NUREG/CR-6431 

ORNL/TM- 13158

Recommended Electromagnetic 

Operating Envelopes for 

Safety-Related I&C Systems in 

Nuclear Power Plants 

Oak Ridge National Laboratory 

U.S. Nuclear Regulatory Commission 

Office of Nuclear Regulatory Research 

Washington, DC 20555-0001
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NUREG/CR-6431 

ORNL/TM-13158 

Recommended Electromagnetic 

Operating Envelopes for 

Safety-Related I&C Systems in 

Nuclear Power Plants 

Manuscript Completed: November 1999 

Date Published: January 2000 

Prepared by 

P. D. Ewing, R. T. Wood 

Oak Ridge National Laboratory 

Managed by Lockheed Martin Energy Research Corporation 

Oak Ridge, TN 37831-6050 

C. E. Antonescu, NRC Project Manager 

Prepared for 

Division of Systems Technology 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

NRC Job Code L1951 

0 

For sale by the U.S. Government Printing Office 

Superintendent of Documents, Mail Stop: SSOP, Washington, DC 20402-9328 

ISBN 0-16-050333-7
NUREG/CR-6431 has been reproduced 

from the best available copy.
ABSTRACT 

This document presents recommendations for electromagnetic operating envelopes to augment test 

criteria and test methods addressing electromagnetic interference (EMI), radio-frequency interference 

(RFI), and power surges that are applicable to safety-related instrumentation and control (I&C) systems 

in nuclear power plants. The Oak Ridge National Laboratory (ORNL) was engaged by the U.S. Nuclear 

Regulatory Commission (NRC) Office of Nuclear Regulatory Research to assist in developing the 

technical basis for regulatory guidance on EMIIRFI immunity and power surge withstand capability 

(SWC). Previous research has provided recommendations on electromagnetic compatibility (EMC) 

design and installation practices, endorsement of EMI/RFI immunity and SWC test criteria and test 

methods, and determination of ambient electromagnetic conditions at nuclear power plants. The present 

research involves development of recommended electromagnetic envelopes that are applicable to nuclear 

power plant locations where safety-related I&C systems either are or may be installed. These 

recommended envelopes establish both emissions criteria and the levels of radiated and conducted 

interference that I&C systems should be able to withstand without upset or malfunction. The EMIIRFI 

operating envelopes are derived from conditions in comparable military environments, and are confirmed 

by comparison with the nuclear power plant electromagnetic environment based on measured plant 

emissions profiles and commercial emissions limits for typical industrial environments. Detailed 

information on specific power surge conditions in nuclear power plants is not available, so industrial 

guidance on representative surge characteristics for susceptibility testing is adopted. An engineering 

assessment of the power surge environment in nuclear power plants leads to the recommendation of 

operating envelopes based on location categories and exposure levels defined in IIEEE Std C62.41-1991, 

IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Power Circuits.

°,. NUREG/CR-6431
CONTENTS 

Page 

A B ST R A C T ........................................................................ iii 

FIG U R E S ......................................................................... vii 

T A B L E S ......................................................................... vii 

EXECUTIVE SUM M ARY ............................................................ ix 

ACKNOW LEDGMENTS ............................................................. xi 

A CR O N Y M S ...................................................................... xiii 

G L O SSA R Y ....................................................................... xv 

1 INTROD U CTION ......................... ....................................... 1 

2 ELECTROMAGNETIC EFFECTS TEST CRITERIA ..................................... 1 

2.1 EM I/RFI Test Criteria ...................................................... 1 

2.2 SW C Test Criteria ......................................................... 4 

3 APPROACH TO RECOMMENDED OPERATING ENVELOPES .......................... 4 

4 RECOMMENDED EMIRFI OPERATING ENVELOPES ................................. 5 

4.1 MIL-STD 461D Conducted EMIIRFI Operating Envelopes ......................... 6 

4.2 MIL-STD 461D Radiated EMI/RFI Operating Envelopes ......................... 10 

4.3 MIL-STD 461C Conducted EMI/RFI Operating Envelopes ........................ 13 

4.4 MIL-STD 461C Radiated EMIIRFI Operating Envelopes ......................... 16 

5 RECOMMENDED SWC OPERATING ENVELOPES ................................... 19 

5.1 R ing W ave .............................................................. 19 

5.2 Com bination W ave ....................................................... 19 

5.3 Electrically Fast Transients ................................................. 21 

6 ASSESSMENT OF EMYRFI OPERATING ENVELOPES ................................ 23 

6.1 ORNL Electromagnetic Survey Findings ...................................... 23 

6.2 Survey Data vs Recommended Operating Envelopes ............................. 27 

6.3 Discussion on the Need for Safety Margins ..................................... 29 

7 IMPLEMENTATION OF THE OPERATING ENVELOPES ............................ 30 

8 CO N CLU SIO N S ................................................................. 31 

9 REFEREN CES ................................................................... 33 

A PPE N D IX ....................................................................... 35 

v NUREG/CR-6431
FIGURES

6.2 Data vs Operating Envelopes, Radiated Magnetic Fields ............. 

6.3 Data vs Operating Envelopes, Conducted Interference - 30 Hz to 50 kHz

6.4 Data vs Operating Envelopes, Conducted Interference - 10 kHz to 400 MHz

Page 

...................... 7 

...................... 7 

...................... 8

4.1 CE 101 Emissions Envelopes for dc Power Leads .... 

4.2 CE101 Emissions Envelopes for ac Power Leads .... 

4.3 CE102 Emissions Envelopes .................... 

4.4 CS 101 Operating Envelope ...................... 

4.5 CS 114 Operating Envelope ...................... 

4.6 RE101 Magnetic Field Emissions Envelopes ........ 

4.7 RE102 Emissions Envelope ..................... 

4.8 RS 101 Operating Envelope ...................... 

4.9 CEO1 Emissions Envelope for dc Power Leads ...... 

t.10 CEO1 Emissions Envelope for ac Power Leads ...... 

1.11 CE03 Narrowband Emissions Envelope ............ 

1.12 CS01 Operating Envelope ....................... 

t.13 RE01 Magnetic Field Emissions Envelope .......... 

1.14 RE02 Narrowband Emissions Envelope ............ 

1.15 RS01 Operating Envelope ....................... 

5.1 100-kHz Ring W ave ........................... 

5.2 Combination Wave, Open-circuit Voltage .......... 

5.3 Combination Wave, Short-circuit Current .......... 

5.4 Waveform of the EFT Pulse ..................... 

5.5 Pattern of EFT Bursts .......................... 

6.1 Data vs Envelopes, Radiated Electric Fields ........

TABLES

2.1 

2.2 

3.1 

6.1 

6.2 

6.3 

6.4

Recommended MIL-STD 461D test criteria .................................... 

MIL-STD 46 1C counterparts to applicable MIL-STD 46 1D test criteria ............. 

Representative power surge waveforms ....................................... 

EMJIRFI survey measurement locations ....................................... 

ORNL highest observations-radiated electric fields ............................ 

ORNL highest observations-radiated magnetic fields ........................... 

ORNL highest observations--conducted EMI/RFI, 300 Hz to 5 MHz ...............

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vii
EXECUTIVE SUMMARY

Until recently, little was known about the prevailing ambient electromagnetic interference (EMI), radio

frequency interference (RFI), and power surge environment in nuclear power plants. This lack of 

information made it difficult to establish electromagnetic operating envelopes for safety-related 

instrumentation and control (I&C) systems-that is, the level of interference that systems should be able 

to withstand without upset or malfunction-with a high degree of confidence in their adequacy. 

Consequently, the Oak Ridge National Laboratory (ORNL) was engaged by the U.S. Nuclear Regulatory 

Commission Office of Nuclear Regulatory Research to profile the electromagnetic emission levels in the 

nuclear power plant environment and provide recommended operating envelopes to augment the 

EMI/RFI and power surge test criteria and test methods discussed in NUREG/CR-5941, Technical Basis 

for Evaluating Electromagnetic and Radio-Frequency Interference in Safety-Related I&C Systems. 

The recommended EMI/RFI test criteria in NUREG/CR-5941 were extracted from Military Standard 

(MIL-STD) 461, Electromagnetic Emission and Susceptibility Requirements for the Control of 

Electromagnetic Interference, and the associated test methods were extracted from MIL-STD 462, 

Measurement of Electromagnetic Interference Characteristics. These test criteria and methods were 

selected because they provide a well-established, systematic approach to ensuring electromagnetic 

compatibility for I&C equipment with the environment in which it operates. These recommended testing 

practices are based on the military services' considerable experience in evaluating EMI/RFI effects. The 

recommended surge withstand capability (SWC) test criteria and associated test methods are based on 

practices described in IEEE Std C62.41-1991, IEEE Recommended Practice on Surge Voltages in Low

Voltage AC Power Circuits. They employ a manageable set of power surge waveforms selected to 

simulate realistic surge environments. 

This report details the recommendations by ORNL for electromagnetic operating envelopes that 

contribute to ensuring that functional problems related to EMI/RFI and power surges are averted in 

safety-related I&C systems. Operating envelopes were first defined based on conditions in military 

environments comparable to the nuclear power plant environment. Electromagnetic measurement 

systems were then assembled by ORNL and used to monitor radiated electric field, radiated magnetic 

field, and conducted interference levels at eight nuclear units over a period of 14 months. Measurement 

data and the resulting electromagnetic emission profiles for the selected plant sites are reported in 

NUREG/CR-6436, Survey of Ambient Electromagnetic and Radio-Frequency Interference Levels in 

Nuclear Power Plants. Those emission profiles were subsequently used to confirm that the 

recommended EMI/RFI susceptibility operating envelopes were appropriately tailored to the nuclear 

power plant environment (i.e., they do bound with high confidence the projected electromagnetic 

conditions as determined from measured data). As an added measure, short-term emissions data 

collected during a 1994 study conducted by the Electric Power Research Institute were also used to 

confirm the recommended susceptibility operating envelopes. As a result, the susceptibility envelopes 

were adjusted in some cases to account for the plant emissions data. Adjustments to the equipment 

emissions envelopes considered margin with the susceptibility envelopes and the primary intent of the 

MIL-STD envelopes (e.g., whether the envelopes were based on protecting sensitive receivers on military 

platforms). Finally, when changes to the operating envelopes from the MIL-STD origin were motivated 

by technical considerations, consistency among the envelopes for comparable test criteria was promoted 

and commercial emissions limits for industrial environments were factored into adjustments of the 

envelopes. 

Detailed information on specific power surge conditions in nuclear power plants was not available so 

industrial guidance on representative surge characteristics for susceptibility testing was adopted. An

ix NUREG/CR-6431
engineering assessment of the power surge environment in nuclear power plants led to the 

recommendation of basing the operating envelopes on location categories and exposure levels defined in 

IEEE Std C62.41-1991. The selected location category and exposure level define applicable amplitudes 

for the surge waveforms that should provide an appropriate degree of SWC. 

The value added by developing the technical basis for regulatory guidance in both NUREG/CR-5941 and 

this report is that it (1) offers clear guidance on necessary practices that are a part of an overall 

electromagnetic compatibility (EMC) program; (2) endorses finalized military and industry standards that 

have wide, long-standing application; (3) specifies complete suites of EMIRFI emissions and 

susceptibility test criteria and methods from the two most prevalent military standards (i.e., no mixing 

and matching of test criteria and methods are promoted) and gives operating envelopes that are framed in 

suitable measurement units and frequency ranges for each specific test method; (4) applies to analog, 

digital, and hybrid (i.e., combined analog and digital electronics) safety-related I&C equipment; and 

(5) identifies acceptable operating envelopes which are based on similar military environments, and 

confirmed with measurement data from nuclear power plants and commercial emissions limits from 

typical industrial environments.

