The NRC issues regulatory guides to describe and make available to the public methods that the NRC staff considers acceptable 

for use in implementing specific parts of the agency’s regulations, techniques that the staff uses in evaluating specific problems 

or postulated accidents, and data that the staff needs in reviewing applications for permits and licenses. Regulatory guides are not 

substitutes for regulations, and compliance with them is not required. Methods and solutions that differ from those set forth in 

regulatory guides will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a 

permit or license by the Commission. 

This guide was issued after consideration of comments received from the public. 

Regulatory guides are issued in 10 broad divisions: 1, Power Reactors; 2, Research and Test Reactors; 3, Fuels and Materials 

Facilities; 4, Environmental and Siting; 5, Materials and Plant Protection; 6, Products; 7, Transportation; 8, Occupational Health; 

9, Antitrust and Financial Review; and 10, General. 

Electronic copies of this guide and other recently issued guides are available through the NRC’s public Web site under the 

Regulatory Guides document collection of the NRC’s Electronic Reading Room at 

http://www.nrc.gov/reading-rm/doc-collections/ and through the NRC=s Agencywide Documents Access and Management 

System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under Accession No. ML093080087. 

U.S. NUCLEAR REGULATORY COMMISSION February 2010

 Revision 1

REGULATORY GUIDE

OFFICE OF NUCLEAR REGULATORY RESEARCH

REGULATORY GUIDE 1.40 

(Draft was issued as DG-1150, dated August 2009) 

QUALIFICATION OF CONTINUOUS DUTY 

SAFETY-RELATED MOTORS FOR NUCLEAR POWER 

PLANTS 

A. INTRODUCTION 

The U.S. Nuclear Regulatory Commission’s (NRC’s) regulations in Title 10, of the Code of 

Federal Regulations, Part 50, “Domestic Licensing of Production and Utilization Facilities” 

(10 CFR Part 50) (Ref. 1), require that structures, systems, and components in a nuclear power plant that 

are important to safety be designed to accommodate the effects of environmental conditions (i.e., they 

must remain functional under postulated design-basis events (DBEs)). General Design Criteria (GDC) 1, 

“Quality Standards and Records,” 2, “Design Bases for Protection against Natural Phenomena,” GDC 4, 

“Environmental and Dynamic Effects Design Bases,” and GDC 23, “Protection System Failure Modes,” 

of Appendix A, “General Design Criteria for Nuclear Power Plants,” to 10 CFR Part 50, contain the 

general requirements for meeting those conditions. The specific requirements in 10 CFR 50.49, 

“Environmental Qualification of Electric Equipment Important to Safety for Nuclear Power Plants,” for 

the qualification of certain electrical equipment important to safety in addition to, the general 

requirements of GDC 1, 2, 4, and 23. In addition, Criterion III, “Design Control,” of Appendix B, 

“Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants,” to 10 CFR Part 50, 

requires that test programs, when used to verify the adequacy of a specific design feature, should include 

the suitable qualification testing of prototype units under the most adverse design conditions. 

This guide describes a method that the NRC staff considers acceptable for complying with the 

Commission’s regulations for the qualification of continuous duty safety-related motors for nuclear power 

plants. 
Rev. 1 of RG 1.40, Page 2 

 

The NRC issues regulatory guides to describe methods that the staff considers acceptable for use 

in implementing specific parts of the agency’s regulations, to explain techniques that the staff uses in 

evaluating specific problems or postulated accidents, and to provide guidance to applicants. Regulatory 

guides are not substitutes for regulations and compliance with them is not required. 

This regulatory guide contains information collection requirements covered by 10 CFR Part 50 

that the Office of Management and Budget (OMB) approved under OMB control number 3150-0011. 

The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information 

collection request or requirement unless the requesting document displays a currently valid OMB control 

number. 

B. DISCUSSION 

The Working Group on Qualification of Motors (Subcommittee (SC 2.2) of the Nuclear Power 

Engineering Committee of the Institute of Electrical and Electronics Engineers, Inc. (IEEE) developed 

Standard 334-2006, “IEEE Standard for Qualifying Continuous Duty Class 1E Motors for Nuclear Power 

Generating Stations.” The IEEE Standards Board approved this standard on September 15, 2006, and it 

was published on January 31, 2007 (Ref. 2). This standard establishes criteria for qualification of 

continuous duty Class 1E motors, located in mild and harsh environments in nuclear power plants, to 

demonstrate their ability to perform their intended safety functions. The standard also provides guidance 

for qualification of refurbished motors and insulation systems for motor rewinds. 

The purpose of qualification is to provide reasonable assurance that safety-related motors perform 

their specified safety functions and that no failure mechanisms exist that can lead to a common-cause 

failure under the postulated service conditions. The standard provides the methods for qualifying safetyrelated motors. 

Applicants and licensees should accomplish qualification by using these 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. 

C. REGULATORY POSITION 

The NRC staff considers conformance with IEEE Standard 334-2006 an acceptable method for 

use in satisfying the Commission’s regulations with respect to qualification of continuous duty safetyrelated motors. 

IEEE Standard 334-2006 references several industry codes and standards. If the NRC’s 

regulations separately incorporate a referenced standard, licensees and applicants must comply with the 

standard as set forth in the regulations. By contrast, if the NRC staff has endorsed a referenced standard 

in a regulatory guide, that standard constitutes an acceptable method of meeting a regulatory requirement 

as described in the regulatory guide. 

D. IMPLEMENTATION 

The purpose of this section is to provide information to applicants and licensees regarding 

the NRC’s plans for using this regulatory guide. The NRC does not intend or approve any imposition or 

backfit in connection with its issuance. 
Rev. 1 of RG 1.40, Page 3 

In some cases, applicants or licensees may propose or use a previously established acceptable 

alternative method for complying with specified portions of the NRC’s regulations. Otherwise, 

the methods described in this guide will be used in evaluating compliance with the applicable regulations 

for license applications, license amendment applications, and amendment requests. It will also be used to 

evaluate submittals for operating reactor licensees who voluntarily propose to initiate system 

modifications.
Rev. 1 of RG 1.40, Page 4 

REFERENCES1

1. 10 CFR Part 50, “Domestic Licensing of Production and Utilization Facilities,” 

U.S. Nuclear Regulatory Commission, Washington, DC. 

2. IEEE Std. 334-2006, “IEEE Standard for Qualifying Continuous Duty Class 1E Motors for 

Nuclear Power Generating Stations,” Institute of Electrical and Electronics Engineers, Inc., 

Piscataway, NJ, January 31, 2007. 2

 

1 Publicly available NRC published documents such as Regulations, Regulatory Guides, NUREGs, and Generic Letters 

 listed herein are available electronically through the Electronic Reading room on the NRC’s public Web site at: 

http://www.nrc.gov/reading-rm/doc-collections/. Copies are also available for inspection or copying for a fee from the 

 NRC’s Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing address is USNRC PDR, 

 Washington, DC 20555; telephone 301-415-4737 or (800) 397-4209; fax (301) 415-3548; and e-mail 

PDR.Resource@nrc.gov. 

2 Copies of the non-NRC documents included in these references may be obtained directly from the publishing 

 organization.