ML19261F260

LER 78-008/01T-0:on 780202,facility Flooded once-through Steam Generator Feedwater Nozzles During Operation Below 5% Full Power Per B&W Recommended Procedure

ML19261F260
Person / Time
Site:	Three Mile Island
Issue date:	02/16/1978
From:	METROPOLITAN EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19261F259	List: ML19261F258 ML19261F260
References
LER-78-008-01T, LER-78-8-1T, NUDOCS 7910250698
Download: ML19261F260 (2)

Text

. February 16,1978 GQL c'%

NARRATIVE OF LICENSEE EVENT REPORT 78-08/1T *

'n' hen the Main Steam Line Break Analysis was originally performed, the B&W recc== ended operating procedure required a 30" vater levs1 in the CTSG's at low power levels. As B&W gained operating experience, flood-ing of the feedvater nozzles at low power levels was recce= ended to prevent thermal shocking of the nozzles. 'IMI-1 has been following the latter B&W recoc= ended operating procedure and operates with the second-ary side feedvater nozzles submerged when belov 5% full power in order to avoid kng-term feedvater nozzle ther=al degradation. Operation .

vith feedvater nozzles submerged, when below 5% full power was apparent ,

ly not considered for the Steam Line Break Analysis and is therefore reportable per section 6.9.2.A(9).

Since these conditions occur during startup and shutdown, which constitutes a small percentage of total operating time, the probability of a steam line . break occurring during startup or shutdown is significantly less than the probebility of a steam line break occurring as analyzed.

Preliminary Met-Ed analysis indicates that should a main steam line break occur during operation belev 5", full power with OTSG nozzles flooded, no return to criticality vill occur following reactor trip. However, the TMI-1 shutdown and cooldovn procedures have been changed to prevent opera-tion below 5". full power vitb the OTSG nozzles flooded. Met-Ed is atte=pting to verify the above preli=inary evaluation, and to obtain B&W's concurrence with Met-Ed's analysis.

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REPCRT DATE EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h 1 lIn accordance with a B&W reccenended overating trecedure. mvI-1 kog wa - c1 mm. e I y 10TSG feedvater nozzles during operatien belev 5% full power. This cenditien was not I g analyzed in the FSAR and is therefore reportable ter 6.9.2. A(9) . Because this utm- 1 y tien occ;rs only during startup ar.1 shutdown, the erobability of a steam line break at1 4

9 l such times u significantly less than the probability of a steem line break cecurrinc !

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CAUSE DESCRITTION AND CORRECTIVE ACTIONS o lWhen the Main Steam Line Break Analysis was originally performed, the B&W recc= mended l i (cperating procedure required a 30" vater level in the OTSG's at lov tower levels. As I 7 lB&W gained operating experience, flooding of the feedvater nozzles at low power levels 3 lvas reccc= ended to prevent ther=al shocking of the nozzles. The shutdown and cooldevnl 4 l procedures were changed to prevent floeding the nozzles when <:5% full power. .

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LOSS OF OR DAMAGE TO FACILITY TYPE D ESCHiP TION 8 9 h 10 NA 80 l

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