05000270/LER-1982-002, Forwards LER 82-002/01T-0.Detailed Event Analysis Encl

Forwards LER 82-002/01T-0.Detailed Event Analysis Encl

ML20041A462
Person / Time
Site:	Oconee
Issue date:	02/05/1982
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20041A463	List: 05000270/LER-1982-002, Forwards LER 82-002/01T-0.Detailed Event Analysis Encl 05000270/LER-1982-002-01, /01T-0:on 820122,three Core Support Assembly Thermal Shield Bolts Found W/Heads Broken Off & Shock Pad Y-2 Attachment Bolts Discovered Broken.Caused by Intergranular Stress Corrosion Cracking.Pad Removed
References
TAC-10985, TAC-11316, NUDOCS 8202220188
Download: ML20041A462 (2)

LER-1982-002, Forwards LER 82-002/01T-0.Detailed Event Analysis Encl

Event date:
Report date:
2701982002R00 - NRC Website

text

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Vec t Pot sr o C N T IC L F PMo te t AREA 704 Sitaw Pa@vcMN February 5, 1982 373-4c83 Mr. James P. O'Reilly, Regional Administrator s M l f c, U. S. Nuclear Regulatory Commission j 'NQ 101 Marietta Street, Suite 3100 C

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Dear Mr. O'Reilly:

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Please find attached Reportable Occurrence Report R0-270/82-02. ThisYpbrt is submitted pursuant to Oconee Nuclear Station Technical Specification 6.6.2.1.a(9), 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.

This incident is essentially the same as Reportable Occurrence Report R0-269/

81-11 for which detailed descriptions and evaluations were provided by W. O. Parker, Jr, to James P. O'Reilly in letters dated July 24, 1981, August 5, 1981, October 5, 1981, and January 8, 1982. The results of the efforts conducted for the Oconee 1 incident are considered to be applicable to this incident at Oconce 2.

Ver -truly yours, s

p.m William O. Parker, Jr.

JFK/php Attachment cc: B&W Regulatory Response Group:

Director, Office of Management and Program Analysis J. J. Mattimoe, SMUD, Chairman J. H. Taylor, B&W Mr. T. M. Novak, U. S. Nuclear W. C. Rowles, TECO Regulatory Commission D. C. Trimble, AP&L G. Beatty, FPC Mr. P. C. Wagner, U. S. Nuclear R. J. Wilson, GPU Regulatory Commission Mr. W. T. Orders Records Center NRC Resident Inspector Institute of Nuclear Power Operations Oconee Nuclear Station 1820 Water Place Atlanta, Georgia 30339 8202220188 820205 0FFtoIALCOPY s/

PDR ADOCK 05000270 S

PDR T O A h J{

DUKE POWER COMPANY OCONEE NUCLEAR STATION UNIT 2 Report Number: R0-270/82-02 Report Date:~ February 5,'1982 Occurrence Date: January 22, 1982 Facility: Oconee Unit 2, Seneca, South Carolina Identification of Occurrence:

Core Barrel Assembly Thermal Shield Bolts Broken Conditions Prior to Occurrence: Refueling Shutdown Description of Occurrence: On January 22, 1982, during the visual inspection of the Oconee 2 Core Support Assembly, three thermal shield bolts were observed to have the heads broken off, but retained in the locking clips. Also, the attachment bolts for shock pad Y-2 were broken. Ultrasonic testing showed

- crack indications on 24 of the 96 thermal. shield bolts. Of these 24 bolts, 19 had their heads-broken off during removal.

Apparent Cause of Occurrence: The apparent cause of the thermal shield bolt failures is intergranular streus corrosion cracking as described in the letter of W. O. Parker, Jr. to James P. O'Reilly dated January 8, 1982.

Analysis of Occurrence: A detailed evaluation has been made of the safety implications of the thermal shield bolt failures for a similar incident on Oconee 1 (RO-269/81-11). Results of this evaluation are: reported in letters of W. O. Parker, Jr. to James P. O'Reilly dated July 24, 1981, August 5, 1981, October 5, 1981, and January 8, 1982 Approximately 25 percent of the bolts from all other major joints which utilize the A286 material have been examined and no indications of deterioration were found. The evaluation performed for Oconee 1 is considered applicable to this incident on Oconee 2; thus, it is considered that the health and safety of the public were not affected by this event.

Corrective Action

The 96 bolts and locking clips will be replaced with stud 3

and nut assemblies as described in the letter of W. O. Parker, Jr. to James P. O'Reilly dated October 5,1981. Shock pad Y-2 has been removed and will not be replaced.

Seven of the 96 thermal shield bolts have been sent to the Lynchburg Research Center for testing and further evaluation. All repairs to affected reactor vessel internals will be completed prior to startup.