U.S. NUCLEAR REGULATORY COMr,'ISSION Revision 3 

October 1997 

REGULATORY GUIDE 

OFFICE OF NUCLEAR REGULATORY RESEARCH 

REGULATORY GUIDE 5.44 

(Draft was DG-5007) 

PERIMETER INTRUSION ALARM SYSTEMS

A. INTRODUCTION 

Part 73, "Physical Protection of Plants and Mate

rials," of Title 10 of the Code of Federal Regulations 

specifies performance requirements for the physical 

protection of nuclear power facilities, independent 

spent fuel storage facilities, fuel facilities, and special 

nuclear materials. Some examples of Part 73 objectives 

and requirements follow. For power reactors, 10 CFR 

73.55(cX4) requires detection of penetration or 

attempted penetration of the protected area or the isola

tion zone adjacent to the protected area barrier to ensure 

that adequate response by the security organization can 

> be initiated. Adversaries are presumed to be determined 

and knowledgeable. For independent spent fuel storage 

installations, 10 CFR 73.50(b)(4), in part, requires 

monitoring of isolation zones to detect the presence of 

individuals or vehicles within the zone. For Category 

I1 fuel fabrication facilities, the use of an intrusion 

detection subsystem with the capability to detect pene

tration through the isolation zones is specifically set 

forth in 10 CFR 73.46(e)(1). (The special case of non

power reactors with Category I types and quantities of 

materials is addressed in 73.60.) Finally, for facilities 

t

Category I means strategic special nuclear material as defined in 10 

CFR 73.2.

possessing Category 112 quantities and types of materi

al, 10 CFR 73.67(d)(3) requires that the controlled ac

cess area be monitored with an intrusion alarm or other 

device or procedure to detect unauthorized penetration 

or activities. 

This guide describes the functions of perimeter 

intrusion detection sensors and detection methods that 

are acceptable to the Nuclear Regulatory Commission 

(NRC) staff for meeting the portions of the NRC's regu

lations specified above. It provides guidance on sensors 

and methods that can be integrated to form an effective 

perimeter intrusion detection system. This guide pro

vides guidance on selecting perimeter intrusion detec

tion systems and on applications for nuclear power 

reactors, independent spent fuel storage installations, 

and certain special nuclear material processing 

facilities. 

In using this guide, it is not the intent of NRC to 

compel a licensee to revise commitments in previously 

approved security plans without benefit of site-specific 

backfit and justification of a significant increase in 

protection of public health and safety. In advising 

affected licensees of the appropriate use of the guide, 

NRC recommends that licensees, in replacing or 

redesigning a perimeter intrusion alarm system, con

2

Category Il means special nuclear material of moderate strategic sig

nificance as defined in 10 CFR 73.2.

/'

USNRC.REGULATORY GUIDES The guides awe Issued in the following ten broad dMsions: 

Regulatory Guides are Issued to describe end make available to toe public such Informa

tion as methods acceptable to the NRC staff for Impleme•ting specific parls of the Com- i. Power Reactors 6. Products 

mission's regulations, techniques used bythestaff Inevaluating specific problems orpos- 2- Research and Test Resactos 7. Transportaston 

tulaed accidents, aid data needed by fte NRC staffi n tsreview ofd appictons for per- a Fuets and Materials Facilities S. Occupational Health 

mlts and boarsa. Regulatory gides are not substltutes for regularions, arnd copliance Environmental nd Siting 9. Antitrutl and Financial Review 

with them is not requlird. Methods and solutions dIfferent from those Set out In egulides & Mateials id Plant Protection 10. General 

win be accp le If they provide a bsss for the findIngs reqeislte to fte Issuance or con tinuance of permit or Icase c by the Commission. 

Single copies of regulatory guides may be obtained fee of charge bywriting ft Printing, Thi gulde was Issued after conslderston of comnments reclved from t•e publicm Corn- Graphics end Distribudon Branch. Ofice of AdminIstrafion, U.S. Nucdesr Regulatory Com

merits andasuggeatons forlmprovements In teseguides waeencouraged atalltimes,aand missIon, Washington, DC 20555-0001; or by fax at (301)415-5272. 

will be revised, as approprate, to sccommodate comments and to reflect new In

= on or mparlence. Issued glides may also be purchased from te National Technical Information Service on Wdtten comments may be submitted to the Rules Review and Directives Branch, DFIPS, a standing order basis. Details on this service may be obtained by writing NTIS, 8285 Port 

ADM, U.S. Nudesr Regulatory Commission. Washington, DC 20555-0001. Royal Road, Springfield, VA 22161.
sider the information in the guide as one factor, among 

others, in the overall planning of the system. A licensee 

may choose to voluntarily commit to this revision of 

the guide, in total or in part. 

The information collections contained in this regu

latory guide are covered by the requirements of 10 CFR 

Parts 50, 72, and 73, which were approved by the Office 

of Management and Budget, approval numbers 

3150-0011, 3150-0132, and 3150-0002. The NRC 

may not conduct or sponsor, and a person is not re

quired to respond to, a collection of information unless 

it displays a currently valid OMB control number. 

B. DISCUSSION 

GENERAL 

The effective use of a perimeter intrusion detection 

system is influenced by a number of factors. These fac

tors include the environment (such as snow, rain, tem

perature, lightning); the selection, application, and 

installation (including proper electrical grounding) of 

equipment; testing and maintenance of the particular 

sensor types used; the ability of the security organiza

tion to assess incoming alarm data in a timely manner, 

and the overall integration of the system. A perimeter 

intrusion detection system generally consists of one or 

more sensors, electronic processing equipment, a 

power supply, signal transmission media, an alarm 

monitor with display, and a means for maintaining and 

providing an alarm history. 

Sensor systems can be classified, from an applica

tions viewpoint, as either line-of-sight or terrain

following, and from a functional viewpoint, as either 

volumetric or planar. For line-of-sight systems to be 

effective, the terrain surface must be relatively flat with 

no significant contour depressions or elevations. In 

terrain-following systems, the sensor's detection pat

tern can adapt to some changes in the terrain's contour. 

The terms volumetric and planar refer to the general 

shape of the sensor's detection zone; the primary differ

ence between these terms concerns their depth dimen

sion, or the distance an intruder must travel to pass 

through the sensor's detection zone. The depth dimen

sion for a planar sensor is minimal to near zero (much 

like a plate of glass). A taut wire system is an example; 

the intruder must contact the wire to cause an alarm. In 

contrast, a microwave sensor creates a volumetric beam 

pattern having a depth of up to several feet. 

An intruder's ability to determine a sensor's detec

tion zone boundary can compromise the sensor. Micro

wave detectors have invisible detection patterns. At

best, an intruder can only estimate points where detec

tion will occur. In contrast, the detection zone of a taut 

wire system can easily and accurately be determined. 

The wires constitute the detection zone. 

In selecting a sensor capable of detecting an 

intruder, it is crucial to select and integrate sensors that 

will minimize false and nuisance alarm rates. (See 

Appendix A, Glossary, for definitions.) Selecting the 

best sensor for a perimeter section will minimize the 

false and nuisance alarm rates. In selecting the best sen

sor for a perimeter location, the following factors are 

considered. 

"* Fence, barrier, and isolation zone conditions 

"* Soil types and conditions, including blowing sand 

* Drainage 

* Suitability of the perimeter for segmenting into 

detection zones 

* Nearby roads, airports, waterways, railroads, and 

the type of traffic they carry 

* Perimeter penetrations (above and below ground) 

such as culverts, pipes, buried wires, and utilities 

* Temperature extremes 

* Precipitation (e.g., rain or snow) amounts and 

rates, including ice accumulation and blowing 

snow 

Lightning frequency and severity 

* Natural foliage 

* Wildlife types, population densities, and activity at 

or near the perimeter 

* Electromagnetic interference potential, including 

radio frequency interference potential. 

Some typical commercially available sensor sys

tems are described below. 

SENSOR SYSTEMS 

Microwave Systems 

Microwave systems are line-of-sight and volumet

ric, and they are found in two basic configurations: 

(1) bistatic, consisting of a transmitter and receiver 

remote from each other at either end of a microwave 

link, and (2) monostatic, with receiver and transmitter 

located in the same unit. 

Each link of a bistatic microwave perimeter detec

tion system is composed of a transmitter, receiver, 

power supply, signal processing unit, signal transmis

sion system, and an output for connection to an 

annunciation device. The transmitter radiates a low5.44-2

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power, three-dimensional, typically modulated micro

wave signal toward the receiver. The receiver detects, 

amplifies, and processes the signal. A reference rate of 

> microwave energy transfer is established while the 

transmitter is unobstructed. When an intruder enters the 

space defined by a conical beam, the total amount of 

microwave signal energy entering the receiver is 

increased or reduced from the established reference 

level. This causes the receiver to generate an alarm. The 

microwave beam is typically modulated to reduce 

interference from spurious sources of radio frequency 

energy, to increase sensitivity, and to decrease the vul

nerability to defeat by the receiver capturing a false 

microwave source. 

