ML20234E780
| ML20234E780 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Bodega Bay |
| Issue date: | 04/30/1964 |
| From: | US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML20234A767 | List:
|
| References | |
| FOIA-85-665 NUDOCS 8709220515 | |
| Download: ML20234E780 (16) | |
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.. OV::CX; US s ONW April 30,196h REPORT TO THE ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
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J PACIFIC GAS AND ELECTRIC COMPANY l APPLICATION FDR CONSTRUCTION PERMIT - d BODEGA BAY REAcr0R j t'() 'l ;gA*
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Note by the Director of Regul.ation This report has been prepared by the Regulatory Staff for consideration by the Advisory Committee on Reactor Safeguards at its May 1964 meeting. !
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.. O V C L U S ::s O W , Y BACKGROUND
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In April 1963 the Committee considered the application by Pacific Gas and Electric for. construction of a 1008 Met boiling water reactor facility at Bodega Head, California. At that time, both the staff and the Committee i concluded that, subject to resolution of potential problems associated with the close proximity of the proposed reactor site to the San Andreas fault J zone, the facility could be designed and built. on Bodega Head with reasonable ..
assurance that it could be operated without undue risk to the health and safety of the public.
l The reactor proposed to be constructed is of the direct cycle forced circulation boiling water type. Reactors of this type have been operated 1
safely at Dresden, Big Rock Point , and Humboldt Bay, California. Based on this experience it appears that the design and operating problems associated l vith this reactor can be adequately resolved. .For containment , the Bodega Bay plant is to utilize the pressure suppression concept. Mock-up_ tests l have been conducted to determine the ma imum pressure the containment vould experience as a result of complete severance of the largest primary coolant l
l pipe under a variety of operating conditions. These tests have provided a suitable basis for designing the system and have shown that the steam exhausted to the suppression pool in the event of such an accident would be completely condensed beneath the pool surface. No desiga problems ;
i other than Qose related to seismic considerations are anticipated for the containment system.
The proposed site is located on Bodega Head, a small peninsula on the coast of California about 50 miles northwest of San Francisco. The property ,
owned by PG&E at the site consists of approximately 225 acres and includes ~
l OEC::A1 US s ON1Y
. OVCLA:1 US3 OF Y i the entire southern end of the peninsula. The nearest residence to the site is approximately 1-1/2 miles away. Bodega Bay (population 350) is the nearest village and is located approximately 2 miles from the reactor site.
The total population within 5 miles is about 500 and there are about 114,000 people within 25 miles. The local meteorology, although not excellent for l 1
certain portions of the time, is as good as or better than that in California !
gene rally. The site is not upstream from any drinking vater intakes. From these standpoints the site is acceptable and well within the Commission's site criteria regarding isolation, distance to populated areas, and distance 1
to large cities, i I
The staff and the Committee have spent the past year evaluating the j 1
i seismological and geological characteristics of Bodega Head. The purpose of this evaluation has been to determine th'e adequacy of the design proposed j l
by PG&E for the Bodega Bay reactor in light of its proposed location within j approximately 1000 feet of the San Andreas fault zone. Assisting the staff i
and the Committee in this review has been the U. S. Geological Survey, l U. S. Coast and Geodetic Survey, and Mr. Frank Neumann of the University of Washington with respect to the geology and seismology of Bodega Head, i
and Dr. Nathan Newmark of the University of Illinois and Mr. Robert Williamson of Holmes & Narver, Inc. concerning the seismic design charac-i teristics of the proposed reactor facility. ,
1 DISCUSSION 1 Our evaluation of the t,dequacy of the facility design proposed has !
proceeded on the assumption that there is a credible possibility that an earthquake may occur some tim during the lifetime of the plant on the San l i
Andreas fault at or near Bodega Head with a magnitude equal to that of the 0?ECLA1 US3 ON1Y
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" San Francisco" earthquake of 1906. On the basis of advice from our.
consultants, we believe this credible earthquake. would have a magnitude of between 0.2 and 8.5 'on the Richter scale. The Alaskan earthquake of 1964 ;
and the Chilean earthquake of 1960 were both of 'approximately the same magnitude. Both occurred in the active zcme of seismic disturbance which i surrounds the Pacific Ocean. The San Andreas fault is part 'of this same ,
I active seismic zone.
