United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 82-03: Environmental Tests of Electrical Terminal Blocks

                                                            SSINS:  6835 
                                                            Accession No.: 
                                                            8202040111 
                                                            IN 82-03 

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C.  20555

                                March 4, 1982

Information Notice No. 82-03:  ENVIRONMENTAL TESTS OF ELECTRICAL TERMINAL
                                  BLOCKS 

Discussion: 

This information notice pertains to the results of NRC sponsored research 
conducted on electrical terminal blocks (type CF-1518 and CR 29605 General 
Electric and type FWM States).  These may be typical of those utilized in 
many nuclear power plants.  The research program was conducted at Sandia 
Laboratories in Albuquerque, NM and consisted of approximately 600 
individual tests made on enclosed and open terminal blocks of the type used 
at TMI-2. The terminal blocks were subjected to 100% humidity conditions at 
186oF which were the conditions experienced by some terminal blocks during 
the TMI-2 accident.  (Note:  To date, there has been no evidence of terminal 
block failure at TMI-2 during the TMI-2 accident or after).  No tests at 
other LOCA conditions were conducted.  Terminal block performance under the 
test conditions was measured by monitoring electrical terminal to ground 
leakage current with terminal to ground voltage of 120, 240 and 480 volts.  
Some terminal blocks were installed in metal enclosures with a 6 mm pressure 
relief hole.  These metal enclosures were mounted in a horizontal plane 
during the tests.  Some tests were made by simulating chemical spray and 
various contaminants that may be found on terminal blocks and could result 
in electrolytic leakage paths in nuclear power plants.  The results of these
tests indicated instances of leakage currents when blocks were directly 
exposed to chemicals and steam. 

The NRC recognizes that the use of properly designed terminal blocks inside 
containment is an option of the applicant.  NRC requires qualification of 
all electrical connections, cable splices as well as terminal blocks, for 
accident conditions. 

It is recognized that cleanliness of terminations and terminal blocks in 
circuits important to safety is of concern to designers, constructors, and 
licensees.  The cleanliness aspects are addressed in Appendix B of 10 CFR 
50. These regulations require the licensee to establish appropriate 
procedures based upon manufacturer's and constructor's recommendations, 
operating experience, and specific component characteristics to assure that 
equipment is stored, installed, and maintained in an acceptable state.  To 
this end, IEEE-336, ANS 3.2, and ANSI 45.2.3 Standards and NRC Regulatory 
Guide 1.39 are being used by designers, constructors, and operators of power 
plants which address the installation, cleanliness, and on-going maintenance 
of Class 1E electrical components, including terminal blocks. 
.

                                                            IN 82-03 
                                                            March 4, 1982 
                                                            Page 2 of 2 

In view of the above, licensees are reminded that the plant preventive 
maintenance program in use at their facilities should assure (1) proper 
operation of all essential components is achieved throughout the life of the
plant; and (2) that periodic inspection of those terminations and terminal 
blocks for cleanliness and installation integrity is performed following any
maintenance activity affecting them. 

The Office of Inspection and Enforcement has general inspection procedures 
which are used by inspectors to monitor compliance with the above Standards,
Guides, and recommendations.  Terminal blocks are specifically identified as
an example of a component which must be inspected for cleanliness during 
construction of the power plant. 

No specific action or response is required at this time.  If you have any 
questions regarding this matter, please contact the Regional Administrator 
of the appropriate NRC Regional Office. 

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