A monostatic microwave unit consists of a trans

mitter and receiver in the same unit along with a power 

supply, signal processing unit, signal transmission sys

tem, and an output for connection to an annunciation 

device. There are two different kinds of monostatic 

microwave, amplitude modulated (AM) and frequency 

modulated (FM). AM monostatic microwave systems 

detect changes in the net vector summation (direct and 

reflected components) of the received signal, similar to 

a bistatic system. FM monostatic systems operate on a 

pulsed doppler principle and thus can provide range in

formation in addition to detection. In general, the useful 

2 range of a monostatic microwave is considerably less 

than that of a bistatic system. For this reason, its exte

rior use is generally limited to short links or volumes 

covering portals or gaps in coverage between bistatic 

microwave transmitters and receivers. 

Electric Field Systems 

An electric field perimeter intrusion detection sys

tem is considered terrain-following if the grade is uni

form between mounting supports. First generation sys

tems are considered planar, while second generation 

systems are more volumetric in nature. A typical sys

tem consists of field wires, a field generator, sensing 

wires, a sensing filter, an amplifier, a discrimination 

unit, and an output for connection to an annunciation 

device. The field generator excites the field wires, 

creating an omnidirectional electrical field primarily 

between the field wires and the sensing wires (a field is 

also created between the field wires and the earth 

ground). Electric field systems range from 4 to 7 wire 

systems, i.e., from 2 sensing and 2 field wires up to 3 

sensing and 4 field wires. A person approaching the 

system changes the pattern of the electric field. Sensing 

2 wires installed at different locations within the trans

mitted pattern detect changes occurring in the pattern. 

If the changes are within the frequency bandpass of

objects comparable to an individual's movement, a 

detection signal is generated. Some systems have addi

tional signal processing to discriminate between people 

and what would otherwise be nuisance alarms. 

Ported Coaxial Cable Systems 

A ported coaxial cable system, considered to be 

terrain-following and volumetric, consists of two bur

ied shielded coaxial cables, transmitters, detectors, 

power supply, processing unit, and an output for con

nection to an annunciation device. Radio frequency 

(RF) energy is transmitted along the transmission line 

and is radiated through ports in the shield strands. This 

RF energy can be either pulsed or continuous wave. The 

pulsed system operates in principle as a guided radar, 

and thus an intruder is both detected and located. The 

continuous wave system detects the intruder but does 

not localize the intruder's presence along the cable 

length. The transmit-receive antenna pattern that is set 

up between the two cables produces a zone of detection 

around and between the transmitting and receiving 

lines. Changes in this electromagnetic field that exceed 

threshold levels cause an alarm. The system detects 

moving targets in the zone of detection, and the signal is 

digitally processed to provide enhanced signal charac

teristic identification. The received signal is generally 

processed to reduce interference from nearby RF 

emitters. 

Active Infrared Multibeam Systems 

Active infrared multibeam systems are considered 

line-of-sight and planar. Each link of an infrared system 

is composed of a transmitter, receiver, power supply, 

signal processor, signal lines, and an output for connec

tion to an annunciation device. The transmitter directs a 

narrow infrared beam to a receiver. If the infrared beam 

between the transmitter and receiver is interrupted, an 

alarm is generated. The infrared beam is usually modu

lated. Since the infrared beam does not diverge signifi

cantly, multiple infrared beams between transmitters 

and receivers can be used to define a "wall." If this 

"wall" is then penetrated, an alarm will result. (Note: 

The term "active infrared" is used to distinguish these 

systems from "passive infrared" systems. Passive 

infrared systems do not emit infrared energy, but 

instead, simply "look" at their field of view and detect 

changes in the ambient infrared patterns or intensity 

levels.) 

Taut Wire Systems 

A taut wire system is a terrain-following (with 

ground leveling) planar system. The system consists of 

a series of steel wires, typically barbed, securely 

anchored on posts and stretched parallel to the ground. 

4-3
The wires are closely spaced to prohibit climbing 

between the wires without causing an alarm and are 

typically tensioned to 36 kg (80 lb). Deflection of or 

cutting one or more of the tensioned wires activates a 

sensing device connecting each wire to either a sensing 

post or anchor post. The sensing device may be a simple 

switch, strain gauge device, or other passive transducer. 

Slider posts are generally used to further support the 

wires, typically at 3-meter (10-foot) intervals. 

Fiber Optic Systems 

Fiber optics refers to light transmission through 

specially constructed optical fibers for communica

tions, sensing, or imaging. Optical fiber consists of a 

light-guiding core and a surrounding optical "insula

tor" called the cladding. The core has a higher index of 

refraction than the cladding, which permits total inter

nal reflection if the angle of incidence is greater than the 

critical angle. light can thus be confined in the core and 

transmitted along the length of the fiber. 

A number of different techniques are being used in 

the developing technology of fiber optic intrusion 

detection. Speckle pattern and interferometry are two 

common techniques. In the speckle pattern technique, 

when light is sent through the optical sensing cable of 

the system, it appears at the end of the cable as a 

speckled pattern of light and dark spots. The patterns of 

light and dark are caused by the many different modes 

or paths through which light can travel in a multi-mode 

fiber optic cable. When the cable is stationary, the pat

tern is stationary. However, when pressure is applied to 

the cable, the light distribution through the cable is 

changed. This change redistributes the speckle pattern 

of light and dark. These speckle patterns are converted 

to usable electrical signals through the use of a photo

diode. An alarm processing unit uses this information 

to determine whether an alarm has occurred. 

Interferometry can also be used to determine 

changes in the optical sensing cable. This technique 

uses wavelength-division multiplexing, which is a 

method capable of sending multiple signals at different 

wavelengths through the same fiber. The detection 

method involves monitoring mode interference 

changes of the light that are caused by pressure, vibra

tion, or motion. To optimize detection capability and 

minimize nuisance alarms for a particular installation, 

the system allows the user to select appropriate process

ing parameters to qualify a disturbance as an alarm. The 

parameters include the frequency band, energy level 

and duration of the disturbance, and the number of dis

turbances within a specified time. Fiber optic systems 

using these techniques for detection are considered

terrain-following and either volumetric or planar, 

depending on the specific installation and use. 

Vibration or Strain Detection Systems 

A variety of devices that detect strain or vibration 

are available for use as fence-mounted intrusion detec

tion systems. ITypically, such systems are considered 

terrain-following and planar. Although the devices 

vary greatly in design, each basically detects strain or 

vibration of the fence on which it is mounted, such as 

that produced by an intruder climbing or cutting the 

fence. In the simplest devices, the vibration or strain 

makes or breaks electrical continuity and thereby gen

erates an alarm. In more complex systems, vibration or 

strain changes light transmission characteristics 

through fiber optics. 

C. REGULATORY POSITION 

1. DESIGN OBJECTIVES AND 

INTEGRATION 

1.1 Layout 

In designing an effective perimeter intrusion detec

tion system, dividing the site perimeter into segments 

that are independently alarmed and uniquely monitored 

assists the security organization in assessing and 

responding to an alarm by localizing the area in which 

the alarm is initiated. The perimeter segment lengths 

should be selected with consideration of such factors as 

range; limitations of the sensor system; and the loca

tion, alignment, and viewing areas for closed circuit 

television (CCTV) cameras, when CCTV is used for 

alarm assessment. Segmenting the perimeter alarm sys

tem also allows testing and maintenance of a portion of 

the system without affecting the remainder of the 

perimeter. The individual segments should generally be 

limited to a length that allows observation of the entire 

segment by an individual standing at one end of the seg

ment. This typically means that segments should not 

exceed 100 meters (328 feet), but shorter segments may 

be needed to achieve the desired performance. 

The ground surface of the detection zone should be 

prepared by stabilizing the soil to prevent the growth of 

vegetation along the length of the zone. Depending on 

the system type, this may help to minimize nuisance 

alarms caused by the movement of high grasses, etc. 

Measures for accomplishing stabilization include sur

facing or soil sterilization. Isolation zones on either 

side of the detection zone also help to provide a clear 

zone for assessment. For all systems, the distance 

between the bottom of the detection zone and the 

ground plane should not be large enough for an

5.44-4

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individual to pass undetected under the detection zone 

and thereby circumvent the system. 

