
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