ML090290185 

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

OFFICE OF NUCLEAR REACTOR REGULATION 

OFFICE OF NEW REACTORS 

WASHINGTON, DC 20555-0001 

January 28, 2010 

NRC INFORMATION NOTICE 2010-02: CONSTRUCTION-RELATED EXPERIENCE WITH 

CABLES, CONNECTORS, AND JUNCTION 

BOXES 

ADDRESSEES 

All current holders of and applicants for an early site permit, combined operating license, or 

standard design certification for a nuclear power plant under the provisions of Title 10 of the 

Code of Federal Regulations (10 CFR) Part 52, “Licenses, Certifications, and Approvals for 

Nuclear Power Plants.” 

All holders of operating licenses or construction permits for nuclear power reactors under the 

provisions of 10 CFR Part 50, “Domestic Licensing of Production and Utilization Facilities,” 

except those that have permanently ceased operations and have certified that fuel has been 

permanently removed from the reactor. 

PURPOSE 

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to alert 

addressees of construction-related operating experience at domestic and international facilities 

associated with the rating, installation, and qualification of cables and junction boxes. 

Recipients are expected to review the information for applicability to their planned activities and 

consider actions to avoid similar problems. The suggestions contained in this IN are not NRC 

requirements, and no specific action or written response is required. 

DESCRIPTION OF CIRCUMSTANCES 

Penly Unit 2 in France—Improper Installation of Shrink-Fit Sheathing 

On September 23, 2003, at Penly Unit 2 in France, an isolation fault was detected in the 

junction boxes of two containment isolation valves for the nuclear sampling system. Electrical 

cables in those junction boxes failed because of “cable insulation cuts” and “improperly shrunk 

thermal shrink-fit sheathing”, which resulted in exposed copper conductors that accessed 

external ground paths. Further inspections found similar damage to the safety-qualified 

electrical cables in 57 out of 122 junction boxes inspected at Penly. Électricité de France 

expanded the inspections of cables and junction boxes to its other nuclear plants in France and 

found similar problems at Flamanville Unit 2, Gravelines Unit 3, Dampierre Unit 4, and Tricastin 

Unit 1. The primary cause of this event is not currently known. Improper installation practices 

are suspected, but it is not clear why the post-installation inspection did not detect the bare 

copper conductors. The most likely cause is expected to be improper installation practices 
IN 2010-02 

Page 2 of 3 

combined with a degradation of the insulating sheaths over time, which caused the cables to 

have exposed bare copper conductors. 

Cattenom Unit 2 in France—Fire in Electrical Cable Penetration 

On May 16, 2004, at Cattenom Unit 2 in France, a cable fire occurred in a fire-resistant, 

electrical penetration carrying 6.6-kilovolt (kV) electrical cables (to the circulating water pumps) 

and other safety-related cables between the electrical building and the turbine hall. The fire was 

detected by alarms indicating an insulation fault on the 6.6-kV electrical switchboards, followed 

by a fire alarm. 

The primary cause of the fire was attributed to undersized cables for the circulating water 

pumps. A contributing factor to this event was the closure of the cable penetration at both ends, 

which allowed a buildup of heat causing carbonization of the cable insulation. 

Modifications were made in the four units of Cattenom by (1) using two cables per phase to 

increase the allowed amperage per phase and (2) by opening one end of the cable penetration 

to eliminate the oven effect on the cables. 

Palisades— Electrical Cables Degraded by Hot Nearby Piping 

On February 17, 2007, an auxiliary operator at Palisades Nuclear Plant discovered that cables 

in a cable tray that are primarily associated with components of the cooling water and service 

water system had sustained damage to their cable jackets from the radiant heat effects of an 

uninsulated hot pipe that was in proximity to the cable tray. These cables, which were rated for 

194 degrees Fahrenheit (90 degrees Celsius), were close to the steam generator blowdown 

pipe, which had a surface temperature of 480 degrees Fahrenheit (248 degrees Celsius). The 

licensee subsequently determined that all of the cables in the cable tray that were potentially 

affected by the radiant heat damage were inoperable because of loss of qualification life and the 

potential for cable-to-cable interaction from degradation of the cable. Licensee corrective 

actions included replacing the damaged cable sections and insulating the steam generator 

blowdown line. Additional information is available in Palisades Licensee Event Report 

50-255/2007-003, dated April 25, 2007 (Agencywide Documents Access and Management 

System (ADAMS) Accession No. ML071230123). 

BACKGROUND 

Related NRC Communications

• Generic Letter 2007-01, “Inaccessible or Underground Power Cable Failures That Disable 

Accident Mitigation Systems or Cause Plant Transients” (ADAMS Accession No. 

ML070360665), dated February 7, 2007, and Summary Report (ADAMS Accession No. 

