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i Note To: John Stolz, Chief Light Water Reactors Branch No.1,_ DPM:
h DEVELOPMENTS CONCEP.NTNG DIABLO CANYON DESIGN RESPONSE SPECTRA
.On August 20,1976,.the staff had given PG&E 'a position on the telephone concerning the design response spectra to be used in the i
seismic reevaluation of Diablo Canyon.
PG&f discussed this position I
with the Director on August 23, 1976, in San Diego, Ca'lifornia..
i After a briefing by the staff on August 25, 1976, Ben Rusche asked I
that we_ talk with PG&E to see what information they could provide on the impact of the staff position.
.The staff (Knight, Sibweil, Kapur Allison, and Hofmann) talked with Bill Lindblad and Dick Bettinger of PG&E on August 25, 1976, to discuss the impact of the staff position.
EG8E's' best infonnation at that time was substantially the same as Bill Lindblad had given to Ben Rusche on August 23 in San Diego.
(Three months of additional analysis at $400,000 per day.
Unknown effects on plant modifications.
Inability to meet next sumer's peak load.) Further details are provided in the enclosure.
i PGSE could not differentiate between an envelope approach and a separate suectra approach, except to say that the separate spectra approach should help them slightly by reducing the responses in a few places where the results are mrginal. We told them that either approach would be acceptable.
PG&E indicated that they could use' both the Newnark spectra and the Blume spectra, as proposed at 1/2 sigma, with less impact. The structural loads would be little mre than with their proposed approach and the additional analysis time would be reduced to one month.
PG8E is willing to meet with our management to discuss matters further.
We said that-we would consider the need for this.
If we decide it is not needed, then they could still request it.
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John Stolz AUG 2 7 1p.
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Rdgarding mean plus one sigma, we told them we did not think the.
standard approach must necessarily be used.
Rather, we thought that a deviation from the standard approach must be justified and it had i-not been.
Further, we had asked Dr. Newnark to justify it if he could, but he had not provided a justification to date. The staff did suggest an approach that might possibiv provide a reasonable
- basis for the 1/2 sigma approach.
I We pointed out to PG&E-that the impact could be very considerable if we should proceed with poorly justified spectra and should have trouble with them later on.
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I On August 26, 1976, Bill Lindblad discussed the matter with R. DeYoung.
He plans to discuss specific aspects of the problem with J. Knight,
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- 0. Allison, et al, on' August 27, 1976. Also,.he said PGltE is looking.
into the suggestion by the staff on a possible method of justifying the 1/2 sigma approach.
He expects to complete this work within a week or so. He asked that we withhold our final detennination on the matter until then.
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D. P. Allison Light Water Peactors Branch No.1 Division of Projec,t, Management
Enclosure:
Impact of Staff Position cc w/ enclosure:
B. Rusche E. Case R. Boyd R. DeYoung D. Vassallo D. Allison H. Denton W. Ganmill J. C. Stepp
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Hofmann R. Heineman J. Knight I. Sibweil i
K. Kapur Docket Files
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9 ENCLOSURE 3
IMPACT OF STAFF POSITION PG&E still estimates that about three months of delay, due to additional calculation time, will be required by the staff position. They can make no distinction between the impact of using the two spectra separately and using the envelope. The time estimate is based on the opinions of PG&E's analysts, which vary fran two months to six months.
It would seem that some of this additional time could be
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eliminated by using more manpower.
I For the option of using the Blume spectrum, as proposed at 1/2 sigma,
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along with the Newmark spectra PG&E can provide a different impact i
estima te.
Structural loads would be little different than with PG&E's initially proposed spectra. Accordingly, the extra analysis time would be reduced to one month and the possible effect on plant modifi-cations would be essentially eliminated.
The ratepayer cost of $400,000 per day of delay for Unit 1 is accurate.
It is an operating expense, the differential cost for generating replacement power by burning oil.
The actual operating expense for a particular delay could be less, depending upon the availability of cheaper replacement power from hydroelectric sources, Rancho Seco (S'4UD) or Trojan (PCE).
However, since the cost of amortizing the unused investment was not included, $400,000 per day is a reasonable estimate in light of the uncertainties.
PME seems to be even more concerned about the inoact on meeting next summer's peak load. The currently estimated PDD is May 1977.
On this basis, they muld miss the summer peak load anyway.
- However, they are hoping to got some kind of permission to load fuel and do some work from the ASLB when the safety hearings start (currently projected for January).
This is an uncertain crospect as it stands now, but a three-month slip would eliminate this prosnect for necting the summer peak load.
PME could not say what differences in plant modifications might be required by the staff position since the analyses are not finished.
They are quite concerned that it may lead to sone problems and they l
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2-i discussed a few. Our information is auite sketchy but it seems reasonable to us that:
t (1) A more detailed analysis of the reactor coolant systen might be needed.
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(2) It might be necessary to examine some pipe hangers and other camponents in detail.
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