ML19309H130

Status Rept on Deficiency Re Rosemount Model 510 Du Trip/ Calibr Units & Model 1152 Pressure Transmitters.Transmitter Has Common Mode Failure of Capacitor When Transmitter Operating Temp Greater than 175F.Review Underway

ML19309H130
Person / Time
Site:	Grand Gulf
Issue date:	04/25/1980
From:	MISSISSIPPI POWER & LIGHT CO.
To:
Shared Package
ML19309H129	List: ML19309H128 ML19309H130
References
NUDOCS 8005080484
Download: ML19309H130 (1)

Text

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? . 800 5080yIf ,

O ATTACHMENT TO AECM-80/86 i

l STATUS REPORT ON PRD-80/11 4

I. Description of Deficiency i Defects in two components supplied by Rosemount are identified under PRD-80/11. These components are the Model 510 DU trip /cali-bration unit and the Model 1152 pressure transmitter.

The trip / calibration unit has a common mode failure of an essential switch that determines the trip output logic. The malfunction open-circuits the logic, thereby providing an inoperable signal.

The transmitter has a common mode failure of a capacitor when the transmitter operating temperature is greater than 17SOF or when the damping potentiometer is rotated clockwise. The failure is manifested as a drop in transmitter output current of up to 10 percent of the correct current.

II. Investigation Status Our preliminary investigation indicated that the defect noted in the trip / calibration units was previously reported by MP&L as PRD-79/18.

Our final report on PRD-79/16 was submitted to the NRC in the letter dated January 30, 1980. That deficiency was determined to be reportable under 10 CFR 50.55(e). Corrective actions associated with PRD-79/18 are documented under Bechtel Management Corrective Action Request (MCAR)

GGNS No. 56.

The defect noted in the Model 1152 pressure transmitters was not previously reported by MP&L. The investigation into this defect, the component's use at GGNS, and the associated safety implications, is in progress.

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