ML20059J685
| ML20059J685 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/08/1993 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9311150012 | |
| Download: ML20059J685 (2) | |
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1 nl Southem Califomia Edison Company 23 PARKER STREET tRVINE, CALIFORNIA 92718 hnde 8,1%3 wAtreR c. uARss MANAGE R OF NUG.F_AR R6 GLJLATORY AFFAIRS (714b 4the-4403 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.
20555 Gentlemen:
J
Subject:
Docket No. 50-362
.l Steam Generator Eddy Current Inspections San Onofre Nuclear Generating Station l
Unit 3 l
As requested by the NRC Project Manager for San Onofre Units 2 and 3,'this letter provides the enclosed summary of the inspection plan for the San Onofre i
Unit 3 steam generators. This plan is scheduled to be implemented during the current Unit 3 Cycle 7 refueling outage.
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The steam generator inspections being performed at Unit 3 are similar to those i
perfonned at Unit 2 during the Cycle 7 refueling outage, with minor revisions based on the recent Palo Verde Unit 2 steam generator inspections, the San j
Onofre Unit 2 steam generator inspections, and the Palo Verde steam generator i
tube failure root cause report. The inspection plan incorporates the results of the Cycle 7 Unit 2 steam generator inspections and Southern. California Edison's review of the Palo Verde Unit 2 tube failure which occurred on March
-I 14, 1993. This inspection plan exceeds the San Onofre Unit 3-Technical' Specification inspection requirements.
If you have any questions regarding this matter, please let me know.
Sincerely, i
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s 3 u q
t L.,
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I Enclosure I
i cc:
B. H. Faulkenberry, Regional Administrator, NRC Region V NRC Senior Resident Inspector's Office, San Onofre Units 1, 2 & 3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 110041 h0\\
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9311150012 931108 f
i PDR ADOCK 05000362
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ENCLOSURE 1
SUMMARY
OF THE UNIT 3 STEAM GENERATOR INSPECTION PLAN i
1.
Eddy Current Bobbin Coil Inspection:
1 The full length of 60% of the Unit 3 steam generator tubes will be
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inspected using an eddy current bobbin coil. This is essentially an inspection of tubes which have not been inspected within the last four years.
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The bobbin coil inspection will also include all tubes adjacent to tie rods and all tubes adjacent to an active area of wear degradation (i.e.,
i at the steam generator tube support structures known as "batwings"). All tubes with previous degradation greater than 20% through-wall'will be inspected, in accordance with the requirements of Technical Specification 4.4.4.2, Steam Generator Surveillance Requirements.
2.
Eddy Current Profilometry Inspection:
Full length eddy current profilometry inspection of all the Unit 3 steam generator tubes adjacent to tie rods will be performed. This testing has been performed for the past several outages in Units 2 and 3.
3.
Eddy Current Motorized Rotating Pancake Coil Inspection:
A Motorized Rotating Pancake Coil (MRPC) probe will be used to inspect the transition reg) ion of all (100%) of the Unit 3 steam generator tubes on the inlet (hot leg side of the steam generators.
The transition region is the region where the steam generator tube decreases from its explosively expanded diameter to its normal diameter.
The transition region of approximately 6% of the tubes on the steam generator outlet (cold leg) side of the steam generator will be inspected.
This inspection includes 20% of the tubes in an estimated region of interest which is based on the San Onofre Unit 2 steam generator inspections. ThE estimated region of interest is a mirror image of the region on the inlet side of the steam generators where indications were identified at San Onofre Unit 2 during the Cycle 7 Refueling outage.
Based on recent Palo Verde Unit 2 experience, approximately 355 tubes in l
the upper bundle in each of the two Unit 3 steam generators will be inspected. The lengths over which these tubes will be inspected is based on the results of steam generator thermal hydraulic modeling using the 4
ATH0S 2 computer program. The ATHOS 2 computer program was developed by the Electric Power Research Institute and aids in predicting where deposits may form on steam generator tubes. Based on an assessment of.the ncent Palo Verde Unit 2 steam generator inspections, the Palo Verde tube failure root cause report, and the San Onofre Unit 2 Cycle 7~ steam i
generator inspection results, the scope of this MRPC inspection of the i
Unit 3 steam generators has been reduced by approximately 55 tubes in each steam generator below the Unit 2 inspection scope.
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