ML20086B242

AO 50-267/74-19A,per Dro Bulletin 74-3,Class I Support Structure Inspected.Design Problems Existed on 24 of 238 Class I Structures.Addl Structural Steel Bracing & Reinforcement Added

ML20086B242
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/05/1974
From:	Reader J, Swart F PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20086B210	List: ML20086B207 ML20086B221 ML20086B234 ML20086B242
References
AO-50-267-74-19, ROB-74-3, NUDOCS 8311170114
Download: ML20086B242 (3)

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j .. REPORT DATE: j! aver [y)1l971. A(v *dtAL OCCURRE!;CE l

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! ' FORT ST. VluI: : UCLEAR CE!;ERATI::C STATIO:i ~.c., -

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PUSLIC SERVICE COMPA?.T OF COLORADO P. O. BOX 361 C 1, PLATTEVILLE, COLORADO 80651 '

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REPORT !;0. 50-267/74/19A I -

l FINAL IDE!TIITICATIO:; 0F OCCURRE!:CE:

As requested in AEC DRO BULLETIN NO. 74-3, Public Service Company of Colorndo and General Atomic Company have conducted on inspection of the Class I support structure at Fort St. Vrain.

The results of the inspection progran indicated that design prob 1cus existed -

on 24 of the 238 Class I support structures at Fort St. Vrain.

This conditien is considered reportable under Paragraph B-3 of AEC DRO Bulletin'::o. 74-3.

CONDITIONS PRIOR TO OCCURRE!:CE: __

Steady State Power Routine Shutdown Hot Shutdown Routine Load Change X Cold Shutdown Other (specify) l Refueling Shutdown Routine Startup

( The major plant. para eters at the time of the event were as follous: ..

1 Power PTR, O }Cith ELECT, O MWe Secondary Coolant Pressure N/A psig l Temperature N/A 'F Flow #/hr.

0 Primary Coolant Pressure O psig l

Temperature 100 ' 'F Core Inlet l 8311170114 741102 PDR ADDCK 05000267 100 'F Core Outlet S PDR Flow o

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M.#/hr.COPf;ligiON

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i The results of the inspection progran of the Class I support structures

! indicated that a problem existed regarding the scismic design of some Class I

sept ort et tuet.ures. The problem related to the support structure natural

! vibratienal f requency and the design carthquake vibrational f requency on 24 i Class I support structures.

The specific types of support structures found to have probicms were:

1.) Ecat Exchanger Support Structures 2.) Filter Support Structurcs

- 3.) Various Tank Support Structures APPARANT CAUSE OF OCCURRENCE: X Design Unusual Service Cond.

Including Environ.

I Manufacture Component Failure

) Installation /

Construction Other (specify)

Operator Procedure ANALYSIS OF OCCURRENCZ:

l The analysis of this problem consisted of a visual inspection of Class I support structures by Concral Atomic Company engineers to verify that the field configuration was accurately reflected in the scismic calculations; and -

i where incorrect assumptions were cade, further analysis and structural additions were specified.

General Atemic Company ciccted to' have the Sargent & Lundy Structural Engineering Departtent perform the additional analysis where required.

$ COFRECTIVE ACTION:

Additional structural steel bracing and reinforcement has been added to those structures (24 in all) found to have scismic design problems. The physical work has been completed and scismic calculations have been forwarded to Public Service Cocpany for review.

Public Service Company is currently in the process of performing an in-dependent review of all calculations and "as-built" configuration for those structures requiring additional reinforecuent.

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During Public Service Company's review of the scismic calculations submitted by Cencral Atenic Ccrpany an error was found on one (1) structure r calculation regarding an assumption made in the General Atomic / ,

Lundy calculations.

and the additional structural steel bracing indicated has been installed on this support structure.

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FAILURE DATA /SI".I',I AR REPORTED OCCURRENCES :

None of the Class I support structures have evidenced any sign of actual fa11ure. Also, there has not been any similiar reported occurrences j

at Fort St. Vrain.

PROGRA'51 TIC IMPACT:

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CODE IMPACT:_

I None i

Approved by:

Prepared by: A

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u Frederic E. Svart A .

N fResident II.' Reader '

Engineer S$1perintendent Nuclear Production Fort St. Vrain Nuclear Generating Station .

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