Perimeter intrusion detection systems should be 

placed to maximize detection and assessment capabili

ties and minimize nuisance and false alarm rates. The 

following factors should be considered in locating the 

detection system. 

1.1.1 The system should be located so that items 

such as existing (or planned) barriers, sensor mounts,3 

light poles, or natural terrain objects (e.g., trees) cannot 

be used as aids for bridging the sensor's detection pat

tern, blocking assessment, or providing cover and 

concealment. 

1.1.2 In determining the distance between the 

zone of detection and any area in which an adversary 

may be concealed, the licensee should consider the time 

needed to circumvent the barriers, the time to reach a 

concealed location, and the specific intruder

assessment capabilities at that location. Digital video 

frame storage systems are one means of addressing site

unique assessment problems by capturing video frames 

before, during, and after an actual intrusion. 

1.1.3 Pedestrian and vehicular traffic should be lo

cated away from the zone of detection to reduce nui

sance alarms. 

1.1.4 Sources of strong, fluctuating electromag

netic fields (such as large transformers and electrical 

power distribution subsystems) should be considered 

when selecting sensors susceptible to such distur

bances (e.g., the electric field sensor and the ported 

coaxial cable system). 

1.1.5 Site-specific environmental conditions 

should be considered in selecting the system. For 

example, sites where fog sometimes obscures visibility 

may not be suitable for beam-breaker type systems, 

such as the active infrared multibeam system, which 

may have its detection capability degraded by the fog's 

beam-scattering effect. 

1.2 Detection and Alarm Capabilities 

Optimum detection capabilities for any particular 

sensor system are achieved when the sensor selected 

has a detection volume suited to specific segment con

figuration and terrain. In general, volumetric systems 

are preferred because they are generally more difficult 

to defeat. However, for certain limited site configura

tions, planar systems may provide coverage with fewer 

false or nuisance alarms compared to a volumetric-type 

sensor. 

3

After adjustments in sensor position are complete, it might be neces

sary to remove excessive lengths of mounting poles.

A single system that by itself does not meet detec

tion performance requirements may, in conjunction 

with another system with a different sensing method, 

provide adequate detection performance. Such com

bination systems should employ dissimilar detection 

techniques. This combination of different sensing tech

niques requires an intruder to defeat two (or more) 

types of different sensing methods at the same time, 

which would significantly increase the difficulty of 

defeating the system. 

The design goal of a perimeter intrusion detection 

system is to detect an individual weighing a minimum 

of 35 kg (77 pounds), whether the individual is running, 

walking, crawling, jumping, or rolling through the 

perimeter of a protected area. Further, the design goal of 

a perimeter intrusion detection system should be to 

limit false alarms and nuisance alarms to a total of not 

more than one false alarm per zone per day and one nui

sance alarm per zone per day. 

Because nuisance alarm rate data are extremely 

specific to location and detection technique, data 

should be gathered for the first year after a new system 

is installed to gain system experience and to allow for 

system alterations. After that period, the data should be 

examined to establish site-specific rates for both nui

sance and false alarms. The findings should be reflected 

in adjustments to security plan commitments based on 

site-specific operational and environmental circum

stances and actual performance at the site. Such revi

sions to security plans may be submitted under the pro

visions of 10 CFR 50.54(p) if the changes do not 

represent a decrease in effectiveness of the security 

plan. Settings of adjustable parameters should be 

recorded and future changes should be recorded with 

justifications. 

Licensees should be able to observe, in a timely 

manner, the bridging of a detection zone or to justify to 

NRC that successful completion of a bridging attempt 

is not feasible. 

The system should be designed to annunciate, 

audibly and visibly, under the following additional 

conditions: 

"* Placement of any portion of a perimeter intrusion 

detection system in the access mode, 4 

"* Aunique indication, other than a normal alarm, of a 

switch over to emergency or secondary sources of 

power, 

4

Access mode means the condition that maintains security over the sig

nal lines between the detector and the annunciator and over the tam

per-switch in the detector but allows access into the protected area 

through the zone of detection without indicating an alarm condition.

5.44-5
"* Any interruption or reduction of system power to 

the degree that any part of the system is not func

tioning properly, 

"* Any indication of tampering (e.g., opening, short

ing, or grounding of the sensor circuitry) that ren

ders the device incapable of normal operations; 

"* Any indication of tampering by activation of a tam

per switch or other triggering mechanism. 

1.3 System Electrical Specifications 

If primary power is interrupted, the security system 

should-contain provisions for automatic switch over to 

emergency power (battery and/or generator) without 

causing false alarms and without causing a loss of sys

tem function or data. Emergency power should be capa

ble of sustaining operation without external support for 

a minimum of four hours for Category I fuel cycle facil

ities, or for a site-specific period of time determined 

according to station blackout criteria for power reactor 

facilities. If emergency power is furnished by battery, 

all batteries (including stored batteries) should be 

maintained at full charge by automatic battery charging 

circuitry designed according to IEEE Standard 450, 

"Recommended Practice for Maintenance, Testing, and 

Replacement of Large Lead Storage Batteries for Gen

erating Stations and Substations" (1987).5 

1.4 Tamper Protection 

All enclosures containing controls that affect the 

operation and sensitivity of the detection system and all 

access point controls should be located within an enclo

sure protected by a tamper-switch. The electronics 

should be designed so that tamper-switches remain in 

operation even though the system may be placed in the 

access mode. At power reactor sites only, cable pull 

boxes and termination points need not be tamper

protected if line supervision is used, unless there are 

splices at the location. 

1.5 System Line Supervision 

All signal lines connecting detection devices to 

alarm stations should be supervised.6 If the processing 

electronics are separated from the sensor elements and 

are not located within the detection area of the sensor 

elements, the signal lines linking the sensors to the 

processing electronics should also be supervised. Line 

5Copies may be obtained from the IEEE Service Center, 445 Hoes 

Lane, Piscataway, NJ 08855. 

6

Signal line supervision is discussed in the NRC's NUREG/CR-5723, 

"Security System Signal Supervision" (September 1991). Copies may be purchased at current rates from the U.S. Government Printing Of

fice, P.O. Box 37082, Washington, DC 20402-9328 (telephone 

(202)512-1800); or from the National Technical Information Ser

vice bywriting NTIS at 5285 Port Royal Road, Springfield, VA 22161.

supervision on these communication paths should pro

tect against simple electrical bridging of the system or 

compromise of the system by any of the following 

means. 

"* Substitution of resistance, voltage, or current, 

"* Substitution of equipment of the same design and 

manufacturer, 

" Reintroduction by playback of signals previously 

recorded onto the communication path, 

" Introduction of signals onto the path that were syn

thesized externally. 

The tamper switch and transmission medium 

should be supervised to the same extent in the secure 

mode as when the sensor is conditioned for authorized 

access. 

1.6 System Vulnerabilities 

Licensees are cautioned that any sensor system 

may have one or more design vulnerabilities that may 

enable the system to be compromised by a knowledge

able intruder. For this reason, it is important that all 

equipment be installed per manufacturers' specifica

tions, meet the performance criteria required by 

10 CFR Part 73 as clarified in this regulatory guide, and 

be thoroughly tested. In some instances, the combina

tion of different sensor types can yield improved per

formance with a reduction in vulnerabilities. (See Reg

ulatory Position 1.2, "Detection and Alarm 

Capabilities," on combining sensors.) Licensees 

should consider requesting that a system manufacturer, 

a qualified engineer, or both be present during final 

acceptance testing of a perimeter intrusion detection 

system to be sure that the system has been properly 

installed. 

1.7 Assessment 

A perimeter intrusion detection system is incom

plete without some means to assess and resolve alarms. 

It is imperative that the assessment techniques identify 

the stimulus in a timely manner before the stimulus of 

the alarm disappears from view. The time an intruder 

takes to run through the isolation zones and disappear 

from the field of view of the assessment mechanism 

should be greater than the time required to visually 

assess the alarm zone. If the required protected area bar

riers and isolation zones adjacent to the intrusion detec

tion system do not provide sufficient delay to ensure as

sessment, additional means should be taken to increase 

delay or improve assessment (e.g., an additional fence, 

concertina rolls, razor tape, higher fence, video-cap

ture monitoring techniques). Care should be taken that 

the means used to provide additional delay do not inter5.44-6

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fere with assessment capabilities. The following are ac

ceptable methods of assessment. 

1.7.1 CCTV systems that are fixed and properly 

> aimed parallel to the barrier or perpendicular to the in

truder's path may be used to provide assessment in

formation to the alarm station operators. It is important 

to select and orient equipment to maximize fields of 

view and, thus, maximize assessment time for evaluat

ing intruders passing through detection zones. These 

systems should be designed to display immediately, 

using the same signal that activates the annunciation. 