ML082760385), dated November 12, 2008. 

• IN 1986-53, “Improper Installation of Heat Shrinkable Tubing” (ADAMS Accession No. 

ML031220693), dated June 26, 1986, discusses problems involving improper installation of 

heat shrinkable tubing over electrical splices and terminations. 
IN 2010-02 

Page 3 of 3 

• NUREG-1055, “Improving Quality and the Assurance of Quality in the Design and 

Construction of Nuclear Power Plants” (ADAMS Accession No. ML063000293), dated 

May 31, 1984, documents the lessons learned from plant construction. 

DISCUSSION 

The operating experience discussed in this IN involves deficiencies with the rating, installation, 

and qualification of cables and junction boxes that originated during construction. Improper 

electrical cable installation techniques can result in conditions that, over time, manifest 

themselves in degraded insulation/sheathing which can lead to electrical shorts and grounds 

that can render technical specification required equipment inoperable. Licensees are required 

by 10 CFR Part 50, Appendix B, Criterion V, “Instructions, Procedures, and Drawings Activities,” 

to establish and implement adequate instructions and procedures for activities affecting quality 

which includes electrical cable installation. NRC regulations in 10 CFR Part 50, Appendix B, 

“Design Control,” includes consideration of cable material qualification (for both fire retardancy 

and installation stresses), qualification of thermal shrink-fit sheathing, and proper cable 

installation processes (to ensure that insulation/sheathing is not damaged during installation). 

CONTACT

This information notice requires no specific action or written response. Please direct any 

questions about this matter to the technical contacts listed below. 

/RA/ /RA/ 

Timothy McGinty, Director Glenn Tracy, Director 

Division of Policy and Rulemaking Division of Construction Inspection and 

Office of Nuclear Reactor Regulation Operational Programs 

 Office of New Reactors 

Technical Contacts: Omid Tabatabai, NRO/DCIP Edmund Kleeh, NRO/DCIP 

 (301) 415-6616 (301) 415-2964 

 omid.tabatabai@nrc.gov edmund.kleeh@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site, 

http://www.nrc.gov, under Electronic Reading Room/Document Collections. 
IN 2010-02 

Page 3 of 3 

• NUREG-1055, “Improving Quality and the Assurance of Quality in the Design and 

Construction of Nuclear Power Plants” (ADAMS Accession No. ML063000293), dated 

May 31, 1984, documents the lessons learned from plant construction. 

DISCUSSION 

The operating experience discussed in this IN involves deficiencies with the rating, installation, 

and qualification of cables and junction boxes that originated during construction. Improper 

electrical cable installation techniques can result in conditions that, over time, manifest 

themselves in degraded insulation/sheathing which can lead to electrical shorts and grounds 

that can render technical specification required equipment inoperable. Licensees are required 

by 10 CFR Part 50, Appendix B, Criterion V, “Instructions, Procedures, and Drawings Activities,” 

to establish and implement adequate instructions and procedures for activities affecting quality 

which includes electrical cable installation. NRC regulations in 10 CFR Part 50, Appendix B, 

“Design Control,” includes consideration of cable material qualification (for both fire retardancy 

and installation stresses), qualification of thermal shrink-fit sheathing, and proper cable 

installation processes (to ensure that insulation/sheathing is not damaged during installation). 

CONTACT

This information notice requires no specific action or written response. Please direct any 

questions about this matter to the technical contacts listed below. 

/RA/ /RA/ 

Timothy McGinty, Director Glenn Tracy, Director 

Division of Policy and Rulemaking Division of Construction Inspection and 

Office of Nuclear Reactor Regulation Operational Programs 

 Office of New Reactors 

Technical Contacts: Omid Tabatabai, NRO/DCIP Edmund Kleeh, NRO/DCIP 

 (301) 415-6616 (301) 415-2964 

 omid.tabatabai@nrc.gov edmund.kleeh@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site, 

http://www.nrc.gov, under Electronic Reading Room/Document Collections. 

ADAMS Accession Number: ML090290185 TAC ME0471 

OFFICE CCIB:NRO TECH EDITOR TL:CCIB:NRO BC:CCIB:NRO BC:EEB:NRO BC:EEEB:NRR

NAME EKleeh KAzariah-Kribbs OTabatabai JStarefos RJenkins GWilson 

DATE 02/04/09 03/16/09 e-mail 02/04/09 02/06/09 02/09/09 02/26/09 

OFFICE BC:OIP PGCB:NRR PGCB:NRR BC:PGCB:NRR D:DPR:NRR D:DCIP:NRO

NAME CAbrams DBeaulieu CHawes MMurphy TMcGinty GTracy 

DATE 4/15/09 07/23/09 1/11/10 1/19/10 1/28/10 1/22/10 

OFFICIAL RECORD COPY