ML20040C065
| ML20040C065 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/14/1976 |
| From: | Stuart R Office of Nuclear Reactor Regulation |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13319A635 | List:
|
| References | |
| FOIA-81-313 NUDOCS 8201270226 | |
| Download: ML20040C065 (3) | |
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R. Stuart, Section B Lcader, Engineering Branch, DDR THRU:
L. Shao, Chief, Engineering Branch, Division of Operating Reactors
SUBJECT:
SU:"9.RY OF MEETING WITH SOUTHERN CALIFORNIA EDISON CO:1PANY (SCEC) AT THE SAN ONOFRE UNIT #1 SITE The subject meeting was held on December 2,1976_ at the San Onofre site.
A list of attendees and a copy of the agenda are enclosed.
Presentations were made by both Bechtel and Westinghouse personnel about the seismic analytical methods and the results of analyses including the results from modeis that included the modifications.
hestinghouse's model included non-linear effects caused by gaps in the system, and Bechtel's analyses of the structures were based upon linear ~
elastic assumptions.
There was excellent correlation between the results of essentially two independent efforts - one by Bechtel and the other by Westinghouse.
The modifications were described in detail and were inspected inside the containment structure by the NRC staff attendees.
Folicwing the in'spection of the plant by the staff attendees, a discussion took place about the dearadation of the antibibration bars in tne hand region of the steam generato.r tubes.
One of the antivibration bars in the bend re.ginn ramnzed from a steaa_. generator was passed around for inspection. The exact causes of the degradation of the antivibration
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bars are under investigation, however, fretting seemed to be the primary cause.
SCEC indicated their intent ~to introduce additional Inconel bars of souare cross-section to provide improved antivibration support at the bend region of the tubes.
One of the staff concerns was the effect of postulated broken antivibration bars.
SCEC did not anticipate any problem from broken antivibration bars because of the restricted space within which they can move, and the low velocity the can attain within the steam space.
The main purpose of the meeting, from the point of view of the Engineering Branch, was (1) to review the analytical tools utilized in the seismic reanalysis, (2) to inspect and actually witness the adequacy of the proposed modifications, and (3) to gain insig.ht into the capability of different structures and components of an existing plant to accomodate additional seismic loadings.
We feel that the audit function of an on site inspection was very useful.
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ri:n rs:. err.:r., c.n; the re :.r cc iSr.. p r.x, are _:ir.g ir.:.talled untr n; criteric of 10 CFR icr: 50.59 i.e.,
that no unrevie;;cd scfety issue is involved.
Curirig a systematic reevaluation of this plant tne current upgrading effort woulc have to be formally reviewed and full credit must be given for them.
Tne current modification effort by SCEC is part of a program to upgrade all the safety related components, systems, and structures.
We recem-mend that any future submittals made under this program be technically evaluated fully using our fori::al criteria.
It has been suggested by Operat~ing Reactors Branch t'o.1 that considering the tragnitude of the voluntary efforts made by the SCEC and.5g design value of the SSE, the seismic upgrading effort may be treated as an "unreviewed safety issue".
An eventual decision would have to weigh both points of view very carefully.
It should be emphasized that complete documentation of the technical justifications and safety evaluation need to be developed.
Pa b M. 1 % d R. Stuart, Section B Leader Engineering Branch Division of Operating Reactors
Enclosure:
As stated
Contact:
G. Bagchi 28060 Docket No. 50-206 cc:
V. Stello L. Shao A. Schwencer A. Burger R. Hofmann
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LIST!::G - I;F.C/5;T I:EETI ;G Decembr 2, 1975 I;RC 1.
Fred Burger 1.
J'. Haynes - SCE 2.
Al Sch.iencer 2.
K. Baskin - SCE 3.
G. Dagchi 3.
D. fiunn - SCE 4.
R. Stuart 4.
T. Mercurio - SCE 5.
Bill La' Pay - Westinghouse 6.
Steve Palm - Westingnouse 7.
R. Warren - Bechtel 8.
P. }oss - Cechtel 9.
G. Mills - Sr.E 10.
T. }:ato - SCE 11.
J. Demsey - Bechtel 12.
R. Blaschke - SCE 13.
H. Otto' son - SCE 14.
W..Griffith - SDG&E 15.
