ML19253B478

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Discusses Completed Field Audit & Preliminary Engineering Analysis of Random Sample of as-built safety-related Piping in Response to 790801 Ltr.Submits Proposal for Concurrence Re Returning of Reactor to Power Operation
ML19253B478
Person / Time
Site: Fort Saint Vrain Xcel Energy icon.png
Issue date: 09/04/1979
From: Justin Fuller
PUBLIC SERVICE CO. OF COLORADO
To: Seyfrit K
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
P-79198, NUDOCS 7910160244
Download: ML19253B478 (2)


Text

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gg . l September 4,1979 Fort St. Vrain Unit No. 1 P-79198 Mr. Karl V. Seyfrit, Director Nuclear Regulatory Ccnaission Region IV Office of Inspection and Enforcement 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012 Decket 50-267

Subject:

Audit of Safety Related Piping Systems

Reference:

PSC Letter P-79161, Dated August 1, 1979 Gentlemen:

Public Service Company of Colorado has completed the field audit and a preliminary engineering analysis of a random sample of as-built safety related piping is , metric and associated hanger drawings as committed to in the referenced correspondence.

The audit included a field verification of the as-built installation of the piping shown on 26 Class I piping isometric drawings and the 94 associated hanger drawings. The general validity of the seismic design inputs documentation on 18 of the isometric drawings and 64 of the hanger drewings was confirmed.

On the remaining 8 isometric drawings and 30 hanger drawings, inconsis-tencies judged to be pote.1tially significant were identified between the field installation and the reference documentation.

An analytical evaluation of the noted isometric drawing inconsistencies indicatas that they would not result in invalidation of the seismic qualifi-cation of the piping depicted on 'be subject isometric drawing.

An analytical analysis of the inconsistencies identified in the hangers indicates that 18 of the hangers of cor;ern fulfill Class I design require-ments.

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Mr. Karl V. Seyfrit September 4,1979 Page 2 The remaining 12 hangers have inconsistencies that may jeopardize the operability of the associated systems in the event of a design basis earth-quake. Because the sampling of isometric drawings and associated hangers was made on a random basis, no conclusions can be drawn as to the continued operability of those systems or portions of systems required to remain operable during and after a design basis earthquake.

On the basis of the results of the audit, Public Service Company of Colorado has determined that the piping system seismic hanger /suppor+ system for the Class I piping may not be installed per the design requirements defined in the FSAR and may require corrective modifications to bring the "as-built" systems into agreement with the design intent.

Because of the inconsistencies noted, the Public Service Company of Colorado has temporarily suspended operation of the Fort St. Vrain unit as of approximately 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on September 1,1979.

Public Service Company would intend to hold the unit out of service until such time as the inconsistencies in the 12 hangers in question can be resolved satisfactorily or until such time that the installation of those systems or portions of systems required to facilitate reactor primary coolant depressurization and decay heat removal thrcugh PCRV liner cooling can be confirmed to be in compliance with the seismic design criteria.

Following resolution of the inconsistencies in the 12 hangers 02 confirnation that those systems or portions of systems required to facilitate reactor primary coolant depressurization and decay heat removal through PCRV liner cooling are in confomance with the seismic design criteria, Public Service Company would propose to return the reactor to power operation and to then complete the confirmation of the seismic design inputs of the remaining Class I piping.

PSC requests NRC concurrence with this proposal.

If there are any questions, please refer them to this office.

Very ::ruly yours, hr J.K. Fuller, Vice President Engineering and Planning JKF/FES:pa A N f* 4 9 l w %