The principal potential effects on the Bodega reactor facility of such an earthquake and.the aftershocks which would be likely to follow are:
(1)- the effects due to vibratory ground motion (acceleration, velocity, and displacement)
(2) the effects of potential inundation and damage due to seismically-induced tidal waves (tsunamis) ]
1 (3) the effects of seismically induced differential ground motion
_ Vibrational Effects PG&E has proposed to use a ground response spectrum derived from the El Centro earthquake of 19h0 for the seismic design of critical' structures and components. A value of maximum ground acceleration of 0.33 g would be used for the design of these . structures and systems at normal'vorking stress.
PG&E has also proposed to design all structures and components important to safe shutdown of the l'acility so that yield stress would not be exceeded or their functioning would not be impaired due to a maximum ground motion of-twice this value (0.66 g). Where appropriate , dynamic analyses of individual systems or components would be performed to assure that'the design would satisfy these criteria.
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Based m advice from our consultants, we believe that the method of I 1
design and the procedures proposed by PG&E vould be suitable, and that the dacping factors are acceptable although not particularly conservative, i
However, in our opinim, an earthquake occurring at or near Bodega Head j vith a magnitude equal to that of the 1906 earthquake could result in a maximum ground acceleratico in basement rock of about 1.0 g at the site.
Thus , the value of maximum ground acceleration proposed as a design criterion by PG&E is approximately h0% too lov. Nevertheless , it appears that the potential effects of ground vibratico could be adequately handled by well understood design measures which could be modified to accommodate l
any ground acceleratico forces that might be deemed necessary. This is a )
l matter of structural engineering design practice videly utilized in !
I California, and we are satisfied that the plant and all important components i could be adequately designed and built to take care of the vibrational effects of a major earthquake on the San Andreas fault.
Effects of Tsunamis The PG&E application does not discus s the probability , magnitude or potential consequences of seismically induced tidal waves which might follow an earthquake of 1906 magnitude somewhere along the San Andreas f ault. The Coast and Geodetic Survey has informed us that a serious tsunami might result from landsliding caused by an earthquake of magnitude 7 0 or greater on the Richter scale at locations within about 10 miles of the coast, or from an earthquake of this magnitude on the underwater portica of the San Andreas fault north of the site.
The Coast and Geodetic Survey has not completed its evaluation of the potential seriousness of this problem. Based on present information, it is not clear to the staff that we could rule out the possibility that 0:77CLA1 USfON1Y
0"TRCL US3 ONW the reactor facility would not be damaged or at least inundated by a i
seismically induced tidal wave. An investigation of the off-shore contours in the vicinity of Bodega Head would be necessary to resolve this matter.
An analysis of the potential effects on the reactor facility of a tsunami vould also be required. Despite the present lack of information, it seems likely that even if a tsunami were to sweep across Bodega Head design i
measures could be taken in order to prevent loss of containment integrity from such an occurrence. However, it is not clear at this time that adequate protection could be provided for cooling and power lines exterior to the containment system. Our calculations indicate that access to a heat sink within about 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is necessary in order to prevent over-pressurization of the containment system due to release of decay heat.
Effects of Differential Ground Motion The U. S. Geological Survey has confirmed by geophysical studies that the proposed site is approximately 1000 feet vest of the commcaly accepted vestern boundary of the San Andreas fault zone. The existence and charac-teristics of a fault complex discovered by the Geological Survey in the bedrock of the reactor pit have been extensively described in reports by the applicant and the Survey. In addition, a number of faults which occurred in 1906 outside of the San Andreas fault zone, including a displacement of about 2.5 feet at Invernes on Pt. Beyes, California, 2000 feet vest of the San Andreas fault zone, have been identified and described.
The quartz diorite on Bodega Head is a good foundation material. Joints and f aults caused by previous earthquakes are common , although they vary greatly in abundance from place to place. The fault complex in the quartz diorite running across the reactor pit, which has been characterized as CPIC A1 USION1Y
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the Shaft f ault , extends upward into the overlying sediments. The Company il estimates that it is over h2,000 years old and perhaps up to h00,000 years old. The geological support for this position. is impressive. On the other j hand, since geologists from the Geological Survey believe that the absence I
of traces of the Shaft fault in sediments younger than h2,000 years could -
also be due to its dying out upward and laterally, the fault in the sediments ,
i may have occurred more recently than h2,000 years ago, but not earlier than j 1
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a few centuries ago. Begardless of its age, the existence of the Shaft f ault does show that ruptures did occur in the basement rock on Bodega -1 Head outside of the main San Andreas fault zone. The Geological Survey i
has stated that the Shaft fault in the sediments probably had a total !
