ML20057F999
| ML20057F999 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 10/13/1993 |
| From: | Chrzanowski D COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| IEB-90-001, IEB-90-1, NUDOCS 9310200061 | |
| Download: ML20057F999 (3) | |
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- {b Commonwealth Edison mr 1400 opus Place oowners orove. ilanois 60515 October 13,1993 i
i U.S. Nuclear Regmatory Commission Office of Nuclear Reactor Regulation Washington, DC 20555 Attention: Document Control Desk
Subject:
Supplemental Information For the LaSalle County Station Response to NRC Bulletin 90-01 Supplement 1.
LaSalle County Station Units 1 and 2, (NRC Dockets 50-373 and 50-374) 9
Reference:
Letter from D.J. Chrzanowski to Dr. T.E. Murley dated March 5, 1993 providing the LaSalle County Station Response to NRC Bulletin 90-01 Supplement 1, "Losa of Fill Oil in Transmitters Manufactured by Rosemount."
The purpose of this letter is to provide supplemental information regarding the LaSalle County Station response to the requested actions of Bulletin 90-01, Supplement 1. This additional information is being provided to assist the staff in their review of the referenced Bulletin response. This letter confirms and documents the information provided in an August 18,1993 teleconference with NRC staff. The questions raised by the staff during this call involved two issues; the status of the monthly surveillance program for LaSalle's Category 1.c Rosemount transmitters, and a description of the monitoring program that is used to detect the loss of fill oil.
j As discussed in the August 18th LaSalle teleconference, has developed and is l
performing an on-line monthly monitoring program for the seventeen (17) category 1.c transmitters identified in the referenced letter. These are transmitters that d
operate at a pressure from 500 to 1500 psi, are installed in RPS or ATWS systems, and have not reached the " time at pressure" maturity criteria (60,000 psi-months).
The development and implementation of this monthly surveillance satisfies the i
requested actions of Bulletin 90-01 Supplement 1.
A discussion of the LaSalle Station monitoring program for both the monthly and refueling outage category transmitters is contained in the attachment to this letter. The monitoring program on a refueling outage frequency has been in place since July of 1990 when the original Bulletin recommendations were incorporated at LaSalle Station.
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4 Document Control Desk October 13,1993
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If there are any questions or comments, please contact this office at (708) 663-7292.
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I Sincerely, kb' David J. Chrza]nowski pw, Generic Issues Administrator Nuclear Regulatory Services
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cc: J. Martin, Regional Administrator-RIII l
J. Kennedy, LaSalle Project Manager-NRIUPDIII-2 D. Ilills, Senior Resident Inspector (LaSalle) i 4
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i Attachment LaSalle County Station l
Rosemount Transmitter Loss-of-Fill-Oil Monitoring Program l
i LaSalle Station maintains two independent methods of detecting a loss of fill oil in Rosemount transmitters. The project was developed in response to NRC Bulletin 90-01 and its supplement. Guidance for and methods of detecting the loss of fill oil were taken from technical bulletins issued by Rosemount.
i in response to Bulletin 90-01 a method of trending transmitters to detect zero drift was implemented in July 1990. The trending program is based on transmitter i
calibration data, previous "as left" values are compared to current "as found" values.
i This comparison results in a value for the zero drift of the transmitter. As more calibrations are performed the data is entered into the program's database and l
cumulative zero drift is calculated and recorded. Using information supplied by i
Rosemount, limitations for acceptable drift are calculated based on transmitter model, calibration span. If a transmitter exceeds these drift limitations it is determined to be suffering from a loss of fill oil and it is replaced.
In response to Supplement 1 to Bulletin 90-01, LaSalle developed a method of j
monitoring transmitters while they are operating. This was done to comply with the supplement's requirement to monthly monitor transmitters in RPS, ESF and ATWS applications. The "online" monitoring is performed by monitoring the transmitters output at the trip unit. The signal from the transmitter is averaged over a period of time (typically three to five minutes) and a value for transmitter operating point, minimum, and maximum voltage seen is recorded. These values are then compared to similar transmitters (same reference legs and sensing lines). One transmitter is taken as the baseline transmitter. The comparison transmitters are then plotted i
against this baseline transmitter in a percentage of deviation. Again drift limitations j
are established based on information taken from Rosemount technical bulletins.
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If a transmitter is found drifting past the limitations, it would be suspected as
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having suffered a loss of fill oil and a calibration would be performed to provide
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additional confirmation of the suspect transmitter response. In addition, these
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category 1.c transmitters are part of the refueling outage monitoring program discussed above. However, LaSalle may elect to remove these transmitters from the refueling outage surveillance schedule and monitor their performance through the i
Supplement 1 monthly surveillances only.
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