ML13317B039
| ML13317B039 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/11/1982 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Dietch R Southern California Edison Co |
| References | |
| LSO5-82-03-065, LSO5-82-3-65, NUDOCS 8203170576 | |
| Download: ML13317B039 (8) | |
Text
DISTRIBUTION UNITEDZeATES ocket NUCLEAR REGULATORY COMMISSION NRC PDR LI.
WASHINGTON, D. C. 20555 Local PDR ORB Reading March 11, 1982 NSIC DCrutchfield HSmith Docket No. 50-206 ORB Reading LS05-82-03-065 WPsulson OELD 01 &E ACRS (10 Mr. R. Dietch Vice President Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800
.Rosemead, California 91770 j
LISLREr Dear fMr.
Dietch:
SUBJECT:
PROPOSED STEAM GENERATOR INSPECTION PROGRAM -
SAN ONOF We are continuing our.review of your submittal dated January 22, 1982 regarding your proposed steam generator inspection program to be con ducted during the current outage. We find that additional information identified in Part A of Enclosure 1 is required. In addition, the results of the staff's evaluation to date are identified in Part B of. Please provide your response to Parts A and B of Enclosure 1 within 30 days of the receipt of this letter.
The NRC staff would also like to meet with your staff and Westinghouse representatives at your earliest opportunity for a follow-up discussion of tube and sleeve wall flaws introduced during the fabrication of the "reference" sleeve joint. Enclosure 2 is a proposed agenda-for this-meetino.
Please inform us as soon as possible of the proposed date for this meeting.
In a reated identifies an additional staff concern.
5 Inareae matter,a regarding the effect of blowdown forces-on non-sleeved tubes during a
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postulated main steam line break or feed line break.
Please provide your
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response to Enclosure 3 within 60 days of the receipt of this letter.
Sincerely, Dennis M. Crutchfield, Aief Operating Reactors Branch #5 Division of Licensing Ehclosures:
' 8203170576 820311 As stated PDR ADOCK 05000206
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Mr. R. Dietch March I, 1982 cc Charles R. Kocher, Assistant General Counsel James Beoletto, Esquire Southern California Edison Company
-Post Office Box 800 Rosemead, California 91770 David R. Pigott Orrick, Herrington & Sutcliffe 6600 Montgomery Street San Francisco, California 94111 Harry B. Stoehr San Diego Gas &.Electric Company P. 0. Box 1831 San Diego, California 92112 Resident Inspector/San Onofre NPS c/o U. S. NRC P. 0. Box 4329 San Clemente, California 92672 Mission Viejo Branch Library 24851 Chrisanta Drive Mission Viejo, California 92676 Mayor
. City of San Clemente SSan Clemente, California 92672 Chairman Board of Supervisors County of San Diego San Diego, California 92101 California Department of Health ATTN+:
Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California 95814 U. S. Environmental Protection Agency Region IX Office ATTN:
Regional Radiation Representative 215 Freemont Street San Francisco."California 94111 Robert H. Engelken, Regional Adminis.trator Nuclear Regulatory Commission, Region V Office of Inspection and Enforcement 1450 Maria Lane Walnut Creek, California 94596
ENCLOSURE 1 EVALUATION AND REQUEST FOR ADDITIONAL INFORMATION RELATING TO PROPOSED STEAM GENERATOR INSPECTION PROGRAM FOR SAN ONOFRE UNIT 1 A. Additional Information Required The following information is required before we can complete our evaluation of the steam generator inspection program at San Onofre Unit I which was submitted by letter dated January 22, 1982.
- 1. Provide ECT qualification data to demonstrate that an adequate inspection of the sleeve and tube walls can be performed at the expansion transition regions of the upper joint and of the tube wall at and near the sleeve ends using a conventional probe..
- 2. What conclusions can be drawn from the baseline inspection of the sleeves regarding the sensitivity of a conventional probe inspection to sleeve wall defects in the presence of maskino sIgnals from through wall IGA penetrations of the outer tube wall? What is the technical basis for these conclusions?