NUREG/CR-6431 X
ACKNOWLEDGMENTS 

The authors wish to thank Christina Antonescu, JCN L1951 Project Manager, of the U.S. NRC Office of 

Nuclear Regulatory Research (RES) for her help in initiating, planning, and implementing this research 

effort. The authors would also like to thank John Calvert, Steve Arndt,, Frank Coffman, and Jit Vora of 

RES for their review and comments on the project. Thanks are extended to Roger Kisner and Bob Kryter 

at ORNL for their management support and technical contributions to this long-term project. Thanks are 

also extended to Steve Kercel, Mike Moore, and Ed Blakeman at ORNL for their assistance in 

interpreting and analyzing the ORNL survey results.

xi NUREG/CR-6431
ACRONYMS

ABB Asea Brown Boveri 

ALWR advanced light-water reactor 

ANSI American National Standards Institute 

B&W Babcock and Wilcox 

BWR boiling water reactor 

CE conducted emissions 

CISPR International Special Committee on Radio Interference 

COTS commercial-off-the-shelf 

CS conducted susceptibility 

EFT electrically fast transients 

EMC electromagnetic compatibility 

EMI electromagnetic interference 

EPRI Electric Power Research Institute 

FCC Federal Communications Commission 

GE General Electric 

I&C instrumentation and controls 

IEC International Electrotechnical Commission 

IEEE Institute of Electrical and Electronics Engineers 

MIL-STD military standard 

NRC U.S. Nuclear Regulatory Commission 

ORNL Oak Ridge National Laboratory 

PWR pressurized water reactor 

RE radiated emissions 

RES Office of Nuclear Regulatory Research 

RFI radio-frequency interference 

RPS reactor protection system 

RS radiated susceptibility 

SWC surge withstand capability

xiii NUREG/CR-6431
GLOSSARY 

ac alternating current 

dB decibel-ten times the logarithm to base 10 of a ratio of two powers, or twenty times the 

logarithm to base 10 of a ratio of two voltages or currents 

dBgA decibels referenced to one microampere, unit of conducted interference 

dBliV decibels referenced to one microvolt, unit of conducted interference 

dBtV/m decibels referenced to one microvolt per meter, unit of electric field strength 

dBpT decibels referenced to one picotesla, unit of magnetic field strength 

dc direct current 

GHz Gigahertz -10' Hertz 

Hz Hertz-unit of frequency, one cycle per second 

I(t) instantaneous current at time t 

I4 peak current 

kA kiloamperes-103 A, unit of current 

kHz kilohertz-103 Hz 

kV kilovolt-103 V, unit of voltage 

MHz Megahertz-106 Hz 

ALs microsecond-10 6 s 

ns nanosecond -10-9 s 

0 ohm, unit of resistance 

rms root mean square- square root of the average square of an instantaneous magnitude 

V(t) instantaneous voltage at time t 

V/m volts per meter, unit of electric field strength 

VP peak voltage 

W watt, unit of power

XV NUREG/CR-6431
1 INTRODUCTION

Instrumentation and control (I&C) systems for advanced light-water reactors (ALWRs) are expected to 

make use of both analog and digital equipment and will be significantly different from the predominantly 

analog-based I&C systems in use for safety-related functions at current nuclear power plants. Limited 

operational experience with digital technology and advanced analog electronics in the nuclear industry 

has caused concern about upsets and malfunctions in safety-related I&C systems due to electromagnetic 

interference (EMI), radio-frequency interference (RFI), and power surges. Hence, the U.S. Nuclear 

Regulatory Commission (NRC) Office of Nuclear Regulatory Research engaged the Oak Ridge National 

Laboratory (ORNL) to assist in developing the technical basis for regulatory guidance on EMI/RFI 

immunity and power surge withstand capability (SWC). 

The NRC-sponsored confirmatory research project, Regulatory Guide and Acceptance Criteria for 

EMIIRFI in I&C Systems, addresses installation practices, test criteria, test methods, and methods for 

establishing operating envelopes for I&C equipment. The objectives of this project are to (1) develop the 

technical basis for regulatory guidance in the areas of EMI/RFI and SWC for safety-related I&C systems, 

(2) formulate testing criteria for evaluating both the susceptibilities and the emissions of such systems, 

and (3) conduct in-plant measurements to characterize the electromagnetic environment in nuclear power 

plants. 

Previous findings and recommendations on EMI/RFI and SWC test criteria, test methods, and installation 

practices were reported in NUREG/CR-594 1, Technical Basis for Evaluating Electromagnetic and 

Radio-Frequency Interference in Safety-Related I&C Systems.' That document discusses the technical 

basis for recommended electromagnetic compatibility (EMC) design and installation practices to ensure 

operational safety in equipment and presents testing techniques to assure that the EMC practices do, 

indeed, achieve their intended purpose. 

Until recently, little was known about the prevailing ambient electromagnetic environment in nuclear 

power plants. This lack of information made it difficult to recommend electromagnetic operating 

envelopes-that is, the level of interference that safety-related I&C systems should be able to withstand 

without upset or malfunction-with a high degree of confidence in their adequacy. Consequently, ORNL 

profiled the electromagnetic emission levels at selected plant sites. Those profiles were reported in 

NUREG/CR-6436, Survey of Ambient Electromagnetic and Radio-Frequency Interference Levels in 

Nuclear Power Plants,2 and have been incorporated into the development of the technical basis for 

realistic operating envelopes. This report details the recommendations of ORNL for electromagnetic 

operating envelopes to augment the test criteria and test methods recommended in NUREG/CR-5941. 

2 ELECTROMAGNETIC EFFECTS TEST CRITERIA 

2.1 EMI/RI Test Criteria 

The EMLR1FI test criteria listed in Table 2.1 were extracted from Military Standard (MIL-STD) 461D, 

Electromagnetic Emission and Susceptibility Requirements for the Control of Electromagnetic 

Interference,3 to evaluate the effects of EMI/RFI in safety-related I&C systems. Table 2.2 lists the 

corresponding counterparts to the recommended MIL-STD 461D test criteria found in the MIL-STD 

461C 4 version of the standard. These two sets of criteria address many important EMI/RFI issues. 

MIL-STD 46 1D provides the latest revision of the EMIRFI test criteria (which includes improvements 

based on experience and the most recent technical information), thus it represents current practice.

I NUREG/CR-6431
However, guidance on the MIL-STD 461C counterparts to the MIL-STD 461D test criteria is also given 

to avoid placing an undue burden on the nuclear power industry by limiting the available test resources to 

those test laboratories with the MIL-STD 462D test capability. It is intended that either set be applied in 

its entirety, without selective application of individual criteria (i.e., no mixing and matching of test 

criteria). The test criteria are specified by alphanumeric codes: the first designation declares the criterion 

to be either radiated (R) or conducted (C), and the second designation specifies whether it covers 

emissions (E) or susceptibility (S). This alphabetic designation is followed by a numbering system that is 

specific to the particular test criterion. 

Table 2.1 Recommended MIL-STD 461D test criteria 

Criterion Description 

CE101 Conducted emissions, power leads, 30 Hz to 10 kHz 

CE102 Conducted emissions, power leads, 10 kHz to 10 MHz 

CS101 Conducted susceptibility, power leads, 30 Hz to 50 kHz 

CS 114 Conducted susceptibility, bulk cable injection, 10 kHz to 400 MHz 

RE101 Radiated emissions, magnetic field, 30 Hz to 100 kHz 

RE102 Radiated emissions, electric field, 10 kHz to 1 GHz 

RS101 Radiated susceptibility, magnetic field, 30 Hz to 100 kHz 

RS103 Radiated susceptibility, electric field, 10 kHz to 1 GHz 

Table 2.2 MIL-STD 461C counterparts to applicable MIL-STD 461D test criteria 

Criterion Description 

CEO0 Conducted emissions, power leads, 30 Hz to 15 kHz 

CE03 Conducted emissions, power leads, 15 kHz to 50 MHz 

CS01 Conducted susceptibility, power leads, 30 Hz to 50 kHz 

CS02 Conducted susceptibility, power and interconnecting control leads, 

50 kHz to 400 MHz 

REOl Radiated emissions, magnetic field, 30 Hz to 50 kHz 

RE02 Radiated emissions, electric field, 14 kHz to 1 GHz 

RS01 Radiated susceptibility, magnetic field, 30 Hz to 50 kHz 

RS03 Radiated susceptibility, electric field, 14 kHz to 1 GHz 

C = conducted, E = emissions, R = radiated, and S = susceptibility.

NUREG/CR-6431 2
The purpo- l he conducted emissions (CE) tests is to ensure that equipment connected to the power 

bus does not corrupt its power quality (introduce distortions in the voltage waveforms) or cause excess 

radiation from the power bus. The conducted susceptibility (CS) tests are intended to ensure that 

equipment performance will not be degraded in the event that distortions in the voltage waveforms and 

high frequency conducted EMI/RFI are somehow introduced on the power bus. The purpose of the 

radiated emissions (RE) tests is to control the magnetic field and electric field emissions from equipment 

and its associated cables. The radiated susceptibility (RS) tests are intended to ensure that equipment 

will operate without degradation in the presence of significant electromagnetic field levels. 

The EMIIRFI test criteria in Tables 2.1 and 2.2 are modified versions of the criteria originally 

recommended in NUREG/CR-5941. The MIL-STD 461D test criteria for radiated and conducted 

susceptibility to voltage spikes (CS 115 and CS 116), along with their corresponding MIL-STD 461 C 

counterparts (CS06 and RS02), are no longer considered necessary. The reason for this recommendation 

is recognition that the results of applying the MIL-STD voltage spike waveforms will be duplicated by 

the application of the surge waveforms of the SWC test criteria discussed in Sect. 2.2. The MIL-STD 

test criteria are significantly less stringent, with the SWC test criteria exceeding them by greater than a 

factor of eight in frequency spectrum coverage and greater than a factor of seven in amplitude. 

The rationale for the recommendation of the MIL-STD test criteria is that they provide a well

established, systematic approach to ensuring electromagnetic compatibility for I&C equipment with the 

environment in which it operates. These recommended testing practices are based on the military 

services' considerable experience (almost 30 years) in evaluating EMIIRFI effects. In particular, the 

MIL-STD test criteria in Tables 2.1 and 2.2 were selected because they are suitable for military ground 

facilities, the military environment that most closely resembles the nuclear power plant environment. 

The resemblance is thought to occur because military ground facilities are land-based structures 

employing earth grounding criteria and are typically used to facilitate industrial-type equipment in a less

than-harsh electromagnetic environment. It may be of interest to note that these test criteria are also 

considered suitable for the military's aircraft, surface ship, and submarine environments. In addition, 

close study of the test criteria indicates that a wide range of EMC issues is thereby addressed, in that the 

criteria cover the gamut of associated problems-conducted and radiated interference, exposure to 

electric and magnetic fields, and noise coupling through power and control leads. 

As indicated by their descriptions, the MIL-STD 461D and corresponding 461C test criteria for 

conducted susceptibility in Tables 2.1 and 2.2 are not generally applicable for conducted EMI/RFI on 

interconnecting signal lines. However, the MIL-STDs do leave open the possibility of specifying test 

criteria for signal lines when the sponsoring agency deems it necessary, but offer no guidance on 

acceptable test levels (these must be determined on a case by case basis). An earlier version of the 

standards, MIL-STD 461A, did address signal lines, but subsequent versions dropped that application 

based on the rationale that conducted EMIRFI on interconnecting signal lines would be addressed by 

system-level EMC requirements. The need to address equipment-level test criteria and operating 

envelopes for conducted EMLRFI on signal lines in nuclear power plants is an open issue and is not 

covered by the present effort to develop the technical basis for regulatory guidance. However, a separate 

investigation has been initiated by NRC in an attempt to address the issue. The result is expected to be 

the development of a comprehensive approach to conducted EMI/RFI on interconnecting signal lines. 

Corresponding test methods in MIL-STD 462D, Measurement of Electromagnetic Interference 

Characteristics,5 are used to demonstrate compliance with the MIL-STD 461D test criteria. The previous 

version of the test methods can be found in MIL-STD 4626 and confirms compliance with the 

corresponding MIL-STD 461C test criteria. The MIL-STD test methods are well developed in that they 

have been reviewed and updated on a periodic basis since their inception in 1967.7 With the

3 NUREG/CR-6431
implementation of the test criteria in Tables 2.1 and 2.2 (and their associated test methods), it can be 

demonstrated through testing that equipment and subsystems can function properly in the presence of 

known EMI/RFI levels and that the emissions levels of that equipment will not appreciably increase the 

electromagnetic ambient conditions at the installation site. 

2.2 SWC Test Criteria 

The SWC practices described in IEEE Std C62.41-1991 (Reaff 1995), IEEE Recommended Practice on 

Surge Voltages in Low-Voltage AC Power Circuits,8 are recommended in NUREG/CR-5941 to control 

the occurrence of upsets in safety-related I&C equipment caused by power surges originating from two 

major sources: lightning effects (direct or indirect) and switching transients. It is acknowledged that 

although the waveforms described in IEEE Std C62.41-1991 cannot completely include all possible surge 

environments, they nonetheless define a manageable and realistic set of surge waveforms selected to 

represent realistic conditions. Tests employing these waveforms should provide reproducible results that, 

in turn, can be expected to provide a reasonable degree of assurance that problems associated with power 

surges are averted. 

Test procedures for the IEEE Std C62.41-1991 practices are described in IEEE Std C62.45-1992, IEEE 

Guide on Surge Testing for Equipment Connected to Low-Voltage AC Power Circuits.9 Hence, IEEE Std 

C62.45-1992 should be used as a companion document to IEEE Std C62.41-1991. The test procedures 

are recognized throughout the power industry and have been endorsed by a number of equipment 

manufacturers and utilities. 

3 APPROACH TO RECOMMENDED OPERATING ENVELOPES 

The EMI/RFI operating envelopes in MIL-STDs 461D and 461C are specified according to the particular 

application and the projected environments in which the equipment and subsystems must operate. 

Military EMI/RFI operating environments vary from low interference levels at ground-based locations to 

extremely high levels on the decks of aircraft carriers, and operating envelopes are selected accordingly. 

As an initial approach, EMI/RFI susceptibility and emissions operating envelopes were developed and 

recommended for the nuclear power plant environment based on those envelopes used to ensure the 

electromagnetic compatibility of military equipment designed for use in the military ground facilities 

described in the MIL-STDs. To confirm that the recommended operating envelopes were appropriately 

tailored to the nuclear power plant environment, ambient EMYRFI conditions were then measured at 

eight nuclear units over a period of 14 months. Measurement data were collected, for up to 5 weeks 

(24 h/day) in each plant location, with electromagnetic spectral receivers assembled by ORNL to acquire 

and record peak radiated electric field, radiated magnetic field, and conducted interference levels. The 

measurement approach is described in detail in NUREG/CR-6436. As an added measure, short-term 

emissions data collected during a 1994 study conducted by the Electric Power Research Institute (EPRI) 

were also used to confirm the recommended EMIIRFI operating envelopes. Results of the EPRI study 

are reported in EPRI TR-102323, Guidelines for Electromagnetic Interference Testing in Power Plants.'0 

As a result, the susceptibility envelopes were adjusted in some cases to account for the plant emissions 

data. Adjustments to the equipment emissions envelopes considered margin with the susceptibility 

envelopes and the primary intent of the MIL-STD envelopes. Finally, when changes to the operating 

envelopes from the MIL-STD origin were motivated by technical considerations, consistency among the 

envelopes for comparable test criteria was promoted and commercial emissions limits for industrial 

environments were factored into adjustments of the envelopes.

