ML20003H476
| ML20003H476 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/14/1981 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-1823, NUDOCS 8105060084 | |
| Download: ML20003H476 (9) | |
Text
N2Ae'LS
-i APR 14 gy
,,d s
,,"I Minutes of the
'- '7
.M ",
ACRS Subcommittee Meeting o g
E San Onofre 283-b ISOI "
Y January 31, 1981
. M umu m C
i?g i
~
' " * * =
Inglewood, California s
.p
~
Rt V&
M.
- glewood,
-The ACRS Subcommittee on San Onofre 283 met on January 31, The purpose was to conduct a site visit and to discuss the seismol-California.
ogy and geology of the site as part of the review for an operating license.
ACRS members present were M. Bender - Subcommittee Chairman, D. Okrent, W. Mathis ACRS consultants attending were S. Philbrick, J. Maxwell, G. Thompson, and D. Ward.
and E. Luco.
Presentations ~were made by H. Rood - NRC/NRR, W. Moody - Southern California Edison (SCE), J. Smitn - SCE Consultant, R. McNeill - SCE Consultant, S.
Biehler - SCE Consultant, P. Ehlig - SCE Consultant, D. Moore - SCE Consultant, R. Shlemon - SCE Consultant, E. Heath - SCE Consultant, S. Smith - SCE Consultant, T. Cardone - NRC/GB, B. Slemmons - NRC Consultant, G. Green -
USGS, J. Devine - USGS, and L. Reiter - NRC/GB.
No written statements or requests for presentation time were received from At the time of the meeting, members of the public prior to the meeting.
however, a request for presentation time by G. Barlow - Intervenor, was received and granted. Following the meeting, an Intervenor report was recieved from M'.
Barlow.
Attachments include the presentation schedule and a list of documents considered by the Subcommittee.
Introductions
The Staff issued in H. Rood - NRC/NRR and W. Moody - SCE gave introductions.
January 1981 a SER on seismology and geology, separate from the main SER, which is to be issued in February 1981. The reason is to expedite licensing, The Staff which has progressed at a slower pace than has plaat construction.
requested the ACRS to review seismology and geology issues at the February fu l
Committee meeting to ease trie schedular difficulities.
I 8105060084
San Onofre 253 Mts anuary 31,1981 The purpose of the Subcommittee meeting was to review information developed since the CP stage and to reaffirm the adequacy of the design basis SSE.
Design Basis SSE Extensive Smith and McNeill, SCE Consultants, decribed the design basis SSE.
studies were
'rformed beginning at the CP stage in 1969.
The plant designs meet the following bases. 2/3g horizontal acceleration; 0.44g vertical acceleration; Modified Mercalli Intensity 10; Ms 7 earthquake 8 km offshore.
The Offshore Zone of No capable faults were found within 5 miles of the site.
Deformation (0ZD) was determined to be the controlling feature for the site.
January 1975 Earthquakes in the San Juan Capistrano Embayment S. Biehler, SCE Consultant, discussed this topic. The earthquakes (magnitudes 3.3 to 3.8) have been attributed to differential settling in the embayment.
They were potential-ly significant in that their epicenters lay close to the Cristianitos fault, which is considered to be e'xtinct.
It has been concluded that the quakes were unrelated to the Cristianitos fault.
Area Mapping and Regional Tectonics The above topics were discussed by J. Smith and P. Ehlig - SCE Consultants.
During excavation for the plants several features, termed "A, B, C, and 0" features, were found. The features are considered to be joints. They were formed over 125,000 years ago and less than 4 million years. The joints are 1/4" to 6" wide; exhibit lateral shear with no veritical displacment; are Their fonnation straight; and are on the order of 50 feet to 800 feet long.
is attributed to localized stress relief of stress patterns that no longer exist. The feature are not uni v. to the site.
The A 24 square mile onshore area around the site was geologically mapped.
l Cristianitos was the only major fault noted.
It passes within 1 km of the plants, but has been stable for at least 125,000 years. A number of wave-cut
(
terraces exist at various elevations above sea level. The t3rraces are of various ages, depending on their elevation. They show no evidence of displace-Consideration of regional geology woula Jndicate ment due to fault movements.
f
January 31, 1981 San Onofre 283 Mtt The that the Cristianitos fault has been inactive for 3 to 4 million years.
Cristianitos fault formed from gravity glide associated with the once deep Los Angeles basin, which is now filled.
