ML19319E099
| ML19319E099 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 10/11/1972 |
| From: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Mallay J BABCOCK & WILCOX CO. |
| Shared Package | |
| ML19319E096 | List: |
| References | |
| NUDOCS 8003310608 | |
| Download: ML19319E099 (1) | |
Text
r%
V. N 9
l
.g
.Cf (q 4.
UNITED STATES
-.g-ATOMIC ENERGY COMMISSION WASHINGTON. D.C. 20545
,%,, f Y OCT 1 1 tgn Mr. James F. Hallay Manager, Licensing i
Babcock & Wilcox l
P. O. Box 1260 Lynchburg, Virginia 24505
Dear Mr. Mallay:
The regulatory staff has completed its review of Babcock & Wilcox Topical Report BAW-10047, Revision 1, dated August 1972 and entitled "A Study of Discontinuities in Control Rod Drive Motor Tube Extensions."
You have indicated that this revision replaces the original Topical Report BAW-10047, June 1972. A sum =ary of our review is enclosed for your information.
As a result of our review, we have concluded that Topical Report BAW-10047, Revision 1, will be acceptable by reference in applications for construction permits and operating licenses provided the results of the testing and surveillance programs are consistent with the information supplied in this report. We understand that Oconee Nuclear Station Unit 2 has been selected for these programs. The results of the testing program should be reported to us within sixty (60) days upon completion of the tests and the results of the surveillance program should be reported within sixty (60) days upon the end of the first of the fuel cycles. The Topical Report should be revised or supplemented to include the results of these programs.
Sincerely, f
./C
- f R. ' C..DeYoung, Assistant Director for Pressurized Wa'ter Reactors Directorate'of Licensing
Enclosure:
1 Topical Report Evaluation l
B o us s1oggy
- C E
1 l
I t
t
?
1 I
I i
i TOPICAL REPORT EVALUATIO4 i
Report Identification: B/N-10047, Revision 1 l
A Study of Discontinuities in Control Rod Drive Motor Tube l
Report
Title:
Extensions
.. Report Date: ' August 1972 Originating Organization: Babcock & Wilcox Materials Engineering Branch, Mechanical Engineering Branch Reviewed By:
and Reactor Systems Branch, AEC Directorate of Licensing 1
SUK4ARY OF TOPICAL REPORT 4
Some motor extension tubes exhibited localized variations in vall thick-ness and disconti,nuities on the inner surface, not detected by ultra-sonic testing techniques certified to be in accordance with ASME Code, The investigation included metallographic and chemical Section III.
examinations, specialized ultrasonic inspection techniques and f racture mechanics analysis.
Tubes meeting the Code-required minimum wall thickne'ss 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
~
-accepted and returned to the field for service.
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 Tubes required wall thickness based-on the original design temperature.
3
- will then be reexamined ultrasonically for discontinuity depth and for i
proper wall thickness.
~ The remaining tubes withheld, because of wall thickness, will be re-evaluated based on a revised design temperature of 450*F, which is a
. more realistic but still conservative value of the maximum temperature The basis for this l
- at which the upper extension tubes will operate.
revised temperature has been established by extensive =ockup testing at A testing i
the Alliance Research Center and measurements at Oconee 1.
and surveillance program will also be implemented on one of the first 71//ohDN
__2
'W WU Qgg j
i i
f
. ~, -
.rv
.,s y
=-r r-
^
i 4
~
2-I
' facilities utilizing the affected motor. tube extensions in order to verify that the mockup tests accurately simulated the operating condi--
i tionsiof a typical facility.
+
sum!ARY OF REGULATORY EVALUATION Repair of tubes which showed excessive discontinuities has been accom-plished by honing the I.D., which is allowable in ~ accordance with ASE Code,Section III, Class 1 Co=ponents, paragraph NB-2558.
2 Some motor tube extensions have localized variat' ions and'some repaired tubes also had a wall thickness below the Code-allowable thickness for a 4
design condition of 650'F and 2500 psig. These tubes were re-evaluted i
on the basis of 450*F and_2500 psig, which.is allowable by ASE Code,Section III, Class 1 Components, paragraph NB-3112.2. The actual
+
- maximum metal temperature which. exists under the specified normal oper-ating condition was determin'ed by ' mockup tes' ting and measurement at Oconee 1.
t' Specialized ultrasonic test inspection techniques have been-developed to accurately define-the depth of discontinuities. Indicated discontinuity depths no greater than 5% of the nominal wall thickness are allowed.
~
1 This is in accordance with ASE Code,Section III, Class 1 Components, paragraph NB-2552.1.
i
- A fracture mechanics analysis by Southwest Research Institute has con-p cluded that a 90 mil notch in the worst case longitudinal direction is a
acceptable for the design 1,1fe of the tub'e.
We concur with the SRI findings.
REGULATORY POSITION l
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-veillance' program are consistent with the mockup tests. These results t
should be documented-by a revision -or supplement to this Topical Report.
k f
1 a
- Nl
^
rf zu
?
-l*""--4
'T F
W4*
- T---f5'T P
- b 4+e--
fWte
- W-M
'N?T
- TtMV FP*"
'#