Information Notice No. 88-29:Deficiencies in Primary Containment Low-Voltage Electrical Penetration Assemblies
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, DC 20555
May 24, 1988
Information Notice No. 88-29: DEFICIENCIES IN PRIMARY CONTAINMENT
LOW-VOLTAGE ELECTRICAL PENETRATION
ASSEMBLIES
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
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
323-1974.
Discussion:
These electrical penetrations are designed to carry some 75 electrical signals
from instrumentation inside the containment to main control room indicators
and
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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
capabilities.
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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Page 3 of 3
References
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
. Attachment
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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.
Components
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
facility
licensees.
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
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