NUREG/CR-6431 4
Since detailed information on specific power surge conditions in nuclear power plants is not available, 

the recommendation of SWC operating envelopes took a different approach. Given the dynamic nature 

of power systems, power surge measurements are very much site-dependent, and prediction of the future 

environment may require several years of monitoring. The surge environment is so complex that no set 

of test waveforms will ever completely simulate all possible surge conditions.'1 Hence, it is prudent to 

use the limited set of representative surge waveforms in IEEE Std C62.41-1991 as a baseline SWC 

environment. As discussed in NUREG/CR-5941, the typical environmental surge conditions in a nuclear 

power plant can be represented by the two standard waveforms-that is, the ring wave and the 

combination wave-plus the electrically fast transients (EFT) waveform. These waveforms were 

developed from data collected on power surges caused by lightning effects and system switching 

transients. Descriptions of the waveforms are given in Table 3.1. 

Table 3.1 Representative power surge waveforms 

Parameter Ring Wave Combination Wave EFT 

Waveform Open-circuit Open-circuit Short-circuit Pulses in 

voltage voltage current 15-ms bursts 

Rise time 0.5 its 1.2 its 8 As 5 ns 

Duration 100 kHz ringing 50,us 20 its 50 ns 

IEEE Std C62.41-1991 describes location categories and exposure levels that define applicable 

amplitudes for the surge waveforms that should provide an appropriate degree of SWC. Location 

categories depend on the proximity of equipment to the service entrance and the associated line 

impedance. Exposure levels relate to the rate of surge occurrence versus the voltage level (e.g., surge 

crest) to which equipment is exposed. An engineering assessment of the power surge environment in 

nuclear power plants for safety-related I&C systems is that withstand levels can be based on Category B 

locations12 and Low to Medium Exposure levels."3 Category B covers feeders and short branch circuits 

less than 10 meters from the service entrance. Low to Medium Exposure levels encompass systems in 

areas known for little load or capacitor switching and low-power surge activity to areas known for 

significant switching transients or medium- to high-power surge activity. The basis for the withstand 

levels provides reasonable assurance that the general power surge environment in nuclear power plants is 

adequately characterized. The withstand levels should be acceptable for locations where safety-related 

I&C systems either are or are likely to be installed and include control rooms, remote shutdown panels, 

cable spreading rooms, equipment rooms, auxiliary instrument rooms, relay rooms, and other areas (e.g., 

the turbine deck) where safety-related I&C system installations are planned. 

4 RECOMMENDED EMIRFI OPERATING ENVELOPES 

The control of conducted EMI/RFI is essential to protect against poor power quality and excess radiation 

from the power bus. The phenomena of concern are distortions of the supplied voltage level caused by 

changing electrical loads and the introduction of high frequency conducted EMI/RFI that can radiate 

from the power bus. The CE operating envelopes limit the maximum voltage distortions and high 

frequency conducted EMIIRFI allowed on the power bus. The CS operating envelopes provide the 

conducted EMI/RFI levels to which equipment can be subjected and continue to operate without 

performance degradation.

5 NUREG/CR-6431
The control of radiated EMIIRFI is essential to protect against equipment malfunctions caused by excess 

electromagnetic emissions. The RE operating envelopes limit the magnetic field and electric field 

emissions allowed from equipment. The RS operating envelopes provide the radiated EMI/RFI levels to 

which equipment can be subjected and continue to operate without performance degradation. 

Recommended EMI/RFI operating envelopes are discussed herein for both the MIL-STD 461D and 

MIL-STD 461C test.criteria. Some EMI/RFI test laboratories are well versed in performing the 

MIL-STD 462D tests associated with the MIL-STD 461D test criteria, and several laboratories are 

equipped to perform the MIL-STD 462 tests associated with the MIL-STD 461C test criteria. With the 

recent downturn in military procurements due to the end of the Cold War, it is difficult to estimate how 

many test laboratories are. actually. implementing a MIL-STD 462D testing capability. Thus, EMIIRFI 

operating envelopes are recbmmended for both test criteria so that testing resources are not limited based 

on the number of available MIL-STD 462D test laboratories. 

Development of the technical basis for the EMI/RFI operating envelopes began with the MIL-STD 

envelopes corresponding to the electromagnetic environment for military ground facilities, which were 

judged to be comparable to that of nuclear power plants based on general layout and equipment type 

considerations. Plant emissions data were used to confirm the adequacy of the operating envelopes. 

From the MIL-STD -starting point, susceptibility envelopes were adjusted to account for the plant 

emissions data reported in NUREG/CR-6436 and EPRI TR-102323. Adjustments to the equipment 

emissions envelopes considered margin with the susceptibility envelopes and the primary intent of the 

MIL-STD envelopes.(e.g., whether the envelopes were based on protecting sensitive receivers on military 

platforms). Finally, when changes to the operating envelopes from the MIL-STD origin were motivated 

by technical considerations, consistency among the envelopes for comparable test criteria was promoted 

and commercial emissions limits for industrial environments were factored into adjustments of the 

envelopes. As a result of these considerations, the operating envelopes presented herein are equivalent or 

less restrictive than the MIL-STD envelopes that served as their initial basis. A detailed technical basis 

for each operating envelope is given in the Appendix. 

4.1 MIL-STD 461D Conducted EMI/RFI Operating Envelopes 

4.1.1 CE101-Conducted Emissions, Low Frequency 

The CE101 test measures the low-frequency conducted emissions on power leads of equipment and 

subsystems in the frequency 30 Hz to 10 kHz. Equipment could be exempt from this test if the following 

two conditions exist. First, the power quality requirements of the equipment are consistent with the 

existing power supply; and second, the equipment will not impose additional harmonic distortions on the 

existing power distribution system that exceed 5% total harmonic distortion (THD) or other power 

quality criteria established with a valid technical basis. When the test is desired, it is applicable to ac and 

dc power leads, including grounds and neutrals, that obtain power from other sources not part of the 

equipment under test. Conducted emissions on power leads should not exceed the applicable root mean 

square (rms) values shown in Figure 4.1 for dc-operated equipment and Figure 4.2 for ac-operated 

equipment. Alternate envelopes are given for ac-operated equipment based on power consumption (less 

than or equal to 1 kVA and greater than 1 kVA). For ac-operated equipment with a fundamental current 

(i.e., load current at the power line frequency) greater than 1 ampere, the envelopes in Figure 4.2 may be 

relaxed as follows: 

dB relaxation = 20 log(fundamental current).

NUREG/CR-6431 6
0.1 1

95 

10 100

Frequency (kHz)

Figure 4.1 CE101 Emissions Envelopes for dc Power Leads

B0 HZ 120 Hz 

0.1 1.15 kHz 

1

86

10 100

Frequency (kHz) 

Figure 4.2 CE101 Emissions Envelopes for ac Power Leads

NUREG/CR-6431

160 

150 

140 

130 

120 

110

C: 

=L

100 

90 

80 

0.01

140 

130 

120 

110 

100 

90

-o 

FD 

::3 0

80 

70

0.01

" AC POWER ,r1 kVA 

~AC POWER LEADS 

SAC POWER > lkVA - ----

•N

7
4.1.2 CE102-Conducted Emissions, High Frequency 

The CE102 test measures the high-frequency conducted emissions on power leads of equipment and 

subsystems in the frequency range 10 kHz to 10 MHz. The test is applicable to ac and dc power leads, 

including grounds and neutrals, that obtain power from other sources that are not part of the equipment 

under test. Conducted emissions on power leads should not exceed the applicable rms values shown in 

Figure 4.3. The values are specified according to the voltage of the power source feeding the equipment 

under test.

110 

106 

103 

100 

94

a 

0 

:0 

0 

4-D 

03

90 

80 

70 

60

UJU 

0.001 0.01

.058 .112 .223 

0.1.158

.5

1 10

79 

73

100

Frequency (MHz) 

Figure 4.3 CE102 Emissions Envelopes 

4.1.3 CS101-Conducted Susceptibility, Low Frequency 

The CS 101 test ensures that equipment and subsystems are not susceptible to EMI/RFI present on power 

leads in the frequency range 30 Hz to 50 kHz. The test is applicable to ac and dc input power leads, not 

including grounds and neutrals. If the equipment under test is dc operated, this test is applicable over the 

frequency range 30 Hz to 50 kHz. If the equipment under test is ac operated, this test is applicable starting 

from the second harmonic of the power line frequency and extending to 50 kHz. 

The equipment under test should not exhibit any malfunction or degradation of performance beyond 

specified operational tolerances when subjected to a test signal with the rms voltage levels specified in 

Figure 4.4. Alternative envelopes are given for equipment with nominal source voltages at or below 28 V 

and those operating above 28 V. The test criterion is also met when the power source specified in 

MIL-STD 462D, adjusted to dissipate 80 W in a 0.5-Q load, cannot develop the required voltage (specified

NUREG/CR-6431

440V 

220V 

115V 

S. . . . . .28V 

- - - - - - - - - - - - - - - - - - - --. .

8
in Figure 4.4) at the power input terminals and the equipment under test is not adversely affected by the 

output of the signal. Acceptable performance should be defined in the test plan by the end user or testing 

organization according to the applicable equipment, subsystem, or system specifications.

160 

150

140

"i:L 

0n 1 

1

1

100 

0.01 0.1 110 100

Frequency (kHz) 

Figure 4.4 CS101 Operating Envelope 

4.1.4 CS114-Conducted Susceptibility, High Frequency 

The CS 114 test simulates currents that will be developed on leads as a result of EMI/RFI generated by 

antenna transmissions. The test covers the frequency range 10 kHz to 400 MHz and is applicable to all 

interconnecting leads, including the power leads of the equipment under test. Equipment tested under the 

RS103 test may be exempted from application of this test in the frequency band from 30 MHz to 400 MHz. 

Although the CS114 test can be applied to assess signal line susceptibility, the test levels given apply only 

to power and control lines. 

The equipment under test should not exhibit any malfunction or degradation of performance beyond 

specified operational tolerances when subjected to a test signal with the rms levels shown in Figure 4.5. 

Acceptable performance should be defined in the test plan by the end user or testing organization according 

to the applicable equipment, subsystem, or system specifications.

9 NUREG/CR-6431
z 

=L 

Ca 

-,I

120 

110 

10: 

100 

90 

80

70

0.01 0.1 1 10 30 100 1000

Frequency (MHz) 

Figure 4.5 CS114 Operating Envelope 

4.2 MIL-STD 461D Radiated EMIIRFI Operating Envelopes 

4.2.1 RE101-Radiated Emissions, Magnetic Field 

The RE101 test measures radiated magnetic field emissions in the frequency range 30 Hz to 100 kHz. 

Equipment not intended to be installed in areas with other equipment sensitive to magnetic fields could be 

exempt from this test. The test is applicable for emissions from equipment and subsystem enclosures as 

well as all interconnecting leads. The test does not apply at transmitter fundamental frequencies or to 

radiation from antennas. Magnetic field emissions should not be radiated in excess of the levels shown in 

Figure 4.6. Magnetic field emissions may be measured at either one of the specified distances of 7 cm and 

50 cm and compared against the corresponding envelope. 

4.2.2 RE102-Radiated Emissions, Electric Field 

The RE102 test measures radiated electric field emissions in the frequency range 10 kHz to 1 GHz. It is 

applicable for emissions from equipment and subsystem enclosures, as well as all interconnecting leads. 

The test does not apply at transmitter fundamental frequencies or to radiation from antennas. 

Electric field emissions should not be radiated in excess of the rms values shown in Figure 4.7. At 

frequencies above 30 MHz, the test criterion should be met for both horizontally and vertically polarized 

fields.

NUREG/CR-6431 10

85

Rt•
180 

160 

140 

126 7!!Envelope at 7 cm 

120 

100 

60 

40 

20 30 Hz 

0.01 0.1 1 10 1C 

Frequency (kHz) 

Figure 4.6 RE1Ol Magnetic Field Emissions Envelopes

50 

0.01 0.1 1 10 

Frequency (MHz)

100

Figure 4.7 RE102 Emissions Envelope

N NUREG/CR-6431

R 

C. 

"2D 

4-' 

CD

110 

100

90 

80 

70

LL 

U

0 

°0 

uJ

)0 1000

1000

60

I1I
4.2.3 RS101-Radiated Susceptibility, Magnetic Fields

The RS101 test ensures that equipment and subsystems are not susceptible to radiated magnetic fields in 

the frequency range 30 Hz to 100 kHz. Equipment that is not intended to be installed in areas with strong 

sources of magnetic fields (e.g., CRTs, motors, and cable bundles carrying high currents) and that follows 

the limiting practices endorsed in NUREG/CR-594lcould be exempt from this test. The test is applicable 

to equipment and subsystem enclosures and all interconnecting leads. The test is not applicable for 

electromagnetic coupling via antennas. 

The equipment under test should not exhibit any malfunction or degradation of performance beyond 

specified operational tolerances when subjected to the rms magnetic field levels shown in Figure 4.8. 

