ML20052A314

Forwards LER 82-004/01T-0.Detailed Event Analysis Encl

ML20052A314
Person / Time
Site:	Oconee
Issue date:	04/09/1982
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20052A315	List: ML20052A314 ML20052A320
References
NUDOCS 8204280190
Download: ML20052A314 (2)

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DUKE POWER COMPANY Powen Dust. DING 422 Socrrr Cucacu Srnzer. CuAur.orre, N. C. 2824a

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WILLIAM O. PA R M E R, J R.

Vicr PersiogNT TELEPwowt:AmEA704 Srtau PaoDuCTION April 9, 1982 373-4o83 9 R' O

Mr. James P. O'Reilly, Regional Administrator ,

, 4 U. S. Nuclear Regulatory Commission g gf Region II _d '

F 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 L 9

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Re: Oconee Nuclear Station 6" 4'e$g:

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Docket No. 50-287 Qi j g g_, \

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-287/82-04. This report is submitted pursuant to Oconee Nuclear Station Technical Specification 6.6.2.1.a(9), which concerns the discovery of conditiens not specifically considered in the safety analysis report or Technical Specifications that require corrective measures to prevent the existence or development of an unsafe condition, and describes an incident which is considered to be of no significance with respect to its effect on the health and safety of the public. My letter of 1: arch 12,1982 addressed the delay in preparation of this report.

Ver trulyyours,k

,s W h. L .

William O. Parker, J .

JFN/php Attachment cc: Document Control Desk Records Center U. S. Nuclear Regulatory Commission Institute of Nuclear Power Operations Washington, D. C. 20555 1820 Water Place Atlanta, Georgia 30339 Mr. W. T. Orders Mr. Philip C. Wagner NRC Resident Inspector Office of Nuclear Reactor Regulation Oconee Nuclear Station U. S. Nuclear Regulatory Commission Washington, D. C. 20555 cod ~

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DUKE POWER COMPANY OCONEE NUCLEAR STATION UNIT 3 Report Number: RO-287/82-04 Report Date: April 9, 1982 Occurrence Date: February 26, 1982 Facility: Oconec Unit 3, Seneca, South Carolina Identification of Occurrence: The 3A2 HPI and normal makeup nozzle thermal sleeve was found loose and the safe end to pipe area was cracked.

Conditions Prior to Occurrence! Cold shutdown Description of Occurrence: As a result of HPI-makeup nozzle safe end cracks at Crystal River in Florida, non-destructive examinations of Unit 3 HPI nozzle areas were conducted. Radiographic Tests (RT) and Ultrasonic Tests (UT) revealed that the 3A2 thermal sleeve was loose and displaced 5/8 inch upstream and that the safe end and upstream piping inside diameters (ID) were cracked. The RT of the 3B1 thermal sleeve indicated a partial radial gap between the thermal sleeve and safe end. 3Al and 3B2 tests revealed no anomalies.

Apparent Cause of Occurrence: The apparent cause of the 3A2 cracked safe end and pipe seems to be thermal fatigue. There appears to be a direct link between loose thermal sleeves and cracks in this area, but exactly why the thermal sleeves are loose is not known at this time. A Babcock and Wilcox owners group task force is investigating this problem to determine the cause.

Analysis of Occurrence: The deepest crack found was 20% through wall, and the material involved (type 316 stainless steel) should exhibit a leak before any break. If the cracks had not been found and a leak progressed to a pipe i rupture it would have resulted in a small break loss of coolant accident (LOCA) .

A small break LOCA has been analyzed in the FSAR, and that analysis indicates that the plant would be able to shut down safely. Thus, the health and safety of the public were not affected by this incident.

Corrective Action: The 3A2 cracked safe end, piping and thermal sleeve were replaced. The new thermal design incorporates features which should better resist movement. The 3B1 thermal sleeve safe end contact area was hard roll expanded to return the thermal sleeve to its intended condition.