ML19317E841
| ML19317E841 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 02/14/1978 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19317E839 | List: |
| References | |
| NUDOCS 8001030976 | |
| Download: ML19317E841 (2) | |
Text
5
'gc h
UNITED STATES
,/4 NUCLEAR REGULATORY COMMISSION yas I<-
' E WASHINGTON, D. C. 20555
- p. 'ha.f al b
t.r.
\\.',',$.
FEB 141978 MEMORANDUM FOR:
A. Schwencer, Chief, Operation Reactors Branch No.1, NRR FROM:
K. V. Seyfrit, Assistant Director for Technical Programs, IE
SUBJECT:
SEISMICITY NEAR_DC03EEJ10 CLEAR GENERATING STATION UNITS NO. 1, 2, AND 3 As discussed in our recent telephone conversation, Region II inspectors have reviewed the seismic monitoring instrumentation operability and surveillance at the Oconee Nuclear Generating Station.
Their sum-marized findings are contained in Enclosure 1 to this memorandum. is the memo from Carl Stepp to you which led to your request. is a draft memo from Duke Power Company to E. G. Case, wherein it is indicated that a report containing the licensee's analyses of the microseismic events will be scbmitted in March,1978.
I trust this information will be adequate for your needs.
'Q.,
j, l :/-
Karl'V.'Seyfri/,'AssistantDirector for Technical Programs Division of Reactor Operations Inspection
Enclosures:
As stated t
88 %,
UNITED 5TATES 2
4 o, _
NUCLEAR HEGULATOF;Y COM.*ilSSION
['*
!.Q
., '- g 230 PE ACHT n t E STR E ET, N.W. SUIT E 1217 REGloN ll y*
5 5,jDgNf ATL ANTA. Gf oRrMA 30303
's, January 30, 1978 MEMORANDUM FOR.
K. V. Seyfrit, Assistant Director, Division of Reactor-Operations Inspection, IE:HQ FROM:
F. J. Long, Chief, Reactor Operations and Nuclear Support Branch, Region II
REFERENCE:
Memorandum dated 1/12/78 from J. C. Stepp to A. Schwencer
SUBJECT:
SEISMIC MONITORING INSTRUMENTATION AT OCONEE NUCLEAR STATION, DOCKET NOS. 50-269, 50-270 AND 50-287 This is in response to your telephone request of January 13, 1978 regarding one of the recommendations in the referenced memorandum.
The strong motion seismic monitoring instrumentation installed at the Oconee Nuclear Station was reviewed during the inspection conducted on January 23-27, 1978.
The review included visual examination of accessible instrumentation and verification that the system is functional.
The inspector examined the triaxial accelerometer package and the starter package located in the Unit 1 tendon access gallery and the control and
{
recorder panels located in the Unit 1 cable room.
The triaxial acceler-ometer located within the Unit 1 reactor building was not examined.
A calibration and functional test was last performed on January 4, 1978.
Review of this record revealed the system is operational and no seismic disturbances have been recorded. The event indicator located on the control panel in the Unit 1 cable room is checked weekly by the plant operators.
Additional details of the inspection findings are presented in IE Inspection i
Report Nos. 50-269/78-1, 50-270/78-1 and 50-287/78-1, Details I, paragraph 6.
D m
w 1
F. J. Long, ChieiU Reactor Operations and Nuclear Support Branch cc:
R.-C. Lewis,.RII F. Jape, RII
!l
~
lt CONTACT:
F. Jape 242-5560 Ii t
8001030
i Ha s s a n... t r
- [
2 '.
NtlCl.!,*.1: 1:1.GUI.A I.:n CG..* P. ::0.!
. 's.i.
~i.
n A:.H;:.Gi % :s t.
- . t.
- t,i
....~
JU; ) 2 tE s
- ET.J.:/J2C.: 702:
Albert Scir. encer, Chief, Op.: rating neactors Drcnch 31, 2 r.;
1 F.e.:
J. Carl St.cpp, CLief, Geoncivace; Eranch, DST
......... S.L....
5., u.. s., I u..
s.
.d, 0 t.v.. i.......L,t_.,....(..
,.,,s...
u 1...
- w..
-- s.
...,..5 1, 9_.3 i,...
Enclosed is cur reecr.e.:ded actions with respect to the oni'oin" c:.rth-l c,u. ele s:ars -. ant -hi-Ocen+e Nucle.2r S* ntion.
'Ti'am reco=endations s:cse preparad b; Irs. Jccison and J. Kalleher of r.y staff cf ter con-i versa:icne. sith y:;r staff. nd the Licensee.
- i'aa ette upon which these racc=and:ti:n cra based arc ver/ linited. Tit 0s our recc,unen-i dations reflect n 2ppropriate level of caution.
To date the activit.: has the characteristics of an carthquake swarm.
Typically e rth: :J.u. -4 warns have nr.nv events of near equal naanitude.
The'lar;; cst carf.r.:the in this swcrn to date has been negnitude 2.2.
l Our experience rich earthcuake e.;: art activity indicates that the lart;est event.:i:h C.vald be expected rill e:cceed by no rore thca about onc =2; nit-.d2.: nit the uagni:ude of the frequent activity.
Since the iracuent activity in this suarn to date is about nagnitude 2.0, we can state conservntivaly that n ncninun eveat larger than about 3.5 should not be enpected unless there is an up,2rd chif t in the n.u-nitude of the frer.uent events. Therefore, tha cetivity to date dcas not indicata an ine.;eliste safety con:cra for the Oconee units, but continued nonitoria;.nd daily reportiu;; is needed.
