05000250/LER-1979-040-01, /01T-0:on 791212,insp in Accordance W/Ie Bulletin 79-14 Revealed Incorrect Modeling of Horizontal Valve Mass. Cause Unknown.Plant Change/Mod Will Be Implemented to Modify Supports Prior to Completion of Refueling Shutdown

/01T-0:on 791212,insp in Accordance W/Ie Bulletin 79-14 Revealed Incorrect Modeling of Horizontal Valve Mass. Cause Unknown.Plant Change/Mod Will Be Implemented to Modify Supports Prior to Completion of Refueling Shutdown

ML17339A520
Person / Time
Site:	Turkey Point
Issue date:	12/28/1979
From:	Schoppman M FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML17339A519	List: 05000250/LER-1979-040, Forwards LER 79-040/01T-0 05000250/LER-1979-040-01, /01T-0:on 791212,insp in Accordance W/Ie Bulletin 79-14 Revealed Incorrect Modeling of Horizontal Valve Mass. Cause Unknown.Plant Change/Mod Will Be Implemented to Modify Supports Prior to Completion of Refueling Shutdown
References
IEB-79-14, LER-79-040-01T, LER-79-40-1T, NUDOCS 8002040549
Download: ML17339A520 (3)

LER-1979-040, /01T-0:on 791212,insp in Accordance W/Ie Bulletin 79-14 Revealed Incorrect Modeling of Horizontal Valve Mass. Cause Unknown.Plant Change/Mod Will Be Implemented to Modify Supports Prior to Completion of Refueling Shutdown

Event date:
Report date:
2501979040R01 - NRC Website

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REPORTABLE OCCUPRENCE 250-79-40 LICENSEE EVENT REPORT PAGE TLJO Additional Event Descri tion and Probable Conse uences:

On Hednesday, December 12, 1979, notification was recei ved from our Architect-Engineer that inspections and reanalyses in progress in accordance with USNRC ISE,Bulletin 79-14 had revealed a potential problem associated with the valve

eights on the feedwater bypass lines.

Specifically, the problem was thought to be associated with a discreoancy between the correct valve weights and the weights used in the model.

.The valves in question were the feedwater bypass regulators (FCV-3-479, FCV-3-489, FCV-3-499), the associated check valves (3-20-131, 3-20-231, 3-20-331),

and the two manual isolation valves. in each of the three feedwater bypass lines (3-20-130, 3-20-132, 3-20-230, 3-20-232,

, 3-20-330, 3-20-332).

Reference FSAR Figure 10.2-2.

USHRC ISE-Region II was notified of the above information both verbally and by fascimile transmission.

Further review and evaluation revealed that there were no problems. with overstressing due to differences in valve weights.

However, review disclosed a modeling error associated with a 6 inch x 4 inch reducer with a different section modulus and not accounting for the valve mass in the X-Z (horizontal) direction.

Results of reanalysis with the correct valve weights and corrected reducer modeling indicates that the line could become non-functional with the existi ng supports during a seismic event in conjunction with other loading criteria.

A similar occurrence (relating to the inspections pursuant to USNRC I&E Bulletin 79-14) was reported'as LER 250-79-26.

Additional Cause Descri tion and Corrective Actions:

The evaluation has revealed that there are no problems with overstressing due to differences in valve weights.

Additionally, the incorrect modeling of the horizontal valve mass was determined to be a unique problem.

Based on the reanalysis, a plant change/modification will be designed and installed, as necessary, prior to completing the current refueling shutdown..

Because of differences in the piping and support configuration on Unit No. 4, the equivalent system segments meet the acceptance criteria.

A full accounting of inspection results and repairs will be made in response to USNRC ISE Bulletin 79-14.