ML19340A419
| ML19340A419 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 10/11/1972 |
| From: | US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19340A418 | List: |
| References | |
| NUDOCS 8003260736 | |
| Download: ML19340A419 (2) | |
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TOPICAL REPORT EVALUATION I
Report Identification: BAW-10047, Revision 1 A Study of Discontinuities in Control Rod Drive Motor Tube Rep' ort
Title:
Extensions Report Date: August 1972 P
Originating Organization: Babcock & Wilcox-
, Materials Engineering Branch, Mechanical Engineering Branch Reviewed By:
and Reactor Systems Branch, AEC Directerate of Licensing
SUMMARY
OF TOPICAL REPORT Some riot'or extension tubes exhibited localized variations in wall thick-ness and discontir,uities on the inner surf ace, not detected by ultra-sonic testing techninues certified to be in accordance with ASME Code, The investigation included metallographic and chemical Section III.
examinations, specialized ultrasonic inspection techniques and fracture mechanics analysis.
Tubes meeting the Code-required m'inimum wall thickness based on the original design temperature of 650*F and having no indicated dis-continuities deeper than 5% of the nominal-finish wall thickness will be I
accepted and returned to the field for service.
I Where wall thickness permits, discontinuity indications greater than 5%
of the nominal-finish wall thickness will be reduced by honing the I.D.
surface of the tubes while maintaining the ASME Code,Section III i
Tubes required-vall-thickness-baseri nn the original design temperature.w j
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proper wall thickness.
l The remaining tubes withheld, because of wall thickness, will be re-
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evaluated based on a revised design temperature of 450*F, which is a i
more realistic but still conservative value of the maximum temperature i
The basis for this at which the upper extension tubes will operate.
i revised.tcperature has' been established by extensive mockup testing at A testing the Alliance Research Center and measurements at Oconee 1.
and surveillance program-wilLalso be implemented on one of the first e
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facilities utilizing the affectdd motor tu6e extensions in order.co, verify that the mockup tests accurately similated the operating condi-
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tions of r. typical f acility.
.SUWARY OF REGULATORY EVALUATION Repair of. tubes which showed excessive discontinuities has been' accore plished by honing: the I.D., which is allowable in accordance with ASME Code, Section' III, Class 1 Components, paragraph NB-2558 Some motor tube extensions have' localized variations and some repaired -
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tubes also had a wall thickness below the Code-allowable thickness for a design condition of 650*F and.2500 psig. These tubes were re-evaluted on tiie basis of 450'F and 2500 psig, which is allowable by ASME Code,Section III, Class 1 Components, pragraph.NB-3112.2 The actual maximum meta 3 temperature which exists under' the specified normal oper-l ating condition was determined by mockup testing and measurement at l
Oconee 1.
Specialized ultrasonic test. inspection techniques have been developed to accurately define the depth of-discontinuities. Indicated discontinuity.
depths no greater than 5%. of tha, nominal wall thickness are allowed.
L' This' is in accordance with ASHE Code,Section III, Class 1 Components, I
paragraph NB-2552.1.
A fracture mechanics analysis by Southwest Research Institute has con-cluded that a 90 mil notch in the worst case longitudinal direction is acceptable f or the design life of the tube. -We concur with the SRI
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i findings.
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- REGULATORY POSITION
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.We conclude' that the motor tube. extensions -accepted under the criteria proposed by B&W have an adequate margin of safety and that the subject report is acceptable provided the results of the testing and sur-l These results
.veillance program are ' consistent with-the mockup tests.
l should be documented by a revision or supplement to this Topical Report.--
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