Acceptable performance should be defined in the test plan by the end user or testing organization according 

to the applicable equipment, subsystem, or system specifications.

190 

180 

170

Ca 

0

0) 

C,n 

a) 

CD 

0) 

2

150 

130 

110

90

70 

0.01

60 Hz 

0.1 1 10 100 1000

Frequency (kHz) 

Figure 4.8 RS101 Operating Envelope 

4.2.4 RS103-Radiated Susceptibility, Electric Fields 

The RS 103 test ensures that equipment and subsystems are not susceptible to radiated electric fields in the 

frequency range 10 kHz to 1 GHz. Equipment tested under the CS 114 test may be exempted from 

application of this test in the frequency band from 10 kHz to 30 MHz. The test is applicable to equipment 

and subsystem enclosures and all interconnecting leads. The test is not applicable at the tuned frequency of 

antenna-connected receivers, unless otherwise specified. 

The equipment under test should not exhibit any malfunction or degradation of performance beyond 

specified operational tolerances when subjected to the radiated electric fields. The impressed electric field 

level should be 10 V/m (rms), measured in accordance with the techniques specified in the RS 103 test

NUREG/CR-6431 12
method. The test criterion should be met for both horizontally and vertically polarized fields. According to 

MIL-STD 462D, circularly polarized fields are not acceptable because radiated electric fields are typically 

linearly polarized. Acceptable performance should be defined in the test plan by the end user or testing 

organization according to the applicable equipment, subsystem, or system specifications. 

4.3 MIL-STD 461C Conducted EMI/RFI Operating Envelopes 

4.3.1 CE01-Conducted Emissions, Low Frequency 

The CE01 test measures the low-frequency conducted emissions on power leads of equipment and 

subsystems in the frequency range 30 Hz to 15 kHz. Equipment could be exempt from this test if first, the 

power quality requirements of the equipment are consistent with the existing power supply, and second, the 

equipment will not impose additional harmonic distortions on the existing power distribution system that 

exceed 5% total harmonic distortion (THD) or other power quality criteria established with a valid technical 

basis. When the test is desired, it is applicable to ac and dc power leads, including grounds and neutrals, 

that are not grounded internally to the equipment or subsystem. The test is not applicable to interconnecting 

signal lines. 

The CE01 test is applicable for emissions on dc power leads from 30 Hz to 15 kHz. Conducted emissions 

on dc power leads in excess of the values shown in Figure 4.9 should not appear when measured with an 

effective bandwidth not exceeding 75 Hz. The CEOI test is applicable for emissions on ac power leads from 

the power line frequency to 15 kHz for low power consumption equipment (less than or equal to 1 kVA) and 

from the first harmonic of the power line frequency to 15 kHz for high power consumption equipment 

(greater than 1 kVA). Emissions on ac power leads in excess of the rms values shown in Figure 4.10 should 

not appear when measured with an effective bandwidth not exceeding the power line frequency plus 20% of 

the power line frequency (i.e., 72 Hz in the United States). For ac-operated equipment with a fundamental 

current (i.e., load current at the power line frequency) greater than 1 ampere, the envelopes in Figure 4.10 

may be relaxed as follows: 

dB relaxation = 20 log(fundamental current). 

4.3.2 CE03-Conducted Emissions, High Frequency 

The CE03 test measures the high-frequency conducted emissions on power leads of equipment and 

subsystems in the frequency range 15 kHz to 50 MHz. The test is applicable to ac and dc power leads, 

including grounds and neutrals, that are not grounded internally to the equipment or subsystem. The test is 

not applicable to interconnecting signal lines. Conducted emissions should not appear on the power leads in 

excess of the rms values shown in Figure 4.11 for narrowband emissions. Broadband emissions 

measurements are not necessary. 

The terms narrowband and broadband refer to the values for the measurement receiver bandwidths to be 

employed during the emissions testing. A factor of 10 is typically specified as the separation between the 

narrowband and broadband bandwidths, and it is used to differentiate between narrowband and broadband 

interference sources. If the interference is broadband (e.g., arc welders and motors), a reduction in the 

bandwidth by a factor of 10 on the measurement receiver should result in at least a 6 dB drop in the 

interference level. Otherwise, the interference is considered to be narrowband (e.g., two-way radios).

13 NUREG/CR-6431
160 

150 

140 

130 

120 

110 

100 

90 

80 L 

0.01 0.1 1 2 10 100 

Frequency (kHz)

Figure 4.9 CE01 Emissions Envelope for dc Power Leads

140 

130 

120 

110 

100 

90 

80

70 

60 

0.01

Frequency (kHz)

Figure 4.10 CEO0 Emissions Envelope for ac Power Leads

NUREG/CR-6431

-Z 

=L

-Z 

CO 

C,

14
90 

86 

80 

70 - 7 

.- 60 

s5 o - -- - - - - - - -- - - - - - - - - - - - - - -- 49 

- - -- - - -- - - - - - - - - 4 5 

40 39 

30 225 kHz 500 kHz 

0.01 0.1 1 10 100 

Frequency (MHz) 

Figure 4.11 CE03 Narrowband Emissions Envelope 

4.3.3 CS01-Conducted Susceptibility, Low Frequency 

The CSO1 test ensures that equipment and subsystems are not susceptible to voltage distortions present on 

the power leads in the frequency range 30 Hz to 50 kHz. The test is applicable to ac and dc power leads, 

including grounds and neutrals, that are not grounded internally to the equipment or subsystem. The test is 

not applicable at frequencies within ±5% of the power line frequency (i.e., 57-63 Hz in the United States). 

The equipment under test should not exhibit any malfunction or degradation of performance beyond 

specified operational tolerances when subjected to electromagnetic energy injected onto its power leads at 

the levels and frequencies given in Figure 4.12. The test criterion can also be met when the power source 

specified in MIL-STD 462, adjusted to dissipate 50 W into a 0.5-0 load, cannot develop the required 

voltage (specified in Figure 4.12) at the power input terminals of the equipment under test and the 

equipment is not adversely affected by the output of the signal source. Acceptable performance should be 

defined in the test plan by the end user or testing organization according to the applicable equipment, 

subsystem, or system specifications. 

4.3.4 CS02-Conducted Susceptibility, High Frequency 

The CS02 test is similar to the CSO1 test except that it covers the higher frequency range 50 kHz to 400 

MHz. The CS02 test is applicable to equipment and subsystem ac and dc power leads, including grounds 

and neutrals, that are not grounded internally to the equipment or subsystem. 

The equipment under test should not exhibit any malfunction or degradation of performance beyond 

specified operational tolerances when subjected to 7 Vrms from a 50-0 source across the frequency range 

cited above. The test signal should be applied directly to the equipment input terminals, not through its

15 NUREG/CR-6431
E 

0 0 

4

0o

8 

7 

6 

5 

4 

3 

2 

1 

0

0.01 0.1 1 10 100

Frequency (kHz) 

Figure 4.12 CS01 Operating Envelope 

power line cord. The criterion can also be met when a 1-W source of 50-4 impedance cannot develop 

7 Vrms at the input terminals of the equipment under test and the equipment is not adversely affected by the 

output of the signal source. Acceptable performance should be defined in the test plan by the end user or 

testing organization according to the applicable equipment, subsystem, or system specifications. 

4.4 MIL-STD 461C Radiated EMIIRFI Operating Envelopes 

4.4.1 RE01-Radiated Emissions, Magnetic Field 

The RE01 test measures the radiated magnetic field emissions from equipment and subsystems in the 

frequency range 30 Hz to 50 kHz. Equipment not intended to be installed in areas with other equipment 

sensitive to magnetic fields could be exempt from this test. Also, the test does not apply to radiation from 

antennas. When the test is desired, levels should be measured with a receiving antenna positioned 7 cm 

from the surface of the equipment under test. Radiated magnetic field emissions should not appear at the 

receiving antenna in excess of the rms values shown in Figure 4.13. 

4.4.2 RE02-Radiated Emissions, Electric Field 

The RE02 test measures the radiated electric field emissions from equipment and subsystems in the 

frequency range 14 kHz to 1 GHz. The test does not apply to radiation from antennas. Levels should be 

measured with receiving antennas positioned 1 m from the surface of the equipment under test. Radiated

NUREG/CR-6431

El E2 

Line El to E2 (30 Hz to 1.5 kHz) - 10% 

of supply voltage or 6.3 Vrms, whichever 

is less, but not less than 2.3 Vrms. 

Line E2 to E3 is obtained by drawing 

a straight line from the adjusted point E3 

E2 to the fixed point E3 (2.3 Vrms). 2.3 Vrms

16
I0. 

U

'0 

'-. 

0) 

Cu C200 

180 

160 

140 

120 

100 

80

60 

40

0.01 0.1 1 10 100

Frequency (kHz) 

Figure 4.13 RE01 Magnetic Field Emissions Envelope 

electric field emissions should not appear at the receiving antennas in excess of the rms values shown in 

Figure 4.14 for narrowband emissions. Broadband emissions measurements are not necessary. 

The terms narrowband and broadband refer to the values for the measurement receiver bandwidths to be 

employed during the emissions testing. A factor of 10 is typically specified as the separation between the 

narrowband and broadband bandwidths, and it is used to differentiate between narrowband and broadband 

interference sources. If the interference is broadband (e.g., arc welders and motors), a reduction in the 

bandwidth by a factor of 10 on the measurement receiver should result in at least a 6 dB drop in the 

interference level. Otherwise, the interference is considered to be narrowband (e.g., two-way radios). 

4.4.3 RS01-Radiated Susceptibility, Magnetic Fields 

The RSO1 test ensures that equipment and subsystems are not susceptible to radiated magnetic fields in the 

frequency range 30 Hz to 50 kHz. Equipment that is not intended to be installed in areas with strong 

sources of magnetic fields (e.g., CRTs, motors, and cable bundles carrying high currents) and that follows 

the limiting practices endorsed in NUREG/CR-594lcould be exempt from this test. A radiating loop 

antenna, positioned 5 cm from the equipment under test, is used to generate the magnetic fields. 

The equipment under test should not exhibit any malfunction or degradation of performance beyond 

specified operational tolerances when subjected to the rms magnetic field levels and frequencies shown in 

Figure 4.15. The level of the imposed field is to be measured with a field strength meter positioned at the 

surface of the equipment under test. Acceptable performance should be defined in the test plan by the end 

user or testing organization according to the applicable equipment, subsystem, or system specifications.

NUREG/CR-6431

96

17
110 

100 

93 --

90 

80 

70 

60 

50 

0.01.

Figure 4.14 RE02 Narrowband Emissions Envelope

0.1 1 

Frequency (kHz) 

Figure 4.15 RS01 Operating Envelope

10 100

NUREG/CR-6431

2 25 

0.1 1 10 100 

Frequency (MHz)

E 

-o 

M 

U-. I:2 

2D 

LL 

w

.. 72 

59 

1000

p CL 

0. 

LL 

0 

4-. 

W 

MU

190 

180

170 

150 

130 

110 

90 

70 

0.01

18
4.4.4 RS03-Radiated Susceptibility, Electric Fields

The RS03 test ensures that equipment and subsystems are not susceptible to radiated electric fields in the 

frequency range 14 kHz to 1 GHz. The fields are to be generated with high-impedance antennas selected to 

cover the specified frequency range. 

The equipment under test should not exhibit any malfunction or degradation of performance beyond specified 

operational tolerances when subjected to radiated electric fields. The electric field level impressed should be 

10 V/m (rms), measured at the surface of the equipment under test with a field strength meter. Acceptable 

performance should be defined in the test plan by the end user or testing organization according to the 

applicable equipment, subsystem, or system specifications. 

5 RECOMMENDED SWC OPERATING ENVELOPES 

Recommended SWC operating envelopes are discussed herein for the representative surge waveforms 

defined in IEEE Std C62.41-1991 (Reaff 1995). The withstand levels are based on a Category B location and 

a Low to Medium Exposure level. The selection of these specific criteria is discussed in Sect. 3. 

The procedures to be employed in performing the surge testing are described in IEEE Std C62.45-1992. A 

surge generator capable of developing the representative surge waveforms is required and the surges are 

injected and monitored using coupling and decoupling circuits. Voltage probes and current transformers are 

used to monitor both the applied surges and the response of the equipment under test. The ac interface of the 

equipment under test is the point of application for the surge tests. 

5.1 Ring Wave 

The Ring Wave simulates oscillatory surges of relatively high frequency on the ac power leads of equipment 

and subsystems, and is represented by an open-circuit voltage waveform. The waveform is an 100 kHz 

sinusoid having an initial rise time of 0.5 As and continually decaying amplitude. A plot of the waveform is 

shown in Figure 5.1. The rise time is defined as the time difference between the 10% and 90% amplitude 

points on the leading edge of the waveform. The amplitude of the waveform decays with each peak being 

60% of the amplitude of the preceding peak of the opposite polarity. 

Vp, the peak voltage value of the Ring Wave, should be 3 kV. During the performance of the test, the 

equipment under test should not exhibit any malfunction or degradation of performance beyond specified 

operational tolerances when subjected to the Ring Wave. Acceptable performance of the equipment under 

test should be defined in the test plan by the end user or testing organization according to the applicable 

equipment, subsystem, or system specifications. 

