ML20010B800

Notifies of Plans to Evaluate Seismic Supports of 2-inch & Under Piping at Facility & to Provide Corrective Action as Required

ML20010B800
Person / Time
Site:	Fort Saint Vrain
Issue date:	09/29/1977
From:	Justin Fuller PUBLIC SERVICE CO. OF COLORADO
To:	Denise R Office of Nuclear Reactor Regulation
Shared Package
ML20010B798	List: IR 05000267/1976007 IR 05000267/1976010 IR 05000267/1976013 IR 05000267/1977009 IR 05000267/1977014 IR 05000267/1978001 IR 05000267/1978010 ML20010B797 ML20010B800 ML20010B801 ML20010B807 ML20010B810 ML20010B811 ML20010B814 ML20010B816 ML20010B819 ML20010B823 ML20010B832
References
FOIA-81-95 P-77199, NUDOCS 8108180089
Download: ML20010B800 (2)

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1 public Service Company F Coh nda l

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S P. O. Box 361, Platteville, CO 80651 D

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1 September 29, 1977 Fort St. Vrain 4

Unit No. I 1

P-77199 f

Mr. Richard P. Denise Asst. Director for Special Projects Division of Project Management Nuclear Regulatory Commission Washington, D.C. 20555 Docket #50-267 i

Gentlemen:

4 Subj ect:

Supports for 2'.' and Under Piping i

As the result of the review of seismic systems and equipment that was performed following discussions with the NRC in May, 1976, it was necessary to review the piping system support design for those portions of systems or equipment that were revised from Class II to Class I status. This revision from Class II to Class I resulted in field checking approximately 500 isometric drawings that defined the affected portions of 2" and under piping systems in the plant.

These isometric drawings serve as the basis for Fort St. Vrain piping seismic certification.

The results of the fi.1d check of thest 300 isometric drawings indicated that in addition to the piping support revisions required because of Class I boundary extensions, other errors in the supports of the existing Class I portions of the piping systems also existed.

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These results prompted an audit conducted by the PSC/QA department on a 5% to l

i 6% sampling of the isometric drawings for field run piping which indicated a I

possible 4% to 5% error rate in the seismic supports in the field. This is a preliminary finding. The errors identified fall into the following general categories:

1) Missing hangers i

2)

Improper hangers used in the installation

3) Hangern not located in the proper location j

4) System piping configuration does not agree with the isometric drawings i

In reviewing the results of these preliminary findings, it would appear that the errors identified exist principally on systems whose isometric drawings were finalized prior to mid-1974. A review of isometric drawings with revision dates i

later than mid-74 reveals a very low error rate although some error does exist.

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Because of the random nature of the errors defined, and the conservatism in-cluded in the design of the 2" and under support system, we do not believe the prob 1cm identified constitutes a condition that could be detrimental to the health and safety of the public should a seismic event occur.

0103180089 810514 PDR FOIA W l% W 4. W E lL-G.

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(s-September 29, 1977 Mr. R. P. Denise Page two Because of the results indicated by our sample audit, we are presently mounting an effort to evaluate the seismic supports of the 2" and under piping and to provide corrective action, as required.

In addition to the evaluation of the seismic supports for 2" and under piping, l

we will also review and evaluate the supports of the small field mounted instrument racks. These racks were installed per a standard specification that had been previously qualified to meet seismic requirements. The review of these instrument rack supports is being made to assure their adequacy and to close the loop on the complete seismic support system.

It is our present thinking that the evaluation and corrective action can be completed in eight to ten weeks.

Based on the extent of the problem identified, j

its effect on the health and safety of the public, and the program outlined to further identify and rectify the problem, we request your concurrence to continue with the rise-to-power program above 40% poser in parallel with the seismic support effort.

k'e request your concurrence at the earliest possible date.

Very truly yours, l

PUBLIC SERVICE COMPANY OF COLORADO I

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K. Fuller j

Vice President j

Electric Engineering and Planning JKF:il l

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