ML20040C097
| ML20040C097 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/04/1978 |
| From: | Burger A Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13319A635 | List:
|
| References | |
| FOIA-81-313 NUDOCS 8201270264 | |
| Download: ML20040C097 (5) | |
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Occket No. 50-206 LICENSEE:
SOUTHERN CALIFORNIA EDISON CO.MpANY (SCECO)
FACILITY:
SAN ONOFRE UNIT NO. 1
SUMMARY
OF MEETING HELD ON MARCH 24, 1978, ON MATTERS CONCERNI:lG THE STEAf1 GENERATORS On March 24, 1978, the NRC staff cet with representatives of Southern California Edison Company (SCEC) and their consultants from Westinghouse to discuss matters concerning the steam generators at San Onofre Unit No. 1 (50-1). A list of attendees is attached.
A's a matter of back' ground on February ?3,1978, SCEC transmitted a report on the " Assessment of the Magnitude and Rate of Steam Generator Support 4
Plate Expansion and Tube Denting" in. support of a request *.o semit operation of 50-1 until the next refueling outage (August 19731 withcut performing the required steam generator inspection. During telepnene discussions, we advised SCEC that the infomation provided was not sufficient to justify the requested delay and that the steam generat:r inspection, to quantify the conditions of tube centing, should be perforned in accordance with existing license requirements.
The purpose of the meeting was to give SCEC an oppcrtunity to presen:
additional infomation on the performance history of the 50-1 steam generators including inspection results relating to tube centing.
Westinghcuse representatives made the presentation which included an analysis of the steam line break to assess the radiation dose cen-sequences of additional leakage frca tubes assumed as a result of the steam line break.
Attached is a copy of SCEC's handout which provides details of the presentation.
Ouring the oiscussion of supcort plate distortion and flowslot geenetry, hestingncuse showed for comparison series of photographs taken at critical support plate locations during the last 50-1 refueling cutage (before April 1977 startup) and during the September 1977 maintenance outage. The upper two support plates in the steam generators appeared to be undistorted, while the lower ones showed distortions witn aoparent "hou rgl as s i ng".
The earlier series of chotograchs app., red to snow cracks in tne 1:wer succert olate at the ficwslot location.
We were nct previously aware of these apparent supcort plate cracks.
Document 12 8201270264 810925 PDR FOIA UDELL81-313 PDR
..; g 33 SCEC stated their coinion that it is safe to continue operation of 50-1 until the next refueling cutage because the condition of the ficwslot gecmetry or tube denting is not expected to change significantly during the remaining core life; also, tnat it would result in a severe econcmic penalty for SCEC to shutdown 501 for steam generat:r inspection in May 1978, and then to resume operation for only 21/2 EFPN (effective full power months) to ccmplete the present fuel cycle.
50-1 shutcown is estmated to cost 5250,000 per cay.
Therefore, SCEC wants us to continue our review of their request to delay the steam generator inspection until the next refueling outage.
We indicated that our primary concerns are:
(1) tne potential consequences
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of an accident tnat might cause concurrent failure of centeo and potentially cracked tubes, and (2) the lack of inspection data to assure the continued long-term integrity of the steam generator support plates ano tubes. We indicated the type of additional information required to continue our review.
As a result of tnese discussions, SCEC will provide tne following:
(1) documentation of the information presented during the meeting, (2) an outline of the scope and criteria for the steam cenerator inspection (to quantify tube wall thinning and tuce denting) to be performed during the next refueling outage,. (3) an outline of the proposed approach using currently available data for developing tube plugging criteria addressed to denting, (4) a commitment to propose lechnical Specifications for inservice inspection of the steam generator, and (5) copies of photographs that shcw the extent of support plate cracking.
SCEC will suomit the final proposals for items 2, 3, and 4 as part of the items reouf ring our review to cbtain approval before startup with the next cre loading.
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, ( j Q p. <-. & -n Alfred Burger, Project Manager Operating Reactors Branch 42 Division cf Operating Reactors
Enclosures:
1.
List of Atter. dees 2.
SCEC Handout cc w/ enclosures:
Southern California Edison Canpany ATTN: Mr. James H. Drake, Vice President 22aa Walnut Grove Avenue Post Of fice Box 200 Rosenead, California 91770
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.1", er i.ev el bdicon is authcrized to operate the reactor at cteady state
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to'.:cr Icycls up to a car.inun of 1347 ceca.! tt
- thercal, B
Technical Scecifications The. Technical Specifications contained in Appendices A and B, as revised throuch Anendment No. 2.!, are hereby incorporated in the license.
The licensee shall operate the facility in accordance with the Technical Speci fications.
3.C.
Fuci shipments shall not be resumed (c.~. cept during
. cold shutdown condition of the reactor) until the raodifications described in the licensce's March 21, r.
1975 report entitled " Spent Fuel Shipping Cask liandling, San Onofre Nuclear Generating Station, Unit 1",
and the initial turbine deck load bearing test'and visual inspection have been satisfactorily completed."
"3 D The f::ility =cy bc : edified by impic enting the " Spher:
Enclosure Project" as described in Ar.cnd=cnt 52 to the Final Safety Analysis for the San Onof re Nuclear Generating Station, Uni.t 1, submitted Dece=ber 3,19 75 ;
Supplccent to the Sphere Enclosure Project Report, a
submitted March 1, 1976; Second. Supple =ent to the Sphcrc Enclosure Report, "subcitted March 25, 1976; additional infor=ation submitted by letter dated Ibrch 25, 19 76, (withheld from public disclosure pursuant to 10 CFR Part 2, Section 2. 790(d))."
(E)
Steam Generator Insoections In order to perform an inspection of the stean generators,
. the plant shall be brought to the cold shutdorin condition within twelve months of operation from April 1,1977.
The scope of this inspection shall provide sufficient data for a reassessnent of the maanitude of innlanc. expansion or "houtalassino" in tha 1.op and bottom tube _ suRDort. oJAtes ca the cf fcct of 30tenti:1 enntinuad stcca qer.cratoi: tube.
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Muclear P.eculatory Co.-3 mission approval shall be obtained before resuming power operation following this inspection.
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Document 13 O
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2-3.E.
Steam Generator inseections The reacter snall be brought to a cold shutdown condition to perforr an ins?cction of the steam generators when the primary coolant s3 stem has been at a temperature of 350'T or above for twelve cumulative contns aftec April 1, 1977.
Tne scope of this inspection shall provide sufficient data for a reesses'sment of the maanitude of inplane expansion or
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"hourglassing" in tne top and botton tube suppor.t plates on the ef fect of potential continued steam generetor tube denting.
Nuclear Regulatory Commission approval shall be obtained before resuming power operation following this inspection.
3.
This license amendment is effective as of the date of its issuance.
FOR THE NUCLEAR REGULATORY COMMISS10l1 h
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Dennis L. Ziemann, CI' ef Operating Reactors Branch #2 Division of Operating Reactors Date of Issuance: March 24,1978 e
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"(F)
Other Ste6m Generator insrections (1) A stear.! cenerator inspection program shall be subr.itted for Nucicar Regalatory Ct mission approval.
The approved progrt.r. shall be carried out during the outage for refuelin:
San Onofre, Unit 1 for Cycie Vl! operation.
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(2)
In the event that reactor coolant 'to secondary leaksgc raN cxceeds 0.3 gal / min in any steam generator, the plant shall be brought to cold shutdown and the I,'RC notified before resumption of plant operation.
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