5.2 Combination Wave 

The Combination Wave involves two exponential waveforms, an open-circuit voltage and a short-circuit 

current. It is intended to represent direct lightning discharges, fuse operation, or capacitor switching on the 

ac power leads of equipment and subsystems. The open-circuit voltage waveform has a 1.2-pAs rise time and 

an exponential decay with a duration (to 50% of initial peak level) of 50 As. The short-circuit current 

waveform has an 8-As rise time and a duration of 20 its. Plots of the waveforms are shown in Figures 5.2 

and 5.3.

19 NUREG/CR-6431
RISE TIME - 0.5 ps

5 10 15 20 25 30 

Time (ps) 

Figure 5.1 100-kHz Ring Wave

0 10 20 30 40 50 60 70 

Time (ps) 

Figure 5.2 Combination Wave, Open-circuit Voltage

80 90 100

NUREG/CR-6431

0. 

-S 

4-

1.00 

0.50 

0.00 

-0.50 

-1.00

0 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0

20
1.0

0.8 

0.6 - FRONT TIME -8 ps 

DURATION - 20 P 

0.4 

0.2 

0.0 Y I I I 

0 10 20 30 40 50 

Time (ps) 

Figure 5.3 Combination Wave, Short-circuit Current 

The rise time is defined as the time difference between the 10% and 90% amplitude points on the leading 

edge of the waveform. The duration is defined as the time between virtual origin and the time at the 50% 

amplitude point on the tail of the waveform. Virtual origin is the point where a straight line between the 30% 

and 90% points on the leading edge of the waveform intersects the V=0 line for the open-circuit voltage and 

the 1=0 line for the short-circuit current. 

VP, the peak value of the open-circuit voltage of the Combination Wave, should be 3 kV. 4, the peak value 

of the short-circuit current, should be 1.5 kA. During the performance of the test, the equipment under test 

should not exhibit any malfunction or degradation of performance beyond specified operational tolerances 

when subjected to the Combination Wave. Acceptable performance of the equipment under test should be 

defined in the test plan by the end user or testing organization according to the applicable equipment, 

subsystem, or system specifications. 

5.3 Electrically Fast Transients 

The EFT waveform consists of repetitive bursts, with each burst containing individual unidirectional pulses, and is intended to represent local load switching on the ac power leads of equipment and subsystems. The 

individual EFT pulses have a 5-ns rise time and a duration (width at half-maximum) of 50 ns. Plots of the 

EFT pulse waveform and the pattern of the EFT bursts are shown in Figures 5.4 and 5.5. The number of 

pulses in a burst is determined by the pulse frequency. For peaks less than or equal to 2 kV, the frequency shall be 5 kHz±1 kHz. For peaks greater than 2 kV, the frequency shall be 2.5 kHz±0.5 kHz. The differences 

in repetition rates are not intended to reflect characteristics of the power surge environment but to 

accommodate existing limitations in pulse generator performance.

21 NUREG/CR-6431
1.0

0.8 

> 0.6 

DURATION - 50 na 

0.4 

0.2 

0 .0 I I I I I 

0 10 20 30 40 50 60 70 80 90 100 

Time (ns) 

Figure 5.4 Waveform of the EFT Pulse 

VOLTAGE 

BURST 

I ,TIME 

'E- • BURST DURATION - 15 me 

BURST PERIOD - 300 ms 

Figure 5.5 Pattern of EFT Bursts 

The rise time is defined as the time difference between the 10% and 90% amplitude points on the leading 

edge of the waveform. The duration is defined as the time between the 50% amplitude points on the leading 

and trailing edges of each individual pulse. Individual pulses occur in bursts of duration 15 ms. 

The peak value of the individual EFT pulses should be 3 kV. During the performance of the test, the 

equipment under test should not exhibit any malfunction or degradation of performance beyond specified 

operational tolerances when subjected to the EFT pulses. Acceptable performance of the equipment under 

test should be defined in the test plan by the end user or testing organization according to the applicable 

equipment, subsystem, or system specifications.

NUREG/CR-6431 22
6 ASSESSMENT OF EMI/RFI OPERATING ENVELOPES 

6.1 ORNL Electromagnetic Survey Findings 

Ambient electromagnetic conditions were measured with electric and magnetic spectral receivers at eight 

nuclear units operated by four participating utilities. The units included one boiling water reactor (BWR) 

supplied by GE Nuclear Energy and seven pressurized water reactors (PWRs) supplied by Westinghouse 

Electric [3 units], Babcock and Wilcox (B&W) [3 units], and ABB Combustion Engineering [1 unit]. 

Measurements were taken over a 14-month period at a variety of operating conditions and observation 

locations within the plants. The operating conditions monitored included full-power operation, coastdown, 

low-power operation, shutdown, outage, startup, and plant trip. The locations for placement of the spectral 

receivers were determined in consultation with the responsible site engineer based on likely high field levels, 

proximity to safety-related I&C systems, and current or planned digital equipment installation sites. The 

EMIIRFI survey measurement locations are shown in Table 6.1. Some participating units provided 

measurement opportunities near reactor protection system (RPS) cabinets containing digital systems, as well 

as near conventional analog equipment. The measurement period at each location ranged from 1 to 5 weeks. 

Descriptions of the spectral receivers and the survey procedures are provided in NIJREG/CR-6436. 

Table 6.1 EMI/RFI survey measurement locations 

Measurement Sites 

Main Control Rooms 

Control Area Equipment Rooms 

Electrical Equipment Rooms 

Auxiliary Instrument Rooms 

Cable Spreading Rooms 

Relay Rooms 

Electrohydraulic Controller 

Room 

Turbine Deck 

Electrical Penetration Rooms 

Comparison of the observations at the different plant sites demonstrated a remarkable similarity, based on 

monitoring locations and operating conditions, in the electromagnetic environment from site to site. For any 

given frequency band, the highest observed electric field strengths varied within ±_10 dB of the mean value 

for each frequency under the compared conditions. The comparison of the highest observed magnetic field 

strengths also showed a similar ±10 dB variation about the mean for most frequencies. The exception to this 

comparison for the magnetic fields occurred in the 5-20 kHz frequency band where a ±20 dB variation was 

observed. 

The range of conditions and locations monitored, and the volume of data taken give a high level of 

confidence that the electromagnetic environment at nuclear power plants has been adequately determined. 

Hence, it is our opinion that operating envelopes that are characteristic of the electromagnetic conditions in

23 NUREG/CR-6431
nuclear power plants can be reasonably developed so that they bound the highest strength observations at 

each plant without setting unduly high expectations for specific plants. While there were differences 

detected in the highest strength observations at the various plants, these differences offer insufficient data to 

warrant plant-to-plant distinctions and do not justify the establishment of separate bounding envelopes. 

These observations are presented in more detail in NUREG/CR-6436. 

The highest strength electromagnetic observations from the ORNL survey at the eight nuclear units are 

presented in Tables 6.2 through 6.4 and reported in rms units. Table 6.2 presents the highest strength 

radiated electric field observations, Table 6.3 presents the highest strength radiated magnetic field 

observations, and Table 6.4 presents the highest strength conducted EMI/RFI observations. The associated 

expanded observation uncertainty (i.e., the interval about the measurement results in which the values of the 

measurand or measured phenomenon can be expected to lie with a 95% confidence level) is also presented 

for each of the highest-strength observations. The confidence level does not provide any guarantee that there 

are no unmeasured events that may exceed the highest strength observations, only that there is reasonable 

assurance that plausible bounds on the characteristic electromagnetic environment have been confirmed. 

Table 6.2 ORNL highest observations-radiated electric fields 

Frequency Field Strength Expanded Observation 

(MHz) (dBtV/m) Uncertainty (dB) 

5-100 130.7 ± 7.8 

100-200 132 ± 3.5 

200-300 109.9 ± 3.5 

300-400 110 ± 3.5 

400-500 127.3 ± 3.5 

500-600 106.2 ± 3.5 

600-700 108.8 ± 3.5 

700-800 115.5 ± 3.5 

800-900 107.6 ± 3.5 

900-1000 125.1 ± 3.5

NUREG/CR-6431 24
Table 6.3 ORNL highest observations-radiated magnetic fields

Frequency

Frequency 

(kHz) 

0.30-0.61 

0.61-1.22 

1.22-2.44 

2.44-4.88 

4.88-9.77 

9.77-19.53 

19.53-39.06 

39.06-78.12 

78.12-156.25 

156.25-312.5 

312.5-625 

625-1250 

1250-2500 

2500-5000

Field Strength 

(dBpT) 

107 

101 

104 

104 

117 

117

106 

100 

101 

102 

101 

101 

51 

51

Expanded Observation 

Uncertainty (dB) 

* 7.5 

* 7.5 

* 7.5 

± 7.5 

±7.5 

±+7.5 

±+7.5 

*±7.5 

* 7.5 

*±4.9 

*±4.9 

*+4.9 

±+4.9 

*+4.9

25 NUREG/CR-6431
Table 6.4 ORNL highest observations-conducted EMI/RFI, 300 Hz to 5 MHz

Frequency 

(kHz) 

0.30-0.61 

0.61-1.22 

1.22-2.44 

2.444.88 

4.88-9.77 

9.77-19.53 

19.53-39.06 

39.06-78.12 

78.12-156.25 

156.25-312.5 

312.5-625 

625-1250 

1250-2500 

2500-5000

Expanded Observation 

Uncertainty (dB) 

* 7.5 

±7.5 

±+7.5 

±_7.5 

±_7 

* 5.8 

*_4.9 

*±4.9 

± 4.9 

±+4.9 

*±4.9 

*+4.9 

±+4.9 

*+4.9

NUREG/CR-6431

Strength 

(dB/uA) 

89.6 

83.8 

78 

78 

73.2 

71.2 

77.5 

71.5 

77.5 

83.5 

83.5 

77.5 

53.4 

53.4

26
6.2 Survey Data vs Recommended Operating Envelopes

A wealth of data was generated during the plant site surveys: -650,000 electric field observations, 

-35.7 million magnetic field observations, and -6.4 million conducted EMI/RFI observations. This large 

volume of data was taken during extended observation periods under a wide variety of power plant 

conditions (reactor type, operating modes, site locations) and, in our opinion, enables the bounding 

electromagnetic conditions to be expected at nuclear power plants to be characterized with high confidence. 

The survey results show that the measured conditions do not exceed the recommended envelopes (the 

smallest difference between the data and the envelopes for any observed EMJIRFI event in any frequency 

band is 8 dB). In addition, when the expanded observation uncertainty is included with the bounding values 

from the survey, the results are still bounded by the envelopes with a high confidence level (the smallest 

difference between the expanded range and the envelopes for any observed EMIIRFI event in any frequency 

band is 1.5 dB). Therefore, the adequacy of the operating envelopes are confirmed by the survey results. 

Figure 6.1 illustrates the comparison of the survey data and the recommended operating envelopes for 

radiated electric fields (RS03 and RS 103). Figure 6.2 illustrates the comparison of the survey data and the 

recommended operating envelopes for radiated magnetic fields (RS01 and RS101). Likewise, Figure 6.3 

illustrates the comparison of the survey data and the operating envelope recommendations for conducted 

interference for the frequency range 30 Hz to 50 kHz (CS01 and CS101), and Figure 6.4 illustrates the 

comparison of the survey data and the recommended operating envelopes for the frequency range 10 kHz to 

400 MHz (CS02 and CS 114). The bounded measurement data from EPRI TR-102323 for the three data types 

are also shown for comparison.

E 

I.

E 

P 

Ax) "U

0 iLi

160 

150 

140 

130 

120 

110 

100 

90 

80 

70 

60 

50

0.01 0.1 1 10 100 1000

Frequency (MHz) 

Figure 6.1 Data vs Envelopes, Radiated Electric Fields

NUREG/CR-6431

RS03 & FS103 Envelopes s% 

I i 

ORNL Data 

:T II 

i II a I , 

O~aE ,, 

"-------------I EPR Data 

N . . ) 

"NJ::

27
E 

i

a) 

Cn 

cc 

"Cu

200 

180 

160 

140 

120 

100 

80 

60 

40 

0.01 0.1 1 10 100 1000 

Frequency (kHz)

10000

Figure 6.2 Data vs Operating Envelopes, Radiated Magnetic Fields

<= 

m 

CD

160 

150 

140 

130 

120 

110 

100 

90 

80 

70 

60 

0.i01 0.1 1 10 100

Frequency (kHz) 

Figure 6.3 Data vs Operating Envelopes, Conducted Interference - 30 Hz to 50 kHz 

NUREG/CR-6431 28

IS0 Envelope 

ERData 

- CS101 (>28V) Envelope 

-ORNL DateJ _
120

110 

CS02 Envelope 

-' 100 

M =< 90 - CS1 14 Enve 

3-c E 80 

70 SDRNL Data EPIData 

60 

50 

0.01 0.1 1 10 100 1000 

Frequency (MHz) 

Figure 6.4 Data vs Operating Envelopes, Conducted Interference - 10 kHz to 400 MHz 

6.3 Discussion on the Need for Safety Margins 

The determination of an "adequate" safety margin is a regulatory issue and falls outside of the ORNL 

research scope. However, ORNL can offer technical evidence to support a high confidence that the 

recommended envelopes are sufficient to bound the anticipated electromagnetic conditions. Application of 

these envelopes provides reasonable assurance that I&C systems successfully tested to those levels of 

interference will function properly in the nuclear power plant electromagnetic environment. 

The nature of the ORNL survey of electromagnetic conditions and the expanded measurement uncertainty 

applied to the bounding EMIIRFI data implicitly account for many of the issues related to a margin. In the 

letter from J. Wermiel to B. Boger dated August 5, 1994, the justification for a safety margin was discussed. 