displacement in a single movement of between 1 and 3 feet. )
Because surface rupturing by tectonic faulting occurred outside the main San Andreas fault zone in 1906 on terrain geologically similar to that i
of the Bodega site, the geologists from the Geological Survey believe that I the possibility should not be ruled out that there might also be a sympathetic movement of several (243) feet on Bodega Head in the event of a large earthquake on the San Andreas fault. They say that the possibility I
of such movement is lov, but not low enough to be ignored in the design ;
1 of this facility. The basis for this opinion is principally derived from observations of surface faulting outside the San Andreas fault zone which !
occurred in 1906. Some of the surface ruptures outside the main fault zone were essentially parallel to the main fault, while others were at angles nearly perpendicular to the main fault zone similar in orientation to the Shaft fault at Bodega Head.
OECLA::_, USIOLY
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j Pertinent examples of rupturing vest of the San Andreas fault zone related to the 1906 earthquake are:
- 1. At Inverness on Pt. Reyes , California, a rupture was observed on a ridge at a point about-2000 feet vest of the San Andreas- fault zone. The horizontal displacement along this rupture was 2-1/2 feet.
- 2. A railroad tunnel near Wright Station. about 100 miles south of I
. Bodega Head was offset horizontally about 5 feet along a fault. Damage over I I
much of the rest of its length consisted of crushed timbers, broken ties -)
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and caving. At a distance of h000 feet from the five foot offset the )
I horizontal deformation was lh inches. It has not been established whether l l
the five foot break was in the main San Andreas zone or was a branch f ault.
The Earthquake Commission Report (Lawson,1908) contains descriptions of other ruptures outside of the San Andreas fault zone.which occurred in 1906 on Pt. Reyes Peninsula, on Sawyer and Cahill Ridges vest of Hillsborough and San Mateo, on Black Mountain southwest of Palo Alto and at several l
localities in the Santa Cruz Mountains south of Los Gatos. In general, the j abundance and magnitude of the displacements increased towards the San Andreas' I fault zone. The trend of the cracks showed great variability, but descriptive accounts give the impression that those close to the fault, like the ones at Inverness , were generally but not uniformly aligned with the San Andreas ;
that prominent and persistent ones in a more perpendicular direction to I San Andreas were farther away from the fault; and that those a number of miles uvay which were " barely discernible" had a random orientation.
l The Company's geologists and seismologists argue that the situation is different on Bodega Head. They particululy point out differences in topography. For example, on Pt. Reyes there was already in existence in 0:7?CLA1 USIONLY
4 OVCL US3 OFN 1906 scarps 'or sags ' indicating previous activity along a fault s Such-topographic conditions are scarce or not readily apparent on Bodega Head .
- However, geologists in the Geological Survey tell us that not enough 1 l
is understood about the causes of sympathetic f aulting to rely unon !
I differences- of surf ace indications between Bodega Head and other locations, l
E and that because of this lack of knowledge the possibility of f aulting on Bodega should be taken into account.
The question then becomes can a reactor' facility of this power. level be designed and built which would safely accommodate the differential ground movements of the magnitude that could be expected. The Company has. proposed i l
a design concept which would accommodate some relative ' displacement. They
-1 plan to fill the annular space between the . sides and bottom of the contain- l ment structure and adjacent rock with a layer of frangible ' material of a j type yet to be selected. Theoretically, displacements of several- feet 1
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i might be accommodated by such a design concept. Tests have been conducted 1 1 '
for the Defense Department in which polyurethane ' foam was success fully used to accommodate relative displacements' of experimental structures of this magaitude. However, such an engineering safeguard has not been used in practice, nor has it been proven for structures approaching the size anc complexity of the Bodega reactor facility with its complicated and sensitive components.
One of the more serious considerations involved in the use of.
frangible materials to protect against earthquake-induced displacements !
vould be the vibrational effects on the structure from aftershocks. vhich vould be likely to follow the major earthquake. The deformations of these materials in the yie? - *
- reversible. Consequently, oscillations f
.. OT?E A., US:s ON"X or displacements of the containment structure causing lateral pressures sufficiently intense to compress the material vould leave un annular void.
In such a situation the facility would then be vulnerable to additional ;
f damage from vibrational effects of the aftershocks. At the very least , it I would appear that a large scale research and development program would be necessary in order to determine the feasibility of designing against large.
l displacements . Since we must assume the possibility of large differential ground movement , we believe that we should not depend upon the integrity and reliability of unproven engineered safeguards to protect against such movements and the aftershocks that might ensue.
