Information Notice No. 91-70: Improper Installation of Instrumentation Modules

                                UNITED STATES
                           WASHINGTON, D.C.  20555

                              November 4, 1991 



All holders of operating licenses or construction permits for nuclear power 


The U.S. Nuclear Regulatory Commission (NRC) is issuing this information 
notice to alert addressees regarding the possible improper installation of 
instrumentation modules that could result in inadequate seismic 
qualification of instrument cabinets.  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 are not NRC requirements; therefore, no 
specific action or written response is required.

Description of Circumstances 

By letter of August 29, 1991, Entergy Operations, Inc., the licensee for the 
Arkansas Nuclear One facility, notified the NRC that it had identified that 
certain instrument modules located in the safety-related Foxboro instrument 
cabinets did not have vibration-dampening material installed.  The licensee 
also noted that the instrument module guide rails were not installed for 
some of the modules and that some of the power supply brackets were missing.  
Through an engineering evaluation and contact with the vendor, the licensee 
determined that the cabinets and the instrumentation modules were not 
seismically qualified in the condition in which they were found.  This 
finding prompted the licensee to declare the affected cabinets inoperable.  
The licensee took immediate action to place the plant in a Hot Shutdown 
condition in accordance with the technical specification requirements.


The licensee reviewed the events leading up to the discovery of the improper 
installation of the instrumentation modules and found that it had purchased 
the Foxboro Specification 200 instrument nests and modules in 1984 as 
separate parts and arranged for their assembly at the site by the licensee's 
general contractor.  In addition, another contractor assembled similar 
equipment offsite and then shipped it to the site for installation.  It was 
noted that the vendor had shipped the subject vibration-dampening material, 
guide rails, and power supply brackets with the equipment.  However, the 
shipping package did not include a parts list or any specific installation 
instructions for 


                                                            IN 91-70
                                                            November 4, 1991
                                                            Page 2 of 2

these components.  While the licensee did procure the applicable vendor 
manuals, the manuals applied to the general line of Specification 200 
equipment and did not address the special instructions for Class IE 
equipment since at that time Foxboro had not as yet developed the pertinent 
instructions.  Also, the vendor's documentation did not include detailed 
installation drawings.  A paragraph in the Class IE qualification test 
results indicated that the standard modules would need to be modified to 
meet seismic qualifications.   However, the test report did not provide 
specific instructions for such a modification, and the licensee's review was 
not adequate to identify the need.  In addition, the contractor personnel 
did not inquire regarding the purpose of the additional parts included in 
the shipping package. 

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

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

Technical contact:  Walter P. Haass, NRR 
                    (301) 492-3219

Attachment:  List of Recently Issued NRC Information Notices 

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