The NRC staff stated that the "selected safety margin should include (1) any instrumentation inaccuracy, 

(2) uncertainties in site survey, (3) variations between the measured sites (plants), (4) possible lack of 

sufficient data, and (5) variations in operating conditions." Instrumentation inaccuracy is explicitly included 

in the expanded observation uncertainty applied to the survey results. ORNL feels that issues #2, #3 and #5 

are addressed by the survey approach taken. The survey measurements were taken at most locations within a 

nuclear power plant where safety-related I&C systems either are or are likely to be installed, were conducted 

at eight nuclear units representing each reactor manufacturer type, and included observations under a full 

range of operating conditions (including transients). In addition, coupling the ORNL results with the 

measurement results from the independent EPRI survey, measured electromagnetic conditions from 

14 different nuclear units are available and have been shown to be bounded by the recommended operating 

envelopes.

29 NUREG/CR-6431
Issue #4 addresses the concern about unmeasured events as well as statistical confidence in the data. As 

stated earlier, the ORNL survey generated -650,000 electric field observations, -35.7 million magnetic field 

observations, and -6.4 million conducted EMI/RFI observations. Therefore, the survey results are based on a 

wealth of data. Regarding unmeasured events, ORNL believes that the survey results provide a realistic 

determination of the characteristic electromagnetic environment with a high confidence but do not absolutely 

guarantee that no higher interference levels are possible. In order to have high confidence in conditions 

determined by a site survey, IEEE 473-1985, IEEE Recommended Practice for an Electromagnetic Site 

Survey (10 kHz to 10 GHz),' 4 recommends a two week observation period to characterize the electromagnetic 

conditions given man-made sources. These observations are to be made every hour for at least three minute 

periods. ORNL greatly exceeded these recommendations in its survey by taking continuous measurements 

for up to 5 week periods. Therefore, ORNL contends that the survey approach addresses many of the 

components expected of a safety margin and that the existing difference between the envelopes and the 

bounding observations with the expanded uncertainty applied provides additional assurance that nuclear 

power plant electromagnetic conditions are bounded. 

7 IMPLEMENTATION OF THE OPERATING ENVELOPES 

Many EMI/RFI issues can be resolved by applying the general operating envelopes developed herein for the 

MIL-STD 461D and 461C test criteria. It is intended that either set of operating envelopes be applied in its 

entirety, without selective application of individual operating envelopes (i.e., no mixing and matching of 

operating envelopes). The recommended electromagnetic operating envelopes are consistent with EML/RFI 

envelopes currently used by both the military and a broad range of industries..1517 

The recommended operating envelopes are applicable for locations within a nuclear power plant where 

safety-related I&C systems either are or are likely to be installed. These locations include control rooms, 

remote shutdown panels, cable spreading rooms, equipment rooms, relay rooms, auxiliary instrument rooms, 

and other areas (e.g., the turbine deck) where safety-related I&C system installations are planned. The 

recommended operating envelopes are also applicable for both analog and digital system installations. 

It is recommended that an assessment of the electromagnetic conditions at the point of installation for safety

related I&C systems be performed to identify any unique EMI/RFI sources that may generate local 

interference. The EMIIRFI sources could possibly include both portable and fixed equipment (e.g., portable 

transceivers, arc welders, power supplies, and generators). Steps should be taken during installation to 

ensure that the systems are not exposed to EMIIRFI levels, from the identified sources, greater than 8 dB 

below the recommended operating envelopes. 

The recommended EMIREI practices, SWC practices, and operating envelopes are only elements of the total 

package that is needed to ensure EMC within nuclear power plants. In addition to assessing the compatibility 

of new or modified safety-related I&C systems with the local electromagnetic environment, nuclear power 

plants should still apply sound engineering practices for nonsafety-related modifications and I&C 

maintenance as part of an overall EMC program. While nonsafety-related systems are not part of the 

regulatory guidance being developed, the control of EMIIRFI from these systems is essential to ensure that 

safety-related I&C systems can continue to perform properly in the nuclear power plant environment. It is 

suggested that, when feasible, the emissions from nonsafety-related systems be held to the same levels as 

safety-related systems. 

To ensure that the recommended operating envelopes are being used properly, equipment should be tested in 

the same physical configuration as that specified for its actual installation in the plant. In addition, the 

physical configuration of the safety-related I&C system should be maintained and all changes in the

NUREG/CR-6431 30
configuration controlled. The design specifications that should be maintained and controlled include wire 

and cable separations, shielding techniques, shielded enclosure integrity, apertures, gasketing, grounding 

techniques, EMI/RFI filters, and circuit board replacements. 

Any modifications to the presently recommended electromagnetic operating envelopes (e.g., lower site

specific envelopes) should be based on comparable technical evidence to that presented herein. Relaxation in 

the recommended operating envelopes should be based on actual measurement data collected in accordance 

with IEEE Std 473-1985. 

Exclusion zones should be established through administrative controls to prohibit the activation of portable 

EMIRFI emitters (e.g., welders, transceivers, cameras, flash attachments) in areas where safety-related I&C 

systems have been installed. An exclusion zone is defined as the minimum distance permitted between the 

point of installation and where portable EMIIRFI emitters are allowed to be activated. The size of the 

exclusion zones is a regulatory issue. The size should be site-specific and depend on the effective radiated 

power and antenna gain of the portable EMI/RFI emitters used within a particular nuclear power plant. The 

size of exclusion zones should also depend on the allowable electric field emission levels designated for the 

area in the vicinity of the installed safety-related I&C system. To establish the size of an exclusion zone, a 

suggested rule of thumb could be that at least an 8 dB difference be maintained between the susceptibility 

operating envelope and the allowed emissions level. Hence, for the radiated electric field operating envelope 

of 10 V/m (140 dB#V/m), the size of the exclusion zones should be set such that the radiated electric fields 

emanating from the portable transceivers are limited to 4 V/m (132 dBAV/m) in the vicinity of safety-related 

I&C systems. The minimum distance of an exclusion zone (d) in meters should be calculated by: 

d=(30PG)°.5/E 

where 

P = the effective radiated power of the EMIRFI emitter (in watts); 

G = the gain of the EMIIRFI emitter antenna (assume G=1 is worst case); and, 

E = the allowable radiated electric field strength of the EMIIRFI emitter (in V/m) 

at the point of installation. 

8 CONCLUSIONS 

The recommended envelopes bound the characteristic electromagnetic operating environment at nuclear 

power plants with high confidence. When used in combination with the test criteria and test methods 

recommended in NUJREG/CR-5941, these electromagnetic operating envelopes provide assurance that safety

related I&C systems will function according to specification within the projected electromagnetic 

environment. Proper testing and sound installation practices (as described in NUREG/CR-5941) will ensure 

with high confidence that EMIJRFI and power surge problems with safety-related I&C systems in nuclear 

power plants are averted for newly installed or modified systems. 

The value added by developing the technical basis for regulatory guidance in both NUREG/CR-5941 and this 

report is that it (1) offers clear guidance on necessary practices that are a part of an overall EMC program; 

(2) endorses finalized military and industry standards that have wide, long-standing application; (3) specifies 

complete suites of EMI/RFI emissions and susceptibility test criteria and methods from the two most 

prevalent military standards (i.e., no mixing and matching of test criteria and methods are promoted) and 

gives operating envelopes that are framed in suitable measurement units and frequency ranges for each 

specific test method; (4) applies to analog, digital, and hybrid (i.e., combined analog and digital electronics) 

safety-related I&C equipment; and (5) identifies acceptable operating envelopes which are based on similar 

military environments, and confirmed with measurement data from nuclear power plants and commercial 

emissions limits from typical industrial environments.

31 NUREG/CR-6431
In a cost-cutting initiative, the Department of Defense took a bold step in 1994 in deciding that it would move 

away from the MIL-STDs and began to purchase commercial-off-the-shelf (COTS) equipment. Thus, 

support for the MIL-STDs may diminish over the next decade and certified testing laboratories that can 

conduct these tests may decrease in availability. There are commercial standards under development by the 

International Electrotechnical Commission (IEC) and ANSI. Upon their completion, the military will likely 

specify these commercial standards in its acquisitions and continued reliance on the MIL-STDs by NRC, as 

consensus commercial standards supersede them, may become burdensome to the nuclear industry. Thus, it 

is recommended that NRC continue to follow the development of the commercial standards, and review them 

as they become available for their applicability to the nuclear power plant environment.

NUREG/CR-6431 32
9 REFERENCES

1. P. D. Ewing and K. Korsah, Technical Basis for Evaluating Electromagnetic and Radio-Frequency 

Interference in Safety-Related I&C Systems, NUREG/CR-5941, Oak Ridge National Laboratory, 

April 1994. 

2. S. W. Kercel, M. R. Moore, and E. D. Blakeman, Survey of Ambient Electromagnetic and Radio

Frequency Interference Levels in Nuclear Power Plants, NUREG/CR-6436, Oak Ridge National 

Laboratory, November 1996. 

3. MIL-STD 461D, Electromagnetic Emission and Susceptibility Requirements for the Control of 

Electromagnetic Interference, U.S. Department of Defense, Jan. 11, 1993. 

4. MIL-STD 461C, Electromagnetic Emission and Susceptibility Requirements for the Control of 

Electromagnetic Interference, U.S. Department of Defense, Aug. 4, 1986. 

5. MIL-STD 462D, Measurement of Electromagnetic Interference Characteristics, U.S. Department of 

Defense, January 11, 1993. 

6. MIL-STD 462, Measurement of Electromagnetic Interference Characteristics, U.S. Department of 

Defense, July 31, 1967. 

7. D. P. Rollinger, "The ABC's of MIL-STD 461: An Overview of Military EMC Standards and an 

Insight into Procurement Procedures," EMC Test and Design, pp. 19-25 (September/October 1991). 

8. IEEE Std C62.41-1991 (Reaff 1995), IEEE Recommended Practice on Surge Voltages in Low

Voltage A C Power Circuits, Institute of Electrical and Electronics Engineers. 

9. IEEE Std C62.45-1992, IEEE Guide on Surge Testing for Equipment Connected to Low-Voltage AC 

Power Circuits, Institute of Electrical and Electronics Engineers. 

10. EPRI TR-102323, Guidelines for Electromagnetic Interference Testing in Power Plants, Electric 

Power Research Institute, September 1994. 

11. F. D. Martzloff and T. S. Gruzs, "Power Quality Site Surveys: Facts, Fiction, and Fallacies," IEEE 

Trans., IA-24 (6), pp. 100-118 (November/December 1988). 

12. IEEE Std C62.41-1991, IEEE Recommended Practice on Surge Voltages in Low- Voltage A C Power 

Circuits, p. 40. 

13. IEEE Std C62.41-1991, IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Power 

Circuits, p. 31. 

14. IEEE Std 473-1985, IEEE Recommended Practice for an Electromagnetic Site Survey (10kHz to 10 

GHz), Institute of Electrical and Electronics Engineers. 

15. ANSI C63.12-1987, American National Standard for Electromagnetic Compatibility Limits 

Recommended Practice, American National Standards Institute.

33 NIUREG/CR-6431
16. D. N. Heirman, "International Activity in Product Immunity Standards and Testing," EMC Test and 

Design, pp. 16-19 (May/June 1992). 

17. W. Sperber, "SAE Automotive Electromagnetic Immunity Standards," 1992 Proceedings of 

EMC/ESD International, Denver, Colorado, Apr. 22-24, 1992.

NUREG/CR-6431 34
APPENDIX-Rationale for RG-1.180 Operating Envelopes

The technical basis for all of the EMIfRFI operating envelopes presented in this NUREG/CR and 

recommended for adoption as part of Regulatory Guide RG-1. 180 begins with MIL-STD envelopes 

corresponding to the electromagnetic environment military ground facilities. The electromagnetic conditions 

in military ground facilities were judged to be comparable to that of nuclear power plants based on general 

layout and equipment type considerations. Plant emissions data were used to confirm the adequacy of the 

EMI/RFI operating envelopes. From the MIL-STD starting point, susceptibility envelopes were adjusted to 

account for the plant emissions data available from the site surveys reported in NUREG/CR-6436 and in 

EPRI TR-102323. Adjustments to the emissions envelopes were based on providing adequate margin with 

the susceptibility envelopes and on consideration of the primary intent of the MIL-STD limits (e.g., whether 

they were specified based on protecting sensitive receivers on military platforms). Finally, when changes to 

the operating envelopes were motivated by technical considerations, consistency among the envelopes for 

comparable test criteria from similar suites of test methods (e.g., between MIL-STD 461D and MIL-STD 

461C or between the RG-1.180 and the SER on EPRI TR-102323) was promoted and commercial emissions 

limits for industrial environments were factored into the adjustments. These considerations contributed to 

meeting the goal of establishing comparable assurance that equipment will indeed be compatible with the 

projected electromagnetic environment. 

It should be noted that in the discussion that follows, the designation RG will sometimes be used to identify 

the EMIIRFI operating envelopes presented in this NUREG/CR. This designation reflects the recommended 

usage of these envelopes in the Regulatory Guide RG-1.180. 

