Ludlum Measurements 52-1 User manual

LUDLUM MODEL 52-1 FAMILY
PORTABLE SCINTILLATION PORTAL MONITORS
July 2018
Serial Number 210041 and Succeeding
Serial Numbers

LUDLUM MODEL 52-1 FAMILY
PORTABLE SCINTILLATION PORTAL MONITORS
July 2018
Serial Number 210041 and Succeeding
Serial Numbers

STATEMENT OF WARRANTY
Ludlum Measurements, Inc. warrants the products covered in this manual to be free of
defects due to workmanship, material, and design for a period of twelve months from
the date of delivery. The calibration of a product is warranted to be within its
specified accuracy limits at the time of shipment. In the event of instrument failure,
notify Ludlum Measurements to determine if repair, recalibration, or replacement is
required.
This warranty excludes the replacement of photomultiplier tubes, G-M and
proportional tubes, and scintillation crystals which are broken due to excessive
physical abuse or used for purposes other than intended.
There are no warranties, express or implied, including without limitation any implied
warranty of merchantability or fitness, which extend beyond the description of the
face there of. If the product does not perform as warranted herein, purchaser’s sole
remedy shall be repair or replacement, at the option of Ludlum Measurements. In no
event will Ludlum Measurements be liable for damages, lost revenue, lost wages, or
any other incidental or consequential damages, arising from the purchase, use, or
inability to use product.
RETURN OF GOODS TO MANUFACTURER
If equipment needs to be returned to Ludlum Measurements, Inc. for repair or calibration, please
send to the address below. All shipments should include documentation containing return shipping
address, customer name, telephone number, description of service requested, and all other necessary
information. Your cooperation will expedite the return of your equipment.
LUDLUM MEASUREMENTS, INC.
ATTN: REPAIR DEPARTMENT
501 OAK STREET
SWEETWATER, TX 79556
800-622-0828 325-235-5494
FAX [phone]

Model52-1Family TechnicalManual
Table of Contents
Introduction 1
Specifications 2
User Operation 3
Assembly Instructions 3-1
Operational Check 3-3
Personnel Monitoring 3-3
Description of Controls and Functions 4
Front Panel 4-1
AC Panel 4-3
Parameters and Functions 4-3
RS-232 Port 4-5
Water Resistant Sleeve 4-6
Theory of Background Management 4-6
Safety Considerations 5
Environmental Conditions for Normal Use 5-1
Cleaning Instructions and Precautions 5-1
Electrical Safety Precautions 5-2
Warning Markings and Symbols 5-3
Maintenance and Recalibration 6
Maintenance 6-1
Recalibration 6-1
Checkout Procedure 7
General 7-1
Equipment Required 7-1
Checkout Procedure 7-1

Model52-1Family TechnicalManual
Recycling 8
Parts List 9
Models 52-1, 52-1-1, 52-5, 52-5-1, 52-6 and 52-6-1 Portable Scintillation Porta Monitors 9-1
Main Board, Drawing 215 x 342-342E 9-1
Detector Interface Board, Drawing 215 x 347 9-4
Power Supply, Drawing 215 x 1072 9-5
1 1/8 inch Voltage Divider, Drawing 435 x 435 9-6
Resistor Board, Drawing 215 x 782 9-7
Wiring Diagram, Drawing 215 x 1044 9-7
Retrofit Miscellaneous 9-8
Drawings and Diagrams 10

Model52-1FamilyTechnicalManual Section1
Ludlum Measurements, Inc. Page 1-1 July 2018
Introduction
The Model 52-1 family includes the Model 52-1, 52-5, and 52-6 series of
instruments. They are Portable Scintillation Portal Monitors, which are
used for beta/gamma personnel radiation monitoring. They are
designed to detect very low levels of radiation coming from personnel
who walk through the portal.
Model 52-1 and 52-1-1
The Model 52-1 and 52-1-1 have four side detectors. The only
difference between the Model 52-1 and the Model 52-1-1 is in the width
of the portal monitor. The 52-1-1 is 8 inches wider.
Model
# of Detectors
Inside Width
Volume (Total)
52-1
4
24 inches
672 in3
52-1-1
4
32 inches
672 in3
Model 52-5, 52-5-1, 52-6, and 52-6-1
The Model 52-5 and 52-6 have the same width dimensions as the Model
52-1. The Model 52-5 is about an inch taller due to the addition of a
detector in the base. It has 5 detectors. The Model 52-6 uses 6 detectors,
with another additional detector located at the top. Both the 52-5-1 and
the 52-6-1 have 8 inches more width in the portal monitor than the 52-5
and 52-6 have.
Model
# of Detectors
Inside Width
Volume (Total)
52-5
5
24 inches
780 in3
52-5-1
5
32 inches
780 in3
52-6
6
24 inches
888 in3
52-6-1
6
32 inches
888 in3
These instruments all meet the Federal Emergency Management
Agency (FEMA) standard for Emergency Response Portal Monitoring
Section
1

