Information Notice 2010-09, Importance of Understanding Circuit Breaker Control Power Indications
| ML101020184 | |
| Person / Time | |
|---|---|
| Issue date: | 04/14/2010 |
| From: | Dan Dorman, Mcginty T, Tracy G NRC/NMSS/FCSS, Division of Construction Inspection and Operational Programs, Division of Policy and Rulemaking |
| To: | |
| Beaulieu, D P, NRR/DPR, 415-3243 | |
| References | |
| IN-10-009 | |
| Download: ML101020184 (4) | |
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
OFFICE OF NEW REACTORS
WASHINGTON, DC 20555-0001 April 14, 2010
NRC INFORMATION NOTICE 2010-09: IMPORTANCE OF UNDERSTANDING CIRCUIT
BREAKER CONTROL POWER INDICATIONS
ADDRESSEES
All holders of an operating license or construction permit for a nuclear power reactor issued
under Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of
Production and Utilization Facilities, except those who have permanently ceased operations
and have certified that fuel has been permanently removed from the reactor vessel.
All holders of or applicants for an early site permit, standard design certification, standard
design approval, manufacturing license, or combined license issued under 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants.
All holders of or applicants for a license for a fuel cycle facility issued pursuant to
10 CFR Part 70, Domestic Licensing of Special Nuclear Material.
All holders of or applicants for a certificate of compliance issued under 10 CFR Part 76, Certification of Gaseous Diffusion Plants.
All holders of or applicants for a license for a uranium conversion facility issued pursuant to
10 CFR Part 40, Domestic Licensing of Source Material.
PURPOSE
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform
addressees about circuit breaker control power indication issues that could result in degraded
circuit breaker protection and control. The NRC expects that recipients will review the
information for applicability to their facilities and consider actions, as appropriate, to avoid
similar problems. Suggestions contained in this IN are not NRC requirements; therefore, no
specific action or written response is required.
DESCRIPTION OF CIRCUMSTANCES
On March 28, 2010, following an automatic reactor trip at H.B. Robinson Steam Electric Plant
Unit 2, a non-safety related electrical circuit breaker did not automatically open to isolate an
electrical fault because this breaker did not have control power to the trip circuit. The lack of
control power was due to a faulty fuse assembly in the breakers control power circuit. The
licensees corrective action program shows that the control power indicating lights on the front
panel of the breaker had not been illuminated for approximately one year. Additional
information is available in Preliminary Notification of Event PNO-II-10-002 dated
March 29, 2010, and can be found on the NRCs public website in the Agencywide Documents
Access and Management System (ADAMS) under Accession No. ML100880412.
BACKGROUND
The NRC previously issued two INs related to circuit breaker control power issues:
(1) IN 1991-78, Status Indication of Control Power for Circuit Breakers Used in Safety- Related Applications, November 28, 1991 (ADAMS Accession No. ML082380373).
(2) IN 2007-34, Operating Experience Regarding Electrical Circuit Breakers, October 22, 2007 (ADAMS Accession No. ML072390061).
The NRC issued IN 1991-78 to inform licensees of the importance of having control power for
circuit breakers used in safety-related applications. This IN highlighted the importance of having
control power indication for both safety-related and non-safety related applications. IN 2007-34 highlighted the importance of identifying possible causes for breaker problems including the lack
of control power indication.
DISCUSSION
Industry operating experience shows similar control power fuse issues where the indicating
lights were either dim or not illuminated. The loss or degradation of control power in circuit
breakers can prevent the breaker from performing its design function of either opening or
closing on demand. Although there is no regulatory requirement for the functionality of the non- safety related breaker discussed in this IN, industry operating experience describes instances of
technical specification required equipment being rendered inoperable due to similar circuit
breaker control power issues.
A recent review of breaker control power operating experience has determined that the following
items are important to ensure proper breaker operation:
- the verification of control power indication for both safety-related and non-safety related
circuit breakers during walkdowns
- the potential impact on safety-related equipment resulting from a loss of control power to
non-safety related circuit breakers when they fail to open to isolate a fault
CONTACT
This IN requires no specific action or written response. Please direct any questions about this
matter to the technical contacts listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
/RA/ /RA/
Timothy J. McGinty, Director Daniel H. Dorman, Director
Division of Policy and Rulemaking Division of Fuel Cycle Safety and Safeguards
Office of Nuclear Reactor Regulation Office of Nuclear Material Safety and Safeguards
/RA/ By John Tappert For/
Glenn Tracy, Director
Division of Construction Inspection
and Operational Programs
Office of New Reactors
Technical Contacts: Jesse Robles, NRR Joseph Giantelli, NRR
301-415-2940 301-415-0504 E-mail: jesse.robles@nrc.gov E-mail: joseph.giantelli@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.
CONTACT
This IN requires no specific action or written response. Please direct any questions about this
matter to the technical contacts listed below or the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
/RA/ /RA/
Timothy J. McGinty, Director Daniel H. Dorman, Director
Division of Policy and Rulemaking Division of Fuel Cycle Safety and Safeguards
Office of Nuclear Reactor Regulation Office of Nuclear Material Safety and Safeguards
/RA/ By John Tappert For/
Glenn Tracy, Director
Division of Construction Inspection
and Operational Programs
Office of New Reactors
Technical Contacts: Jesse Robles, NRR Joseph Giantelli, NRR
301-415-2940 301-415-0504 E-mail: jesse.robles@nrc.gov E-mail: joseph.giantelli@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: ML101020184 TAC ME3754 OFFICE DIRS:IOEB DIRS:IOEB Tech Editor ABC:DIRS:IOEB D:NRR:DIRS BC:DE:EEB
NAME JRobles JGiantelli KAKribbs EThomas FBrown GWilson
DATE 04/14/10 04/14/10 04/12/10 e-mail 04/14/10 04/14/10 04/14/10
OFFICE LA:PGCB:NRR PM:PGCB:NRR BC:PGCB:NRR D:NMSS:DFCSS D:DCIP:NRO D:DPR:NRR
NAME CHawes DBeaulieu MMurphy DDorman GTracy TMcGinty
OFFICE 04/14/10 04/14/10 04/14/10 04/14/10 04/14/10 04/14/10
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