Offshore Geology B. Moore, SCE Consultant, described the offshore geology, including the Offshore Zone of Deformation (0ZD). A topic of study has been whether the Cristianitos fault intersects the 0ZD. The Cristianitos fault was traced as far as 2 km There is no evidence that it extends further, which indicates it offshore.
is separated from the OZD byaw6 km.
The mechanisms that formed the Cristianitos fault were said to be no longer operable. The Cristianitos fault appears to be diiTerent in age and style from the OZO.
The USGS has named it the A region of folding and faulting exists offshore.
"Cristianitos Zone of Defermation".
It does not appear to be associated with the Cristianitos fault nor with the OZD.
Coastal Geomorphology R. Shlemon, SCE Consultant, discussed the characteristics and origins of the coast. During the past 125,000 years, the San Onofre site has been very stable relative to Southern California as a whole.
The offshore morphological evidence supports the onshore mapping discussed previously.
In particular, there are wave-cut terraces 40,000 and 80,000 years old that are not displaced by the Cristianitos fault.
Earthquake Magnitude on the OZD E. Heath, SCE consultant, presented an evaluation of maximum earthquake magnitude The OZD is considered to be the controlling feature for design of San on the OZD.
Onofre 253. The OZD runs along the Southern California coast north toward Santa Monica and south toward San Diego.
Its total length is uncertain. There are a rumber of segments which, for the purpose of determining a magnitude for the SSE, are presumed to be joined together, though there is no evidence to indicate this is so.
There are several methods for postulating earthquake magnitudes that could result from a fault. They are:
January 31, 1981 San Onsfra 2&3 Mts,
' fault length; generally no more than 20-30% of the fault ruptures during a single event.
' historic evidence.
' slip rate, i.e. there is a correlation between slip rate along a fault and resultant earthquake magnitude.
' moment magnitude, which is slip rate times fault area times shear modulus.
' total displacement.
All were used to support the design basis SSE.
Upper-Baja Studies Because of the importance of fault length in determining possible earthquake magnitude, geologic studies were made in the region south of San Diego to No connections determine whether the 0ZD connects with faults in the Baja region.
were discovered.
Intervenor Presentation G. Barlow, intervenor, presented information in disagreement with SCE and NRC.
The points made were as follows:
'By linking the CDZ to a couple of faults in the Baja region, a total length for the OZD of 350-390 km can be obtained, as opposed to 200 km that was postulated for design analysis.
'The Cristianitos fault is connected to the OZD and to the Whittier-Elsinore fault.
'There is evidence of movement on the Cristianitos fault within the past 10,000 years.
'The phenomena of focusing can cause higher-than-expected ground accelerations at the plant site.
' Earthquake data indicate the design value used for vertical acceleration (0.44 ) is too low.
9
'Other studies have postulated higher earthquake magnitudes on the OZD.
'The "A,11, C, 0" features are part of the Cristianitos fault system.
' Settling for anything more than zero risk in the operation of San Onofre is criminal.
s-
~ -
January 31, 1981 San Onofre 2&3 Mts SCE Response to Intervenor Coments SCE was allowed the opportunity to respond to Barlow's comments:
'Further offshore evidence was sited, showing that the Cristianitos has been inactive for at least 80,000 years.
'No evidence exists that the Cristianitos extends further than previously indicated.
'No evidence to link the OZD with various Baja faults.
' Focusing was analyzed and found to be not significant for the plant.
' Evidence was sited that the 0.449 design value for vertical acceleration was adequately conservative
'The "A, B, C, D" features are local joints and are not part of a fault.
Vibratory Ground Motion R. McNeill, SCE Consult =nt, discussed methods used to validate the 0.67g design value for ground acceleration. Data from the 1979 Imperial Valley earthquake was A survey of used to verify the San Onofre analysis, with good results obtained.
worldwide earthquake data was also used, which again confirmed the conservatism of For design purposes, peak vertical and horizontal accelerations the San Onofre value.
wereassumedtobein-phase,wheritasinactualitythisisseldomso.
NRC Review of Geology and Seismology T. Cardone (NRC/GB), B. Slemons (NRC Consultant), G. Green (USGS), and J. Devine The (USGS) described the fault structure associated with San Onofre site.
information was in general agreement with that presented by SCE, with no signif-icant points of contention.
Dr. Maxwell indicated that he sees little likelihood of the OZD being a The USGS makes no connection between the :cistianitos continuous fault.
fault and the Cristianitos Zone of Deformation.
It was noted that a USGS report prepared for FEMA and used as a reference by Barlow
~
was used by him in a incorrect manner.