Model52-1Family TechnicalManual Section1
Ludlum Measurements, Inc. Page 1-2 July 2018
(FEMA-REP-21). They are designed to be disassembled for ease of
transportation and storage, and can be assembled in five minutes or
less without tools. All parameters are stored in non-volatile memory,
which requires no battery backup. These parameters allow easy
operation with minimal setup by minimally trained personnel. The
parameters are pre-set at the factory to detect a 1.0 µCi (37.5 kBq) 137Cs
source in a 10 µR/hr (0.1 µSv/h) background field, in accordance with
the FEMA standard.
These instruments also comply with the applicable European Standards
required for CE marking of the instruments.
The electronics are microprocessor-based for ease of setup and
reliability. Status LEDs indicate count cycle status. Audible signals
(which may be turned off to avoid alarming the occupants) accompany
the LEDs for additional indication. Audio levels can also be controlled
by rotating the baffle at the front of the audio device. Detector counts,
background, and all parameters may be viewed on the Liquid Crystal
Display (LCD). All setup is accomplished by way of push buttons
located below the LCD.
These portal monitors can be operated in a walk-through basis with a
quick scan occurring while a person is positioned within the portal. In
this mode, checking is performed every 200 milliseconds while the
portal is occupied, 600 milliseconds before, and 600 milliseconds after
the portal is occupied. The portal monitor can also monitor in a stop-
and-count mode, allowing for a more sensitive scan. In stop-and-count
mode, the fixed count time may be set from 1 to 20 seconds.
These instruments have automatic background update and dynamic
alarm setting capabilities. On startup, the instrument will take a
background count and calculate alarm levels for each detector. Self-
diagnostic routines check the background count and warn if the
background becomes either too high or too low. Alarms are calculated
with a user-adjustable sigma parameter and the current background
count. During setup, the user can also specify individual alarms only,
sum alarm only, or both individual and sum alarms. The sum alarms
combine the results of the top detectors and of the bottom detectors.
All four models are able to operate from 85-250 Vac 50/60Hz. They
may also be operated from three or six “D” cell batteries using a
supplied power supply or from the supplied cigarette lighter adapter
cable. Battery lifetime is approximately 28 hours.

Model52-1FamilyTechnicalManual Section2
Ludlum Measurements, Inc. Page 2-1 July 2018
Specifications
Display (Setup): 2 line-by-20-character LCD, backlit when operated from
AC power
Display (User): five large status LEDs on one side of portal, and detector
LEDs to show alarm location
Detector High Voltage: 700-1200 V
Detector Threshold: -4 mV
Count Time: adjustable from 0 to 20 seconds (“0” indicates walk-through
mode)
Power: can be powered from either a 85-250 Vac, 50/60 Hz, using a
supplied 12 Vdc wall adapter; supplied 12 Vdc cigarette lighter adapter
cable; or from three or six D cell batteries. Typical battery life is 69 hours
using six fresh alkaline batteries and 28 hours using three fresh batteries.
Output: RS-232 and dry contacts for radiation alarm and failure
conditions
Sensitivity: 1 µCi (37.5 kBq) 137Cs in walk-though mode in 10 µR/hr (0.1
µSv/h) background field
Energy Response: 30 keV to 3 MeV
Audio: an alarm with an adjustable baffle for portal entry and incomplete
audio, and a continuous beeping for radiation alarm and instrument failure
audio. The "AUDIO ON?" parameter in setup mode (default Yes or
enabled) can be changed to NO to disable the audio.
Section
2

