ML20234D817

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Draft Notes on Geologic Questions Relating to Bodega
ML20234D817
Person / Time
Site: 05000000, Bodega Bay
Issue date: 03/25/1964
From: Beck C
US ATOMIC ENERGY COMMISSION (AEC)
To:
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ML20234A767 List: ... further results
References
FOIA-85-665 NUDOCS 8709220204
Download: ML20234D817 (4)
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[ 3/25 /64 NOTES ON GEOLOGIC-QUESTIONS RELATING TO BODEGA)

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1. Two aspects of earthquakes are of concern in considering the suitability )

of the proposed site for this reactor:

a. The vibrations which would result from the earthquake
b. The possibility of faulting, differential ground motion, in the earth (n which the reactor structures rest.

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2. The frequency, amplitude and accelerations of vibrations from future ..

J earthquake can only be estimated by reference to what has happened in the past, as best these can be determined from seismic records (Coast j i

and Geodetic Survey). Generally, structures can be designed to withstand severe vibrational damage, j 3. From other sources, we are establishing the magnitude of a fault which

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could be tolerated in a reactor structure, by design, etc., before serious nuclear hazard would be a possible consequence. We must establish as best we can the likelihood or probability of faulting in the earth on which the proposed reactor facility would rest, and, the magnitude of the -.

faults that might be expected. It is this basic question on which we 'l f

seek the evidence (and judgments) that can be obtained from geology (and )

the Geologic Survey): whassim the likely expectation or probability of

, faults, in. relation to the size or magnitude of faults. Defined more i explicitly, how likely are faults of (a) less than 1"; (b) of less than-10" or 12"; (c) of greater than a foot of differential displacement?

When we have this infonnation, we must then match it up with what can be tolerated in the plant design, and make a final decision.

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4. The estimation of possible future faulting rests on (a) the observation of faulting in this area in the past (and the assumption that what has happened in the recent past may happen again); and (b) the general knowledge and judgments of expert geologists based on their experience with faulting in general. ,

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5. It is obvious, of course, that 1906 type earthquakes will occ)ur again -

perhaps each 70-100 years, within the St. Andreas fault zone. What is r

the expectation of surface [ocation within the zone near Bodega, and what is the significance of this with respect to the proposed reactor site?

6. One of the clues to past earthquake faulting is found in the shaft fault in the excavation at the reactor site. To arrive at the to significance of this fault,/the possibility of future faulting, a number of facts, observations and questions are involved,
a. What is relationship and relevance of the bedrock shaf t fault to other faults and the geologic regime of Bodega?

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b. What is the over-all significance of the sediment. shaft fault to the possibility of future f aulting and the magnitude of faulting in the plant foundations?

(1) Location and orientation of sediment fault (vis-a-vis St. Andreas).

(2) Geologic event that may have caused the sediment f ault.

l (3) The bedrock. fault is complex -- many branches, possibly caused by multiple movements (?); the sediment fault may have arisen during only one or few (?) events. What is relevance of this, and age of bedrock and sediment, to fault probability?

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(4) The age of the sediment fault may be (a) not less than a few centuries, e.g., 6 - 800 years.

From 6 or 800 years to 40,000 years i

From 40,000 years to 400,000 years.

What is evidence on and likelihood on each of these from color banding l

age of the deposits i I

" die-out" of the offset (upwards) j l

l the frequency of major faults on San Andress. I 1

(5) The magnitude of the sediment offset. Conclusion on over-all l I

significance of shaft fault to the likelihood and magnitude of l faulting within the next 100 years or so. In the context of all j l

the known facts, does the discovery of the shaft fault increase, decrease, or change in no substantial way the expected pattern of future faulting in the plant foundations.

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7. Another clue to past earthquake faulting is the observation that faults outside the main San Andreas zone did occur in 1906 on Point Reyes at Inverness and Mt.

Wittenberg. What is the relevance of these events to future faulting in the l plant foundations at Bodega?

a. Geologic similarity and geologic dissimilarity between Pt. Reyes and Bodega.
b. What are facts and significance on the Pt. Rayes events being associated with established and previously active fault sage, scarfs?... Topolo ical 7 differences between Pt. Reyes and Bodega.
c. Does the Pt. Reyes observations increase, decrease, or make no substantial change in the expected pattern of future faulting in the plant foundations?