Video-image capture devices with the capability to 

record an adversary within the zone of assessment and 

immediately prior to detection are an acceptable alter

native to alarm-activated display monitors. At Cate

gory I fuel cycle facilities, alarm-activated display 

monitors should continuously display and not "go 

blank" during quiet periods (periods of no alarm). Con

sideration should be given to the use of pan/tilt/zoom 

(PTZ) cameras to augment fixed camera installations, 

as an adjunct to the fixed camera systems. 7 

1.7.2 Fixed guard posts can be effective if the 

posts are positioned so that there is a clear field of view 

of the assigned segment. These posts generally should 

be positioned at the end of the assessment area with the 

guard observing in one direction only. The intrusion 

detection system should annunciate in the local guard 

> post as well as in both alarm stations. Consideration 

should be given to compensation for loss of guard 

observation capability during periods of reduced visi

bility such as darkness, rain, fog, and snow. 

1.8 Maintenance 

The regulations in 10 CFR Part 73 require that the 

perimeter intrusion detection system be maintained in 

an operable condition, thus a preventive maintenance 

program is necessary. Maintenance of the detection, 

alarm communication, annunciation, and assessment 

system is critical to successful operation. Licensees 

should establish an ongoing program for maintenance. 

In addition, maintenance may be initiated by the testing 

program, operational requirements, the routine peri

odic maintenance program, or a trending program or 

analysis. 

7

Video systems are discussed in NUREG/CR-5721, "Video Systems 

for Alarm Assessment" (D. A. Greenwoll and J. C. Matter 

(SAND9g-0947), USNRC, September 1991). Copies may be pur

chased at current rates from the U.S. Government Printing Office, 

P.O. Box 37082, Washington, DC 20402-9328 (telephone 

(202)512-1800); or from the National Technical Information Ser

vice bywriting NTIS at 5285 Port Royal Road, Springfield, VA22161. 2 Copies are available for inspection or copying for a fee from the NRC 

Public Document Room at 2120 L Street NW., Washington, DQ the 

PDR's mailing address is Mail Stop LL-6, Washington DC 

20555-0001; telephone (202)634-3273; fax (202)634-3343.

The amount of time that equipment is out of service 

should be minimized to preclude the overuse of com

pensatory measures. The maintenance group should be 

effective and respond in a timely manner. The use of 

dedicated on-site maintenance technicians has proven 

effective to ensure perimeter intrusion detection system 

operability and proper performance. 

2. PERIMETER INTRUSION DETECTION 

SYSTEMS-MINIMUM SPECIFICATIONS 

2.1 Microwave Systems 

2.1.1 Installation Criteria 

Bistatic transmitters and receivers should be 

installed on even terrain clear of trees, tall grass, stand

ing or running water, and bushes. Typically, a bistatic 

microwave perimeter detection system should .be 

installed to operate effectively in a range not more than 

100 meters (approximately 328 feet) long. Some mod

els are designed to operate over short ranges, e.g., 

across perimeter portals. Successive microwave links 

and corners should overlap to eliminate dead spots 

(areas where the microwave beam cannot detect) below 

and immediately in front of transmitters and receivers. 

The required amount of overlap of successive links is 

contingent on the antenna pattern and unit height. In 

zone overlap areas, the equipment for the overlapped 

zones should either both be transmitters or both be 

receivers; this is to minimize interference between the 

successive links that could otherwise result in 

decreased sensitivity and greater false alarm rates with

in the zones. Each unit should be mounted rigidly on 

secure posts at a sufficient distance above the ground so 

that incident and reflected signals combine positively, 

typically 60 cm (24 inches) for 100 meters (328 feet), or 

according to the manufacturer's installation criteria. 

Because of variances in the antenna patti.rns of different 

microwave systems, the height may have to be varied 

slightly to obtain coverage adequate to detect crawling 

intruders. Accordingly, the mounting mechanisms for a 

system should permit adjustment of antenna height and 

position to correct poor performance or alignment. 

Receiver units for a microwave link may also need 

to be specially protected because of their susceptibility 

to tampering by a knowledgeable intruder or to 

"receiver capture" through electronic means. "Receiver 

capture" occurs when a receiver recognizes a false 

transmission signal as its own. Means available to 

minimize vulnerabilities include the use of monostatic 

microwave to protect the area where the receiver head is 

located or the use of additional perimeter intrusion 

detection equipment, such as an electric field system, 

configured to require penetration of a detection zone in

5.44-7
order to access a receiver head. As with bistatic receiver 

heads, monostatic transceiver heads may be vulnerable 

to certain tampering methods and must also be pro

tected, possibly by placement inside another sensor's 

detection zone as described above. 

Stacking of microwave sensors is one means of 

increasing the elevation-detection-zone height of the 

system to enhance its detection capabilities. The stack

ing technique, in effect, fills in the dead zones that can 

be inherent in simple bistatic systems. Additionally, the 

use of stacked units can help detect the bridging or 

jumping of a detection zone. Multichannel microwave 

units should be used in an alternating pattern around the 

perimeter. 

Since the bistatic transmitter/receiver link is a line

of-sight system, variations in ground level (e.g., 

ditches and valleys) may allow some intruders to crawl 

under the beam, and variable obstructions (e.g., snow 

drifts or accumulations) may interrupt the beam. To 

prevent passage under the microwave beam, variations 

in the ground should be leveled, ditches should be 

filled, and obstructions should be removed so that the 

area between the transmitter and receiver is clear of ob

structions and free of rises or depressions. The distance 

between the bottom of the detection zone and the 

ground plane should be such that a person cannot crawl 

under the zone undetected. Typically, the distance 

between the bottom of the detection zone and the 

ground should be 15.24 centimeters (6 inches) or less. 

The clear area should be sufficiently wide to preclude 

the generation of alarms by legitimate movements near 

the microwave link (e.g., personnel walking or vehicu

lar traffic) and to preclude system degradation caused 

by reflections from any structure, such as the perimete&r 

fence. Approximate dimensions of the microwave pat

tern should be provided by the manufacturer. 

Motion or disturbance of objects such as tumble

weed, paper, and bushes moving in the path of the beam 

can cause nuisance alarms. Since the beam is relatively 

wide, care should be taken to ensure that reflections 

from authorized activities do not create nuisance 

alarms. With the microwave link installed inside a 

perimeter barrier or between a double perimeter barrier, 

the transmitter and receiver should be positioned to 

detect anyone jumping over the microwave beam into 

the protected area from atop the perimeter fence or wall. 

Typically, the distance between a chain link security 

fence with an overall height of 2.4 meters (8 feet) and 

the center of the microwave beam should be a minimum 

of 2.4 meters (8 feet). In addition, the microwave link 

should be positioned within the isolation zone to 

enhance assessment once detection is made. Neither a

transmitter nor a receiver should be mounted on a fence 

unless prior approval is received from the NRC. Over

lapping transmitter/receiver paths should also be 

designed to prevent bridging from transmitter or 

receiver posts and to prevent an intruder from moving 

undetected behind units. Similarly, care should be 

taken to be sure that mounting posts cannot be used as 

step-off points for jumping over the zone of detection. 

2.1.2 Performance Criteria 

A microwave perimeter detection system should 

be capable of detecting an intruder weighing a mini

mum of 35 kilograms (77 pounds) passing through the 

zone of detection between the transmitter and receiver, 

including the area in front of both the transmitter and 

receiver, whether the individual is walking, running, 

jumping, crawling, or rolling. Provision should be 

made to ensure detection in spite of the dead spots in 

front of transmitters and receivers. The beam should be 

modulated and the receiver should be limited to 

respond to selected frequencies to decrease susceptibil

ity to "receiver capture." 

2.2 Electric Field Systems 

2.2.1 Installation Criteria 

Electric field systems should be installed with 

zones that are limited to 100 meters (328 feet) or less in 

order to have effective detection sensitivity for assess

ment and response. The system can be mounted on 

metal, plastic, or wooden posts using specially de

signed electrical isolators that allow for small move

ments of the posts without disturbing the wires. The 

wires need to be under a high degree of spring tension to 

produce high-frequency vibrations when they are 

struck by small foreign objects or blown by the wind, 

both of which are out of the bandpass of the receiving 

circuitry. 

The electric field sensor's wires should be spaced 

so that an individual moving between the wires can be 

detected. It is important that the lowest wire of any elec

tric field system be consistently close enough to the 

ground to detect crawling under the wire. Accordingly, 

the bottom wire should be located 15.24 centimeters (6 

inches) or less above ground level. The field wires and 

sensing wires should be located and spaced per the 

manufacturer's specifications. The electric field detec

tor is not a line-of-sight system and therefore can be 

installed on uneven terrain and in an irregular line. 

