ML20010J322

Final Deficiency Rept Re Cracking of Guide Lug Inserts for Reactors Internals,Initially Reported on 810817.Existing Inserts Removed from Svc & Type 304 Stainless Steel Guide Inserts W/Hardface Being Installed

ML20010J322
Person / Time
Site:	San Onofre
Issue date:	09/16/1981
From:	Papay L SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8109300314
Download: ML20010J322 (3)

Text

{{#Wiki_filter:_ _ _ _ _ _ _ _ 50.55(e) Report

                 * ,   e a D"6     Eros. 50-361/362 Southern California Edison Company \p1 yp ;y p y -gG P. O. DOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770              **5>    .

L.T. PAPAY vics eatseOEnt 213 - 5 72. f 474 September 16, 1981 i Mr. R. H. Engelken, Director  % f l\ . Office of Inspection and Enforcement / \ (fff s U. S. Nuclear Regulatory Commission l[ dChG Region V gg . r Suite 202, Walnut Creek Plaza l87 t 9 798fm 1990 North California Boulevard Walnut Creek, California 94596 h\g, '*c4p ['

Dear Mr. Engelken:

6 Subj ect: Docket Nos. 50-361 and 50-362 San Onofre Nuclear Generating Station, Units 2 and 3 In a letter to your office dated August 17, 1981 we identified a condition which we considered potentially report-able in accordance with 10CFR50. '5(e) . The condition involves cracking of the guide lug inserts (shims) for the reactor in-ternals. Enclosed in accordance with 10CFR50.55(e) are twenty-five (25) copies of a Final Report entitled " FINAL REPORT ON CORE SHROUD GUIDE LUG INSERT SURFACE INDICATIONS, San Onofre Nuclear Generating Station, Units 2 and 3." If you have any questions regarding this report, we would be pleased to discuss this matter with you at your con-venience. Very truly yours, Y7 Enclosures

                                                                                              #I bI   I cc:        Victor Stello (NRC, Director I&E)

A. E. Chaffee (NRC, San Onofre Units 2&3)

                      ~'8109300314 8109 3f]

gDRADOCK 05000361-PDR f _

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FINAL REPORT ON CORE SHROUD GUIDE LUG INSERT CURFACE INDICATIONS San Onofre Nuclear Generating Station, Units 2 and 3 INTRODUCTION This report is submitted pursuant to 10CFR50.55(e) . It describes a condition involving surface liquid penetrant indications on the core shroud guide lug inserts in the heat affected zone near the interface of the base material and hardface. This report includes a description of the surface indications, an analysis of the safety implications and a summary of the corrective actions being taken. By letter dated August 17, t 1981, Southern California Edison confirmed notification to the NRC of this condition which was considered potentially report-able in accordance with 10CFR50.55(e). 7 BACKGROUND I The condition was found by dye penetrant examination to contain some surface indications which were confirmed by ultrasonic examination. The function of these inserts is to provide a wear resistant alignment surface which will maintain the upper guide structure fuel alignment plate in position relative to the core shroud

;                                                             and lower support - core support plate, thus maintain lateral alignment and support for the core relative to the core shroud during operation. There are four pairs of guide lug inserts (total of eight) which r.re attached to the four guide lugs located on top of the core shroud. They are fabricated to provide a close fit with four slots in the UGS fuel alignment                                                                                               ,

plate. The guide lug inserts are constructed of a base material i of type 348 stabilized stainless steel, overlayed with Haynes i Alloy No. 25 hard facing material of a maximum 1/4" thick. 1 , DESCRIPTION OF THE DEFICIENCY l Surface indications up to 1/2 inch in depth and in varying  ; lengths were found in all of the guide lug inserts. The indica-

,                                                              tions were located below the heat affected zone of the base I
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FINAL REPORT ON CORE SHROUD GUIDE LUG Page Two INSERT SURFACE INDICATIONS San Onofre, Units 2 and 3 material and the hard face. The cause of the indications is believed to be due to the presence of non-metallic inclusions in the plate material, which, together with the tension stresses produced by the welding operation, resulted in the mechanism for Lamellar tearing during application of the hardface. ANALYSIS OF SAFETY IMPLICATIONS It is considered very unlikely that this condition would progress to the point where all of the hardface material on one or more shims would be removed. It is also unlikely that the hardface would break up into small pieces due to the ductility of the material. Therefore, it is expected that no significant increase in reactor vessel internal structure motions would occur. How-ever, if it should occur, the vibration monitoring system is capable of detecting significant motion of the internals, and such motion can also be inferred from variations in excore neutron detector signals. CORRECTIVE ACTION Stainless steel material from a different heat which does not exhibit this phenomenon has been satisfactorily used in similar applications. The existing inserts are being removed from service and type 304 stainless steel (in lieu of type 348) guide inserts with hardface are being installed in San Onofre Units 2 and 3. l j}}