ML20108F156
| ML20108F156 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 02/22/1985 |
| From: | Tucker H DUKE POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| SD-414-85-02, SD-414-85-2, NUDOCS 8503120346 | |
| Download: ML20108F156 (3) | |
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DUKE POWErt GOMPANY P.O. HOK G3180 CHARLOTTE, N.O. 28242 HAL B. TUGKER ret ernon 35 FEB 20 P I
February 22, 2 -
(704)373-4s
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Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission
. Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Re: Catawba Nuclear Station Unit 2 Docket No. 50-414
Dear Mr. O'Reilly:
Pursuant to 10 CFR 50.55e, please find attached Significant Deficiency Report No. SD 414/85-02.
Very truly yours, l&
Hal B. Tucker LTP/mjf Attachment ec: Director Mr. Robert Guild, Esq.
Office of Inspection & Enforcement Attorney-at-Law U. S. Nuclear Regulatory Commission P. O. Box 12097 Washington, D. C. 20555 Charleston,~S. C. 29412 NRC Resident Inspector Mr. Jesse L. Riley Catawba Nuclear Station Carolina Environmental Study Group 854 Henley Place Palmetto Alliance Charlotte, North Carolina 28207 2135 Devine Street Columbia, South Carolina 29205 INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 l
8503120346 850222 OTRdAC COPY-PDR ADOCK 05000414 S
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CATAWBA NUCLEAR STATION INTERIM REPORT REPORT NUMBER: SD 414/84-02 REPORT DATE:
February 22, 1985 FACILITY:
Catawba Nuclear Station Unit 2 IDENTIFICATION OF DEFICIENCY:
While performing a preservice inspectiva on the shell to upper-head weld on Safety Injection Accumulator Tank 2D, Babcock & Wilcox discovered multiple rejectable indications. Due to this discovery and rejection by Babcock &
Wilcox, Duke radiographed the tank weld in question which was made by Southwest Fabricating and Welding Company, 'a Westinghouse sub-vendcr.
The subsequent radiograph, divided into 34, 12" intervals, yielded 31 intervals rejectable due to possible slag in the fill of this vendor weld.
Examination of radiographs determined 1that slag may possibly be present in 4-5% of weld thickness in 33-34% of weld length. This was reported as Duke Nonconforming Item (NCI) 19227.
INITIAL REPORT:
On January 25, 1985, C. Burger, NRC Region II, Atlanta, GA was notified of this deficiency by L. M. Coggins, D. M. Collings and T. L. Utterback of Duke Power Company, P. O. Box 33189, Charlotte, N. C. 28242.
COMPONENT AND/OR SUPPLIER:
Safety Injection System Accumulator tank Supplier:
Westinghouse Electric Corporation Haymaker Road / Northern Pike Pittsburgh, PA 15230 Manufacturer:
Southwest Fabricating and Welding 7525 Sherman Street Houston, Texas 77261-u
I DESCRIPTION OF DEFICIENCY:
The accumulators are part of the Safety Injection System (SIS), which provides emergency core and containment cooling in the event of a pipe break in either the primary Reactor. Coolant or secondary Main Steam system. In the worst of these cases, rapid depressurization of the Reactor Coolant system occurs and the SIS provides rapid injection of the tank contents (borated water) when the reactor coolant pressure drops below the tank cover gas pressure.
The weld containing theLindications joins the shell to the hemispherical upper-head. Both the shell and head are made from SA-264 composite material consisting of SA-537 Class 1 base steel with 5/32" SA-240 Type 304 cladding.
The minimum composite thickness of.the head is 0.95 inches and the minimum composite thickness of the shell'is 1.88 inches.
ANALYSIS OF SAFETY IMPLICATIONS:
A fracture evaluation was performed by the. Westinghouse Materials Technology Group to determine the safety significance of these indications. This evaluation concluded that even in the worst case, where the indications are assumed to extend to the inside surface and to be continuous around the vessel, sufficient safety margin exists to preclude tank failure. In any case, there would be a leak before break condition.
CORRECTIVE ACTION AND STATUS:
A review of vendor's radiographs, along with subsequent ultrasonic inspection, revealed indications on other SIS Accumulator Tank welds. Further examination of these. indications by Duke and Southwest personnel has determined that-some of these, including those on tank 2D, may actually be gaps in the shell to cladding bond, which would have no impact on the structural integrity of the vessel. A complete evaluation.will include examination from the inside-of the tanks, which will be complete by March 15, 1985. Duke will then schedule any repair work which is needed, and issue another report by March 26, 1985. This problem is also being investigated for Catawba Unit 1, the
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only other unit on the Duke System with tanks fabricated by Southwest Fabricating.
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