ML20106B613

Discusses Visual Insp of Top Longitudinal Tendons,Per 850115 Meeting Request.Visual Insp of 30% of Longitudinal Tendons for Buttonheads Noted.Inconsistency Exists Between Last Mapping of Raised Buttonheads & Current Insp Results

ML20106B613
Person / Time
Site:	Fort Saint Vrain
Issue date:	01/31/1985
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
P-85038, TAC-54639, NUDOCS 8502110706
Download: ML20106B613 (2)

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Company of Colorado P.O. Box 840 Denver, CO 80201 -0840 l

(303) 571 -7511 1

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January;31, 1985 Fort St2 Vrain Unit Noi 1 P-85038l Regional Administrator Region IV b$$N$

Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 g,g Arlington, Texas 76011 , fj Attention: Mr. E. H. Johnson Docket No. 50-267

SUBJECT:

Visual Inspection of Top Longitudinal Tendons

Dear Mr. Johnson:

As per your request at the January 15, 1985 meeting, 30% of the longitudinal tendons have been visually inspected for raised buttonheads. It was noted that some inconsistencies existed between the last mapping of raised buttonheads and the current inspection. In the Spring of 1984, liftoff testing was performed on all accessible top longitudinal tendons. Subsequent to liftoff testing, the tendons were mapped for raised buttonheads. A short period later, all raised buttonheads were to be removed for metallurgical examination. During this wire removal program the removed wires were not mapped since mapping had just been completed as part of the liftoff testing.

The current surveillance identified that a few wires were removed and not previously reported. Therefore, the surveillance was expanded to map all accessible top longitudinal tendons (89 out of 90). The results are as follows:

1.) Six wires were removed just after the Spring of 1984 liftoff testing without being reported. Four out of VM10, one out of VM30 and one out of VI35 were removed.

l 2.)i One tendon wire out of VM29 was mapped as missing / failed on both

, the current surveillance and the previous surveillance but was i

not reported in the metallurgical report as being failed. HOOe 3 8502110706 8501.31 M l PDR ADOCK 05000267 G t-O 8.M PDR I 1

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3.) Five new . raised buttonheads were reported to you per telecon..

.In actuality, only two new failed wires were found. The ,

confusion existed because three of the failed wires that were to j be removed. in the Spring .of.1984 for metallurgical examination l were not removed. The two new wire failures are one-in VM8 and

.one in VM42.. The total number of failed wires in these tendons are four in VM8 and two in VM42. These. two new raised buttonheads bring the total number of failed wires under-the~ top longitudinal tendon' caps to 58, which is.0.38% of the total longitudinal tendon wire population. ,

Considering ~t he extent of work which has been completed and is being pursued, PSC will submit a report .by March 18, 1985 which will

.summarizeJour work to date and. future plans regarding the tendon prestressing. system at Fort St. Vrain.

LIf you have any ~ questions, please contact M. H. Holmes at (303) 571-8409.. -

Very truly yours, hlY'7Y D. W. Warembourg

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Nuclear Engineering Division DWW/MJF/1dr 5

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