However, the terrain between posts must be of uniform 

grade so that the field and sensing wires can be installed 

parallel to the ground. 

Because of the characteristics of an electric field 

detection pattern, the system should not be mounted on

5.44-8

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or near a fence that an intruder could use to jump over 

the field. Consideration may also need to be given to the 

ability of intruders to set up, without observation, such 

> hand-carried equipment as small ladders for jumping 

over the electric field without detection. In general, 

evasion of detection by jumping over a planar system 

need not be considered if the overall height of the sys

tem is about 3.7 meters (12 feet) or greater, because of 

the impact of jumping from those heights. For electric 

field systems, wires that are not connected to either 

field generators or field change sensors may prove use

ful for altering the field contours to fill in gaps or to 

extend the effective height of the field. In addition, if 

the electric field system is mounted on the side of a 

wall, the stand-off from the supporting barrier should 

not permit passage between the barrier and the system. 

The surrounding terrain within 3 meters (10 feet) of 

field wires should be free of all shrubs, trees, and under

growth. 

The system should be well grounded per the 

manufacturer's recommendations along its entire 

length with special care given to the sections that go 

over walls or buildings. The control unit should be well 

grounded using a 1-meter (39-inch) or longer ground

ing rod or equivalent electrical ground. Grounding may 

be difficult under dry earth conditions. The resistance 

j- between ground rods and earth should also meet 

manufacturer's recommendations. 

Electric field systems should be tuned or over

lapped if necessary to overcome any lack of sensitivity 

in the areas around tension springs and end insulators. 

Monostatic microwave could also be used to protect 

these areas. Another alternative is to install barriers in 

these areas to either channel an intruder into the higher 

sensitivity envelope or require increased activity to 

penetrate the barrier sufficient to be detected even in the 

reduced sensitivity region. Each wire should be kept 

free of nicks, cuts, etc., and be properly tensioned per 

manufacturer's recommendations along its entire 

length. Systems mounted on chain-link fence are sus

ceptible to wind-caused alarms and should be avoided. 

There may be some loss of sensitivity in the vicinity of 

metal posts used to support electric field fences. If site 

conditions necessitate installations over buildings, 

nonmetallic posts (e.g., wood or fiberglass-reinforced 

plastic) should be used to prevent gaps in the detection 

zone. 

2.2.2 Performance Criteria 

2 An electric field perimeter detection system should 

be able to detect an individual weighing a minimum of 

35 kilograms (77 pounds) whether the individual is

crawling or rolling under the lowest wire, stepping or 

jumping bet:,een the wires, or jumping over the wires. 

The field and sensing wires should be supervised to pre

vent undetected cutting or bypassing of the system by 

electronic or clandestine means. 

2.3 Ported Coaxial Cable Systems 

2.3.1 Installation Criteria 

Ported coaxial cable systems should be installed 

per the manufacturer's specifications. The maximum 

and minimum separation of the transmitter and receiver 

can vary. Generally, this type of system can operate in 

longer segments than other detection systems. How

ever, it is recommended that detection zones be 

restricted to segments of 100 meters (328 feet) or less to 

facilitate assessment. The system is terrain-following 

and can be curved around corners. The lines are gener

ally buried approximately 18 centimeters (7 inches) 

deep and I to 3 meters (3 to 10 feet) apart. The installa

tion of ported coaxial cable perpendicular to buried 

metal conduit for electrical cables or metal pipes used 

for water or storm drains may degrade detection or 

cause nuisance alarms. Soil conductivity should be 

considered when installing this type of sensor. Soil 

found to have relatively high conductivity may cause 

the detection field to be reduced. Highly conductive 

soil includes soil that contains concentrations of iron or 

salt. Moving objects in the zone of detection such as 

foliage, rippling water, and grasses may create nuisance 

alarms. Rodents can chew through ported coaxial 

cable. Sensor locations should be selected carefully to 

prevent nuisance alarms from such sources as person

nel and vehicular traffic. Similarly, the cleared area 

above the sensor should be controlled to prevent the 

placement of objects within the area, even temporarily, 

which would degrade the detection zone. The transmit

ter and receiver transducer lines should be installed on 

well-drained terrain cleared of trees, tall grass, and 

bushes. System sensitivity may be affected by freezing 

or thawing of the surrounding terrain. Because local 

anomalies can cause variances in the antenna pattern, 

the separation between the lines may vary slightly in 

order to obtain proper ground coverage. Neither the 

transmitter nor the receiver lines should be mounted 

above ground. Approximate dimensions of the detec

tion pattern should be provided by the manufacturer. 

The system should be installed relative to perime

ter fencing, so that the transmitter and receiver lines are 

positioned to prevent someone from avoiding detection 

by jumping over the electromagnetic field. Typically, 

the distance between chain-link security fencing with 

an overall height of 2.4 meters (8 feet) and the center of

5.44-9
the detection zone should be a minimum of 2.4 meters 

(8 feet). 

Manufacturer's instructions should be followed 

when installing cable across concrete or asphalt areas. 

Particular attention should be paid to the binding agent 

and applying epoxy over the cable groove after the 

cable is installed in the concrete or asphalt. 

2.3.2 Performance Criteria 

A ported coaxial cable perimeter detection system 

should be capable of detecting an individual weighing a 

minimum of 35 kilograms (77 pounds) passing over the 

transmitter and receiver wires, whether the individual 

is walking, running, jumping, crawling, or rolling. The 

electromagnetic field should be modulated, and the 

receiver should be frequency selective to decrease sus

ceptibility to "receiver capture." 

2.4 Active Infrared Multibeam System 

2.4.1 Installation Criteria 

When installing an active infrared multibeam sys

tem, the maximum distance between transmitter and 

receiver should permit proper operation during condi

tions of severe atmospheric attenuation that are typical 

for the site. The maximum distance between transmit

ter and receiver is generally 80 meters (260 feet). The 

infrared perimeter system should be installed so that, at 

any point, the lowest beam is 15.24 centimeters (6 

inches) or less above grade and the highest beam is at 

least 2.6 meters (8.5 feet) above grade to prevent 

bridging. 

Consideration should be given to the ability of 

intruders to set up, without observation, such hand

carried equipment as small ladders for jumping over the 

infrared beams without detection. In general, evasion 

of detection by jumping over a planar system need not 

be considered if the overall height of the system is about 

3.7 meters (12 feet) or greater, because of the impact of 

jumping from those heights. The beams should be suf

ficiently interlaced that an individual could not pene

trate between the beams and remain undetected. The 

transmitters and receivers should be rigidly mounted 

(e.g., installed on a rigid post in a concrete pad extend

ing below the frost line) to prevent nuisance alarms 

from vibrations or ground shifting. Systems with 

heights greater than 2.6 meters (8.5 feet) should be spe

cially stabilized to prevent vibration-caused alarms, for 

example, by mounting on a building wall. Each post on 

which a transmitter and receiver is mounted should be 

provided with a pressure-sensitive cap to detect 

attempts at scaling or jumping over the post. As an 

alternative, successive infrared links should overlap at

angles, with sufficient overlap to preclude the use of the 

mounting posts for jumping over the plane of detection; 

this installation precludes the use of common posts. 

Fog, rain, and snow can attenuate and disperse the 

infrared beam and can cause nuisance alarms. How

ever, the system can be designed to compensate for 

severe atmospheric attenuation. Dust on the face plates 

will also attenuate the infrared beam, as will an accu

mulation of condensation, frost, or ice. 

Condensation, frost, or ice may be eliminated by 

using heated face plates. Sunshine on the receiver may 

cause nuisance alarms. A misalignment of transmitter 

and receiver caused by frost heaves may also cause nui

sance alarms. Like the microwave system, vegetation 

such as bushes, trees, or grass and accumulated snow 

will interfere with the infrared beam. The passage of an 

intruder may go undetected on irregular ground sur

faces, ditches, or hills. 

The transmitter and receiver units should be posi

tioned a minimum of 3 meters (10 feet) from perimeter 

fencing. The infrafted detection system should not be 

installed directly adjacent to a barrier, since the barrier 

may provide a solid base from which an intruder could 

jump over the beams into the protected area. 

2.4.2 Performance Criteria 

An infrared perimeter detection system should be a 

multibeam modulated type, consisting of a minimum 

of six beams per segment. The system should be capa

ble of detecting an individual weighing a minimum of 

35 kilograms (77 pounds) passing between the trans

mitters and receivers whether the individual is walking, 

running, jumping, crawling, or rolling. This means that 

the infrared beams should be placed and interlaced to 

form an infrared "wall." Furthermore, the systems 

should be able to operate as above with a factor of 20 

(13dB) insertion loss from atmospheric attenuation 

(e.g., fog) at a maximum range of 80 meters (260 feet). 

