IE Circular No. 80-16, Operational Deficiencies in Rosemount Model 510du Trip Units and Model 1152 Pressure Transmitters
SSINS No.: 6830
Accession No.:
8005050067
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
June 27, 1980
IE Circular No. 80-16
OPERATIONAL DEFICIENCIES IN ROSEMOUNT MODEL 510DU TRIP UNITS AND MODEL 1152
PRESSURE TRANSMITTERS
Description of Circumstances:
The NRC has recently been advised through a 10 CFR 21 report that operational
deficiencies exist in Rosemount Inc. Model 510DU trip units and Model 1152
pressure transmitters as follows:
MODEL 510DU TRIP UNITS
The 510DU trip units have common mode failures of two switches; S1 in the
trip status output, LED logic circuit and S2 in the trip output logic
circuit. The trip units involved are those with serial Numbers 3001 to 4203.
The 510DU units having serial numbers within this range that are not trip
units are not affected (i.e., Card Files, Readout Assemblies, Calibration
Units, etc.). Malfunction of these switches appears as an open circuit in
the output logic upon receipt of an actual trip signal. Switch (S2) failure
could result in failure to automatically activate a safety function.
MODEL 1152 PRESSURE TRANSMITTERS
The model 1152 pressure transmitters have a common mode failure of a
capacitor when the transmitter operating environmental temperature is
greater than 175F, and when the damping potentiometer is rotated clockwise.
The failure results in a decrease in transmitter output current of up to 10
percent of the correct current. For example, when the transmitter is used
in an indication circuit, the parameter indication would be correspondingly
lower than the correct value if the capacitor failure occurred. The failure
potentially involves all pressure transmitters with the following model
designations:
Rosemount Pressure Transmitter Models:
1152 _ _ _ E _ _ T0280
1152 _ _ _ E _ _ T0445
1152 _ _ _ E _ _ T0400
Available information indicates that the problems outlined above have been
reported to each customer who was furnished the Model 510DU trip units and
Model 1152 pressure transmitters.
.
IE Circular No. 80-16 June 27, 1980
Page 2 of 2
RECOMMENDED ACTION FOR LICENSEES AND HOLDERS OF CONSTRUCTION PERMITS
All licensees of nuclear power reactors and holders of construction permits
should be aware of the potential problems discussed above. It is recommended
that the following actions be taken:
1. Determine if your facility has installed or plans to install the Rosemount
Model 510DU trip units and/or the pressure transmitters described herein in
any safety-related equipment.
2. If it is determined that your facility has installed or plans to install
any of the affected units described herein, contact the supplier for
performance of the required modifications to the units to resolve the
problems.
3. Modifications should be performed on all affected units prior to plant
operation. If the affected units are installed in plants that are operating,
the following actions are recommended for continued operation until the units
are modified.
a. 510DU Trip Units
A functional test verifying proper operation of the trip units should be
performed.
b. Model 1152 Pressure Transmitters
On pressure transmitters that are affected and that may be subjected to
operating environmental temperatures greater than 175xF, the transmitters
should be operated with the damping potentiometer (R12) in the fully
counterclockwise position.
CAUTION
The circuit output should be monitored to assure that no action detrimental
to operation results from placing R12 in the counter clockwise position,
such as spurious tripping caused by unstable operation.
No written response to this circular is required. If you require additional
information regarding this matter, contact the Director of the appropriate
NRC Regional Office.
Page Last Reviewed/Updated Thursday, March 25, 2021