The Staff is in L. Reiter (NRC/GB) summarized the NRC review of seismology issues.
basic agreement with the Appitcant. The Applicant's analyses were performed in a reasonable and conservative manner.
--w, yew-v-i.-w-,
-c y,-.,,-,e
-e--,----w-
.m+r,,. _w
,p, y---
m-p-
-w
+,,,,-_ _ _ = -
.,me._
-.m e.
,.ww--
e-y
January 31, 1981 San On:fra 233 Mts Future Meetings The Subconnittee will meet on Februsry 18, 1981 and on March 11, 1981 in Washington, CC to discuss the licensing review of San Onofre 283; non-seismology and geology issues.
9 9
I e
I
\\
- c..
January 31, 1981 San Onfre 2&3 Meeting DOCUMENTS CONSIDERED BY THE SUBCOMMITTEE Southern California Edison Presentation -99 slides 1
B. Slemmons - 2 slides Earthquake Magnitude Potential of the OZD:
2 G. Green - 2 maps USGS Mapping of Faulting in the San Onofre Vicinity:
3.
T. Cardone - 10 slides NRC Conclusions from Review of Geology:
4.
5.
NRC Review of Seismology:
L. Reiter - 33 slides From Intervenor Report on San Onofre 233 Seismology and Geology:
Richard Wharton to Richard Savio, cated February 2,1981.
6.
l l
l
- Tcntative Presentation Schedule -
3 San Onofre 283 Subcommittee Meeting Airport Park Hotel 600 Avenue of Champions Inglewood, California January 31, 1981 Organization /
Presentation
- pproximate Speaker Time Time MEETING WITH THE APPLICANT AND THE NRC STAFF (OPEN SESSION) 10 min 8:30 am 1.0 Subcommittee Chairman's Opening Remarks NRR/H Rood 10 min 8:40 am Staff Introduction - Purpose and 2.0 Scope of Review SCE/W.C. Moody 5 min 8:50 am 3.0 Applicant Introduction SCE/J. Smith 20 min 8:55 am 4.0 Basis for Selection of the SSE at the CP Stage 5.0 Additional Information since the CP Review SCE/S. Biehler 20 min 9:25 am 5.1 January 3,1975 Earthquake SCE/J. Smith, 20 min 9:55 am 5.2 Area mapping & regional SCE/P. Ehlig tectonics 10 min 10:25 am Break SCE/B. Moore 20 min 10:35 am 5.3 Offshore Geology Offshore Zone of Deformation SCE/R. Shlemon 30 min 11:05 am 5.4 Coastal Geomorphology 5.5 Maximum Earthquake Magnitude on SCE/E. Heath 30 min 11:40 am the Offshore Zone of Deformation 12:25 pm Break for Lunch SCE/R. McNeill 30 min 1:25 pm 5.6 Vibratory Ground Motion 10 min 2:05 pm 6.0 Summary and Conclusion SCE/J. Smith
- Geology SCE/S. Smith PSeismology & Ground Motion we
--,..,-v.+
2
- Tentative Presentation Schedule -
San Onofre 2&3 Subcommittee Meeting Airport Park Hotel 600 Avenue of Champf ens Inglewood, Cal f fornia January 31,1981 Organization /
Presentation Approximate Time Time Soeaker 7.~
'C Review of Information Since tne CP Stage NRC/GS 10 min 2:20 pm 7.1 Geologic Introduction T. Cardone NRC/GB 15 min 2:35 pm 7.2 Offshore Zone of Deformation B. Slemmons Slip rate vs. Earthquake Magnitude 10 min 3:00 pm Break USGS/ Green 15 min 3:10 pn 7.3 Offshore Geology, Cristianitos Fault NRC/G3 25 min 3:30 pm 7.4 Seismology L. Reider
- Magnitude of SSE
' Vibratory ground motion
' Issues raised in Diablo Canyon review relevant to San Onofre SCE/W.C. Moody 15 min 4:10 pm 8.0 Applicant Response to NRC Remarks NRR/H. Rood 10 min 4:30 pm 9.0 Concluding NRC Remarks 20 min 4:40 pm 10.0 Executive Session 10.1 Future Meetings 10.2 Future Agenda 5:00 pm ADJOURNMENT A maximum of 30 minutes will be allowed for receiving oral statements from members of the public, if requested.
NOTES _ (1)
The speakers should limit their prepared presentations to the An allowance, anounting to approximately 50%
(2) time allowed.
of the presentation time, has been made for questioning by the Subcocmittee.
L