CON CLUSIONS Although the design criteria proposed by PG&E are not in agnecment with i
criteria suggested by our consultants to protect against vib"c.tism0 uri*wt.a and possibly the effectn or tnunamis recultin6 from a large earthquake occurring on the San Andreas fault at or near Bodega Head, it appears that these problems might be adequately resolved by changes in ' design criteria and more complete analyses. However, despite the fact that the risk of a large differential ground movement on Bodega Head is lov, we do not believe that unproven design measures should be cepended upon to solve this problem.
Present geological and seismological information indicates that the rink )
could be effectively eliminated by moving the plant to a location a counle 1
of miles distant from a main f ault zone. On this basis , we have concluded )
l that the site proposed by PG&E is not suitable for a reactor of the general I type and power level proposed.
The conclusions expressed in this report . are subject to reconsideration 1
in light of any new information which may be received at the ACiC meeting, '!
and the recommendations of 'the ACRS. !
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88Tu CONGRESS i 20 Sr.88 ION l e e e 1
I IN THE HOUSE OF REPR.ESENTATIVES Arn1L 22,1964 51r. BenTow of California introduced the following joint resolution; which was ,
referred to the Joint Committee on Atomic Energy 1 l
JOINT RESOLUTION j With respect to the proposed location of a nuclear power plant at Bodega Head, California.
Whereas the Pacific Gas and Electric Company proposes to con-struct a nuclear power plant at Bodega Head, Sonoma County, California, within one thousand feet from the rift zone of the San Andreas fault, and has already expended j ahnost S4,000,000 for excavation and other site develop-ment for such plant; Whereas the Good Friday earthquake of 1964, centering in Alaska, with tremors reaching into California, is the latest i of many in the Pacific Basin that have demonstrated over the years the continuing danger of earth movement along the major faultlines of the basin; Whereas the San Andreas fault, which traverses B,odega Head, I-O l
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is one such major fracture in the earth's crust whose move- l ment caused the San Francisco carthquake of 1906; Whereas Doctor J. P. Eaton, the seismic hazards investigator of j the Geological Survey, Department of the Interior, in a re-port prepared in September 1968 for the Atomic Energy Commission, concluded that Bodega Head. "is not an ade-quately safe location for a nuclear li ower plant";
Whereas, subsequent to the period cdvered by Doctor Eaton's j study, a fault was observed in the sediments above bedrock at said site, and still later in October 1963 when the Pacific Gas and Electric Company's excavation at the site reached forty feet below sea level it was discovered that this geologic fracture extends into the bedrock fetmdation of the proposed i
1 Power plant; i Whereas the Atomic Energy Commission then requested' a sec- l ond study of said site by the Geological Survey, resulting in a second report prepared in December 1963 by Doctor q Julius Schlocker and Doctor Manuel G. Bonilla who sum-marized the situation as follows: u
" Faults that occurred on Point Reyes peninsula in rock similar to that of Bodega Head as a result of the earthquake faulting that occurred in 1906 indicate that if some future i
earthquake, in which fault displacements comparable to those l
that occurred on the San Andreas fault zone in 1906, took place near Bodega Head, rupturing of near-surfae granitic bedrock would be expected somewhere on ' Bodega Head."
Whereas an internationally known seismologist, Doctor Pierre Saint-Amands, head of the Earth and Planetary Sciences.
Division, Naval Ordnance Test Station, China Lake,,Cali-i fornia, has publicly stated with respect to said site that "a 1 -
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3 worse foundation situation would be difficult to envisage;"
and Whereas despite these warnings and despite the fact that no construction permit yet has been obtained for such plant, the Pacific Gas and Electric Company is prueceding with its l plans and preparations for use of said site for such plant:
Now, therefore, be it 1 Resolved by the Senate and House of Representatives ,
2 of the United States of Amer!.ca in Congress assembled, 3 That the Atomic Energy Conunission is directed to make a a 4 full and complete report to the Joint Committee on Atomic 5 Energy of. the Congress with respect.to t).e extent of the >
6 '
Commission's investigation into the risks to t[ie public health '
7 and safety involved in locating a nuclear powerplant at said 8 site, inchtding in such report an account of the consideration i
9 given to the dangers cited in the_ reports with respect to 10 the site by the Geological Survey; and be it further 11 Resolved, That the Atomic Energy Commission shall !
.i 12 withhold the grantin;[of any pennit for,. construction of 13 a nuclear powerplant at Bodega Head until the Commis-14 sion can certify to the Congress, with reasonable scientific 15 assurance, the geologic adequacy and seismic safety of said 16 site. 4 i
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