United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 88-29: Deficiencies in Primary Containment Low-Voltage Electrical Penetration Assemblies

                                  UNITED STATES
                          NUCLEAR REGULATORY COMMISSION
                              WASHINGTON, DC  20555

                                  May 24, 1988

                                   LOW-VOLTAGE ELECTRICAL PENETRATION 


All holders of operating licenses or construction permits for nuclear power 


This information notice is being provided to alert addressees to potential 
problems resulting from the findings of a recent NRC environmental qualifica-
tion (EQ) inspection concerning low-voltage penetration assemblies.  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:

Braidwood 2.  During an EQ inspection conducted by Region III from February 
20, 1988 to March 4, 1988, a deficiency was discovered in test documentation 
for four penetration assemblies.  Insulation resistance readings had not been 
taken frequently enough to determine the performance of the assemblies in 
testing to simulate conditions for a loss-of-coolant accident (LOCA).  The 
first reading was taken between 8 and 20 hours into the test.  These 
assemblies were manufactured by the Bunker Ramo Company.

In response to the finding, the licensee, Commonwealth Edison Company, 
provided a test report (Reference 1) from another plant to demonstrate that 
the configuration installed at Braidwood 2 is environmentally qualified.  A 
review of this test report, however, showed that the insulation resistance 
readings were not taken at a frequency consistent with the guidance provided 
in the Institute for Electronic and Electrical Engineers (IEEE) Standard 


These electrical penetrations are designed to carry some 75 electrical signals 
from instrumentation inside the containment to main control room indicators 

.                                                                 IN 88-29
                                                                 May 24, 1988
                                                                 Page 2 of 3

protective circuitry while maintaining the integrity of the containment pres-
sure boundary.  The deficiency described above relates to the quality of the 
signal transmission of the assemblies, not to their pressure-retaining 

The specific instruments involved provide inputs to the reactor protection 
system and the engineered safety features actuation system as well as 
providing certain post-accident monitoring functions.  Some of those functions 
are required to mitigate a LOCA, a main feedwater line break, and a main steam 
line break.  These are the design basis accidents that produce the harsh 
environments the penetration must withstand.  During accident conditions, 
failure of these assemblies could affect the accuracy of Class 1E instruments 
and thus mislead operators.

Instrumentation required to mitigate the consequences of design basis 
accidents typically operates on 4 to 20 milliamps; therefore, cable insulation 
resistance is essential for the accuracy of these instruments.  The 
qualification information provided by the licensee did not have cable 
insulation resistance readings taken frequently enough to determine the 
performance of the penetration assemblies under LOCA simulation testing.  
Thus, environmental qualification for these assemblies has not been 
demonstrated (Reference 2).

A generic communication addressing similar equipment has been issued 
previously (Reference 3).

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

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

Technical Contacts:  Raj Anand, NRR
                     (301) 492-0805

                     Vern Hodge, NRR
                     (301) 492-1169

Attachment:  List of Recently Issued NRC Information Notices 
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                                                                 May 24, 1988
                                                                 Page 3 of 3


1.   Midland Containment Penetration Environmental Qualification Test Report 
     No. 123-2201, Revision A, February 1979, Docket 329/330.  A copy of this 
     report is available in the NRC Public Document Room 1717 H Street, N.W., 
     Washington, D.C.  20555 for inspection and copying.

2.   NRC Generic Letter No. 88-07, "Modified Enforcement Policy Relating to 
     10 CFR 50.49, 'Environmental Qualification of Electrical Equipment Im-
     portant to Safety for Nuclear Power Plants,'" April 7, 1988

3.   NRC Bulletin No. 82-04, "Deficiencies in Primary Containment Electrical 
     Penetration Assemblies," December 3, 1982

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                                                            IN 88-29 
                                                            May 24, 1988 
                                                            Page 1 of 1

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

88-28          Potential for Loss of         5/19/88        All holders of OLs
               Post-LOCA Recirculation                      or CPs for nuclear
               Capability Due to                            power reactors. 
               Insulation Debris Blockage 

88-27          Deficient Electrical          5/18/88        All holders of OLs
               Terminations Identified                      or CPs for nuclear
               in Safety-Related                            power reactors. 

85-35,         Failure of Air Check          5/17/88        All holders of OLs
Supplement 1   Valves to Seat                               or CPs for nuclear
                                                            power reactors. 

88-26          Falsified Pre-Employment      5/16/88        All holders of OLs
               Screening Records                            or CPs for nuclear
                                                            power reactors and
                                                            all major fuel 

88-25          Minimum Edge Distance for     5/16/88        All holders of OLs
               Expansion Anchor Bolts                       or CPs for nuclear
                                                            power reactors. 

88-24          Failures of Air-Operated      5/13/88        All holders of OLs
               Valves Affecting Safety-                     or CPs for nuclear
               Related Systems                              power reactors. 

88-23          Potential for Gas Binding     5/12/88        All holders of OLs
               of High-Pressure Safety                      or CPs for PWRs. 
               Injection Pumps During a 
               Loss-of-Coolant Accident 

88-22          Disposal of Sludge from       5/12/88        All holders of OLs
               Onsite Sewage Treatment                      or CPs for nuclear
               Facilities at Nuclear                        power reactors. 
               Power Stations 
OL = Operating License
CP = Construction Permit 
Page Last Reviewed/Updated Friday, May 22, 2015