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- T. Novak, DL W. Russell, Acting Director, DHFS
-i J. Knight, Acting Director, DE i
R. Bernero, DSI I
T. Speis, DST B. Snyder, TMIPO, NRR G. Holahan, ORAB G. Lainas, DL D. Crutchfield, DL THRU:
George W. Knighton, Chief a
Licensing Branch No. 3 1
Division of Licensing
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FROM:
Hans Schierling, Project Manager Licensing Branch No. 3 8
Division of Licensing
SUBJECT:
DAILY HIGHLIGHT Diablo Canyon Unit 2 RCP Failure On August 31 a Unit 2 reactor coolant pump failed while in Mode 3 (subcritical) as a result of failure of the motor winding. The cause for failure is under investigation. The motor is being removed offsite for rewinding.
PG&E expects a delay of about 6 weeks in the Unit 2 low power testing program (the Unit has not yet exceeded 5% power level). Unit 1 is currently operating at 100%' power level.
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Hans Schierling, Project Manager Licensing Branch No. 3 Division of Licensing Distribution:
Docket Fiie 50-275 LB#3 Reading JLee gdieuluesusurg AD/L Technical Assistant (E. Weinkam)
DL Director's Technical Assistants S. Black)
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MEMORANDUM FOR:
Robert J. Bosnak, Acting Assistant Director for Components & Structures Engineering Division of Engineering FROM:
Leon Reiter, Acting Chief Geosciences Branch, DE
SUBJECT:
GE0 LOGICAL RECONNAISSANCE OF THE DIABLO CANYON SITE AND REGION The attached is a summary of a trip made to the Diablo Canyon site region on June 24 and 25, 1985 by S. Brocoum, R. Rothman and R. McMullen. Also in attendance were representatives from PG&E and its consultants, representatives from the University of Nevada and the U.S. Geological Survey, advisors to the NRC. An attendance list is attached.
The purposes of this trip were (1) to hold a kickoff meetin,r; for the geological work relative to the seismic license condition; (2) examine significant geological features in the region and at the site; (3) to familiarize the NRC advisors with the geology of the site, and (4) to give all participants a relatively common understanding of the geology of the site and region.
Leon Reiter, Acting Chief Geosciences Branch, DE
Enclosure:
As stated cc: w/ enclosure J. Knight L. Reiter g Knighton S. Brocoum R. Rothman R. McMullen H. Schierling GSB D ei n s o d > Q G S-
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i GEOLOGICAL RECONNAISSANCE OF THE DIABLO CANi NUCLEAR SITE AND THE SURROUNDING REGION A geological reconnaissance was made of the Diablo Canyon site and the region around the site on June 24 and 25, 1985.
Participants included PG&E, its geological consultant, Dr. D. Hamilton, the NRC and Dr.'s D.B. Slemmons and R.
Schweickert, geological consultants to the NRC, and Dr. R. Brown of the l'SGS.
A list of attendees is attached. The purposes of the trip were:
(1)tohold a " kick off" meeting for the geological work to satisfy the license condinion; (2) to examine geological features in the region from the air and certain significant tectonic structures on the ground; (3) to familiarize several of the participants with the geology of the coastal central California region as it relates to the Diablo Canyon Site; and (4) to give all participants a relatively common understanding of the area.
The entire day of June 24 was spent in aircraft. The plan had been to take advantage of the early morning low angle sunlight in the wider ranging, fixed wing aircraft, but most of the coastal and near inland area was obscured by fog. The flight was, therefore, made eastward to the Cholame Valley, and then south, zig-zagging across the San Andreas Fault, tracing it southward across the Carrizo Plain down to its intersections with the Big Pine and Garlock Faults. Examination of the San Andreas Fault had been planned early in the site visit so that observations could be used as a barometer to gauge activity of other faults in the region.
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i The intent was to fly northward beyond Pasos Robles and examine th'e Rinconada Fault, but clearance to use the air space around Army Camp Roberts could not be obtained until after 5:00 p.m.
Following this airplane flight, a site reconnaissance was made to the Diablo Canyon site. The group concentrated on examining the sea cliff between the cooling water intake and discharge structures.
The prominent geological feature exposed here is a complex series of assymetrical folds probably related to Tertiary or early Quarternary compression that caused uplift and reverse faulting. The folding is truncated by the 80,000 to 120,000 year old marine terrace and therefore predates the formation of that terrace.
The party then flew by helicopters along the strike of the West Huasna Fault and along the trace of the Edna Fault from its southern mapped extension to Morro Bay. Also noted was the Los Osos Fault. Returning to the south we overflew the San Miguelito Fault which approaches to about i mile of the site. The San Miguelito Fault is capped by undisturbed Pleistocene sediment. We then traveled along the coast from south of Pismo Beach to the site area, examining and photographing the geologic structures exposed in the sea cliff, particularly the assymetrical folds at the site.
From there we con-tinued along the sea cliffs to Morro Bay, over Morro Rock and on up the coast past Cambria to San Simeon Point.