Model52-1Family TechnicalManual Section2
Ludlum Measurements, Inc. Page 2-2 July 2018
Outside Dimensions (when set up):
For Model 52-1: 211 x 81.3 x 45 cm (83 x 32 x 17.5 in.) (H x W x L)
For Model 52-1-1: 211 x 102 x 45 cm (83 x 40 x 17.5 in.) (H x W x L)
For Model 52-5: 213 x 81.3 x 48 cm (84 x 32 x 19.3 in.) (H x W x L)
For Model 52-5-1: 213 x 102 x 49 cm (84 x 40 x 19.3 in.) (H x W x L)
For Model 52-6: 217 x 81.3 x 49 cm (85.3 x 32 x 19.3 in.) (H x W x L)
For Model 52-6-1: 217 x 102 x 49 cm (85.3 x 40 x 19.3 in.) (H x W x L)
* With the optional stabilizer legs, add 91.4 cm (36 in.) in length to all
models.
Inside Dimensions (when set up):
For Model 52-1: 206 x 61 cm (81 x 24 in.) (H x W)
For Model 52-1-1: 206 x 81 cm (81 x 32 in.) (H x W)
For Model 52-5: 206 x 61 cm (81 x 24 in.) (H x W)
For Model 52-5-1: 206 x 81 cm (81 x 32 in.) (H x W)
For Model 52-6: 206 x 61 cm (81 x 24 in.) (H x W)
For Model 52-6-1: 206 x 81 cm (81 x 32 in.) (H x W)
Case Dimensions: 122 x 61 x 30.5 cm (48 x 24 x 12 in.) (H x W x D)
(Same case is used for all four models.)
Detector Size: Each of the four side detectors has 2753 cm3(168 in3) of
plastic scintillator. The foot (base) and head detectors in the Model 52-5,
52-5-1, 52-6, and 52-6-1 all have 1770 cm3(108 in3) of plastic scintillator.
Weight:
Models 52-1 and 52-1-1: approximately 32 kg (70 lb), 45 kg (100 lb) in
case
Models 52-5 and 52-5-1: approximately 36 kg (80 lb), 50 kg (110 lb) in
case
Models 52-6 and 52-6-1: approximately 41 kg (90 lb), 54 kg (120 lb) in
case

Model52-1Family TechnicalManual Section3
Ludlum Measurements, Inc. Page 3-1 July 2018
User Operation
0
his section gives instructions how to set up and use the instrument to
monitor a person for radiation.
Assembly Instructions
This section gives instructions on how to assemble these instruments
and get them ready for use.
The portal monitor comes in a container that can be used for shipping
and storage. The pieces and quantities that make up the system are:
1 - Base
1 –Bottom Left (Section L1)
1 –Top Left (Section L3)
1 - Top Section
1 - Electronics Section
1 - Power Cord
1 - Remote electronics extension cable (optional)
2 –Stabilizer Legs (optional)
Unpack the container and inventory to ensure that all pieces are present.
Any of the four models of the portal monitor can be assembled without
tools. All connections are made with latches. To connect a latch, lift up
the bottom tab, hook the top cross bar into the hook on the piece that
you are attaching, and push tab back down until it snaps into place.
Caution!
Exercise care when unlatching pieces, as the latches can spring
open violently.
Section
3
T

Model52-1Family TechnicalManual Section3
Ludlum Measurements, Inc. Page 3-2 July 2018
To unlatch, lift up the tab and unhook the top cross bar.
Set the BASE on the ground with the rectangular tubes pointing up.
If optional stabilizer legs are provided, attach to the BASE, front and
rear, with screws provided.
Insert the male end of the Bottom Right section into the female side
bracket of the base marked RIGHT SIDE BASE and attach the
latches. The detector screens must be facing the middle of the portal.
Insert the male end of the Top Right section into the female end of the
Bottom Right section and attach the latches.
Repeat the process for the LEFT side.
Insert the TOP into the tops of the side sections and attach the latches.
The top can be installed in either direction. It does not matter which
end goes to the right.
Plug the connector end onto the back of the Bottom Left section with
the blank end facing down. First, engage the black connectors. Then
ensure that the pin on the back of the Bottom Left section goes into the
hole on the electronics. Attach the latches. If you are using the optional
Remote Electronics Extension Cable, connect one end of the cable to
the Bottom Left section and the other end to the Electronics. Locate
the electronics as desired.
If you have line voltage available, plug the POWER CORD into the
connector on the bottom of the electronics marked INPUT. If not,
install 3 “D” Cell batteries into the battery compartment. The power
cord and batteries may both be installed at the same time, but the portal
monitor does not charge the batteries.
Turn on the POWER switch located on the bottom of the electronics
and allow the instrument to finish updating. If the preprogrammed
settings are acceptable, it is ready for use. Proceed to the next section.
If the settings need to be changed or checked, proceed to Parameter
Setup, Section 4.
Disassembly is reverse of assembly.