2.5 Taut Wire Systems 

2.5.1 Installation Criteria 

Manufacturer's specifications should be followed 

in the installation of the system. However, because of 

the basic operating principle of the system (i.e., ten

sioned wires), the length of the segments should be lim

ited to 60 meters (200 feet) or less. The overall height of 

the system should be 3.7 meters (12 feet) or greater. 

Wires should be spaced so no intruder can pass between 

the wires without detection, normally a distance of 

15.24 centimeters (6 inches) or less between wires. A 

sensing post should be placed approximately halfway 

between anchor posts. (Anchor posts may function as

5.44-10

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sensor posts in certain models.) To provide addition• 

system support, slider posts should be spaced approx 

mately every 3 meters (10 feet) between the anchor pc 

> and sensor post or between anchor posts. The systei 

may be installed on chain link fencing or an existir 

wall with a standoff equal to or less than 15.24 centimi 

ters (6 inches). When installed on chain-link fencin 

the taut wire system should be installed on the interii 

or protected area side of the fence. The ground withir 

meter (39 inches) on either side of the taut wire syste 

should be stabilized to prevent erosion and to mainta 

the bottom wire at 15.24 centimeters (6 inches) or le 

above the ground. 

2.5.2 Performance Criteria 

The system should be installed so that an alarm 

received on deflection of any wire that causes a verti( 

opening greater than 15.24 centimeters (6 inches). 

2.6 Fiber Optic Systems 

2.6.1 Installation Criteria 

Since the use of fiber optics in intrusion detecti4 

is a fairly new technology, licensees are encouraged 

consult with the NRC on site-specific usage. Manufa 

turer's guidelines for installation should be followe 

Segments should be limited in length to 100 mete 

> (328 feet). Since such systems detect pressure, motic 

or vibration, they are sensitive to many of the vulnel 

bilities found under vibration- or strain-sensitive s3 

tems or buried line technologies. 

2.6.2 Performance Criteria 

A fiber optic detection system should be capable 

detecting an individual weighing a minimum of: 

kilograms (77 pounds) passing over the cable, whett 

the individual is walking, running, jumping, crawlin 

or rolling. 

2.7 Vibration or Strain-Detection Systems 

If used, a vibration or strain-detection syst4 

should be installed in accordance with the followi 

criteria and used only as a secondary intrusion detecti 

system to augment the detection capabilities of a y 

mary system. 

2.7.1 Installation Criteria 

Depending on the variety of sensor, each sensor 

monitor a length of fence ranging from about 1 me 

(39 inches) to several hundred meters. Vibration 

strain-detection devices for fence protection genern 

2 are susceptible to nuisance alarms caused by w 

vibrating the fence, hail stones, or large pieces of tr 

blowing against the fence. The frequency of nuisai

al alarms caused by the wind can be reduced by rigidly 

1- mounting the fence and thereby lessening the propen

ist sity of the fence to vibrate in the wind. Electronic 

m signal-processing equipment used in conjunction with 

kg signal-generating strain transducers can effectively 

D- reduce nuisance alarm rates without sacrificing sensi

g, tivity to climbing or cutting the fence. Increasing the 

r fence height also appears to enhance sensor perfor

i1 mance. Consideration should be given to the ability of 

Im intruders to set up, without observation, such hand

in carried equipment as small ladders for jumping over the 

ss infrared beams without detection. In general, evasion 

of detection by jumping over a planar system need not 

be considered if the overall height of the system is about 

3.7 meters (12 feet) or greater, because of the impact of 

is jumping from those heights. However, most fence 

Na1 detection systems can be bypassed easily by a variety of 

methods. 

2.7.2 Performance Criteria 

Vibration or strain-detection systems used for 

fence protection should detect an intruder weighing a 

on minimum of 35 kilograms (77 pounds) attempting to 

to climb the fence. The system should also detect any 

Zc- attempt to cut the fence or lift the fence fabric 15.24 

4. centimeters (6 inches) or more above grade. The system 

rs should not generate excessive nuisance alarms. In addi

)n, tion to the testing described in Regulatory Position 3 of 

ra- this guide, the vibration or strain detection systems 

Ms- should be tested for their ability to detect fence cutting 

attacks or other means of defeating detection unique to 

these systems. 

of 2.8 Other Intrusion Detection Systems 

35 Some systems currently under development may 

ier be acceptable, when fully developed, for use at NRC

.g, licensed facilities. Other systems that currently do not 

have an acceptable detection performance capability 

may at some future time be refined and be found suit

able. In either case, these systems would have to be per

em formance tested by the licensee and a qualified inde

ng pendent agent (such as a national laboratory) prior to 

[on consideration by the NRC. 

iri- 3. RECOMMENDED TESTING 

PROCEDURES 

In conducting any testing procedures, care should 

:an be taken to ensure the safety of the individuals perform

ýter ing the testing. The standard Occupational Safety and 

or Health Administration procedures and practices should 

illy be followed. 

ind Specification testing should take place at the initial 

ash installation of the equipment. If available, test proce

ice dures recommended by the manufacturer should be fol

5.44-11
lowed. As in all test situations, the area under test 

should be maintained under visual observation by a 

member of the security organization while the test is 

being conducted. For each perimeter segment, the test 

should (1) ensure that the system meets manufacturer's 

specifications and NRC-recommended detection prob

ability, (2) verify that no dead spots exist in the zone of 

protection, and (3) verify that line supervision and 

tamper-protection in both the access and secure modes 

are functional. Records of initial testing capabilities, 

equipment sensitivity settings, or voltage outputs 

should be maintained by the licensee so that deteriora

tion in equipment capability can be monitored. 

Two acceptable options for testing are described 

below. Other testing methods may be used if the meth

ods are fully documented and are approved by the 

NRC. 

3.1 Testing Option I 

After the equipment has been installed and specifi

cation tested, the perimeter intrusion detection and 

alarm systems should be operationally tested in all seg

ments at least once each seven days in the following 

manner. Testing may be conducted during routine 

patrols by members of the licensee's security force. The 

testing should be conducted by crossing the zone of 

detection or by disturbing the fence on which the sys

tem is attached to cause the system to alarm. Before the 

test, the individual making the test should notify the 

alarm stations that a test is about to be conducted. The 

detection system in all segments should be walk-tested 

in a different, preferably random, order every seven 

days, and the testing should be conducted throughout 

the week rather than conducting all tests on the same 

day. The testing should result in 100% detection on all 

segments every seven days. If the perimeter alarm sys

tem fails to detect an intrusion on one or more seg

ments, corrective actions should be taken and docu

mented. Records should be maintained to document 

that all required testing has been accomplished. 

In addition to operational testing, at least semi

annually, as well as after each inoperative state and after 

any repairs, the system should be performance tested. A 

90% probability of detection with 95% confidence 

should be the design goal of the system. An acceptable 

performance testing method follows. 

Model Performance Testing Program 

Determine the most vulnerable area of each seg

ment and determine the method of approach most likely 

to penetrate that segment, e.g., walking, running, jump

ing, crawling, rolling, or climbing. This determination

will, in most cases, be sensor- and location-dependent. 

Note that vulnerability to penetration also varies with 

environmental conditions. Inclement weather may be a 

particularly good time for a realistic evaluation of pe

rimeter vulnerabilities. 

Test each segment using a combination of all the 

applicable penetration approaches at the most vulner

able area a total of 30 times. All 30 tests should result in 

successful detections. 

If the minimum number of successful detections is 

not achieved, the system should be checked. If no prob

lems with the system are discovered, 10 more tests 

should be made. If the minimum number of successful 

detections is achieved, in this case 39 out of 40 (see the 

following table), the testing for this segment can be en

ded. If no problems with the system can be discovered 

and less than 9 out of 10 additional intrusions are 

detected, the system must be upgraded to increase the 

detection probability to the required level. If problems 

with the system are discovered, the system should be 

repaired and 30 new tests performed. If there are 30 suc

cessful detections, testing can be ended. 

Minimum No. Maximum No. 

Total No. of of Successful of Failures 

Tests Detections Detected 

30 30 0 

40 39 1 

50 48 2 

The penetration approach that is most difficult to 

detect should be attempted more frequently if an equal 

number of tests for each approach is not possible. 

The segments should be tested in random order. 