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8. In view of the location and orientation of the plant site to the San Andreas fault line, the shaft fault and its significance, the events on Pt. Reyes and their significance, and other' aspects of .

this situation, what can be said about the future likelihood 'of faults in the plant foundations in relation to the magnitude of possible faults?

9. Hydrology also-is one of the subjects of relevance to the location and design of reactor facilities. Of particular interest are:

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l. a. The possibility of ocean flooding of the plant.

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b. The normal level of the water table; the flow rate and eventual destruction of the vater table.

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c. The circulation, mixing and dispersion characteristics of the water on the ocean side where the cooling water effluent will b'e discharged. ,
d. The location, dimensions, and run-off characteristics of any water sheds in the area which feed into reservoirs or serve as l

water sources for htsnan use.

l Relevant information on these phenomena would be helpful.

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pi$ \ EFORE THE UNITED STATES ATOMIC ENERGY COMMISSION 4

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' Irt the Matter of PACIFIC GAS

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Docket No. 50-205 l AND ELECTRIC COMPANY Amendment No. 6

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Now comes PACIFIC GAS AND ELECTRIC COMPANY (the .

Company) and amends its above-numbered application by submitting herewith Amendment No. 6. This amendment sets forth further {

l details with regard to the earthquake design criteria for Unit No. l'of the Company's Bodega Bay Atomic Park and supersedes Amendment No. 4 to the application and the material superseded in said amendment.

The Company has established earthquake. design criteria for the Unit based upon the recommendations of Dr. George W.

l Housner. In general, the usual methods of earthquake resistant design will be followed except that the lateral force factor which will be assumed as a basis for designing each critical structure, item of equipment or system will vary with the natural 3

period and damping characteristics of the particular structure, item of equipment, or system and its support.

The earthquake design criteria for all critical structures, equipment and systems are based on the maximum credible earthquake ground motion on the granite at Bodega Head.

The design of critical structures, equipment and systems will be- 1 based on the curves set forth in the attached design spectrum prepared by Dr. George W. Housner, dated September 6, 1963. -The  ;

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i cuYves amplify the information given in Appendix V of the Pre-liminary Hazards Summary Report (PHSR) by expanding the low period range (below 0.3 seconds) and by depicting response for additional low values of critical damping. Stress levels to be used in design will conform, where applicable, to the ASME Boiler and Pressure Vessel Code,Section VIII, including applicable nuclear code cases, the ASA Code for Pressure Piping, and the Uniform Building Code of the International Conference of Build-ing Officials, 1961 Edition (except that the usual one-third allowable over-stress for structures during earthquakes will not

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be applied).

The above design will be based on the following typical damping factors:

Structure, Equipment, System  % of Critical Damping  !

Steel frame structures 2.5 ,; . u ,ui A j Reinforced concrete frame structures 4.5 /

t Reinforced concrete reactor contain- 10 #*N Z (f 6 'd h ment structure Welded assemblies 1.0 Bolted assemblies 2.0 Vital piping systems 0.5 -v b ' ' "' '

In addition, the design of the Unit will be checked to assure that all critical structures, equipment and systems will be capable of withstanding earthquake ground motions cor-responding to spectrum displacement, velocity and accelerations two times as great as shown on the attached design spectrum with-out impairment of functions necessary for containment and safe plant shutdown.

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Critical structures (referred to as Class 1 Structures  ;

in Appendix V to the PHSR) include the reactor containment structure, reactor refueling building, control building, and ventilation stack. Critical equipment and systems include the nuclear steam supply system inside containment, isolation valves, liquid poison system, emergency cooling systems, emergency electrical power system, and the necessary associated instruments-tion and controls.

All noncritical structures, equipment, and systems will be designed in accordance with applicable Company aseismic.

I design practices, j Subscribed in San Francisco, California, this 16th day of March, 1964 Respectfully submitted, PACIFIC GAS AND ELECTRIC COMPANY S. L. SIBLEY By S. L. Sibley Vice President and General Manager RICHARD H. PETERSON l PHILIP A. CRANE, JR.

Attorneys for Pacific Gas and Electric Company 1

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By '

  • l Philip A. Crane, Jr.

Subscribed and sworn to before me 1

this 16th day of March, 1964.

RITA J. GREEN l

(SEAL)

Rita J. Green, Notary Public in and for the City and County of San Francisco, State of California My Commission Expires' July 16, 1967 3

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