ML20055G688

Submits Results of Analysis of Component Cooling Heat Balance to Support Operation at 2,700 Mwt.Prior Administrative Controls Overly Conservative & No Longer Required

ML20055G688
Person / Time
Site:	Maine Yankee
Issue date:	07/19/1990
From:	Nichols S Maine Yankee
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
MN-90-72, SEN-90-209, NUDOCS 9007240072
Download: ML20055G688 (2)

Text

-_

Cw g,'

\\

)

1 s

u4 D E

MaineYankee L

- niTiIsiT tttemcny Fon uMNt siwet 1972 i

' EDISON ORiVE A AUGUSTA, MAINE 04336 + (207) 622 4868 i

bl 1

]

q July 19. 1990 MN-90-72 SEN-90-209 u

c o A

UNITED STATES NUCLEAR REGULATORY COMMISSION l

Attention:: Document Control Desk Washington, DC 20055-

References:

(a) : License No. DPR-36 (Docket No. 50-309)

(b) ~MYAPCo letter to-USNRC dated May 30, 1989 (MN-89-74)

Subject:

. : Component Cooling Heat Balance h

' Gentlemen:'

c Rdference (b) provided additional information regarding Maine Yankee's-component' cooling. water heat balance to support operation at 2700 MWth.' Based on J

the results' of. a preliminary analysis, certain conservative. administrative

. controls to restrict plant operations were established with the expectation that i hen a more detailed and realistic. analysis, was-completed, the restrictions could-w L"

be: reduced or eliminated. That analysis is now complete, supports the heat L

exchanger design-capability, and confirms that.the prior established Ladministrative controls were overly conservative and are no longer required.

y y Stone 4 Webster Engineering. Corporation (SWEC) has performed an updated heat lead analysis for the Primary and Secondary Component: Cooling (PCC and SCC) and the Service Water systemstfor design basis LOCA conditions. The analysis results show that the-PCC/ SCC systems can meet all required safety functions for service water inlet temperatures'up to 90*F and plant operation at 2700 MWth when'both-

'"new" service water heat'exchangers (E-4A and 58) are~ in service. The analysis resultsL also show.that:the' PCC/ SCC systems can meet all required safety. functions:

ateservice water' inlet-temperatures up to.80*F and plant operation at 2700 MWth' i

with'thef"old" (E-4B and E-5A)' service water heat exchangers.

d JMaine'. Yankee procedures for operation of the PCC/ SCC and service water

' systems:normally line up the new heat exchangers (E-4A and.E-5B) in service and the old heat exchangers (E-4B and E-5A) in standby (except for infrequent mussel cleaning operations).

Peak service water inlet temperatures are generally less

'than:75*F and there-has been only one known period of very brief duration when

service' water temperature exceeded 78'F and this occurred during an unusually hot l

summer.

Using Probabilistic Risk Assessment, Maine Yankee has calculated that the probability' service water will exceed 77'F, combined with a LOCA requiring aSEN90209.LTR

,j

^/T 9007240072 900719

$[

<PDR ADOCK 05000304,

/p r

PDC

.f

.p m

[4.L...

,, 7.

4,.

1. "0 '

~E Lw

' UNITED STATES NUCLEAR REGULATORY COMMISSION-MN-90-72' Attention: Document Control Desk Page 2 g

recirculation and a failure of. one train of ECCS is-less than' 4.8E-8.

Based on

. the low probability of this worst case scenario, administrative controls related to' service water' inlet temperature are not necessary.

Please contact.us should you have any questions-regarding this matter, Very truly yours,.

. S' A.)

Yb f

S. E. Nichols Licensing Stction Head SEN:SJJ c:.

Mr. Thomas T.-Martin Mr. Charles S. Farschall

Mr. Eric J. Leeds s

6 S I i

( ' i r

.SEN90209.LTR.

a

&