Model52-1Family TechnicalManual Section3
Ludlum Measurements, Inc. Page 3-3 July 2018
Operational Check
To ensure that these instruments are functioning correctly, an operational
check should be performed routinely or before using the instrument. This
check verifies that the instrument is turned on, that the settings are
appropriate, and that the system alarms when the detectors are exposed to
excess radiation (above background level). Ludlum Measurements suggests
that this operational check be performed after setup and before use. As long
as the system passes the operational check, no calibration or other checks are
necessary. If the response or any function of the portal monitor changes,
the instrument should be checked and brought into compliance with the
manufacturer’s original specifications.
Check each of the detectors for sensitivity to beta/gamma radiation. Verify
that you get a RADIATION ALARM, using the check source supplied with
the instrument (normally a 137Cs, 1 µCi or 37.5 kBq activity source.
In walk-through mode, simply walk through the portal, holding the source in
proximity to a detector. This action should cause the portal to enter the
RADIATION ALARM status until the alarm time parameter is complete.
In stop-and-count mode, you should stand in the portal for the duration of
the count time. At the end of the count time, the portal should enter the
RADIATION ALARM status until the alarm time parameter is complete.
Repeat alarm checks for all four sections to confirm that all detectors are
functioning.
To also provide assurance that the instrument meets the FEMA emergency
response criteria prior to operation of this portal, do the following: Pass the
1 µCi (37.5 kBq) 137Cs checksource through the center of the portal at several
points between 15.2 and 168 cm (0.5 and 5.5 ft) from the floor of the portal
and verify that the alarm is triggered each time. If the portal does not alarm
each time, the user may need to adjust the count time, the alarmpoints, or
move the portal to a location with lower background radiation.
Personnel Monitoring
A count starts when someone blocks the infrared beam. A count can
only be started when the system is in the ENTER mode. Do not enter
the portal while the yellow UPDATING status LED is flashing.
Prior to personnel monitoring, the monitor must be allowed to update the
background count. This mandatory update occurs just after power-up, and
takes one minute. New background data is compared to the low and high

Model52-1Family TechnicalManual Section3
Ludlum Measurements, Inc. Page 3-4 July 2018
background setpoints that have been programmed into the unit. If the
setpoints have been exceeded, an INSTRUMENT FAILURE alarm is
given, and the unit attempts to update background. The instrument will
continue to update the background until the alarm condition has been
corrected; that is, when the background goes down or failed detectors are
repaired. Please note, however, that high levels of external radiation can
cause the INSTRUMENT FAILURE alarm.
To check someone for radiation, follow the steps below:
The green ENTER light must be illuminated in order to use the
instrument. A yellow UPDATING light may be flashing,
indicating that a background update is taking place. When the
UPDATING light is flashing, the system should not be used,
and all people to be checked should remain at least 1.8 m (6 ft)
away until the ENTER light is illuminated.
The subject steps into the portal, breaking the infrared beam,
and the green READY light will start flashing, indicating that
the portal is now CHECKING. A soft, low-pitched beep will
also occur.
In walk-through mode, the subject may simply continue walking
through the portal. In stop-and-count mode, the yellow
INCOMPLETE light will illuminate if the subject leaves the
portal before the count is complete. A soft, low-pitched beeping
will also warn the subject to return to the portal to finish the
count.
When the count is complete, the green ENTER light or the red
RADIATION ALARM light will be illuminated. In stop-and-
count mode, a second soft, low-pitched beep will occur.
The subject then steps out of the portal.
During operation, a buffer zone of at least 3 m (9.8 ft) (in all directions)
should be established around the monitor, to reduce the possibility of
measurement interferences from external sources. Subjects waiting to be
measured should remain outside the buffer zone until it is their turn to be
measured.
If a measurement results in an alarm, the subject should walk through the
monitor a second time from the opposite direction (and possibly a third
time) to validate the alarm. This alarm validation process minimizes the

Model52-1Family TechnicalManual Section3
Ludlum Measurements, Inc. Page 3-5 July 2018
possibility the alarm was caused by a momentary, coincidental high-
background event.
Once an alarm has been validated after one (or two) confirming
measurements, the subject can be moved away (>10 m) from the monitor,
and a secondary scan with a hand-held meter can be performed to identify
the location(s) of the contamination or point source.
Note:
The red detector alarm light LEDs will offer guidance as to the
probably location(s) of the radioactivity on the subject.

