ML20031D041
| ML20031D041 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/28/1981 |
| From: | Rhode D NIAGARA MOHAWK POWER CORP. |
| To: | Brunner E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8110090235 | |
| Download: ML20031D041 (2) | |
Text
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M Y N1 RA "Ol RU AWK NIAGARA C.C HAWK POWER CORPORATION /300 ERIE BOULEVARD WEST. SYRACUSE, N.Y.13202/ TELEPHONE (315) 474-1511 September 28, 1981 Nil.jh'4{
Office of Inspection and Enforcement Region I
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Attention: Mr. Eldon J. Brunner, Acting Director
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[{s fj AC Division of Resident and Project Inspection 007 yp U.S. Nuclear Regulatory Comission
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gg 8 J 637 Park Avenue King of Prussia, PA 19406
Dear Mr. Brunner:
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Re: Nine Mile Point Unit 2 Docket No. 50-410 On September 6,1979, Niagara Mohawk sub.nitted a final 50.55(e) report regarding inadequate nondestructive exa71 nation of the Unit 2 containment liner welds.
In this report it was stated that a sample of the instrument penetration adaptor to sleeve welds would be ultrasonically reexamined by September 1979 to ensure that the ultrasonic technique used by the fabricator provided a 100 percent volumetric examination of the welds.
If the sample revealed an unacceptable number of indications,100 percent reexamination would be performed.
Niagara Mohawk's letter of April 27, 1981 provided an updated status and schedule for completion of the correc.tive action for each containment liner weld type discussed in our September 6,1979 50.55(e) final report.
In this letter it was indicated that the instrument penetration adaptor to sleeve welds were reexamined and required repairs completed in September 1979.
However, the following additional information regarding the documented corrective action is provided.
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0110090235 810920 e)DR ADOCK 05000 S
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/ September 28, 1981 Page 2 The results of the ultrasonic reexamination conducted in September 1979 on the adaptor to sleeve welds produced numerous aisleading indications when scanning the weld area. This is believed to be due to the configuration of the joint, the thickness of the base metal (3/16 inch), the small diameter of the sleeve (2 3/8 inches and 2 5/8 inches), and the stainless steel to carbon steel weld. This prevented evaluation of indications to the ASME code cri teria. Therefore, the quality of the welds could not be determined by ultrasonic techniques.
In accordance with the ASME Code Sections NB or NE.. the weld configuration in question is required to be examined by either an ultrasonic or a liquid penetrant method. Therefore, since a code acceptable ultrasonic examination could not be achieved, attempts to verify the fabricator's ultrasonic examinations were stopped and the requirement was deleted from the specification. Since a liquid penetrant examination had also been specified and is all that is required by code, a program was then initiated to verify by sample testing the validity of the fabricator's liquid penetrant examinations.
In January 1980, samples of 12 instrument penetrations in four different assemblies were liquid penetrant examined with satisfactory results, assuring that the fabricator's original liquid penetrant examinations were valid. This verification of the liquid penetrant examinations and subsequent acceptance of the weld joints without repair is documented in N&D 1626 dated January 25, 1980.
Very truly yours, NIAGARA M0 HAWK POWER CORPORATION n/
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%2%^%V Vice President, System Project Management PEF / jab l