ML20044A909

Responds to NRC Bulletin 90-001 Re Loss of Fill Oil in Transmitters Mfg by Rosemount.None of Listed Transmitters Installed at Plant in Aug 1988 Identified as Having High Failure Fraction Due to Loss of Fill Oil

ML20044A909
Person / Time
Site:	Point Beach
Issue date:	07/06/1990
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-90-067, CON-NRC-90-67, REF-PT21-90 IEB-90-001, IEB-90-1, VPNPD-90-318, NUDOCS 9007160339
Download: ML20044A909 (2)

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231 w tAchcan, ro. Box 2cn woukee. wi 53201 gtaj 22i 2345-w .

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• NRC 0 67 -

I,7 LJuly 6,r1990:

y  : U. . S . Nuclear Regulatory Commission 9W ATTN: 1 Document Control Desk '

. Mail Station P1-137 4

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,a Gentlemen:

L 1 j ' DOCKETS 50-266 AND 50-301  !

~ NRC BULLETIN NO. 90-01.' LOSS OF FILL-OIL  :

'IN TRANSMITTERS MANUFACTURED BY ROSEMOUNT

POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 j h Thisil'atteriis in response to NRC Bulletin No. 90-01 regarding the:

. failure.of Rosemount Model 1153 Series B, Model 1153 Series D, and:

1 Model 1154 transmitters due to'a gradual loss of fill-oil'from the .,

transmitter's sealed sensing modules, y

, Wisconsin Electric'- (WE) installed . four' Rosemount Model 1154DP6 J " differential pressure transmitters at the Point Beach Nuclear Plant J

-(PBNP)LinAugust 1988 to measure Safety Injection (SI). flow rates. E'

@ There are no other ?Model 1154 - or - any ~ Model 1153 transmitters.

' installed'at PBNP.

" Listed below are the equipment ID's'and serial

+jnumbers of;the SI: flow transmitters. <

.7 R PB11FT-00924 S/N 0420045 .:

Ne 7 4 PBliFT-00925 '

S/N-0420046 I PB2 FT-00924 'S/N 0420047

=PB2-FT-00925- S/NL0420048 3 N'Uw, ,

,b ' None of these transmitters are" from the ~ manufacturing lots' that-

'have been. identified by Rosemount.as having. a high failure fraction.

= due-: to loss However,,.these transmitters w e r e .i L3 of. fill-oil.

to the. July ull, 1989 date provided in' the x

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manufactured prior s 1

bulletin, and thus are potentially susceptible to an oil-loss 1 y + . failure.:  !

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These transmitters are on a stand-by system.and, therefore,;they.

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are L normally not - pressurized. Since the oil' loss mechanism' is

!: l pressure dependent,-these unpressurized transmitters should=not .

exhibit-oil.. leakage while in stand-by. The SI pumps are tested

= 1 approximately.once per month for in-service testing and once per i yearf during refueling . outages. The SI flow transmitters are l

' pressurized during-these' operations, which amount to about 15-20

, . hours per year. .In light'of this minimal time at pressure and the 0W 1 c9007160339 900706

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- July _6, 1990 4 Page 2

- amount ~ of; time required for a significant amount of oil- loss to . '

occur, there is no reason to believe that any significant oil' loss would have occurred in these transmitters. This was verified.by a  ;

review ' of' calibration, records for the transmitters. 1 They. are '

calibrated once'per year, just prior to their respective unit's refueling outage. As a result, they have each been calibrated.

- twice since-their original installation calibration. A review of

- the calibration records shows no indication of a zero or span shift that may -be associated with a loss of fill-oil. Although some transmitters show a shift in.zero and span in the same direction for both calibration periods, it is not believed that this is.due

to alloss of fill-oil, since the percent change is approaching zero with each. subsequent calibration. Thus, calibrations for zero and span are holding better, not worse, as time goes on.

Rosemount has indicated that additional quality control 'and-modified assembly specifications used on sensing modules 4

' manufactured after July 11, 1989 should significantly reduce the  !

- possibility for failure due to loss of fill-oil. In light of this, t Wisconsin Electric is planning to replace the sensing modules in the four SI flow transmitters installed at Point Beach. Enhanced <

surveillance of these transmitters will not be required once the sensing. modules are replaced. The replacement ' of- the sensing modules will'be completed:in 1991. Since these transmitters are .

installed on a- stand-by system - and thus far calibration records  !

show no' indication of-loss of fill-oil, we have concluded that

there is no need to perform enhanced surveillance of the; installed t transmitters .up until the time that the sensing modules are

- replaced.

o Very-truly yours, jf pu y n 1 l' -

C. W. Fay

-Vice resident Nuclear Power -

Attachment i SWO/alg i

- Copies to:- NRC Resident-Inspector '

NRC Regional Administrator, Region III y i

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