ML19329A191
| ML19329A191 | |
| Person / Time | |
|---|---|
| Site: | Oconee, Vermont Yankee  |
| Issue date: | 02/15/1977 |
| From: | Gammill W Office of Nuclear Reactor Regulation |
| To: | Goller K Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7912300222 | |
| Download: ML19329A191 (6) | |
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I l-MEtORANDUM FOR: Karl R. Collar. Assistant Director for j
Operating Reactors, DOR l
FRON:
William F. Camm411, Assistant Director for Site Technology, DSE gf..Lbf
SUBJECT:
OCONEg/JOCASSEE DAM SEISMICITY We have been following the situation at oconee/Jocassee dam since July 1976, and this memorandum will update what has happened since that time. At the July 27, 1976 site visit the staff requested that Duke Power Company provide a report discussing the earthquake j
l activity at Jocaa se Dam. On July 21, 1976, you were informed that
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another meeting with the utility would probably be needed (July 21, 1976 mano Cammill to Coller, enclosed). This memorandum also itam-j ised a number of conearns relating to the seismicity near Jocasses -
l dam. The staff also recommended that operation of a seismic moni-l toring network be reinstituted.. As a result, a meeting with the i
utility was held on September 21, 1976 to discuss responses to these i
questions. At that time the applicant supplied several reports relating to the observed seismicity and site geology (see enclosed meeting suussary by C. Zach). On October 25, 1976 we were infonned that a seismic monitoring program would be reinstalled and operational on November 1,1976 (letter, Parker to Rusche, October 25,1976).
On January 7,1977 we met with Drs. Dave Simpson and Klaus Jacob of Lamont-Doherty Geological Observatory to seek advice on methods' of resolving this situation.
Our consideration of this issue to date has indicated a need to meet with the applicant as soon as possible to discuss specifies of dan design, the earthquake activity since July, the seismic monitoring program, and local geology. It is my understanding that D. Neighbors of your staff is arranging for such a meeting this month. An agenda for the proposed meeting is' enclosed.
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7912800 M 2
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L; 2-Karl R. Collar FEB 15 B77 1
Because of the existence N reservoir-induced seismicity in the vicinity of this larga dam upstream froen the Oconee nuelaar plants Moderately large damaging we do have a high level of concerne earthquakes have occurred in other parts of the world naar similar larga dams. 'Iha prasenes of this seismicity requires that the seismicity, site geology and their possible impact on the dam be ernmined Yigorously and as soon as possible by both the staff 'and i
I the utility.
Original Signed by f
W. P. Gammill I
William P. Garunill, Assistant Director for Sita Technology Division of Sits Safety and Ih:vironmental Analysis Office of Nuclear Reactor Regulation
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Enclosurest As stated j
cc w/o encist I
' D. NaiEhbors.
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R. Jackson J. Kelleher I
J. Stepp R. Hofmann L. Haller W. Bivins i
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DISTRIBUTIM:
DOCKET FILE (50-287) i l
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DSE RDG I
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O u... oovanmusNT Paturine orrects sore eae.sa4 NRC FORM 318 (9 76) NROt 0240 l
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10D40 UM yOR: Earl R. Coller, Assistant Director for l
Operating Reactors, DOE William P. Cammill, Assistant Di ctor for I
I FROM Site Technology DSE i
ONEE/JOCASSEE DAM SEISMIC i
SUBJECTt l
We have been follow the situation at O ee/Jocassee dan since
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'l July 1976, and this orendum will upda what has happened since that time. At the July 7, 1976 site it the staff requested that Duke Power Company provi a report di ussing the earthquake
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activity at Jocassee Dam.
July 21 1976, you were informed that another meeting with the uti ty wo d probably be needed (July 21, 1976 memo cammill to Coller, e clos d).
This memorandum also item-
~ ized a number of concerns relat to the seismicity near Jocasses l
dam. The staff also recommended t operation of a seismic moni-l
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' toring network be reinstituted. As result, a meeting with the l
utility was held on September
, 19 to discuss responses to these questions. At that time the plicant upplied several reports relating to the observed sei city and its geology (see enclosed
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meeting summary by G. Zech)
On October
,1976 we were informed that a seismic monitoring ogram nould be ainstalled and operational on November 1,1976 (lett, Parker to Rusch, October 25,1976).
j on January 7, 1977 we me with Drs. Dave Simp and Klaus Jacob of Lamont-Doherty Geolo cal Observatory to se advice on methods of resolving this sit ion.
f Our consideration of is issue to date has indicat e need to meet soon as possible to discuss spe ifies of das with the applicant i
design, the earthq e activity since July, the seis moeitoring l
program, and loca geology. An agenda for the proposed ting to be held this mon is enclosed.
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ed It is anticipa d that our continued involvement will be requ in order to r av data gathered by the utility. In addition, to for additional information relating to seismic further req adequacy of he dam, local geologic conditions, and other seismologic
' questions 11 be forthcoming. Dr. Dave Simpson of Lamont-Doherty Geologica Observatory, an expert in reservoir-induced seismic activity has indicated a willingness to act as consultant to as on this review.
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e TENTATIVE DISCUSSION ITEMS FOR MEETING WITH DUKE POWER COMPANY OCONEE/JOCASSEE DAM 1.
Geology and Seismology Staff Objectives 2.
Specifics of Seismic Network Operation a.
Station locations b.
Network capability - magnitude and threshold, distance and depth capability c.
Discussion of hypocentral activity since July 1976,
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including focal plane solutions d.
Reporting procedures to NRC staff 3.
Specific Information on Geologic Reconnaissance of Site Area a.
Locatior of discovered faulting b.
Basis of fault age dating c.
Available photos of dam abutments and foundation d.
Subsurface geology - models 4.
Reservoir-Induced Seismicity Similarities - difference Jocassee to known damaging a.
carthquakes i
5.
Scicmic Adequacy of Dam a.
Construction prc,ress photos /airphotos b.
Groundwater elevation before/after dam filling (time-head plots)
Embankment construction specifications (engineering properties c.
for design and basis, density, gradation for all zones, settlement and alignment of c. rests and slope as a function of time) l 1
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Seepage rates (relief wells, weiss, drains)
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Simple strain computations to assess approach to threshold of e.
cracking core i
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History of inspections and repairs to date Sensitivity of. dam to surf ace fault movement (thickness and g.
location of filters, strain distribution - rough calculations) h.
Time - acceleration plot of expected earthquake (reference
.12g for 5.6 Mt earthquake - considerations, basis, justification)
We request personnel that can discuss the above items and other related This should include the peripheral items be present at the meeting.
seismological consultants and dam engineers.
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