ML20030D287
| ML20030D287 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 08/26/1981 |
| From: | William Jones OMAHA PUBLIC POWER DISTRICT |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8109010130 | |
| Download: ML20030D287 (3) | |
Text
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Omaha Public Power District 1623 HARNEY a OMAHA, Pd E B R A S M A 68102 e TELEPHONE 536.*000 AREA CODE 402 August 26, 1981
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hdOID Mr. Robert A. Clark, Chief
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UG 31gp U. S. Nuclear Regulatory Commission P
Office of Nuclear Reactor Regulation
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Division of Licensing Operating Reactors Branch No. 3 b
Washington, D.C.
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Reference:
Docket No. 50-285
Dear Mr. Clark:
Omaha Public Power District will be performing ultrasonic exami-nations of the reactor vessel head stids for the Fort Calhoun Station during the refueling outage scheduled to start September 18, 1981.
The District requests Comr..ission approval to use ASME Boiler and Pressure Vessel Code Case N-307 for ultrasonic examinations of vessel studs when conducted from the center drilled hole. The attached Southwest Research Institute letter provide additional information in support of this request. Additionally, the District would appreciate a response to this request by September 29, 1981.
Sincerely, plril Vy $v}$@ '
v W.C.Jhnes Division Manager Production Operations WCJ/KJM/TLP:jmm Attachment cc:
LeBoeuf, Lamb, Leiby & MacRae l
1333 New Hampshire Avenue, N.W.
Washington, D.C.
20036 6m 8109010130 810826 k
PDR ADOCK 05000285 P
Attachment ASME BOILER AND PRESSURE VESSEL CODE CASE N-307 REVISED ULTRASONIC EXAMINATION VOLUME FOR CLASS 1 BOLTING, EXAMINATION CATEGORY B-G-1, SECTION XI, DIVISION 1, WHEN THE EXAMINATIONS ARE CONDUCTED FROM THE CENTER DRILLED H0LE Attached for your consideration is a copy of the subject Code Case N-307. This Code Case was submitted and approved by ASME because there was no practicable method to comply strictly with the Summer 1975 Addenda of Section XI, Figure IWB-3515.1, which requires examination of 100% of the volume of the stud. Even using various combinations of the Code Section V ultrasonic method of using a 0-degree straight beam applied to both ends of the stud and the Southwest Research Institute (SwRI) method of a 60-degree angle beam from the access hole would not be totally Code compliant, and would require the addition of side-drilled holes and a 3/8-inch by 3-inch, plugged, flat-bottomed, end-drilled hole to the existing stud calibration blocks.
Code Case U-307 solves the problem outlined above with one proviso; since Code Case N-307 is not included in Regulatory Guide 1.147, In-spection Code Case Acceptability, it can only be used upon written approval by the Commission.
The Fort Calhoun Station Long-Term Inspection Plan indicated that reactor vessel head stud examinations are scheduled during the next refueling outage. Accordingly, the District requests Commission author-ization to use Code Case N-307.
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e CASE N-307 CASES OF ASME BOILER AND PRESSURE VESSEL CODE Meeting of October 31,1980 Approved by Council, January 15,1981 This Case shall expire on Jar.uary is,1984 unless previously annulled or reaffirmed.
Case N 307 Revised Ultrasonic Examination Volume for Class 1 Bolt-ing, Examination Category B-G 1,Section XI, Division 1, When the Examinations Are Conducted frorn the Center.
Drilled Hole Inquiry: When ultrasonic examinations are conducted from the center-drilled hole of Clau 1 bolts or studs to satisfy the examination requirements of Examination Category B-G 1, nwy the examination volume be limited to the cylindrical region defined by A B C-D E F A in the attached sketch?
(See next page for sketch)
I Reply: It is the opinion of the Committee that, when conducting ultrasonic examinations from the center-drilled hole of Class I bolts or studs to satisfy the exami-nation requirements of Examination Category B G 1, the examination volume may be lindied to the cylindrical region defined byA B-C-D E F Ain the sketch referenced by the Inquiry.
1 679 suPP. 4 - NC
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