Daily Rules, Proposed Rules, and Notices of the Federal Government
The U.S. Nuclear Regulatory Commission (NRC) has issued for public comment a draft guide in the agency's “Regulatory Guide” series. This series was developed to describe and make available to the public such information as methods that are acceptable to the NRC staff for implementing specific parts of the NRC's regulations, techniques that the staff uses in evaluating specific problems or postulated accidents, and data that the staff needs in its review of applications for permits and licenses.
The draft regulatory guide, entitled, “Qualification of Safety-Related Motor
This regulatory guide describes a method that the staff of the NRC deems acceptable for complying with the Commission's regulations for the qualification of safety-related motor control centers for nuclear power plants.
IEEE Std. 649-2006, “IEEE Standard for Qualifying Class 1E Motor Control Centers for Nuclear Power Generating Stations,” published on December 29, 2006, was developed by the Working Group on Motor Control Centers (SC 2.14) of the Nuclear Power Engineering Committee of the Institute of Electrical and Electronics Engineers (IEEE) and was approved by the IEEE-SA Standards Board on September 15, 2006. The standard provides basic principles, requirements, and methods for qualifying safety-related motor control centers for both harsh and mild environment applications in nuclear power plants. The demonstration that an installed motor control center will meet its design specification requires many steps: A program of quality assurance, design, qualification, production quality control, installation, maintenance, periodic testing, and surveillance. However, the scope of IEEE Std. 649-2006 is limited to qualification.
The purpose of qualification is to provide assurance that the motor control center is capable of performing its required safety functions with no failure mechanisms that could lead to common mode failures under the postulated conditions specified in the equipment specification.
Clause 9.5 of IEEE Std 649-2006 references IEEE Std 344-2004, “Recommended Practice for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations,” and provides additional guidance for seismic qualification of motor control centers. The vast majority of seismic qualification tests on motor control centers were performed with input frequencies up to only 33 Hz. Attempts to utilize such past test experience data for seismic qualification of motor control centers is not considered appropriate. Recent studies related to the early site permit applications at certain east coast hard rock-based plants indicated that the site-specific spectra may exceed the certified design spectra of new proposed plants in the very high frequency range (from 20 Hz up to 100 Hz). Plants located in the Central and Eastern United States on hard-rock should evaluate whether motor control center's components (such as digital components) could be affected by the high frequency earthquake ground motion.
These objectives should be accomplished using qualification methods (type testing, operating experience, analysis as a supplement to type testing and operating experience, ongoing qualification, or any combination thereof). However, the preferred method of qualification is type testing.
The NRC staff is soliciting comments on DG-1149. Comments may be accompanied by relevant information or supporting data, and should mention DG-1149 in the subject line. Comments submitted in writing or in electronic form will be made available to the public in their entirety through the NRC's Agencywide Documents Access and Management System (ADAMS). Personal information will not be removed from your comments. You may submit comments by any of the following methods:
Requests for technical information about DG-1149 may be directed to the NRC Senior Program Manager, Satish Aggarwal at (301) 415-6005 or e-mail to
Comments would be most helpful if received by September 19, 2008. Comments received after that date will be considered if it is practical to do so, but the NRC is able to ensure consideration only for comments received on or before this date. Although a time limit is given, comments and suggestions in connection with items for inclusion in guides currently being developed or improvements in all published guides are encouraged at any time.
Electronic copies of DG-1149 are available through the NRC's public Web site under Draft Regulatory Guides in the “Regulatory Guides” collection of the NRC's Electronic Reading Room at
In addition, regulatory guides are available for inspection at the NRC's Public Document Room (PDR), which is located at 11555 Rockville Pike, Rockville, Maryland. The PDR's mailing address is USNRC PDR, Washington, DC 20555-0001. The PDR can also be reached by telephone at (301) 415-4737 or (800) 397-4209, by fax at (301) 415-3548, and by e-mail to
Regulatory guides are not copyrighted, and Commission approval is not required to reproduce them.
For the Nuclear Regulatory Commission.