3 rovioe a Ssessment of UT capabilities to detect sleeve and tube wall defects at the "reference" joint which may.have been introduced during joint fabrication or in service, or the feasibility of adapting UT.for this purpose.
- 4.
Provide the status and description of the program to develop eddy current techniques and probes to improve the inspectability of the "reference" joint.
-2 B. Staff Evaluation of the Proposed Inspection Program
- 1. We believe that the proposed 100% inspection of all tubes within two rows of the previously defined inspection boundary to be generally acceptable subject to the following:
- a.
Tubes should be inspected beyond two rows at locations where previous eddy current data indicate the potential for activity further out toward the periphery of the bundle. An example of such an area is the block of tubes bounded by rows 32 and 35 and columns 73 and 79 in steam generator A based on previous RPC results and 100 KHZ conventional probe data in this region. The licensee should commit to inspecting these areas.
This commitment can be satisfied by reviewino the previous RPC and/or 100 KHZ absolute data for areas where a consistant pattern of distorted or non-ouantifiab e ECT signals exists which may be indicative of early stages Of IGA, and adjusting the inspection boundary to include these areas.
- b.
The ProDosed prograM areaV makes provi S ion for expandi no the inspection program beyond two rows from the previous repair boundaryIf detectable IGA indications are found.
The licensee should commit to expanding the inspection by at least one additional row of tubes beyond any location where a consistant pattern of non-quatifiable or distorted signals is found, to reduce the potential for missing possible out-lying tubes with significant IGA penetrations.
- 2.
Repair criteria should include the plugging of all unsleeved tubes within the broad boundary formed by tubes with detectable IGA indications and those tubes adjacent.to tubes with detectable IGA indications. This is consistent with the repair boundary rationale implemented during the previous inspection.
- 3.
Our review of the pulled tube data from the previous inspection outage indicates that tubes containing*
50% field ECT indications are generally penetrated between 90 and 100% through wall as determined by laboratory examination.
The licensee concluded that IGA penetrations beyond repair boundary were e50% (compared *to staff estimate of<70%) and that additional penetration prior to the upcoming inspection would be less than 8%. Therefore, the finding of any significant numbers of 50% indications during the upcomi nG CUtoCe Should not be eXDected.
The licensee's evaluation of the results of the upcoming inspection should include an assessment as to whether the results support the conclusions made during the previous outage regardino the degree of IGA penetration outs-ide the repair boundary Ind its rate of progression, and the conservatism of the repair, criteria.
.~
ENCLOSURE 2 TOPICS TO BE DiC5CUSSED AT PART OF NEETING WITH WESTINGHOUSE AND SOUTHERN CALIFORNIA EDISON REGARDING TUBE AND SLEEVE WALL DEFECTS AT REFERENCE JOINT 1
Brief review of the Reference joint design and joint fabrication procedures.
- 2. Description of the dissolution phenomenon (we would also like to see metallographic photographs of severe dissolution and actual lab specimens)
- 3. Caustive factors for the introduction of these defects.
- 4.
Specific problems encountered at San Onofre.
- 5.
Input values for rele vant fabrication parameters for each of the tubes which leaked as a result of dissolution
- 6. Baseline eddy current and ultrasonic results for the tubes which leaked.
- 7.
Corrective actions taken following the occurrence of problem.
- 8. The basis for the corrective actions.
. 10.
Current development efforts in the NDE area to improve the inspectability of the sleeve and tube wall at the reference joint.
When are improved NDE procedures to become available for field use?
- 11.
Safety Assessment (including consideration of ECT uncertainties, tube integrity considerations, and potential for. axial and lateral loadings during normal and-accident conditions).
ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION SAN ONOFRE UNIT NO. 1 Evaluate the effect of dynamic blowdown forces associated with a MSLB or FLB on the potential for propagating preexisting IGA defects in non-sleeved tubes to a gross or double-ended failure.
The results of this evaluation should be presented as a function of %1: through wall penetration..This evaluation should include the effects of loss of lateral support for inner row tubes as a result of support plate cracking and islanding.
Conclusions regarding safety significance should consider effects of eddy current uncertainty for IGA and address the conservatism of the current repair criteria.