Information Notice No. 91-61: Preliminary Results of Validation Testing of Motor-Operated Valve Diagnostic Equipment

                                  UNITED STATES
                          NUCLEAR REGULATORY COMMISSION
                             WASHINGTON, D.C.  20555

                               September 30, 1991 



All holders of operating licenses or construction permits for nuclear power 
reactors and motor-operated valve (MOV) diagnostic equipment vendors 
identified herein.


The U.S. Nuclear Regulatory Commission (NRC) is issuing this information 
notice to alert addressees to the preliminary results of the validation 
testing of MOV diagnostic equipment conducted by the MOV user's group (MUG) 
of nuclear power plant licensees.  It is expected that recipients will 
review the information for applicability to their facilities and consider 
actions, as appropriate, to avoid operability problems with MOVs.  However, 
suggestions contained in this information notice are not NRC requirements; 
therefore, no specific action or written response is required.

Description of Circumstances

In 1990, the MUG initiated a program to conduct tests of MOV diagnostic 
equipment to validate the accuracy of the equipment asserted by the 
diagnostic equipment vendors.  The MUG requested the Idaho National 
Engineering Laboratory (INEL) to provide a test stand for the program and to 
collect test data.  The NRC Office of Nuclear Regulatory Research (RES) 
provided funds for INEL to participate, with the stipulation that the 
results of the testing would be made available to the NRC and the public.

The diagnostic equipment vendors participating in the MUG test program were 
ASEA-Brown Boveri (ABB) Impell, ITI-MOVATS, Liberty Technologies, 
Siemens/KWU, Teledyne, and Wyle Laboratories.

The INEL test stand included a Limitorque motor operator which drives a 
valve stem into a water reservoir with a compressed air overcharge.  INEL 
obtained accurate measurements of actuator torque and thrust using a torque 
arm and a stem-mounted load cell, respectively.  Each diagnostic equipment 
vendor installed and operated its own equipment to obtain measurements of 
torque, thrust, and various other parameters.

Several diagnostic system vendors did not meet all of their stated claims of 
accuracy.  Differences in the time response of the INEL test stand equipment 
and the diagnostic systems being tested may have contributed to deviations 

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the observed thrust measurements.  Further, some of the diagnostic equipment 
exhibited problems and anomalies, such as failed sensors or difficulties in 
calibration, during the testing program.  Of particular concern to the NRC 
is that these time inaccuracies, problems, and anomalies may not have been 
detected during normal use of the diagnostic equipment at a nuclear 

The MUG is comparing the data collected by INEL with the data collected by 
each of the diagnostic equipment vendors.  At a meeting in Richmond, 
Virginia, on July 30, 1991, the MUG released a progress report of the 
validation testing.  The NRC has placed this report, "MOV User's Group - 
Progress Report of the Validation Committee," in the NRC Public Document 
Room (PDR), 2120 L Street, N.W., Washington, D.C. 20555 (telephone (202) 
634-3273).  The MUG is continuing to review the test data and intends to 
release a final report in January 1992.  The NRC will place the final MUG 
report in the PDR.

During its July meeting, the MUG stated that licensees and diagnostic 
equipment vendors should review the progress report for its applicability to
the MOVs installed in nuclear power plants.  The MUG also alerted licensees 
and diagnostic equipment vendors to their responsibilities under "Reporting 
of Defects and Noncompliance," Part 21 of Title 10 of the Code of Federal 

Discussion of Safety Significance

In NRC Bulletin 85-03, "Motor-Operated Valve Common Mode Failures During 
Plant Transients Due to Improper Switch Settings," and its supplement, the 
NRC recommended that licensees develop and implement a program to ensure 
that motor-operator switch settings for MOVs in several specified systems 
are selected, set, and maintained so that the MOVs will operate under 
design-basis conditions for the life of the plant.  In NRC Generic Letter 
89-10, "Safety-Related Motor-Operated Valve Testing and Surveillance," and 
its supplements, the NRC recommended that the program to verify switch 
settings be extended to ensure MOVs operate properly in all safety-related 
fluid systems.

To meet the recommendations of the bulletin and the generic letter, 
licensees have placed increasing reliance on diagnostic equipment to set the 
motor operator switches and to ensure the operability of MOVs.  The accuracy 
of the diagnostic equipment has a direct impact on the operability of entire 
safety systems because the same diagnostic equipment is generally used to 
set the motor operator switches of the valves in all trains of a safety 

This concern for the effect that the use of diagnostic equipment can have on 
overall system operability prompted NRC to participate in the MUG validation 
testing.  The NRC will continue to monitor the activities of licensees and 
diagnostic equipment vendors in evaluating the results of the MUG test 


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This information notice requires no specific action or written response.  If 
you have any questions about the information in this notice, please contact 
one of the technical contacts listed below or the appropriate Office of 
Nuclear Reactor Regulation project manager.

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

Technical contacts:  Thomas G. Scarbrough, NRR
                     (301) 492-0794

                     Owen O. Rothberg, RES
                     (301) 492-3924

Attachment:  List of Recently Issued NRC Information Notices

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