ML20137J670

Forwards Info Obtained Form 970402 Telcon Re GL-96-06

ML20137J670
Person / Time
Site:	Callaway
Issue date:	04/02/1997
From:	Mcnally B NRC
To:	NRC
Shared Package
ML20137J649	List: ML20137J645 ML20137J670
References
GL-96-06, GL-96-6, NUDOCS 9704040093
Download: ML20137J670 (2)

Text

r j , 3 PR 02 '97 10:07AM LE NUCLEAR P.2 l

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INFORMATION FOR ,

4/2/97 TELECON ON GL 96-06 l

Attached is some information for today's 2:00 P.M. EST phone call regarding Generic Letter 96-06.

11 McNally l i

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l 9704040093 970402 PDR ADOCK 05000483 p PDR

,,APR 02 '97 10:08AM UE NUCLEAR p.3

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l Unlan Electrida Paal*taa on the Ther-al Overnrassurimatlan issue of GL96-06 i

i j The overpressuriratian concern of OL96-06 does not constitute a ocodition outside of Callaway's design basis. Callaway's Design basis is that the piping meet the requirements of ASME. This

. condition is only a concem nlative to faulted /cmergency conditions. Faulted stresses as addressed by ASME involves an evaluation of primary stresses.

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' Since the manhanism that is sa!.4 the pipe is selflimiting, once the pipe has expanded enough i to acwoo-edste the increased volume, no further strain will be i=aaa A hisis ddinedby ASME

as a ==aadaty smos. De maximum amount of strain calculated for Callaway piping is only a j fraction of the strain required to cause failure.

' NB 3213.9 states: "The basic characteristic of a =arnadary stress is that it is self-linuting Local

yackhng and minor distortions can satisfy the condrtions to occur and fhilure from application of j the stass is not to be -a~*ad_ " %is is ai ai8aa'*y diffemnt than a pressure stress. Prosaure i stress is a prunary stress that is not selflimiting As the piping expands with a primary stress, the

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pressure is not relieved as it is in this case. This particular F++= == (expansion of the fluid) will l

! not reach plastic instability, the yistding and distortions of the piping will satisfy the condition

causmg the strain to occur. Ca==~;n~*1y, a single application of the strain will not cause the piping to fail. While the expansion of the fluid will cause the pressure to increase in the pipe, this pressure does not act as a primary stress and the use of the hoop stress equations of NC-3641, and the pressure stress terms ofNC 3650 are not applicable to this condrtion. These equations are designed to ensure there is sufficient eiAmans to prevent the pressure froin ever yielding the pipe, since pressure stmas will rupture if taken past yield (and stram hi kog does not nutigate the increasing deformation). His clearly cannot happen in the instance of the ==^adary stresses described in the scenario of OL96-06. In fact, it is the deformation of the pipe (past yield in some cases) that prevents the pressure fkom failing the pipe. Additionally, increasing the Mdma== of the pipe will not reduce the amount of strain incurred by the expansion of the fluid.

ASME III Section NC 3621.2 requires that the system be designed to withstand the pressure increase due to the expansion of fluid. De code does not delinasta =p- 18aany how this analysis is to be performed, or what the opgegiate allowable stress values may be. Callaway's analysis demonstrates that the piping will withstand this increase. The equations in NC 3650 deal with primary stresses (pressure, dead weight, live loadmg, etc.) with the exception of equation 10 and 11 which evaluate thermal stresses These equations (10 and 11) are excluded from evaluation in Emergency and Fauhed aaadhiana. Section NC-3611.3( c) specifically excludes the evaluation of

~ ==*icos 10 and 11 for omergency conditions. App = dix F (Rules for Evaluatice of Faulted ~

Condrtions) specifically states "Only linuts on primary stresses are prescribed. Dermal stresses resulting imm Faulted Conditions need nor % considered."

FSAR section 3.9(b) does not require that Wa'y stresses (thermal stresses) be included in the analysis of piping fbr fkuhed condrtions.

Since the existing condition meets the requhements of NC 3621.2, and is explicitly exempt fhxn enamidaration as emerscocy and faulted condstions, this meets ASME code requirements and is therefore not outside the design basis.

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