Model52-1Family TechnicalManual Section4
Ludlum Measurements, Inc. Page 4-1 July 2018
Description of Controls and
Functions
Front Panel
Readout: Liquid Crystal Display (LCD), 2-line, 20-character
alphanumeric display. Background and alarm data is displayed.
Increment (Up Arrow ) Button: increases or changes a parameter
when in setup mode. To enter setup mode, press and hold the Up
Arrow button while turning ON the instrument at the switch under the
control box. Instrument parameters may only be changed while in the
setup mode.
Decrement (Down Arrow ) Button: decreases or changes a parameter
when in setup mode. During instrument operation, pressing this key
will show the number of alarms and the number of passages since
power-up.
Enter Key: selects or advances display. If the ENTER key is pressed
while turning the instrument ON, the instrument is loaded with a set of
default parameters. The parameters that are set are:
Default Value
Language English
Month 1 (January)
Day 2
Year 00
Hour 8
Minute 15
Count Time 0 sec
Alarm Time 15 sec
Incomplete Time 10 sec
RDA Size 500
Low Bkgnd (background) 20
High Bkgnd (background) 2000
Sigma 4.5
LT Active Y
LB Active Y
Section
4

Model52-1Family TechnicalManual Section4
Ludlum Measurements, Inc. Page 4-2 July 2018
RT Active Y
RB Active Y
*HD Active Y (* for Models 52-5 and 52-6 only)
*FT Active Y (* for Models 52-5 and 52-6 only)
Individual Alarms Y
Sum Alarms Y
# of Samples 2
Bkgnd Update 8
LT Attenuation 0.0%
LB Attenuation 0.0%
RT Attenuation 0.0%
RB Attenuation 0.0%
*HD Attenuation 0.0% (* for Models 52-5 and 52-6 only)
*FT Attenuation 0.0% (* for Models 52-5 and 52-6 only)
Audio On Y
The default condition is for all detectors to be active.
Detector LEDs: indicate location of radiation alarm (see front panel
drawing in front of manual for LED layout).
Status LEDs (side of portal): (see front panel drawing in front of manual
for LED layout).
Enter/Checking green LED: normally illuminated prior to any personnel
entry, indicating that the system is ready to take a count. It flashes to
indicate the system is checking for excess radiation. It stops flashing at
the end of the count time in stop-and-count mode or whenever the user
leaves the portal in walk-through mode.
Incomplete/Updating yellow LED: indicates that a count was in progress
and the subject stepped out of the portal before the count was complete.
The INCOMPLETE LED stays on for the incomplete time or until the
subject steps back into the portal. An INCOMPLETE resets the count
time.
If no one steps back into the portal during the incomplete time, the portal
monitor goes back to the ready state, illuminating the ENTER LED.
This LED also indicates UPDATING background while flashing. Do
not enter or allow personnel within 1.8 m (6 ft) while the unit is updating
background.
Radiation Alarm red LED: indicates that the system has detected
radiation levels above background.
Instrument Failure red LED: indicates that the system has detected a
high- or low-background condition. If there is a background problem, the
UPDATING LED will also be illuminated.

Model52-1Family TechnicalManual Section4
Ludlum Measurements, Inc. Page 4-3 July 2018
Low Battery red LED: indicates the batteries are low and must be
replaced immediately.
AC Panel
Line Fuse: fuses to limit current from the AC outlet. The
fuses are Littlefuse F-1A or equivalent.
Input: line voltage input, 85-250 Vac, 50/60 Hz, 250 W
RS-232:RS-232 port so that instrument can be connected to
a printer or a computer
Batteries: instrument may be powered using three or six
each “D” cell batteries
Relay: 6-pin connector to connect internal relays
Relay pinouts:
P1 Alarm Normally Closed
P2 Alarm Common
P3 Alarm Normally Open
P4 Instrument Fail Normally Closed
P5 Instrument Fail Common
P6 Instrument Fail Normally Open
EXT Switch: 3-pin connector for an external activation
switch. External switch can be a passive push-button switch,
or can be an NPN-transistor output infrared sensor.
Parameters and Functions
This section lists the different parameters of these instruments and their
functions. To enter setup mode, press and hold the Increment (Up Arrow)
Button while turning ON the instrument at the switch under the control
box. This will allow the user to change the parameters.
Language: The language is set to English.
Month: adjustable from 1 to 12, which indicates the month.
Day: represented by one number, from 1 to 7.
Year: represented by two numbers.
Count Time: adjustable from 0 to 250 seconds, where 0 sets the portal in
the walk-through mode.