Information Notice No. 89-42: Failure of Rosemount Models 1153 and 1154 Transmitters

                                  UNITED STATES
                          NUCLEAR REGULATORY COMMISSION
                      OFFICE OF NUCLEAR REACTOR REGULATION
                             WASHINGTON, D.C.  20555

                                 April 21, 1989


Information Notice No. 89-42:  FAILURE OF ROSEMOUNT MODELS 1153 AND 1154 
                                   TRANSMITTERS


Addressees:    

All holders of operating licenses or construction permits for nuclear power 
reactors.

Purpose:  

This information notice is being provided to alert addressees about recent 
failures of Rosemount models 1153 and 1154 pressure and differential pressure 
transmitters.  It is expected that recipients will review the information for 
applicability to their facilities and consider actions, as appropriate, to 
avoid similar problems.  However, suggestions contained in this information 
notice do not constitute NRC requirements; therefore, no specific action or 
written response is required.

Description of Circumstances:

During 1986 and 1987, five Rosemount model 1153 HD5PC differential pressure 
transmitters malfunctioned at Northeast Utilities' (NU) Millstone Nuclear 
Power Station, Unit 3.  During power operation, the Millstone operators noted 
that the signals from the Rosemount 1153 transmitters were deviating from 
redundant channel signals and that the transmitters were indicating reduced 
levels of process noise.  The transmitters were declared out of service by 
NU personnel, and the affected channels were placed in the tripped condition.  
After attempts to calibrate the transmitters failed, NU returned the trans-
mitters to Rosemount and informed them that the malfunctions had occurred 
with transmitters of the same model and related serial numbers.  Destructive 
testing performed by Rosemount determined that the failures were caused by the 
loss of oil from the transmitter's sealed sensing module.  However, Rosemount 
indicated that the failures appeared to be random and not related to any 
generic problem with Rosemount 1153 pressure transmitters.  NU submitted a 10 
CFR Part 21 notification to the NRC on this issue on March 25, 1988, and 
provided additional information on the failures via a letter dated April 13, 
1989.  

Discussion:

After additional evaluations by NU and Rosemount, Rosemount issued a letter 
to its customers on December 12, 1988, regarding the potential malfunction 
of models 1153 and 1154 pressure and differential pressure transmitters.  The 



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Rosemount letter was supplemented with a letter dated February 7, 1989, to 
customers who had purchased transmitters from specific lots that were identi-
fied by Rosemount as being potentially defective.  Rosemount issued a separate 
letter dated February 16, 1989, to customers who had purchased model 1153 and 
1154 transmitters from lots that were not considered suspect.  Rosemount indi-
cated that transmitters from the suspect lots were susceptible to a loss of 
silicone oil from the transmitter sealed sensing module and to possible fail-
ure.  According to Rosemount, as the oil leaks out of the sensing module the 
transmitter's performance gradually deteriorates and may eventually lead to 
a detectable failure.  

Some of the symptoms that have been observed during operation and before 
failure include slow drift in either direction of about 1/4 percent or more 
per month, lack of response over the transmitter's full range, increase in 
the transmitter's time response, deviation from the normal signal 
fluctuations, decrease in the detectable noise level, deviation of signals 
from one channel compared with redundant channels, "one sided" signal noise, 
and slow response to a transient or inability to follow a transient.   Some of
the symptoms observed by NU personnel during calibration include the inability 
to respond over the transmitter's entire range, slow response to either 
increasing or decreasing hydraulic test pressure, and drift of greater than 1% 
from the previous calibration. 

Although some of the defective transmitters have shown certain symptoms before
their failure, it has been reported that in some cases the failure of a trans-
mitter may not be detectable during operation.  In addition, Rosemount now 
indicates that the potential for malfunction may not be limited to the speci-
fied manufacturing lots previously identified in the February 1989 letter.  

It is important for addressees to determine whether any Rosemount models 1153 
and 1154 pressure and differential pressure transmitters, regardless of their 
manufacturing date, are installed in their facilities and to take whatever 
actions are deemed necessary to ensure that any potential failures of these 
transmitters are identified.  Although it may not be possible to detect the 
onset of failure in all instances, some transmitters have exhibited some of 
the aforementioned symptoms before failure.  It is important for potential 
failure modes to be identified and that operators be prepared for handling 
potential malfunctions.  In addition, careful examination of plant data, 
calibration records, and operating experience may yield clues that identify 
potentially defective transmitters.  Addressees may wish to contact Rosemount 
for assistance in determining appropriate corrective actions whenever any of 
the aforementioned symptoms are observed or if failures are identified.

On April 13, 1989, the NRC staff met and discussed this matter with Rosemount 
and several industry groups.  Rosemount has launched a program to identify the
root cause of the loss of oil from the sensing module and to determine recom-
mendations for its customers to address potentially defective transmitters.  

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No specific action or written response is required by this information notice.  
If you have any questions regarding this matter, please contact one of the 
technical contacts listed below or the Regional Administrator of the appro-
priate regional office.




                                   Charles E. Rossi, Director
                                   Division of Operational Events Assessment
                                   Office of Nuclear Reactor Regulation

Technical Contacts:  Kamal Naidu, NRR
                     (301) 492-0980

                     Jaime Guillen, NRR
                     (301) 492-1170

Attachment:  List of Recently Issued NRC Information Notices
..                                                            Attachment 
                                                            IN 89-42
                                                            April 21, 1989
                                                            Page 1 of 1

                             LIST OF RECENTLY ISSUED
                             NRC INFORMATION NOTICES
_____________________________________________________________________________
Information                                  Date of 
Notice No._____Subject_______________________Issuance_______Issued to________

89-41          Operator Response to          4/20/89        All holders of OLs
               Pressurization of Low-                       or CPs for nuclear
               Pressure Interfacing                         power reactors.
               Systems

88-75,         Disabling of Diesel           4/17/89        All holders of OLs
Supplement 1   Generator Output Circuit                     or CPs for nuclear
               Breakers by Anti-Pump                        power reactors.
               Circuitry

89-40          Unsatisfactory Operator Test  4/14/89        All holders of OLs
               Results and Their Effect on                  or CPs for nuclear
               the Requalification Program                  power reactors.

89-39          List of Parties Excluded      4/5/89         All holders of OLs
               from Federal Procurement                     or CPs for nuclear
               or Non-Procurement Programs                  power reactors.

89-38          Atmospheric Dump Valve        4/5/89         All holders of OLs
               Failures at Palo Verde                       or CPs for nuclear
               Units 1, 2, and 3                            power reactors.

89-37          Proposed Amendments to        4/4/89         All U.S. NRC 
               40 CFR Part 61, Air                          licensees. 
               Emission Standards 
               for Radionuclides

89-36          Excessive Temperatures        4/4/89         All holders of OLs
               in Emergency Core Cooling                    or CPs for nuclear
               System Piping Located                        power reactors.
               Outside Containment

88-86,         Operating with Multiple       3/31/89        All holders of OLs
Supp. 1        Grounds in Direct Current                    or CPs for nuclear
               Distribution Systems                         power reactors.

89-35          Loss and Theft of Un-         3/30/89        All U.S. NRC 
               secured Licensed Material                    byproduct, source 
                                                            and special 
                                                            nuclear material 
                                                            licensees.

_____________________________________________________________________________
OL = Operating License
CP = Construction Permit 
..