G. Hawkins - SCE 16.
J. Seoietto - SCE
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Southern California Edison Corr.any (SCEC)
Fl.CILITY:
5:.n Onofre. Unit 1:o. 1 SZ '.J. "..' OT S ITE i'I S I T ",:: ICODER 2,1976 FGR ERIEFI:!G C:( ST/.TUS OF SEIS"IC
':EC','P_'.mTIO:: N00F1." FOR SA'l O':0FRE, ir!IT i:0.1 On Deced.er 2, i?75. W',C rapr2scatatives rat with. representatives of SCEC La3 tacir contractors at the Scq Or.ofre, Unit.';o. I clant site for a brief:np on the crasent status and schedules of the seis cic raavaluaticr. r,r: gram for Scn Dr.ofrc, ' ait *'o. I and for viewinn ti;e J
, seisr.ic bachfit r.03ificaticas in oracess of being co oleted 'during the crasent refueling and r.aintenance oucaga.
A list cf attend 2cs is enclosed.
i' Sige.ificant points discussed at the naeting are str~arized belcw and the r..terial :rcsented by SCEO is +1so enclosed.
SCEC cemitted to and inititt i e s'isnic reavaluatic7 prcgrrr ds.rir.c im.
~h e-rennalpis utilizes thu 90cssncr respcase sosctra nurmlized to a r.ni :um horizc7tal ground acceleration of 0.579 for the Safe Shut-dcun Earthquake (SSE).
SCEC ctrnlated the raanalysis of the contain-r.ent sph2re the concrete reactor building inside the sahare cnd th:
orircry copinnt locos, 'using the rethods described in their 3.oril 1G 1975 ie;iort.This is the first parc of a phased a:proach in the seis'r.ic reevaluatica progra:r. *!ith a scope based on hgulatory C-uide 1.25.
In addition, SCEC has also submitted as part of th: overall prograra the Operasing T, asis Earthquake (0]E) 7:ecurrence Interval Study -
October 1975 and the Site Soccific Earthquake Drrgram Plan Saote:rer 1976. The ouruosa of the site specific mdelling studies being r,crfer:r.2d by SCEC is to show that the 0.579 iicusner Spectra used for seisnic' in. nut in the April 13.' 1975 seisnic reenalysis recort is conservative cc:aared to the site specific spectra for a 0.679 horizontal ground acceleration.
?.s a result of the initial Phase I of the seisric raevalu: tion progrra SCEC identified needed nodificaticas for acceptably increasing tha strst r.srains in the supports for the pressa-izer, staan generator and for the reactor coolant ;,u ps.
SCEC orasEnted the design details during tha taeting.
The NRC reprgsentatives vie.?ed the r. difictitions insida contain.nt and noted that the e cch is substentiall.y co plat 2d.
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SCEC or2sentad the progrca schMules cover ing Ph?:S II of the tre'r:r, ny-2iy,tne balance of the pler.: systc: s nac.csary to cssura the cacability to shutd:r.-n the rasctor and raintain it in 2 tr.'a shutdc>:n co,dition.
Phase II raevaluatico uould b2 cor,-
oletti uitn nodification.'ork, if found to ba nacassary, co c.encing in 6 :ry 1372.
Phn III of the pre : ram includas th: balance of oltit systcr necessary T.o assure the ccoability to oravant or ritigate tha con:ar;u2nce of accidents.
Phase III is scheduled during 1979.
In t.ddition, SCEC util provid2 a schedule for evaluating the seisnic qualification for Category I equipment.
The liRC staff found the scope and schedules of the seismic reevaluation program to b2 acce? table; the analysis rcthods for d2terminir.g the response of the systcm to the 0.679 horizontal ground acceleration are advanced comared to analysis nathc.ds used in current license coalica-tier.s; and the nodifications which have been carried out during this refuelin; outage will provide increased safety margins and are acceptable.
The staff requasted and SCEC agreed.to subr:it a su :.ary of the stress renort which details the analysis technicues and state of stress for critical components affected by the recent codifications.
Original signed by Alfred Bure.er, Project !'anacer Onerating naactors Branch r1 Division of Operating Eeactors Enclnsuras:
1-- List of Attend 2es 2.
SCEC Presentations cc tt/enciosures:
See next page DISTRIBLITION Docket ORB #1 Reading o
Subject File ABurger I
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- ATTE:: DANCE LIST NRC/SCE l'.EETING DECE!GER 2,1976 liUCLEAR REGULATORY CO:C41SSION i
A. Schwencer A. Burger G. Bagchi R. Stuart SOUTHERN CALIFORNI A EDISON C0!?ANY J. Haynes K. Baskin D. llunn T. l'ercurio 4
G. Mills T. Kato R. Claschke H. Ottoson G. Hawkins e'
J. Beoletto SAN DIEGO GAS & ELECTRIC COMPANY W. Griffith L
WESTINGHOUSE CORPORATION B. La Pay S. Palm J
BECHTEL CORPORATION R. Warren P. Koss J. Demsey i
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