This will protect against the possibility that environ

mental effects and other unknown factors that may af

fect the test results (detection or nondetection) always 

favor or handicap the same segment or method of ap

proach. For example, if Segment 1 is always tested in 

the morning and Segment 2 is always tested in the after

noon and if the detection equipment is slightly more 

sensitive to intrusions in the morning, the conclusion 

might be drawn from the test results that Segment 2 is 

less protected than Segment 1. However, the difference 

noted between the two segments might only be due to 

the morning versus afternoon difference. Similarly, us

ing random methods, no approach will be continually 

favored if the time sequence (ordering) affects the test 

results. This will protect against disturbances that may 

or may not occur and that may or may not be serious if 

they do occur. A random numbers table can be used to

5.44-12

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determine the order in which the segments will be 

tested. 

Maintain records of the results of all tests per

formed. These records should include the segment 

number, date, time, and relevant environmental condi

tions when tests were performed. Records should be 

maintained consistent with 10 CFR 73.70. 

3.2 Testing Option II 

Under this option, one pass (i.e., one attempt to cir

cumvent the zone of detection) of a performance test is 

conducted in place of an operational test and the burden 

for semi-annual performance testing is greatly reduced. 

With proper system performance, semi-annual perfor

mance testing need not be conducted. Instead of a sim

ple "go, no-go" operational test conducted by a member 

of the security force passing through the zone of a 

detector on a weekly basis as with operational testing, 

this performance type of test that is conducted weekly 

represents a challenge to the system. The weekly per

formance test is conducted by determining the most 

vulnerable area of each segment and determining the 

method of approach most likely to penetrate that seg

ment, e.g., walking, running, jumping, crawling, roll

ing, or climbing. This determination will, in most 

cases, be sensor- and location-dependent. Note that 

vulnerability to penetration also varies with environ

mental conditions. Inclement weather may be a particu

larly good time for a realistic evaluation of perimeter 

vulnerabilities. 

Over time, each segment should be tested by using 

a combination of all the applicable penetration 

approaches at the most vulnerable area. The penetration 

approach that is most difficult to detect should be 

attempted more frequently if an equal number of tests 

for each approach is not possible. 

The segments should be tested in random order. 

This will protect against the possibility that environ

mental effects and other unknown factors that may 

affect the test results (detection or nondetection) always 

favor or handicap the same segment or method of 

approach. For example, if Segment 1 is always tested in 

the morning and Segment 2 is always tested in the after

noon and if the detection equipment is slightly more 

sensitive to intrusions in the morning, it might be con

cluded from the test results that Segment 2 is less pro

tected than Segment 1. However, the difference noted 

2f between the two segments might only be due to the 

morning versus afternoon difference. Similarly, using 

random methods, no approach will be continually

favored if the time sequence (ordering) affects the test 

results. This will protect against disturbances that may 

or may not occur and that may or may not be serious if 

they do occur. A random numbers table can be used to 

determine the order in which the segments will be 

tested. 

Because this option for testing is conducted on a 

weekly basis, the performance of the system need only 

be determined annually, as opposed to semi-annually as 

with Test Option I. At the conclusion of a 12-month 

period, data accumulated from the weekly testing can 

be applied to totals used in determining performance 

levels. 

In essence, improved weekly testing is conducted 

throughout the year, as opposed to Test Option I in 

which rudimentary weekly testing is conducted over 

6-month periods along with extensive performance 

testing at the end of the period. The goal is improved 

testing over a year with reduced overall burden on the 

licensee. 

Under Test Option II, if a sensor achieves 50 detec

tions over a 52-week (annual) period through weekly 

testing of the segment, additional performance testing 

need not be conducted at the end of the year. (Tradi

tional performance testing would still be required after 

each inoperative state or repair.) Testing must never 

conclude on a nondetection. If three or more nondetec

tions occur, accumulated data for the period may not be 

counted toward totals for performance testing and the 

accumulation of data must be restarted. 

As described in the model performance testing pro

gram in Section 3.1, records of all tests performed 

should be maintained. 

D. IMPLEMENTATION 

The purpose of this section is to provide informa

tion to applicants and licensees regarding the NRC 

staff's plans for using this regulatory guide. 

Except in those cases in which an applicant or 

licensee proposes an acceptable alternative method for 

complying with the specified portions of the NRC's 

regulations, the methods described in this guide will be 

used in the evaluation of submittals in connection with 

applications for construction permits and operating 

licenses. This guide will also be used to evaluate sub

mittals from licensees who propose system modifica

tions that are voluntarily initiated by the licensee if 

there is a clear nexus between the proposed modifica

tions and this guidance.

5.44-13
APPENDIX A 

GLOSSARY

Access mode 

Active system 

Bistatic system 

Bridging 

Cladding 

Crawling 

Dead spot 

Design stimulus

The condition that maintains security over the signal lines between the detector and the annun

ciator and over the tamper switch in the detector but allows access into the protected area 

through the zone of detection without indicating an alarm condition. 

A type of intrusion detection sensor that emits a signal from a transmitter and detects changes in 

the reception of that signal. 

As used with a microwave sensor, a sensor consisting of a transmitter and receiver remote from 

each other at either end of a microwave link. 

Circumvention of a perimeter detection system by traversing above the zone of detection using 

hand-carried aids or nearby objects. 

The reflective outer layer of an optical fiber that surrounds the light-carrying core. The cladding contains the light in the core and allows the fiber to guide light from one end to the other. The 

cladding has a lower index of refraction than the core. 

Crossing the detection zone lying prone on the ground with a low profile at an approximate velocity of 0.03 meter (1 inch) per second, body aligned perpendicular to the zone of detection. 

An area in an intrusion detection zone where there is no detection capability. 

An individual weighing a minimum of 35 kilograms (77 pounds), running, walking, crawling, 

jumping, or rolling through the perimeter of a protected area.

False alarm An alarm generated without an apparent cause. 

False alarm rate The frequency at which a particular alarm zone indicates a false alarm, the design goal for . which is no more than one per zone per day. 

Index of refraction A measure of a transparent material's ability to bend light, usually abbreviated as "n." The 

index of refraction is the ratio of the speed of light in a vacuum to the speed of light in the 

material. 

Interferometry Using the interference of light waves to precisely determine the wavelength of the light. 

Isolation zone An area adjacent to a physical barrier, clear of all objects that could conceal or shield an individ

ual. For facilities required to have double protected area barriers, this zone should extend 6.1 

meters (20 feet) on either side of the protected area barriers and include the area bounded by the 

barriers. For facilities required to have a single protected area barrier, the isolation zone should 

extend 6.1 meters (20 feet) on either side of the protected area barrier. 

Jumping Leaping over the zone of detection, including standing on a fence and attempting to leap across 

the zone of detection. 

Line-of-sight As used with intrusion detection systems, a sensor that requires a terrain surface that is relatively 

system flat, with no significant contour depressions or elevations.

Monostatic 

system 

Multimode fiber

"I.

K

As used with a microwave sensor, a sensor that has the receiver and transmitter located in the 

same head or unit. 

Optical fiber that permits more than one light mode to be propagated. 

5.44-14
Nuisance alarm 

.2 Nuisance alarm 

rate 

Operational 

testing 

Passive system 

Performance 

testing 

Planar system 

Receiver capture 

Rolling 

Running 

Secure mode

Segment 

Specification 

testing 

Speckle pattern 

Terrain-following 

system 

Volumetric system 

Walking

An alarm generated by an identified input to a sensor or monitoring device that does not repre

sent a safeguards threat. 

The frequency at which a particular alarm zone indicates a nuisance alarm, the design goal for 

which is no more than one per zone per day. 

Testing performed at the beginning and end of any period in which a system is used. If the period 

of continuous use is longer than seven days, under operational testing the system must be tested 

at least once every seven days. 

A type of intrusion detection sensor that produces no signal from a transmitter but simply 

detects energy emitted in its vicinity. 

Testing conducted at least semi-annually, after each inoperative state, or after any repairs to ensure 

the design stimulus will be detected properly. An inoperative state for an alarm system or com

ponent exists, for example, when the power is disconnected to perform maintenance or when, 

for any other reason, both primary and backup power sources fail to provide power. Placing a 

properly operating alarm system in access would not constitute an inoperative state unless 

accompanied or followed by any of the conditions above. 

A system in which the distance an intruder must travel to pass through the detection zone is 

considered more two-dimensional, as a flat plane, than three-dimensional or volumetric. 

As used with a sensor system, the condition that occurs when a receiver recognizes a false trans

mission signal as its own. 

Crossing the detection zone on the ground with a low profile, body parallel to the zone of detec

tion, and moving at an approximate velocity of 0.03 meter (1 inch) per second. 

Entering and leaving the zone of detection at an approximate velocity of 5 meters (16 feet) per 

second. 