Susceptibility Operating Envelopes 

CS101/CS01-Conducted Susceptibility, Low Frequency 

CS 101 (conducted susceptibility, power leads, low frequency) in MIL-STD 461D provides two envelopes for 

military ground facilities. These envelopes correspond to equipment with source voltages at or below 28 V 

and equipment with source voltages above 28 V. The similarity in the military ground facility environment 

and the nuclear power plant environment supports the use of these envelopes. These envelopes are adopted 

without change in this NUREG/CR. In addition, notation is included specifying that the starting frequency 

for testing of ac powered equipment is the second harmonic (as is the case in the MIL-STD). An adjustment 

in envelope level from the MIL-STD basis is effected for the CS01 (conducted susceptibility, power leads, 

low frequency) envelope for use in this NUREG/CR. This adjustment enhances consistency between the 

envelopes for comparable test criteria from similar suites of test methods and meets the goal of establishing 

comparable levels of assurance among the test criteria. 

Figure A. 1 provides a comparative plot of the RG (i.e., NUREG/CR) envelopes for CS 101 and CS01, the 

baseline MIL-STD envelopes, the corresponding envelope endorsed by the SER on EPRI TR-102323, and the 

plant emissions data presented in NUREG/CR-6436 and EPRI TR-102323. The RG and MIL-STD envelopes 

are converted from voltage to current for comparative purposes based on an assumption of 0.5 0 impedance. 

It is seen that the RG and SER envelopes are similar in level. The most notable exception is the less 

restrictive RG envelope for equipment with source voltages at or below 28 V. As can be observed from the 

plot, this envelope only provides a 4 dBjMA margin above the highest measured plant emissions data reported 

in EPRI TR-102323. However, in the frequency range below 120 Hz, the 4 dB margin is judged to be 

sufficient for two reasons. First, the starting frequency for testing of ac powered equipment is 

specified to be the second harmonic so the ac limit does not apply over the frequency range with the 

4 dB margin. Second, although the envelope does apply over the frequency range with the 4 dB margin

35 NUREG/CR-6431
z 

1 RG CSI1O (above 28v) 

481D CSIO1 (above I8v) 

140 MIC C301 

130 

120 12 EPRI data .. 

E 

110 

"In. 

-- 100"

0 90 

80 

L~ ~ON datas t.,, 

70 

6o 

0.01 0.1 1 10 100 

Frequency (kHz)

Figure A. 1 Comparison of low-frequency conducted susceptibility envelopes
for dc powered equipment, the bounding plant data resulted from ac powered equipment according to EPRI 

so adequate margin for dc powered equipment is probable. 

CS] 14/CS02-Conducted Susceptibility, High Frequency 

The operating envelope for military ground facilities (Army) from CS 114 (conducted susceptibility, bulk 

cable injection, high frequency) in MI1L-STD 461D are adjusted to account for conducted emissions levels 

measured in nuclear power plants. As a minimum, modifications of safety-related equipment must 

demonstrate that they can withstand the ambient conducted emissions in the plant. In the absence of other 

technical considerations, the level to which the operating envelope is raised is selected to be consistent with 

the operating envelope addressed in the SER on EPRI TR-102323. The break frequency at 30 MHz and the 

level at 400 MHz are maintained because of practical considerations regarding the ability of the test 

equipment specified in MIL-STD 462D to generate the desired test levels. The envelope from CS02 

(conducted susceptibility, power and interconnecting control leads, high frequency) in MIL-STD 461C is 

also raised to account for conducted emissions levels measured in nuclear power plants. Again, the level to 

which the operating envelope is raised is selected to be consistent with the operating envelope addressed in 

the SER on EPRI TR-102323. These adjustments to the CS 114 and CS02 operating envelopes are motivated 

by the need to provide adequate margin above plant emissions data and meet the goal of establishing 

comparable levels of assurance among the test criteria. 

Figure A.2 provides a comparative plot of the RG (i.e., NUREG/CR) envelopes for CS114 and CS02, the 

baseline MIL-STD envelopes, the corresponding envelope endorsed by the SER on EPRI TR-102323, and the 

plant emissions data presented in NUREG/CR-6436 and EPRI TR-102323. The RG and MIL-STD envelopes 

for CS02 are converted from voltage to current for comparative purposes based on an assumption of 50 Q 

impedance. The conflict between the MIL-STD emissions envelopes and the plant emissions data is clearly 

seen. For this reason, the RG envelopes are adjusted from their MIL-STD basis. It is also seen that the RG 

and SER envelopes are similar in level. The most notable exception is the less restrictive RG envelope 

CS1 14 above 30 MHz. This difference accounts for practical considerations regarding the ability of the test 

equipment specified in MIL-STD 462D to generate the desired test levels. 

RSlO1/RSO1-Radiated Susceptibility, Low Frequency 

The operating envelope for military ground facilities (Army) with equipment sensitive to magnetic fields 

from RS101 (radiated susceptibility, magnetic field, low frequency) in MIL-STD 461D is adopted 

unchanged. The similarity in the military ground facility environment and the nuclear power plant 

environment supports the use of this envelope. The operating envelope for military ground facilities from 

RSO 1 (radiated susceptibility, magnetic field, low frequency) in MIL-STD 461 C is adjusted to account for 

radiated emissions levels measured in nuclear power plants. In the absence of other technical considerations, 

the envelope is adjusted to match the corresponding RS101 operating envelope. The resulting RS101 and 

RSO1 operating envelopes in this NUREG/CR are also consistent in level with the comparable envelope 

addressed in the SER on EPRI TR-102323. The adjustment to the RSO1 operating envelope is motivated by 

the need to provide adequate margin above plant emissions data and meets the goal of establishing 

comparable levels of assurance among the test criteria. 

Figure A.3 provides a comparative plot of the RG (i.e., NIJREG/CR) envelopes for RS101 and RSO, the 

baseline MIL-STD envelopes, the corresponding envelope endorsed by the SER on EPRI TR-102323, and the 

plant emissions data presented in NUREG/CR-6436 and EPRI TR-102323. The conflict between the 

MIL-STD emissions envelopes for RS01 and the plant emissions data is clearly seen. For this reason, that 

RG envelope is adjusted from its MIL-STD basis. It is also seen that the RG and SER envelopes are 

identical.

37 NUREG/CR-6431
Z 

110 

SER envelope RG C802 

100 --------

S~~EPRI data , _ r ° R0 CA114 

- P •at 4610 C114 4. 4, 

90 

481C CSO2 

ORNL data 

70 

CD 60/"" 10 8 

- 4. 

00 50 

00I, 404. 40. - 444 

30 

20 

10 

0.01 0.1 1 10 100 1000 

Frequency (MHz)

Figure A.2 Comparison of high-frequency conducted susceptibility envelopes
200 

180 

160 

140 

120 

100 

80 

60

0.1 1 10 100

Frequency (kHz)

Figure A.3 Comparison of low-frequency radiated susceptibility envelopes

EPRI data e --. 

" •' RG R801 

461D R8101 

ORNL data 

"-S4•10 RSO1 

"N

E 

C

U

02

40 

20 

0

0.01

z

1000
RSlO3/RSO3-Radiated Susceptibility, High Frequency

The operating envelope for military ground facilities from RS 103 (radiated susceptibility, electric field, high 

frequency) in MIL-STD 461D is based on envelopes for Navy and Air Force facilities. The Army ground 

facility envelope is higher across the frequency range, presumably to account for emissions from specialized 

transmitters and portable transceivers. Since administrative controls (exclusion zones) are specified in 

RG-1. 180 to limit the contribution of such devices, it is considered appropriate to use the lower levels. In 

addition, the RS 103 operating envelope in RG-1.180 is consistent with the comparable envelope addressed in 

the SER on EPRI TR-102323. The operating envelope for military ground facilities (Army) from RS03 

(radiated susceptibility, electric field, high frequency) in MIL-STD 461C is adjusted to account for radiated 

emissions levels measured in nuclear power plants. In the absence of other technical considerations, the 

RS03 envelope is raised to be consistent with the RS 103 operating envelope. These adjustments to the 

RS 103 and RS03 operating envelopes are motivated by the need to provide adequate margin above plant 

emissions data without being unduly restrictive and meet the goal of establishing comparable levels of 

assurance among the test criteria. 

Figure A.4 provides a comparative plot of the RG (i.e., NUREG/CR) envelopes for RS 103 and RS03, the 

baseline MIL-STD envelopes, the corresponding envelope endorsed by the SER on EPRI TR-102323, and the 

plant emissions data presented in NUREG/CR-6436 and EPRI TR-102323. The MIL-STD 461D RS103 

envelope for Army ground facilities is shown to illustrate differences that can result if administrative controls 

are not in place. The RG envelope is identical to the MIL-STD envelope for Navy and Air Force facilities. 

The conflict between the MIL-STD emissions envelopes for RS03 and the plant emissions data is clearly 

seen. For this reason, that RG envelope is adjusted from its MlL-STD basis. It is also seen that the RG and 

SER envelopes are identical. 

Emissions Operating Envelopes 

The equipment emissions operating envelopes described in this NUREG/CR and adopted for use in 

Regulatory Guide RG-1.180 have a clear technical basis. They are based on the equipment emissions 

operating envelopes for military ground facilities that are presented in MIL-STD 461D and MIL-STD 461C. 

The electromagnetic environment in military ground facilities is judged to be comparable to that for nuclear 

power plants based on general layout and equipment type considerations. A review of the rationale for the 

MIL-STD limits indicates that there are some instances where MIL-STD limits are primarily intended to 

protect sensitive receivers, which would not be common in nuclear power plants. In those cases, the Federal 

Communications Commission (FCC) Part 15 and International Special Committee on Radio Interference 

(CISPR) limits for industrial class equipment are factored into adjustments of the MIL-STD envelopes. 

CElO1/CEO1-Conducted Emissions, Low Frequency 

A review of the MIL-STD 461D specifications and rationale shows that the intent of the MIL-STD 461D 

CE101 (conducted emissions, power leads, low frequency) envelopes is to limit the "amplitude of harmonic 

currents conducted on the power distribution system." The envelopes are "based on maintaining the 

harmonic distortion of the (platform) power distribution system within 5% of the supply voltage with any 

single harmonic being less than 3%." The MIL-STD rationale also states that total harmonic distortion 

(THD) that is greater than "5% is above the tolerance of most electronic equipment, induction motors, 

magnetic devices, and measuring devices." Therefore, the MIL-STD envelopes provide a sound basis for the 

NUREG/CR envelopes.

NUREG/CR-6431 40
160 461D RS103 (Army) 

1 40 RO R8103 SER envelop. 4_ lD R81 (N__ _0 _ A&AF)_ _ _ 

RG R803 .. _ 'J.. i "I''- I " 

481C RSOS ,ORNL dta 

120 __,___ 

CDI Er I II] 

I10 100 _ ,,___ Ii ,t , , 

III I I I 

""- EPRi data ', -80 - - II I l I Ii 

" 80 __________ __________ - -- • II . I _ 

ii I gI 

-- I I "1 I * I 

* I I II 

S 60 ' a' 'l 

so 

LU 

A~ 40__ _ _ _ ___ _ _ _ _ 

20 

0 

0.01 0.1 1 10 100 1000 

Z 

Frequency (MHz) 

"Figure A.4 Comparison of high-frequency radiated susceptibility envelopes
MIL-STD 461C CEO1 (conducted emissions, power leads, low frequency) for military ground facility 

platforms and MIL-STD 46 1D CE10 1 for surface ship platforms each offer a single envelope for application 

to dc power leads and two separate envelopes for application to ac power leads for 60 Hz equipment. The 

operating envelopes for military ground facilities in MIL-STD 461C are adopted as the basis for the CE101 

and CE01 emissions envelopes in this NUREG/CR. The two ac power lead envelopes correspond to 

equipment operating at input power ratings greater than 1 kVA and less than or equal to 1 kVA and these 

envelopes provide the guidance for variations in power consumption. The envelope for ac power leads on 

equipment operating at less than or equal to 1 kVA ranges from the power line frequency to 10 kHz for 

CE1O0 and to 15 kHz for CE01. The envelope for ac power leads on equipment operating at greater than 

1 kVA ranges from the first power harmonic to 10 kHz for CE101 and to 15 kHz for CEO1. The break 

frequency for the envelope for ac power leads on equipment operating at less than or equal to 1 kVA is 

1.15 kHz. The high frequency range (> 1.15 kHz) of the CE101 and CE01 envelopes for ac power lead 

emissions are adjusted from their MIL-STD starting points for use in this NUREG/CR to promote 

consistency among the conducted emissions operating envelopes at 10 kHz for CE101 and CE102 (conducted 

emissions, power leads, high frequency) and at 15 kHz for CE01 and CE03 (conducted emissions, power 

leads, high frequency). The dc power lead emissions envelopes for CElOl and CEO0 are adopted unchanged. 

Finally, notation is included in this NUREG/CR to identify an allowed relaxation of the emissions envelopes 

for ac-operated equipment and subsystems with a fundamental current (i.e., load current at the power 

frequency) that is greater than 1 ampere. The adjustments to the CEO1 operating envelopes and the adoption 

of the CEOl envelope as the basis for CE101 are motivated by the need to adequately control harmonic 

distortion of the power distribution system and meet the goal of establishing comparable levels of assurance 

among the test criteria. 

Since MIL-STD 461D CE101 provides no specific guidance on operating envelopes for military ground 

facilities, which have been identified as having electromagnetic conditions most comparable to nuclear power 

plants, it is appropriate to adopt the operating envelopes from MIL-STD 461C CEO0. The technical basis for 

establishing immunity levels for a particular phenomenon (e.g., conducted EMIIRFI) over a selected 

frequency range (e.g., 30 Hz to 50 kHz) is not dependent on testing criteria or methods but rather on the 

environment in which the equipment will be installed. Therefore, the caution against mixing and matching 

test criteria and methods is not at issue. 

