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Potentially Nonconforming HEMYC and MT Fire Barrier Configurations

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Information about this document as published in the Federal Register.

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Nuclear Regulatory Commission.


Notice of issuance.


The U.S. Nuclear Regulatory Commission (NRC) has issued Generic Letter (GL) 2006-03 to all holders of operating licenses for nuclear power reactors, except those who have permanently ceased operation and have certified that fuel has been removed from the reactor vessel. The NRC is issuing this GL to:

(1) Request that addressees evaluate their facilities to confirm compliance with the existing applicable regulatory requirements in light of the information provided in this GL and, if appropriate, take additional actions. Specifically, although Hemyc and MT fire barriers in nuclear power plants (NPPs) may be relied on to protect electrical and instrumentation cables and equipment that provide safe shutdown capability during a fire, 2005 NRC testing has revealed that both materials failed to provide the protective function intended for compliance with existing regulations, for the configurations tested using the thermal acceptance criteria from the National Fire Protection Association (NFPA) Standard 251, “Standard Methods of Fire Tests of Building Construction and Materials.” The NRC staff applied the supplemental guidance in GL 86-10, Supplement 1, “Fire Endurance Test Acceptance Criteria for Fire Barrier Systems Used to Separate Redundant Safe Shutdown Trains Within the Same Fire Area” for Start Printed Page 24872the test details of thermocouple number and location, and

(2) Require that addressees submit a written response to the NRC in accordance with NRC regulations in Title 10 of the Code of Federal Regulations Section 50.54(f).

This Federal Register notice is available through the NRC's Agencywide Documents Access and Management System (ADAMS) under Accession Number ML061080011.


The GL was issued on April 10, 2006.


Not applicable.

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Daniel Frumkin at 301-415-2280 or by email or Angie Lavretta at 301-415-3285 or email

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NRC Generic Letter 2006-03 may be examined, and/or copied for a fee, at the NRC's Public Document Room (PDR) at One White Flint North, 11555 Rockville Pike (first floor), Rockville, Maryland. Publicly available records will be accessible electronically from the ADAMS Public Electronic Reading Room on the Internet at the NRC Web site,​NRC/​ADAMS/​index.html. The ADAMS number for the GL is ML053620142.

If you do not have access to ADAMS or if you have problems in accessing the documents in ADAMS, contact the NRC Public Document Room reference staff at 1-800-397-4209 or 301-415-4737 or by e-mail to

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Dated at Rockville, Maryland, this 20th day of April 2006.

For the Nuclear Regulatory Commission.

Christopher I. Grimes,

Director, Division of Policy and Rulemaking, Office of Nuclear Reactor Regulation.

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[FR Doc. E6-6342 Filed 4-26-06; 8:45 am]