The condition that maintains security over the signal lines between the detector and the annun

ciator and over the tamper switch in the detector; the secure mode does not allow access into the 

protected area through the zone of detection without indicating an alarm condition. 

One of several sections into which a perimeter intrusion zone might be subdivided to optimize 

sensor performance, compensate for unique terrain features or vulnerabilities, improve alarm 

assessment capabilities, or facilitate response force deployment. 

Testing done after completion of the system's initial installation or replacement of any major 

component to verify that the system complies with (1) the manufacturer's specifications for 

design, installation, and adjustment, (2) performance criteria set by the NRC and the site, and 

(3) any other criteria on which the system's acceptability is based. Specification testing is more 

comprehensive than performance testing. 

A light-interference pattern produced at the end of a multimode fiber that is being illuminated 

by a laser source. 

As used with intrusion detection systems, a sensor with a detection pattern that can adapt to 

some changes in the terrain's contour. 

A system in which the distance an intruder must travel to pass through the detection zone is 

considered more three-dimensional than two-dimensional or planar. 

Entering and leaving the zone of detection with a normal stride (2 30-inch steps per second).

5.44-15
APPENDIX B 

CHECKLIST

This appendix contains checklists for each type of 

detection system described in this guide. They may be 

used as reminders when planning, installing, or using 

the systems. 

MICROWAVE 

"* Ensure that microwave sensors are set up so that 

they have a clear line of sight between transmitters 

and receivers. 

" Ensure that microwave sensor systems are 

installed over flat ground or ground with a constant 

slope to prevent shadowing (inadequate detection 

in depressions). 

"a For corner overlap applications, keep intersection 

angles of microwave beams as close as possible to 

90 degrees, i.e., orthogonal. 

"* Never mount on the same post two microwave re

ceivers for different segments or zones (or on the 

same channel). 

"* Remember that dynamic multipath signals from 

microwave sensors can be subject to constructive 

and destructive interference. 

" Consider that the detection pattern is relative to the 

mounting position, and it is sometimes possible for 

an adversary to crawl under the detection beam 

when microwave sensor antennas, i.e., receivers 

and transmitters, are relatively high. 

" Consider that it is sometimes possible to jump over 

the zone of detection when microwave sensor 

antennas, i.e., receivers and transmitters, are 

mounted low so the detection zone is close to the 

ground. 

" When a boundary system is to be established using 

microwave sensors and multiple zones or sectors, 

the detection zones should overlap to achieve a 

continuous detection pattern with no areas of 

reduced detection capability at the ends of each 

sector. 

" Be aware that reflections of microwave signals 

from nearby structures, traffic, or surface disconti

nuities may cause nuisance alarms. However, 

reflection of microwave signals may sometimes be 

used effectively to extend coverage where terrain

or structures are not amenable to standard instal

lation. 

" Be aware that microwave sensor detection zones 

that parallel a road with vehicular traffic or long 

fence lines may produce nuisance alarms unless 

sufficient offset is established between the sensor 

axis and the interference source, e.g., traffic on the 

roads or swaying fence lines. 

" Note that standing water, e.g., from heavy rain, 

under the microwave sensor detection zone can 

produce an increased nuisance alarm rate when the 

water is rippled by winds. Crowned surface grades 

and gravel beds can reduce or eliminate standing 

water. 

" Note that, after a heavy rain, moving water under 

the microwave detection zone may produce nui

sance alarms. 

" Note that significant snow depths and drifts can 

produce voids in the detection zone. 

" Consider that the dead spot in detection immedi

ately below and in front of microwave units 

increases with mounting elevation. 

" Consider that heavy rain exceeding 5.6 cm (2.2 

inches) per hour is likely to cause microwave sen

sors to produce nuisance alarms. 

" Consider that electro-magnetic interference (EMI), 

either reflected or direct, can strike the microwave 

receiver and cause nuisance alarms. Shielded 

radomes or enclosures with shielded wiring and 

proper grounding can reduce or eliminate the 

effects of EMI. 

" Note that acoustic noises and vibrations, e.g., seis

mic activities or mechanical disturbances, can 

adversely affect some microwave sensors and not 

affect others, depending on their design, signal 

processing, and installation parameters. 

" Remove food and water sources from the vicinity 

of the sensor system to prevent foraging animals 

from causing nuisance alarms. 

" Limit grass heights to 10 cm (3.9 inches) to prevent 

nuisance alarms caused by the wind moving the 

grass.

5.44-16

K

K
ELECTRIC FIELD SYSTEMS 

. Avoid installation in areas that are subject to drastic 

environmental changes, such as temperature 

extremes. 

Ensure that angles of corners are kept as close to 90 

degrees as possible. 

Note that electric storms can cause electric field 

systems to malfunction and can cause false alarms. 

When electric field systems are installed on perim

eter fencing, the perimeter fencing must be kept in 

good condition at all times. 

For electric field sensor zones located parallel to 

roads, provide sufficient offset from the road to 

prevent nuisance alarms. 

" Note that significant snow drifts and depths can 

degrade detection capabilities. 

" Ensure that wires are retensioned after extreme sea

sonal temperature changes. 

PORTED COAXIAL CABLE SYSTEMS 

- Ensure that the ground in which a ported coaxial 

cable system is buried is firm and is not subject to 

movement. 

• Note that ground water can cause ported coaxial 

cable systems to generate false alarms. 

* Note that rodents can chew through ported coaxial 

cable. 

* Avoid intersecting irrigation pipes and power lines 

with the coaxial cable. 

a Note that the detection zone may be elongated at 

curves. 

0 Note that the sensor may react to strong sources of 

radio frequency energy. 

Perform soil conductivity tests to ensure that high 

conductivity, such as is caused by high concentra

tions of iron or salt in the soil, does not "short out" 

the radio frequency field. 

ACTIVE INFRARED MULTI-BEAM SYSTEMS 

"* Note that active infrared multibeam systems 

require a clear line of sight. 

"* Be aware that active infrared multibeam systems 

require flat ground to prevent shadowing.

" Be aware that the detection capability of active 

infrared multibeam systems can degrade in adverse 

environments such as heavy rain, dense fog, seis

mic activity, and vibration as from vehicle traffic. 

" Install systems so that intruders can not crawl 

under or jump over the detection zone. 

" Install systems so that the ends of adjacent zones 

overlap. 

" Note that wildlife activity can cause nuisance 

alarms in active infrared multibeam systems. 

TAUT WIRE 

"* Make sure that a constant tension is maintained on 

the wires through periodic checking and adjust

ments. 

"* Be aware that certain environmental conditions, 

such as icing or frozen ground heaves, can cause 

nuisance alarms. 

* Ensure that, prior to installation, terrain under the 

system is leveled to a constant grade. 

Ensure that the path along the alignment of the sen

sor fence is cleared of all vegetation, tree branches, 

and other debris. 

Consider the installation of curbing under the fence 

system to prevent tunneling or trenching. 

Ensure that fence posts are securely anchored. 

FIBER OPTICS SYSTEMS 

Install according to manufacturer's recommenda

tions, since many new and different technologies 

are being used in fiber optic detection. 

For buried lines, be advised that nuisance alarms 

may be caused by tree-root movement in high 

winds and by nearby vehicular traffic. 

For installation on chain-link fencing, many of the 

same precautions apply as with vibration- or strain

detection systems. 

VIBRATION- OR STRAIN-DETECTION 

SYSTEMS 

* Foliage and debris touching or being blown against 

a fence can create nuisance alarms. 

* Fence fabric must be securely fastened down. 

* All gates in the fencing system on which the sen

sors are mounted should be prevented from vibrat

ing to prevent nuisance alarms.

5.44-17
Ensure vibrations from nearby vehicles do not If not encapsulated in conduit, system wiring 

cause nuisance alarms. should be interwoven in the fence fabric, rather 

than simply clipped to it, to prevent removal as a 

Wildlife activity can cause nuisance alarms. means of defeating the system. , 

K 

K

5.44-18
VALUE/IMPACT STATEMENT

A separate value/impact statement has not been prepared for this Revision 3 to 

Regulatory Guide 5.44. A value/impact statement was prepared for the upgraded 

physical protection amendments to the regulations that were published in the Fed

eralRegister on November 28, 1979. This analysis is also appropriate for this reg

ulatory guide. A copy of the value/impact statement is available, with Revision 3 

of Regulatory Guide 5.44, for inspection or copying for a fee in the Commission's 

Public Document Room at 2120 L Street NW., Washington, DC; the PDR's mail

ing address is Mail Stop LL-6, Washington, DC 20555-0001; telephone 

(202)634-3273; fax (202)634-3343.

V

NMI\. onwLe

Federal Recycling Program

5.44-19
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