Fe anticipate that tha investi;;ctions ve have recon.anded will enable us to evaluate the tectonic cause of these earthquakes and the hazard that is inplied.
e.
., -m r
.e I-l-.,51,/ ) 01,
/
(
l J Carl' Repp,,.Citie f C'coscience's Srnach
.' Division of Site Safety and Envir. anental.\\nalysis W
t cc t;/ encl:
- 11. Danton D. 1:uller E. Coller U. rm tLil D. i'el;;hborr.
K. Sayfrit Dkoseley C..;.ica 11)
POR L. seal i'JR
~
l 700/020fso
Occi:KE EU(:1.CA1; Gi-:. *:AT I!;G STAT 1.G! 1.':1.TS 1,
iW C OM:4!C.TED AC rio:;S 1-flT:i
".S'*;t:T *io AN
..u'.TI:';;.'A;;..v.;fCt:?
. C:.. /. *OM
" h:ii k'e consider the recent microcar thquake acti ity in the vicinity of St:. p Crack Church, South Carolina to be a t.:atter of conearn because of tha pro::ir.ity of Oco:.ae ucclear p unt.
The activity, at present, e::hibits the character of un carthqu.de swarm in thct n:any events cecurred ::hich : crc of about c';tal en,;ait ide (near 2) without the occurrence of a single dominant carthquake. Should the activity persist without significant increase in ecrthquake nugnitude, this activity trill not pose a safety hacard to the Oconee units.
However, even though similar r.icroearthquake sequences have
- occurred else.chere without accompaniment by larger shocks, it is our judgment that this activity ba treated with caution until the tectonic causes and i=plications are understood. Duhe Power should aggres ively s
develop the infornation required to assess the nature of this micro-carthquake activity and its relationship to tectonic structure.
L'e reco:rnend that a program include as a nininum the following objectives:
a)
A network cf microearthquake instruments should be maintained in the area to determine hypocentral locatloas and when feasible magnitudes and composite focal plane solutions. This network should be continued in operation for at least some weeks af ter the apparent cessatiun of activity.
n
+
6 6 6 e.~
.~
..w..
s nr r
w
-r
r b)
A cajor 1;oni is to reveal any potentini rc3atic,nd..gs bet een
.s the microtarthe.uake activity and significant geologie structures.
Tor this pur;:osa there c::st i.e developed b th a adequate base of regional nuclogie dr.ca sc.c a hypceen;rni catalog of reasonable quality.
4
.c)
Apart fren t;eologic conditions the hypseentral catalog itself shou 19 he ensnined fer indicctions of internal consistency That is, ge:n=trically planar j;roups of hypocenters or coherent focal plane solutions may provide evidence of a larger fault
- i surface orer vhich tectonic stress may have accuuulated d)
The spa-'M c--
ant of hypocenters should be carefully tonitored.
Duke Po.cer Ccepany should carefully look for indications of significant increcse in this spatial c:: tent.
L'e regard the above as a minimca program to be follo ed by D k ue Power Conpany.
The EP,C should be informed daily by telephone of the number of microearthquakes, the maxinum n2;nitude and any signifi cant changes in hypocentral locations.
In addition Duke Power Company
'should provide as soon as reasonably po I
ssible a written report detailing:
I (1) whatever evidence exists for the presence or absence of geologic structures that ruy be associated with the nicrocarthquake acti
- vity, (2)_ a discussion of the trends, dip and extent of any structuren uith which the earthquakes can be associated, and' (3) a discus sion nad presentation of any data _ defining the tectonic structure at i
the site.
l 1
-1
]
r
~-~
, W alsa reco==e.td tha t the 1)ivision of In :I.>r t t'an n:id Enforcenent be informed of this activi ty and th.: they certi f. thL-strong ::otica instrt::ents et th.. plant 7;t6 are func Io:ing, c
4 4
I
D u iu: l'owipe Con i'.u:
n,wl:it n. ii i,m.
- 3 *J*_*. f)1;Til Clll'ItCil Stilt I:I. (*ll A ltl.es t' l' t;. N
(*. Vec 22, N
we' Lt Ama o. saassis t s.,.Jse.
T f.t e'=* *.. A m
- a
- 2 7 2 a, ~;
v.r y Pet 5 tet s.'
$* t s ** P*CO st* 04
- !.' g.((
i j
Mr. E. G. Case, Acting Director
-" ''8 Office of ':uclear neactor Regulation IC'l !!C'OR ATION U. S. Nuclear ~..:ulatory Commission AND/OM Ra';'.W Ott'i Usshington, D. C.
20555 RE:
Oconee ::uclest Station Docket !;o. 50-269. -270, -287
Dear Mr. Case:
In recent weaks there has been a general increase of seismic activity.
in the Jocassea/Kecuee area, centered near Star.p Creek Church, three
. miles northwest of 0:enee Nuclear Station. The number of nicro earth-quake events and the aximum local riagnitude have been reported to 29,
. daily b; telephone since their initial detection on December you 1977.
Duke Power Company is currently assessing the nature of this recent Seismic monitoring of this area will continue in order to activity.
An attempt will be made to relate the activity support this analysis.
l to known geologic structures.
Additionally, the tectonic struc-re
.in this-area will be examined.
a written report will be submittedIn Itarch 1978, it is anticipated that which will include an analysis of these events.
4 Very truly yours, bec: lir,T, USC. Dr.;1, LJ 3, KR'J, LCD,
SD!!, RSS William'O. Parker, Jr.
i RLC:ge K6U1nMn y,y h Y