It has been suggested that the straitness of the Cambria coastline may be controlled by a southeast extension of the San Simeon Fault Zone.
Faults of the San Simeon Fault Zone were very apparent in the topography from where the fault comes ashore east of San Simeon Point and northward east of Piedras Blancas to merge with the western slope of the Santa Lucia Mountains. The San Simeon Fault Zone returns to sea at Ragged Point.
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The fault zone juxtaposes Tertiary rocks against Franciscan (Jurassic) at San Simeon, then it is entirely within the Franciscan Formation farther north.
At Ragged Point, the westernmost mapped splay of the San Simeon Fault Zone separates ophiolite on the West from Franciscan melange on the east. Many of the drainages from the mountains appear to be offset in a rignt lateral sense.
C. Hall (1979) maps the San Simeon Fault Zone as being comprised of several splays, the major ones being the San Simeon Fault to the west and the Arroyo Laguna Fault to the east. A more westerly splay, the Arroyo del Oso Fault, offsets the latest Pleistocene marine terrace approximately one foot on the coast about 2 miles north of Point Piedras Blancas.
The return flight was made farther inland along the traces of faults in the Oceanic Fault Zone.
Clearance had been obtained to enter the air space of Camp Roberts after 5:00 p.m.
To utilize the time until 5:00 we flew in the fixed wing craft southward to the town of Solvang near the Transverse Ranges, picked up the Santa Ynez Fault and flew along its trace in an easterly direction.
The topography was extremely rugged. The flight path followed a V-shaped valley in the Santa Ynez Mountains. 'The Santa Ynez Fault cut across the lower slope of the ridge to the south, and the Pine Mountain Fault trended along the lower slope of the mountain ridge to the north. The two faults eventually merge together and are truncated by the northwest striking San Gabriel Fault. The flight turned northwestward at this point and flew along the trace of the San Andreas Fault beginning between its intersection with Garlock Fault to the east and the Big Pine Fault
e to the west. The flightline followed the San Andreas northwestward ^across the Carrizo Plain and the lower Cholame Valley, at which point we turned west at about the latitude of San Luis Obispo and picked up the Rinconada Fault Zone.
The Rinconada strikes northwest through Pasos Robles, then passes just east of the Nacimiento and San Antonio Reservoirs. Although some indication of the presence of the fault could be seen in the topography, the Rinconada Fault Zone was far less obvious in the sunlight at that time of day than the San Andreas Fault or even the San Simeon Fault Zone. We returned to San Luis Obispo after flying once more over the Nacimiento Fault Zone, the Oceanic Fault, and Morro Bay.
On June 25, a trip on ground was made to the San Simeon Fault Zone. The exposure at San Simeon was not accessible because the San Simeon State Park was closed due to the making of a movie. We traveled up to the northernmost land exposure of the fault zone about 3/4 mile north of Ragged Point. The easternmost splay, the Arroyo Laguna Fault is entirely within the Jurassic Franciscan Formation and shows a reverse sense of displacement with an approximate 35' dip to the northeast. This outcrop area is subject to continuous landsliding and the outcrop of the fault examined here is not the same one observed last year as it has been covered by fallen rock. An interesting feature seen here as pointed out by R. Brown, USGS, is the common occurrence of large blocks of rock (several feet to more than 100 feet wide and high) within the Franciscan Mellange that were emplaced there intact when this area was part of a subduction zone. The fringes of these blocks and the surrounding melange show evidence of plastic deformation and shearing much
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like that within fault zones, but instead, were formed by rotation and
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compression of the rock during subduction.
The westernmost landfall of the San Simeon Fault Zone outcropped on the coastline at Ragged Point. At Ragged Point these faults separated ophiolite rocks to the west from the Franciscan Formation to the east. A relationship between the fault and the contact between the Franciscan and Pleistocene marine terrace was examined near the top of the sea cliff.
It appeared that there could be minor offset of this horizon above the faulted Franciscan, but the evidence was not clear cut. At any rate, the staff assumes that the San Simeon Fault Zone is a capable fault.
One of the principal goals of this trip was to familiarize NRC consultants with the tectonic setting in which the Diablo Canyon site is located.
It is recognized that none of the faults or other structures examined are more significant to the seismic safety of the Diablo Canyon Nuclear Power Plant than the Hosgri Fault Zone.
The importance of investigating many of these structures is not to demonstrate that, but to identify clues that will aid in determining what is happening tectonically in this region.
Issues such as whether tectonic activity is related to predominently strike-slip as along the San Andreas, to dip-slip as at Coalinga, or to a combination of both senses of displacement are important in the reevaluation of the earthquake design bases for Diablo Canyon.
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LIST OF ATTENDEES Pacific Gas and Electric Company Frank Brady Lloyd Cluff Earth Sciences Associates Douglas Hamilton U.S. Geological Survey Robert Brown University of Nevada Reno 1
Burt Slemmons 4
Dick Schweikert i
NRC Stephen Brocoum Robert Rothman l
Dick McMullen 4
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