Figure A.5 provides a comparative plot of the RG (i.e., NUREG/CR) envelopes for CE101 and CEO1, the 

baseline MIL-STD envelopes, and the corresponding envelope endorsed by the SER on EPRI TR-102323. 

The envelopes for ac power leads are less restrictive than the MIL-STD envelopes in the higher frequency 

band (> 1.15 kHz) because of adjustments to promote consistency between the conducted emissions 

operating envelopes at 10 kHz for CElO0 and CE102 and at 15 kHz for CE01 and CE03. The RG emissions 

envelope for dc power leads is less restrictive than the corresponding SER emissions envelope. The RG 

emissions envelopes for ac power leads are somewhat more restrictive than the corresponding SER emissions 

envelope. Nevertheless, the power quality basis for ac-power-lead emissions envelopes provides an 

appropriate foundation for the RG envelopes. 

CElO2/CEO3-Conducted Emissions, High Frequency 

The rationale in MIL-STD 461D Appendix states that the levels for the low frequency band for CE102 

(conducted emissions, power lead, high frequency) are set to address power quality, which is a common issue 

with nuclear power plant applications. The levels for the higher frequency band are based on controlling 

potential radiated EMI that could affect sensitive receivers, which are not normally present in nuclear power 

plants. Therefore, the levels in the low frequency band of the MIL-STD emissions envelopes for CE102 and 

narrowband CE03 (conducted emissions, power lead, high frequency) are adopted unchanged while the levels

NUREG/CR-6431 42
150 

140 

130 

120 

110 

100 

90

0.1 1 10

Frequency (kHz)

Figure A.5 Comparison of low-frequency conducted emissions envelopes

N\ 

461 CCE01 ac (<1 WVA) 

N\ 

RG CE101 ac (<1 WvA) _ 

RG CE01 ac (<1 kVA) 461C CE01 dc 

'N RG CEO1 dc 

N . 

461C CE01 ac (>1 kVA) %S• 

G CE1•o0 ac •1kvA) . " 

RG CE01 ac(>1 kVA) 

N. 

N. ________________________ N

S 

E 

L_ 

m 

0

80 

70 

60

z 0.01 100
in the higher frequency band are raised for application to nuclear power plants. The CISPR Class A and FCC 

Part 15 Class A conducted emissions levels are used as the basis for setting the envelope levels presented in 

this NUREG/CR. Thus, each envelope retains the low frequency slope and level of the corresponding 

MIL-STD envelope but the upper frequency levels are set to be equivalent to the CISPR limit, which 

encompasses the FCC limit. These adjustments to the CE102 and CE03 operating envelopes are motivated 

by consideration of the underlying MIL-STD rationale for the envelopes and incorporate equipment 

emissions limits for industrial environments. This approach supports the goal of establishing operating 

envelopes that are appropriately tailored for the nuclear power plant environment. 

Figure A.6 provides a comparative plot of the RG (i.e., NUJREG/CR) envelopes for CE102 and CE03, the 

baseline MTL-STD envelopes, the corresponding envelope endorsed by the SER on EPRI TR-102323, and the 

Class A equipment emissions limits for CISPR and FCC Part 15. The RG and MIL-STD envelopes for 

CE102 are converted from voltage to current for comparative purposes based on the test apparatus impedance 

established in MIL-STD 462D. The CISPR and FCC limits are converted from voltage to current for 

comparative purposes based on the test apparatus impedance defined for those test methods. The RG 

envelopes completely encompass the CISPR and FCC conducted emissions limits. The RG envelopes are 

slightly more restrictive than the corresponding SER envelope. Nevertheless, the power quality basis for the 

low frequency component of the emissions envelopes and the industrial emissions limit basis for the high 

frequency component of those envelopes provide an appropriate foundation for the RG envelopes for CE102 

and CE03. 

REJO1/REO1-Radiated Emissions, Low Frequency 

The RE101 (radiated emissions, magnetic field, low frequency) operating envelope is based on the Army 

ground facility envelope in MIL-STD 461D. The RE1Ol operating envelopes are adjusted because virtually 

no margin exists between the MIL-STD operating envelope for equipment emissions measured at 7 cm and 

the RS 101 (radiated susceptibility, magnetic field, low frequency) operating envelope for radiated 

susceptibility over the same frequency range. Some margin is deemed necessary to control the potential 

future growth of radiated magnetic field levels within specific areas of nuclear power plants. In the absence 

of other technical considerations, the lowered level for the operating envelope for emissions measured 7 cm 

away from the equipment is selected to be consistent with the operating envelope addressed in the SER on 

EPRI TR-102323. A comparable shift in field strength is enacted for the operating envelope for emissions 

measured 50 cm away from the equipment. The operating envelopes for military ground facilities from REO 1 

(radiated emissions, magnetic field, low frequency) in MIL-STD 461C is adjusted to provide greater 

consistency between the RE101 envelope for emissions measured 7 cm from equipment and the REO0 

envelope. The envelopes are similar in level with the comparable envelope endorsed in the SER on EPRI 

TR-102323. These adjustments to the RE101 and REO0 operating envelopes are motivated by the need to 

adequately control the growth of plant emissions and meet the goal of establishing comparable levels of 

assurance among the test criteria. 

Figure A.7 provides a comparative plot of the RG (i.e., NUREG/CR) envelopes for RE101, REO0, and 

RS 101, the baseline MIL-STD envelopes, and the corresponding envelope endorsed by the SER on EPRI 

TR-102323. It is seen that the RG envelope for emissions measured at a distance of 7 cm from the equipment 

and SER envelopes are similar in level. The RG envelope for emissions measured at a distance of 50 cm 

from the equipment provides an alternate envelope for area emissions control.

NUREG/CR-6431 44
110 

100 

90 \481D CE102 (44OV) 

so N RO CE102 (440~ 

80 

E 70 

L< 60 

ROCE1O2(28V) s. -% " 50 • 

481D CE10 (28V, \" *-b 

0 40 " . . - .. . . . . . 

4 FCC Cims A 

30 

20 

481C CEOS (mmana 

10 

0.01 0.1 1 10 100 1000 

Frequency (MHz) 

Figure A.6 Comparison of high-frequency conducted emissions envelopes
ý4 200 

180 

160 RG RS101 

140 RGRE101 7cm 

120 , , -,, 

S.... ". ,,., RG HE01"• 

S1 0 0 , - ; . - 461 D RE1 01 7 cm 

',• ,.,=• *" .. ,.,461DF -115 c 

S 60 

40 461C REO0 

20 

0 

0.01 0.1 1 10 100 1000 

Frequency (kHz)

Figure A.7 Comparison of low-frequency radiated emissions envelopes
RElO2/REO2-Radiated Emissions, High Frequency

The basis for the RE102 (radiated emissions, electric field, high frequency) operating envelope is the Army 

ground facility envelope in MIL-STD 461D. The basis for the MIL-STD envelope below 2 MHz is a 

relationship with CE102 (conducted emissions, power lead, high frequency), which addresses power quality 

issues that are common for nuclear power plants. The rationale for this envelope given in the MIL-STD 

461D Appendix states that the primary intent of the RE102 test is to protect sensitive receivers. Therefore, 

the very restrictive levels for the envelopes are raised but the slope of the lowest frequency band (which is 

related to the CE102 envelope) is maintained. The highest frequency component is adjusted using the CISPR 

Class A and FCC Part 15 Class A radiated emissions levels as the basis for setting the slope and level for the 

envelopes above 25 MHz. The emissions envelope component over the remaining frequency band (below 

25 MHz) is adjusted in level from its MIL-STD basis to correspond to the industrial emissions basis for the 

component of the envelope in the high frequency band. Thus, the RE102 emissions envelope presented in the 

NUREG/CR retains the low frequency slope of the MIL-STD envelope at levels comparable with those 

endorsed in the SER but the envelope levels in the upper frequency band are set to encompass the CISPR and 

FCC limits. Finally, the RE02 (radiated emissions, electric field, high frequency) narrowband envelope 

presented in this NUREG/CR adopts the RE102 envelope shape and level based on the same underlying 

rationale. The adjustments to the RE102 and RE02 operating envelopes are motivated by consideration of 

the underlying MIL-STD rationale for the envelopes and incorporate equipment emissions limits for 

industrial environments. This approach supports the goal of establishing operating envelopes that are 

appropriately tailored for the nuclear power plant environment. 

Figure A.8 provides a comparative plot of the RG (i.e., NUJREG/CR) envelopes for RE102 and RE02, the 

baseline MIL-STD envelopes, the corresponding envelope endorsed by the SER on EPRI TR-102323, and the 

Class A equipment emissions limits for CISPR and FCC Part 15. The RG envelopes completely encompass 

the CISPR and FCC radiated emissions limits. The RG envelopes are somewhat more restrictive than the 

corresponding SER envelope in the mid-frequency range and less restrictive in the lower and higher 

frequency ranges. Nevertheless, the relationship to the power quality criteria for the low frequency 

component of the emissions envelopes and the industrial emissions limit basis for the high frequency 

component of those envelopes provide an appropriate foundation for the RG envelopes for RE102 and RE02.

47 N4 JREG/CR-6431
Z 160 

140 

120 

E 100 

E 

RO RE102 

,., 8 RG RE820( arrowband) 

"CO 

FCC Cla A 

'j 60 

00,. -. CISPR Class A 

"U 40 4610 RE1O2 02 

S20 4810RE02 (n) - -"--

0 

0.01 0.1 1 10 100 1000 

Frequency (MHz)

Figure A.8 Comparison of high-frequency radiated emissions envelopes
NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER (2-89) (Assigned by NRC. Add Vol., Supp. Rev., NRCM 1102. and Addendum Numbers. If any.) 3201, 3202 BIBLIOGRAPHIC DATA SHEET 

(See Instructions on te re NUREG/CR-6431 

2. TITLE AND SUBTITLE ORNL/CM-13158 

Recommended Electromagnetic Operating Envelopes for Safety-Related 

I&C Systems in Nuclear Power Plants 3. DATE REPORT PUBLISHED 

MONTH F YEAR 

Oanuary 2000 

4. FIN OR GRANT NUMBER 

L 1951 

5. AUTHOR(S) 6. TYPE OF REPORT 

P. D. Ewing Technical 

R. T. Wood 7. PERIOD COVERED (InclusA. Dates) 

8. PERFORMING ORGANIZATION - NAME AND ADDRESS (If NRC, provide Divnsion, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address; if contractor, 

provide name and mailing address.) 

Oak Ridge National Laboratory 

P.O. Box 2008 

Oak Ridge, TN 37831-6010

9. SPONSORING ORGANIZATION - NAME AND ADDRESS (If NRC. type Same as abovel; if contractor, provide NRC Division, Office or Region, U.S. Nuc/ear Regulatory Commission, and mailing address.) Division of Engineering Technology 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001

10. SUPPLEMENTARY NOTES 

C. E. Antonescu, NRC Project Manager

11. ABSTRACT (200 words or less) 

This document presents recommendations for electromagnetic operating envelopes to augment test criteria and test methods 

addressing electromagnetic interference (EMI), radio-frequency interference (RFI), and power surges that are applicable to safety

related instrumentation and control (I&C) systems in nuclear power plants. The Oak Ridge National Laboratory (ORNL) was engaged by the U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research to assist in developing the 

technical basis for regulatory guidance on EMI/RFI immunity and power surge withstand capability (SWC). Previous research was provided recommendations on electromagnetic compatibility (EMC) design and installation practices, endorsement of 

EMIIRFI immunity and SWC test criteria and test methods, and determination of ambient electromagnetic conditions at nuclear 

power plants. The present research involves development of recommended electromagnetic envelopes that are applicable to 

nuclear power locations where safety-related I&C systems either are or will be installed. These recommended envelopes establish 

both emissions criteria and the levels of radiated and conducted interference that I&C systems should be able to withstand without 

upset or malfunction. The EMI/RFI operating envelopes are derived from conditions in comparable military environments and are confirmed by comparison with the nuclear power plant electromagnetic environment based on measured plant emissions profiles. 

Such detailed information on specific power surge conditions in nuclear power plants is not available, so industrial guidance on representing surge characteristics for susceptibility testing is adopted. An engineering assessment of the power surge environment 

in nuclear power plants leads to the recommendation of operating envelopes based on location categories and exposure levels 

defined in IEEE Std C62.41-199 1, IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Power Circuits.

12. KEY WORDS/DESCRIPTORS (List words or phrases that will assist researchers in locating the report.) 13. AVAILABILITY STATEMENT 

electromagnetic compatibility (EMC) unlimited 

electromagnetic interference (EMI) 14. SECURITY CSSIFICATON 

electromagnetic receivers (This Page) 

instrumentation and control (I&C) unclassified 

(This Report) nuclear power plant unclassified 

radio-frequency interference (RFI) 15. NUMBER OF PAGES 

16. PRICE

NRC FORM 335 (2-89)
Federal Recycling Program 

ISBN 0-16-050333-7 

j111111,! 11111 il90000 

9780160 503337
RECOMMENDED ELECTROMAGNETIC OPERATING ENVELOPES FOR 

SAFETY-RELATED I&C SYSTEMS IN NUCLEAR POWER PLANTS

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, D.C. 20555-0001

JANUARY 2000

FIRST CLASS MAIL 

POSTAGE AND FEES PAID 

USNRC 

PERMIT NO. G-67

NUREG/CR-6431